This is consistent with the 1996 IPCC GLs method where country -specific d ata are used, in section 1.7.2.4, Equation 5 and the text on page 1.111: "In most cases, if the Tier 2 approach is used to estimate methane emissions from surface mines, post -mining emissions from surface-mined coals are assumed to be zero." Furthermore, the UK approach is consistent with the general equation for estimating fugitive emissions from surface coal mining presented in section 4.1.4 of the 2006 GLs, as the UK EF comprises all methane in the coal produced that could be released at any stage post -mining. As a result, the UK estimate for open -cast coal mining activities is likely to be an over - estimate, as some methane will be retained within the coal up to the point of combustion, especially for lump coal used in domestic grates, where desorption of the methane is much slower than for fine coal processed for use in other sources such as power stations. The basis for this open -cast coal production factor also explains why the EF on methane from coal storage and transport (see paragraph above) is only

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 209 applied to the activity of deep -mined coal in the UK, rather than to the total UK coal production data; to apply it to open -cast production also would introduce a double - • Other In the UK energy balance, there is an additional line for coal prod uction which is for “other” sources of coal into the UK economy, which are typically very small numbers (95 kt in 2013 and zero since 2014) and represent coal obtained from slurries, ponds and rivers. We therefore include the activity data for "other" sour ces of coal within the UK energy balance, as part of the overall supply of coal as reported in the production source, as it is not coal that has been abstracted from open -cast or deep • Decline in emissions from deep -mined coal . The 96% reduction in emissions reported in 1B1a1i since 2015, is fully consistent with the almost complete closure of UK deep-mined coal production. Between 2018 and 2019, deep mined coal production increased from 24kt to 99kt as the Aberpergwm Colliery started up production again There have been no recalculations to data for 1B1a1i. No improvements to this method are currently planned. Emission factors and activity data are kept under review. As the UK deep-mined coal market continues to undergo restructuring and closures due to economic constraints, we anticipate that the number of mines that will remain operating and reporting may continue to reduce and therefore the data availability and method options may be further impacted. Activity data for coal production in deep -mined and open -cast mines in the UK are quality - checked through comparison of data reported within DUKES and data reported directly by the UK Coal Authority, which provides regional and UK totals of coal production. The information provided directly by colliery operators regarding their methane recovery systems are also checked against the data published by BEIS on coal mine methane projects in the UK (which encompasses both operating and closed / abandoned mines with coal mine methane recovery The factors for coal mining are all based on UK industry research. Emission factors from coal storage and transport, licensed mines and from open-cast mines do not vary through the time series; in each case the same factor is applied to the UK activity in every year. For deep-mined coal emissions there is a variable emission factor across the time series, derived from operator reporting and reflecting the changing methane management practices within UK collieries, especially to increase methane capture and oxidation for power -raising in recent years, leading to a gradually declining methane emission factor per unit coal produced since the early 2000s. The variability in the factor also reflects the changes in production from different mines that have different methane management practices, as for some UK collieries the capture and use of methane has not proved cost -effective and therefore the technology is not uniformly implemented. The variability of the time series of emission factors represents changes in UK coal mining, and not time series consistency issues. As described in the methodology section above, the latest years of reporting (since 2015) the Inventory Agency has extrapolated the latest EFs from 2014 in order to maintain time-series consistency of the method, in light of the

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 210 decline in the industry and the cessation of any operator -reported data on methan e elution, utilisation (in gas engines) and emissions to atmosphere. The uncertainty in the coal production statistics is low, since these are based on national statistics. The emission factors applied are country specific, and in some cases based on mine specific data, and therefore the uncertainty is lower than using default literature values. Additional uncertainty is introduced through the application of emission factors based on a sub-set of mines to represent full UK coal production, but we note that the total UK deep mined production where a methane elution factor is applied based on data from other sites is typically smaller sites that together produce (for many years in the time series) only around 10% of UK coal. However, we also note that the proportion of UK production at non-reporting deep mines has grown due to recent closures to 28%, 22% and 15% in 2013, 2014, and 2015 respectively and now 100% in 2016 to 2021. Therefore the overall uncertainty of deep-mined coal methane emissions is higher for these years, but it this is set against the context that deep mined coal emissions only account for less than 0.06% of total methane emissions in the UK in 2021, whilst open-cast coal mining only accounts for 0.02% of total UK methane emissions.
Relevant Categories, source names Modelled emissions of releases of residual methane within coal seams from abandoned coal mines, including from the flooding of mine seams following closure. Methane emissions from closed coal mines are accounted for within category 1B1a1iii of the UK inventory. Emission estimates are based on a study funded by DECC (WSP, 2011) which updated research from 2005 (White Young Green, 2005) • reflect the UK trend in mine closures and re-openings driven by fluctuations in energy prices since the 2005 research; and • improve the representation of methane recovery and utilisation at closed collieries (Colliery methane combustion emissions are reported in the energy sector, 1A). Methane emissions from closed mines reach the surface through many possible flow vents, ol d mine entries, diffuse emission through fractured and permeable strata. Direct measurement of the total quantity of gas released from abandoned mines is not practical. Data for 32 mines closed between 1990 and 2015, and 121 mines closed before 1990 are included in the model. The model also includes projections, which can be changed to account for mine closures occurring earlier or later than predicted. Note that all major UK deep coal mines were closed by the end of 2015, leaving a very small number of operating small mines. The abandoned mines model was updated to reflect this for the 2017 submission, and there has been no further update to the model in the 2023 submission. Methane utilisation has increased significantly across the time-series, up to a maximum of 94% in 2004. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 211 WSP, 2011 and White Young Green, 2005 An accompanying spreadsheet “Energy_background_data_uk_2023.xlsx” lists all emission information for common activity data sources. The UK model was developed in 2005 (White Young Green, 2005) and revised in 2011 (WSP, 2011). The 2011 study used the same method, updating data for mine closures during 2005- The model generates both historic and projected methane emission estimates from closed UK coal mines, combining two separate sets of calculations to estimate emissions • coal mines that were closed before 2005 and included in the 2005 update; and • mines that were not included in the 2005 update, including mines closing or predicted to close between 2004 and 2028. The model uses a relationship between emissions and the quantity of the underlying methane gas within the abandoned mine workings, including site -specific considerations of the most appropriate decay model for the recently closed mines. The model calculates methane reserves for all UK coalfields that are not totally flooded from 1990 with projections to 2050. The gas reserves are calculated by totalling all the gas quantities in individual coal seams likely to have been disturbed by mining activity. To enable calculation of the reserves over time, the rise in water levels in the abandoned mines due to water inflow has been calculated based on industry consultation, with a date estimated for each of the mines to be fully flooded; as mine workings become flooded they cease to release significant amounts of methane to the surface. The development of the model has drawn on industry monitoring to measure methane emission from vents and more diffus e sources, including measurement of the flow rate and methane concentrations of vented mine gases. The industry knowledge of these methane sources has increased greatly in the UK over the last 10 years as the technology to capture and utilise the methane f or power generation has developed alongside new economic incentives to utilise the mine methane in this way. Monitoring of more diffuse sources involves the collection of long-term gas samples to measure any increases in background atmospheric methane level in the locality. Methane flows measured by both methods showed a general increase with the size of the underlying gas reserve. The data indicate an emission of 0.74% of the reserve per year as a suitable factor to apply to the methane reserve data in ord er to derive methane emission estimates for abandoned UK coalfields for 1990 to 2050, and this factor is applied within the model to derive the UK emission estimates. Estimates have been made for both deep-mined and open-cast coal. WSP (2011) derived estimates for historic methane emissions from closed coal mines and also generated projections to 2050, based on forecasts for UK coal mining activity and industry information on the quantity of underlying methane gas and expected rates of flooding of each mine following closure. The 2021 emission estimates in the 2023 UK GHGI submission were therefore taken from the projections of emissions within the 2011 WSP report, with the emission profiles through time for all major UK deep mines recently closed (i.e. since the study

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 212 in 2011) brought forward to the actual date of closure, as all such mines were closed by the end of 2015. Each large deep mine within the model has a profile of projected flooding and emissions of methane upon closure; the closure dates in the model have now been fixed to the actual dates rather than projected dates, and the emissions of methane following closure are therefore now occurring for every deep mine, and will diminish over time. Following the rapid decline of the UK deep -mined coal industry, this source is now the most significant emission source in 1B1, and accounts for 0.8% of total UK methane emissions in 2021. The emissions from all abandoned mines are included within the 1B1a1iii source category. All large deep mines in the UK have now closed, and therefore this source category will decline in significance in future years. There were no recalculations or method changes to the closed coal mines source category in this submission.
All remaining large deep coal mines closed by the end of 2015, and the model was modified to reflect the closures in deriving estimates for the 2017 submission; no further updates to the model have been made for subsequent submissions, as the modelled futu re profile of emissions across the sector is unchanged. Improvements (completed and planned) No improvements to this method are currently planned. The model is periodically reviewed and updated. However, as all large deep mines in the UK that contribute si gnificantly to this emission source are now closed, the emissions trend is diminishing through time and in 2021 only accounts for 0.8% of the UK methane inventory total, this source is considered a low priority for future improvement work. This source category is covered by the general QA/QC of the greenhouse gas inventory in Section 1.6. WSP (2011) was subject to review by a steering committee, and final sign off by DECC. The research also includes benchmarking of UK specific estimates with other inventories to ensure that the method used remains appropriate for the UK. No time-series consistency issues have been identified. The uncertainty in the emissions from this source was assessed as part of WSP (2011). The uncertainty assessment indicated a range of ±17% to ±41% over the period 1990-2050. This level of uncertainty is in line with IPCC guidance on Tier 2 and Tier 3 methodologies. This considered the uncertainty in the future mine closure dates, gas reserve estimates, the annual methane emissions rate as % of gas reserve, the open cast mine methane emissions factor and the methane utilisation factor. MS 18 1B2 Oil refining, storage and distribution (1B2aiv to v) and natural gas distribution (1B2biii to v) Relevant Categories, source names 1B2a1: Onshore, offshore oil well exploration; Oil offshore well testing 1B2a2: Upstream oil fugitive s, direct processes; Onshore oil production (conventional); Oil other fugitives, direct processes

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 213 1B2a3: Upstream oil onshore, offshore oil loading; Oil transport pipelines, 1B2a6: Abandoned oil onshore, offshore 1B2b1: Unconventional gas well exploration; Onshore, offshore gas well exploration; Gas offshore well testing 1B2b2: Onshore natural gas production (conventional); Onshore natural gas gathering 1B2b3: Upstream gas fugitives, direct processes; Gas other fugitives, 1B2b6: Abandoned gas onshore, offshore 1B2c1i: Upstream oil venting; Oil venting 1B2c1ii: Upstream gas venting; Gas venting 1B2c2i: Upstream oil flaring; Oil flaring 1B2c2ii: Upstream gas flaring; Gas flaring All fugitive releases from oil and gas production, excluding leakage from gas transmission and distribution. Distribution of oil products is not descri bed since there are no direct GHG The activity data for well exploration and also for wells abandoned are the number of wells (drilled or abandoned, accordingly) per year. The activity data for well testing is the mass of flared gas arising from the well tests, whilst the activity data for all other gas flaring is also the mass of gas flared. The activity for the oil transport source categories is the annual mass of crude oil transported The activity data for source categ ories in 1B2b2 is the annual volume of natural gas For other source categories the methods are based on the sum of reported emissions and there are no associated activity data. These source categories across 1B2 cover fugitive emissions arising from the exploration, production, transportation, processing and storage of liquid and gaseous fuels. It excludes fuel combustion emissions associated with upstream oil and gas exploration and production which are reported within 1A1cii Oil and Gas Extraction, the method for which is presented in MS2. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 214 The UK has been producing oil and gas, predominantly offshore in the North Sea, for decades, and there are several hundred oil and gas platforms that have been operating across the time series. Oil and gas exploration activities (well drilling, completions, well testing) lead to fugitive and flaring emissions; similarly at the end of the production life of each well there may be emissions from abandoned wells, whether they are plugged or not, and from purging of infrastructure during decommissioning. Process treatments (e.g. acid gas treatment) and fugitive releases give rise to GHG emissions during the production phase at offshore facilities and in subsequent material processing at onshore terminals to prepare oil and gas products [Emissions from leakage during gas transmission and distribution, and the point of use are Offshore oil and gas is transported to onshore terminals via pipelines and marine tankers; emissions of CH 4 and NMVOC occur during loading of oil into the ship's tanks and the subsequent the unloading. This includes when onshore storage tanks. Emissions of CH4 and NMVOC also occur from storage tanks at oil terminals. There are also a small number of onshore oil and gas wells in the UK. This is a very small component of the upstream sector. Fugitive emissions do arise from well drilling, the production of oil and gas, flaring of waste gases, from well abandonment and fr om the transfers of oil product to rail and road tankers for deliver to oil terminals and refineries. Shale gas reserves have been identified and some preliminary testing to explore the prospects for shale gas production has occurred during the inventory time series, but there is no active exploration or production of shale gas currently in the UK. Activity EEMS (BEIS OPRED, 202 2), DUKES (BEIS, 2022a), IED/PRTR- reported data (EA, NRW and SEPA, 2022) UK ETS data (BEIS, 2022b), UKOOA (2005), UKPIA ( 2022), PPRS data ( BEIS, 2022c), DTI Brown Book (DTI, 2004), WONS data (NSTA, 2022). Emission EEMS (BEIS OPRED, 2022), UK ETS (BEIS, 2022b), UKOOA (2005), IPCC 2006 Guidelines (IPCC, 2006), 2019 Refinement to the 2006 GLs An accompanying spreadsheet “Energy_background_data_uk_202 3.xlsx” lists all emission information for common activity data sources.
The Inventory Agency has researched and analysed all available activity and emissions data for the UK upstream oil and gas sector across the time series during a recent inventory improvement project (Thistlethwaite et al, 2022). The inventory methods for sources across 1B2 dr aw upon the best available data from the sector, through a range of reporting mechanisms that have been developed by UK regulatory agencies across the time series. A more detailed summary of the oil and gas sector improvement project is presented in Annex 3.1.6. The methods developed impact both fuel combustion emissions reported in 1A1cii (see MS 2) and all upstream oil and gas fugitive emission sources reported in 1B2. 65 This can be found as one of the additional documents to the NIR Note that there can be a delay between the NIR being published on the NAEI website after official submission. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 215 An overview of the data sources and methods used to derive estimates for the categories included in this MS is below, with further details presented in Annex 3.1.6. Note that in the UK there are different regulatory mechanisms that govern the activities (i) offshore oil & gas exploration and production, (ii) onshore conventional oil & gas exploration and production, and (iii) onshore unconventional shale gas exploration (of which, there is no current production). These different re gulatory systems dictate data availability for upstream oil and gas activities, which impacts on the best available method for each sector of the inventory; for example, the data available for offshore rigs is more detailed (source -specific) than for onshore terminals (where only some resolution of emissions by source is feasible). It is important to note however that despite these different methods and data availability, the UK Inventory Agency does report in a time series consistent manner for each source, and that the UK inventory is complete for all emission sources, with the exception that there are no data available currently to estimate emissions from oil and gas well blowouts other than for the 2012 blow-out at the Elgin platform, as outlined below. 1B2a1 Oil Exploration Onshore wells, all IPCC Tier 1 (2019 Refinement) method. Emission = #wells drilled x IPCC default EF (per conventional oil well) Offshore well testing, 1990-1997: UKOOA 2005 (Tier 2). Assumptions to derive time series using well drilling time series. Offshore well testing, 1998 – Latest year : ∑operator emissions per facility, bas ed on EEMS (BEIS OPRED, 2022 ), which includes well testing emissions per facility, per year. Tier 2/3 as EFs are from EEMS 1B2a2 Oil Production Onshore oil Hybrid Tier 2 method. ∑ Large + small sites. Larger sites, Emissions = ∑operator emissions per wellsite (EA, 2022) Smaller sites, Emissions = Production AD (PPRS) x EF derived from larger sites, IEF from (PI emissions / PPRS production data) Offshore oil production, 1990-1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends; residual category for CH4. Offshore oil production, 1998 - Latest ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022). Tier 3 as emissions for process emissions are derived from operator reporting; fugitives derived Oil terminals, 1990-1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends; residual category for CH4. Oil terminals, 1998 - Latest year : ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022) and PI, SPRI (EA, SEPA, 2022). Tier 3 as process emissions are based on operator reporting; fugitives derived from EEMS guidance EFs. 2011 - only RI data, so estimates modelled on previous years share of RI total; source is also used to report 1B2a3 Oil Transport Offshore oil loading, all IPCC Tier 1 (2019 Refinement). UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 216 Emission = OTL production (PPRS/BB) x IPCC default EF ( assumes no Onshore oil loading, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends. Onshore oil loading, 1998-latest ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022) and PI/SPRI (EA, SEPA, 2022). Tier 2/3 as emissions for oil loading are derived from operator reporting and use of EEMS guidance EF s (CS). 2011- only RI data, so estimates modelled on previous years share of RI total; Seal Sands data from Onshore oil transport (pipelines), all years : IPCC Tier 1 (2019 Refinement). Emission = Wytch Farm production (PPRS/BB) x IPC C Onshore oil transport (road/rail), all years : IPCC Tier 1 (2019 Refinement). Emission = Onshore production less Wytch Farm Oil terminal storage, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends. Oil terminal storage, 1998 – latest year : ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022) and PI/SPRI (EA, SEPA, 2022). Tier 2/3 as emissions for oil storage are der ived from operator reporting and use of EEMS guidance EFs (CS). 2011 - only RI data, so estimates modelled on previous years share of RI total. 1B2a6 Oil - Other Oil wells abandoned, all IPCC Tier 1 (2019 Refinement) method. Emission = #wells abando ned per year (cumulative) x IPCC default EF (per well abandoned where it is unknown if plugged or not) The AD are taken from the NSTA wellbore database search facility. The AD comprise all historic oil and gas wells, so the estimates include IPCC Refinement states that leaks from abandoned offshore wells are assumed to be 2% of those onshore, as 98% of the gases are dissolved in the water column. This assumption is applied in the method for Onshore conventional gas wells, all IE, reported within 1B2a1, as there are no AD specific to gas wells drilled, only oil and gas Onshore unconventional gas well drilling : Activity only evident in 2011, 2012, 2014, 2018 and 2019. ∑operator emissions per facility, based on operator and regulator information. Offshore well testing, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on #wells drilled per year, from NSTA.
Offshore well testing, 1998 – Latest year : ∑operator emissi ons per facility, based on EEMS (BEIS OPRED, 2022 ), which includes well testing emissions per facility, per year. Tier 2/3 as EFs are from EEMS

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 217 Onshore gas production, all years : IPCC Tier 1 (2019 Refin ement) Emission = natural gas produced (Mm 3) x IPCC default EF (for onshore activities with higher-emitting technologies and practices) Onshore gas gathering, all years : IPCC Tier 1 (2019 Refinement) Emission = natural gas produced (Mm 3) x IPCC default EF (for onshore activities with higher-emitting technologies and practices) Offshore gas production, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on natural gas production trends; installation -level direct process emissions from key sites (i.e. Elgin, Rough) based on their gas production trends. Residual category for CH4 and NMVOC. Offshore gas production, 1998- Latest ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022 ). Tier 3 as process emissions are based on operator reporting; fugitives derived from EEMS guidance EFs. Also includes one -off estimate of emissions from Elgin blow-out, 2012, based on Lee et al publication from aircraft monitoring of Gas terminals, 1990-1997: UKOOA 2005 (Tier 2). Time series based on natural gas production trends; installation -level estimates of process emissions from key sites (i.e. SAGE, CATS) based on ga s throughput. Gas terminals, 1998 - Latest year : ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022) and PI/SPRI (EA, SEPA, 2022). Tier 3 as process emissions are based on operator reporting; fugitives derived from EEMS guidance EFs. 2011 - only RI data, so estimates modelled on previous years share of RI total. Gas terminal storage, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on natural gas production trends. Gas terminal storage, 1998 – latest year : ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022) and PI/SPRI (EA, SEPA, 2022). Tier 2/3 as emissions for gas storage are d erived from operator monitoring and use of EEMS guidance EFs (CS). 2011- only RI data, so estimates modelled on previous years share of RI total. Gas wells abandoned, all years : Included Elsewhere. Reported within 1B2a6, as there are no AD specific to gas wells abandoned, only oil and Offshore oil venting, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends. Offshore oil venting, 1998 - Latest y ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022). Tier 3: venting emissions are based on operator monitoring. Oil terminals venting, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 218 Oil terminals vent ing, 1998 - Latest year : ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022) and PI/SPRI (EA, SEPA, 2022). Tier 3: venting emissions are based on operator monitoring. 2011- only RI data, so estimates modelled on previous years share of RI total. Offshore gas venting, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on natural gas production trends. Offshore gas venting, 1998 - Latest year : ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022). Tier 3: venting emissions are based on operator monitoring. Gas terminals venting, 1990-1997: UKOOA 2005 (Tier 2). Time series based on natural gas production trends. Gas terminals vent ing, 1998 - Latest year : ∑operator emissions per facility, based on EEMS (BEIS OPRED, 2022) and PI/SPRI (EA, SEPA, 2022). Tier 3: venting emissions are based on operator monitoring. 2011- only RI data, so estimates modelled on previous years share of RI total. Offshore oil flaring, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends. Offshore oil flaring, 1998- Latest ∑operator emissions per facility, based on UK ETS (BEIS, 2022b), EEMS (BEIS OPRED, 2022). Tier 3: flaring emissions are based on operator reporting. CEFs from flare gas sampling, analysis, 98% oxidation factor. Oil terminals flaring, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on crude oil production trends. Oil term inals flaring, 1998 - Latest year : ∑operator emissions per facility, based on UK ETS (BEIS, 2022b), EEMS (BEIS OPRED, 2022). Tier 3: flaring emissions are based on operator reporting. CEFs from flare gas sampling, analysis, 98% oxidation factor. Offshore gas flaring, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on natural gas production trends. Offshore gas flaring, 1998 - Latest year : ∑operator emissions per facility, based on UK ETS (BEIS, 2022b), EEMS (BEIS OPRED, 2022). Tier 3: flaring emissions are based on operator reporting. CEFs from flare gas sampling, analysis, 98% oxidation factor. Gas terminals flaring, 1990 -1997: UKOOA 2005 (Tier 2). Time series based on natural gas production trends. Gas term inals flaring, 1998 - Latest year : ∑operator emissions per facility, based on UK ETS (BEIS, 2022b), EEMS (BEIS OPRED, 2022). Tier 3: flaring emissions are based on operator reporting. CEFs from flare gas sampling, analysis, 98% oxidation factor. [Where BB = DTI Brown Book “Development of the Oil and Gas Resources of the UK”] Key data sources for the 1B2 inventory methods • Oil and gas operators submit annual source -specific emission estimates to the Environmental and Emissions Reporting Syst em (EEMS) , regulated by BEIS Offshore Petroleum Regulator for Environment and Decommissioning (BEIS OPRED). UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 219 • Industry survey data from 1990 onwards were used to derive a time -series of sector estimates from 1990 to 2003, reported to UK Government studies b y the trade association (UKOOA, 2005).
Whilst the data resolution per source is limited in this dataset, it is the best available information to inform estimates prior to the EEMS • Well testing emissions estimates on an install ation-specific basis are also included within the EEMS datasets from 1998 onwards at all sites of offshore exploration activities within UK’s territorial waters, including data on both activity and emission factors of excess gas that is flared or released to the atmosphere. Emissions released at the seabed are not included in estimates; it is assumed that any such releases will dissolve in the water column without subsequent release to the atmosphere. • Onshore well drilling for oil and gas exploration leads to fugitive emissions. These are estimated using a Tier 1 method from the 2019 IPCC Refinement, with the number of wells drilled per year obtained from the North Sea Transition Authority’s Well Operations Notification System (WONS). Abandoned wells also r elease fugitive methane and NMVOC, and again a 2019 IPCC Refinement Tier 1 method is applied, using NSTA wellbore database information on the number of wells abandoned. • Annual reporting of emissions by pollutant aggregated across all emission sources under the IED/PRTR reporting system to the UK environmental regulatory agencies (i.e. EA, NRW, SEPA) are available for onshore sites only (i.e. including oil and gas terminals, but excluding all offshore oil and gas installations). These data are available from 1998 in England and Wales and for 2002 and 2004 onwards in Scotland and include emission estimates for a suite of GHG and air quality pollutants including CO2, CH4 and N2O. Whilst there is a high level of complete reporting from onshore oil and gas terminals, operators only report to these Regulatory Inventories (RIs) where the annual pollutant emission is above a reporting threshold; hence there is very little RI data reported by operators of onshore well sites in the UK, where emissions are low. • For 1995 to 2009, all terminals reported source -specific emission estimates to the EEMS system. For combustion and flaring sources, the EEMS dataset for this period includes mass-based activity data, and emission estimates for GHG and air quality pollutants. Since 2010 onshore terminals report voluntarily to EEMS, but the reporting is incomplete across UK terminals; reporting to EEMS was deemed a duplication of the reporting requirements under IED/PRTR and hence was no longer a mandatory duty on terminal oper ators. Hence from 2010 onwards the EEMS dataset is not a comprehensive record of emissions from onshore terminals. The UK GHGI estimates are based on the IED/PRTR data in conjunction with UK ETS data, which provides emissions of CO2 from combustion and flaring sources. • Under the Energy Act and Petroleum Act, upstream oil and gas operators are mandated to report on their economic activities to the North Sea Transition Authority (NSTA). Whilst these data are not specific to environmental reporting, they do provide a full time series of useful activity data such as UK oil production and gas production; detailed data per oil and gas field are now reported via the Petroleum Producers Reporting System (PPRS), which began in 2000. Prior to PPRS, the same data were published in annual statistical releases such as the historic DTI publication “ The Development of the Oil and Gas Resources of the UK” , known as the Brown Book, which ceased to be published in 2004. Together these resources provide a full, time - series consistent dataset on activity for the sector, as well as a wealth of installation - level detail. They are used in inventory method development primarily to support the use of IPCC good practice gap -filling techniques, as they provide a useful proxy dataset of activity to help address reporting gaps per source, per installation and/or at

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 220 • The Inventory Agency continues to investigate ways in which methane and NMVOC emissions from oil and gas well blow outs can be estimated, although there is no IPCC methodology for such events, and only limited data are available in the UK with which to estimate emissions. The Inventory Agency has researched the UK Health and Safety Executive (HSE) hydrocarbon release database, and there is only one major blow-out event recorded by upstream operators and reported to the HSE across the time series, which was the Elgin blow-out of 25th March to 16th May 2012. In this case, the Inventory Agency has estimated the total methane and NMVOC released by the blowout and added it to the fugitive emission estimates for the year 2012. The UK emission estimate is based on reported daily methane flow-rate observations taken on 5 days during the blow-out period (30th March, 3rd April, 17th April, 24th April and 4th May 2012). Thes e estimated flow rates of methane are derived from air sampling and analysis by research aircraft flights, as reported by Lee et al. (2018)66.The Inventory Agency will continue to research data from UK academic and industry researchers, regulators and operators, in order to develop emission estimates for any similar historic • All UK onshore production to date is from conventional oil and gas wells. These installations are all regulated under the IED/PRTR by UK environmental regulators (EA, SEPA) and the operators report on annual methane emissions and these estimates are aggregated and included within the UK GHGI under 1B2a2. However, the Inventory Agency has sought to estimate methane emissions from onshore shale gas exploration activities, though t o date there has been no production of natural gas from unconventional shale gas resources in the UK. Since 2010 there have been twelve shale gas wells spudded in the UK. None of these sites are actively producing gas and none of the shale gas sites are yet under IED/PRTR regulation by the EA or SEPA, and there are no annual reported emission estimates by operators from their initial well spudding and completion activities.
Also, as there has been no production of natural gas at any of these sites, there is no activity data available to chapter of the IPCC 2006 Guidelines. Therefore the Inventory Agency has consulted with the regulatory agencies ( NSTA, EA) and obtained one -off reports, where available, from each unconventional gas well site. o The EA has confirmed that 12 wells were spudded during the period of August 2010 to January 2019 in England and that no extraction of products has occurred. It has been confirmed with the Regulator that all shale wells are now abandoned, and permits surren dered or suspended, with no foreseeable exploration and production activity67. o One report to the EA provides methane emission estimates during a nitrogen gas lift operation at one of the larger shale gas well sites; review of the other sites identified that several wells did not strike any hydrocarbon deposits. o Based on the limited data available, a conservative estimate of emissions for methane from the well exploration activities has been made and added to the UK GHGI; methane emissions are estimated to p eak at 60t CH 4 in 2010 and 2011, with well drilling emissions in 2014 of 20t CH4, and 25t CH4 in 2019. o Further information can be made available to an ERT, to access the NAEI research report which contains commercial in confidence details on a site -by- site basis (Thistlethwaite, Gorji and Passant, 2021). 66 Atmos. Meas. Tech., 11, 1725-1739, 2018. 67 Personal communication with the Environment Agency, March 2021

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 221 The source resolution in the UKOOA 2005 data reference is limited across the 1990 -1997 period, and a series of proxy datasets have been used to derive time -series estimates per source back to 1990. These are described in more detail in Annex 3.1.6. The resolution of data by source type within the EEMS dataset is such that fugitive emission sources are typically reported aggregated for each installation, without any further information on the specific source/unit. Further, the emissions reported from gas terminals are aggregated across all sources under the IED/PRTR reporting system. These national circumstances of data availability mean that the UK inventory data cannot be disaggregated to separate fugitive emissions from gas processing units, from other fugitives, such as tie -ins to transmission systems, acid gas removal units, other connectors, flanges and pipeline infrastructure. Hence the emissions from all of these sources are reported together under 1B2biii. The 2019 Refinement method has been applied as the better resolution of fugitive EFs in the 2019 Refinement enables the UK to address the emissions from the onshore gas production and gathering sector . UK production is a v ery small part of the upstream industry and predominantly takes place at small gas well sites that do not typically report emissions (e.g. of hydrocarbons) to UK regulatory mechanisms (e.g. to the Pollution Inventory of the Environment Agency). Therefore a pplying the 2019 Refinement method to the total UK onshore gas production AD ensures that the inventory is complete. Implementing mitigation practices / technologies is unlikely to be cost -effective at small gas well sites and so the Inventory Agency has applied the 2019 Refinement EFs for "activities occurring with higher - emitting technologies and practices". Noting that the 2019 Refinement is based on latest scientific research, this is considered to be the most representative approach to estimating UK We note that the emissions reported in 1B2b3 (natural gas processing) do not include any pollutant emissions that are also reported in 1B2b2, i.e. there is no double -counting of emissions. The 1B2b2 emissions are all associated with onshore production at well sites and the associated gathering systems. The 1B2b3 emissions are based on separate data streams of production and treatment at (i) offshore dry gas and associated gas platforms/FPSOs, and (ii) UK onshore gas terminals that process the gas from offshore sources and inject the gas to the National Transmission System. There have been minor recalculations to estimates in recent years with more significant recalculations due to the method improvement for the early part of the time series, as a result of the oil and gas improvement project. The most notable recalculations for CO2 and CH4 • 1B2a1 Upstream Oil Exploration Improvements (completed and planned) The oil and gas sector improvement project (Thistlethwaite et al , 2022) has assessed all available UK data to improve the quality of the UK GHGI submission across 1A1cii and 1B2, and is described in more detail in Annex 3.1.6. Emission factors and activity data remain under review. The Inventory Agency will maintain dialogue with regulators and industry experts in order to seek any new data on emissions from oil and gas well blowouts, and to follow -up on the reporting of well testing within the new EEMS system. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 222 The Inventory Agency will also maintain a watching brief on the development of the shale gas industry, in order to ensure that if the industry does start to produce gas in the UK, that the Inventory Agency will have access to information to allow emission estimates to be derived for The EEMS dataset quality system is managed by the regulatory agency (BEIS OPRED) and developed in conjunction with the trade association , Offshore Energies UK (OEUK ). EEMS uses an online reporting system with controls over data entry, together with guidance notes provided to operators to provide estimation methodology options and emission factors for specific processes. The IED/PRTR system is similar to EEMS, but regulated by the onshore environment agencies (EA, NRW, SEPA); it also has operator guidance on emission estimation and reporting, and a system of annual checks on data submitted by operators, by a Site Inspector / Process Engineer assigned by the regulator to manage the performance and compliance assessments for each installation. The data reported under IED/PRTR however are installation-wide, rather than source-specific.
The UK ETS dataset quality system is managed by the regulatory agency (BEIS OPRED). The reporting standards of the ETS currently operating in the UK are consistent with the EU ETS, with estimation methods that operators may use defined within their permit. The data are third party verified and submitted to the regulator. The Inventory Agency combines UK energy statistics, the EEMS data, UK ETS and IED/PRTR data to derive the oil and gas sector estimates, then conducts time series consistency checks using other sector activity data from PPRS and the Brown Book to identify and address any potential data reporting ga ps or outliers. Where the UK ETS or IED/PRTR data are inconsistent with the EEMS data, the Inventory Agency works with BEIS OPRED and facility operators to help determine the best available data for each source to ensure that the reported data are complete for each installation. The Inventory Agency also conducts time -series consistency checks to identify missing sites or sources, and for those sources where the EEMS data includes emissions and activity data the Inventory Agency reviews the time-series of implied emission factors to identify outliers. Any sites or sources where the quality checks identify gaps, outliers or inconsistent reporting between different regulatory systems are resolved in consultation with regulators and operators, as required. The emission estimates for the offshore industry are based predominantly on the EEMS dataset for 1998 onwards, whilst emission estimates for 1990-1997 are based on sector data submitted to UK Government (UKOOA, 2005). The method is com promised by the lack of source -specific data for the 1990 -1997 period, where only aggregate emissions data across all sources in 1A1cii and 1B2 are available from the industry submissions to UK Government; this coincides with a period where consultation with the BEIS energy statistics team has confirmed that that the UK energy statistics were not gathering complete data for all oil and gas terminals. Wherever possible the Inventory Agency has filled data gaps with operator -reported estimates and applied IPC C good practice gap - filling methods to ensure that the time series consistency is as good as practicable given the available data; this is possible as there are a defined number of installations that are active in this sector and their activities (and emissions) are generally well documented with gaps in data Further, the Inventory Agency has conducted time series consistency checks between the aggregated emissions reported in the 1990 -2003 data submission (UKOOA 2005) and the

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 223 installation-level EEMS and NAPs data (BEIS OPRED, 2022), across the overlap years of 1998 to 2003. This analysis shows close consistency, indicating that the scope of reporting in the UKOOA 2005 dataset is consistent with the later installation -level EEMS data. Further details are presented in Annex 3.1.6. We further note that whilst the emission estimates specific to fuel combustion in 1990 -1997 are uncertain, that the total emissions across all upstream oil and gas sources (∑1A1cii, 1B2) in the UK GHGI are aligned with the industry submission to UK Government (UKOOA, 2005) and hence are regarded as the most accurate data available. The EEMS dataset (BEIS OPRED, 2022) provides a consistent time -series of emission estimates for many facilities and sources, but si nce 2010 the reporting by onshore terminals is voluntary. Furthermore, whilst the EEMS data quality appears to be improving over recent years, the completeness of EEMS data for specific facilities and sources is still subject to uncertainty; reporting gaps appear to be systematic for some facilities, such as frequent non- reporting of oil loading / unloading emissions at some terminals. For this reason, the Inventory Agency has moved away from using EEMS data for the estimates of oil loading, and instead uses the PPRS activity data on oil production at OTLs, in conjunction with industry EFs, as this method delivers a more complete and time series consistent estimate. The Inventory Agency continues to work with the regulatory agency, BEIS, in the continued development of emission estimates from this sector. Uncertainties for both activity and emission factors are based on expert judgement, informed by the understanding of the available data, the level of uncertainty that is accepted within the reporting systems (e.g. UK ETS) and the likelihood of error compen sation across the UK The uncertainty analysis set out in Annex 2 provides details of these uncertainty values. Emissions data taken from the EEMS reporting system 1998 onwards are considered to be high quality, emissions data for other year s are subject to greater uncertainties . A s noted above, while the uncertainty per source may be high due to the limited source resolution in the UKOOA 2005 dataset, the overall uncertainty in the sum of emissions across 1A1cii and 1B2 is much lower and is based on the best available data for that period. Relevant Categories, source names 1B2b4: Natural Gas (transmission leakage) 1B2b5: Natural Gas (distribution leakage) Natural Gas (leakage at point of use) Leakage from gas transmission and distribution, leakage at the point of use

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 224 The UK GHG inventory includes estimates of methane and carbon dioxide emissions from natural gas leakage from the downstream gas supply networ k, including releases high pressure transmission network; distribution network; gas leaks at point of use. Annual activity data and gas compositional analysis are provided by National Grid, four companies (formed in 2005) that operate the low-pressure gas distribution networks within Great Britain, and three gas suppliers in Northern Ireland. Activity Natural gas leakage data in energy and mass units, from the UK downstream natural gas network National Grid, Cadent Ga s, SGN, Northern Gas Networks, Wales & West, and Phoenix Gas and AD for gas use in domestic and commercial sectors from DUKES (BEIS, 2022a) are used to generate leakage at point of use estimates.
Emission Natural gas compositional d ata (mass % data nitrogen, carbon dioxide, methane, ethane, propane, i -butane, n-butane, neo-pentane, i- pentane, n -pentane, hexanes+) supplied by the GB gas network operators as listed above. UK estimates of natural gas consumption within each Local D istribution Zone (LDZ) are used to generate a weighted-average UK compositional analysis of natural gas consumed annually. From 2007 these data are available from Long Term Development Plans published by each of the gas network operators; earlier data by L DZ are based on Local Authority -level consumption estimates aggregated into LDZs (CLARE database, 2012). EFs for the gas leakage at point of use are derived from UK data on gas fitting performance and assumptions regarding unit operational cycles, An accompanying spreadsheet “Energy_background_data_uk_2023.xlsx” lists all emission factors used in the energy sector, including a full list of references49. The leakage estimates are calculated using separate methodologies to 1. Natural gas leaks from the high -pressure transmission mains (National Grid Gas); (reported under 1B2b4 Transmission) 2. Natural gas leaks from the low pressure distribution network, medium pressure gas mains, Above Ground Installations (AGIs), AGI working losses and interference (Cadent Gas, SGN, Northern Gas Networks, Wales & West, Phoenix Gas, Firmus Energy); (Reported under 1B2b5 Distribution) 3. Other losses of natural gas at the point of use (BEIS DUKES, UK research); (Reported For methods 1 and 2 above, from 2004 onwards the gas network operators provide annual gas leakage estimates on a mass basis, providing a breakdown of emissions across all 14 regional gas networks in the UK, which are called Local Distribution Zones (LDZs). National Grid Gas operates the high-pressure natural gas transmission network; Cadent Gas operates 5 of the LDZs; Northern Gas Networks operates 2 LDZs; SGN operates 3 LDZs; Wales and West Utilities operates 3 LDZs; Phoenix Gas, SGN and Firmus Energy toge ther supply gas within the Northern Ireland network. In addition, each of the gas network operators provides

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 225 annual natural gas compositional analysis for their networks. Prior to 2004, the data on gas leakage (activity data and compositional analysis) was all provided by British Gas, which operated all of the UK networks before the industry was privatised. The information on methane losses from the high pressure transmission system (1B2b4) are estimated by National Grid (NG) based on (i) periodic fugitive emission surveys for the National Transmission System (NTS), compressor stations and LNG terminals, (ii) NG records of intentional venting actions on the network, (iii) estimation of fugitive emissions from AGIs using Marcogaz model and (iv) estimation of emissions as the result of incomplete combustion using compressor station turbine specification and site running hours. These data have not been available for every year across the time -series, with only two data points in the 1990s, annual data from 2000 -2004, and for 2011 -2021, with data for other years estimated using interpolation (2005-2010) and extrapolation (early time-series). The UK GHG inventory estimates for 1B2b5 (distribution leakage) are based on the aggregate of mass of gas leaked across all networks (low pressure mains and other losses), with the methane content of the natural gas based on compositional analysis from all of the gas The activity data reported in the CRF for these sources are the final UK annual gas demand data. These data are not used within the GHG inventory estimation method, but are presented to enable IEFs to be derived, to aid comparability of the UK estimates with those of other The UK gas network operators use a common industry leakage model to derive their annual estimates of gas leakage from the low and medium pressure distribution systems. The UK gas network leakage model was developed by British Gas and uses factors and assumptions on leakage rates for different types of gas mains and installations, based on measurements and surveys conducted in 1992 and 2002, with annual updates to maintain the representation of the UK gas network infrastructure (such as length and type of pipelines and other units) and reflect the rolling programme of network replacement. Historical data for the leakage from the low-pressure distribution network and other losses is based on studies from British Gas in the early 1990s (British Gas, 1993; Williams, 1993). Natural Gas Compositional Data Data on the methane and NMVOC content of natural gas have been provided by contacts within British Gas Research for 1990-1996 and by UK Transco from 1997 to 2005 (Personal Dave Lander, 2008), and from the gas network operators from 2006 onwards. NMVOC content for 2001-2003 has been estimated by interpolation due to a lack of data; CO2 compositional data from 2004 onwards are derived from annual compositional analysis by gas network operators, whilst the 1990 -2003 data have been extr apolated back from the 2004 Each of the gas network operators obtain their compositional analysis from a central system of data logging from the automated sampling and analysis network that was operated previously under the Transco ownership, prio r to the network being opened up to greater The calculation of the reported Great Britain (GB) average gas composition is derived from the sum -product of the annual Local Distribution Zone (LDZ) compositional data and the estimated gas consumption through each of the LDZs. No gas composition data have been provided by any operator in Northern Ireland, and in the absence of data, the average composition of the gas available in GB’s network is assumed to be applicable in Northern Ireland.
The estimates of gas consumption within each LDZ are based, from 2007 onwards,

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 226 on LDZ throughput data presented within Long Term Development Statements by each of the gas network operators; prior to 2007 these data are unavailable, and the best available data to inform the UK weighted average composition are sub -national gas use statistics at local authority level (then aggregated to LDZs) which are published by BEIS annually and processed for UK Local Authority CO2 emission estimates via the CLARE database. The gas infrastructure in Northern Ireland is much newer than in the rest of the UK, as the gas pipeline (from Scotland) was only commissioned in 1999. Since then, the gas network has continued to develop across Northern Ir eland. Annual estimates of gas leakage from 2005 onwards have been provided by the main gas operator (Phoenix Gas, 2022; SGN, 2022; Firmus Energy, 2022), and the data for 1999 to 2004 have been extrapolated back from the Gas Leakage at the Point of Use The third inventory estimation methodology is used to determine estimates of natural gas leakage at the point of use, and these estimates are also reported in 1B2b5. Leakages are estimated for a range of different appliances that use gas, combined with national statistics on natural gas consumption in the domestic and commercial sectors (BEIS, 2022). Methane releases are assumed to be “ Not Occurring ” from these appliances, based on consultation with technical experts tha t advise the UK Government for the CHP QA scheme (Personal R Stewart, 2011). Larger boilers typically operate almost permanently once ignited (particularly if used for steam -raising) with little or no cycling from on to off states. Furthermo re, releases of un -burnt natural gas are strictly controlled in industrial locations for safety reasons. Domestic Heating, Water Heating Boilers and cooking Methane emissions from pre-ignition losses of gas appliances domestic properties are based on activity data from Energy Consumption in the UK (BEIS, 2022) which provides a time-series of gas use for heating, water heating and cooking in the domestic sector, using a series of assumptions regarding the size of units, number of units, age of units, gas flow rates, air flow rates, delays to ignition, operation times from used to determine the percentage of gas that is not burned. The estimates of UK appliance stock, by capacity and design and estimated average gas consumption per appliance per day are all de rived from Ecodesign studies (energy efficiency analysis) through the UK Government Market Transformation Programme (Ecodesign Lot 22 and Lot 23, 2011). The estimates of appliance cycle operation times and estimated delays to ignition for different applian ces are based on expert judgement of UK combustion technology experts (Personal communication, Stewart, 2012). Commercial Gas Catering and other uses Methane emissions from pre -ignition losses of gas appliances used in commercial catering and other uses are based on activity data from ECUK (BEIS, 2022) which provides a time series of gas use for catering and other uses in the commercial sector to 2021. The method then applies a series of assumptions regarding the operational cycles and delays to ignition, to derive a simple percentage non -combusted estimate for each gas appliance type using references and expert judgements as noted above for domestic appliances. An overview of the time series of gas leak at point of use estimates in the UK, toget her with overall gas use by economic sector and appliance type is presented in Annex 3. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 227 Assumptions used to estimate the leakage at point of use for domestic heating and water heating boilers are as • average boiler size in the UK of 30kW; • a burn chamber size, natural gas flow rate taken from a typical combination boiler; • estimated delay to 0.25 seconds for automatic ignition, 2 seconds for manual • an air flow rate based on 25% excess oxygen in the combustion chamber when compared to stoichiometric ratio; • an equation for a mixed reactor (1-ex) that when integrated will provide an estimate of the concentration of un-burnt air/fuel mixture released; and • assumptions relating to the boiler yearly ope ration and cycling frequency, between heating and water heating applications o On average in the UK domestic properties have heating systems operating for half of the year and on average the heating is on for 5 hours per day. It is also assumed that during each hour that the boiler providing heating cycles on and o All UK domestic properties that have hot water heating systems also have gas o Average water heating is on for 4 hours per day every day of the year. o During each hour that a boiler is heating water, the boiler cycles on and off 5 The number of boilers across the time series is thought to have increased (ca. 22 million in 2008) due to the increasing use of gas central heating for space heating, and the increase in the number of houses. However, it is assumed that pre-ignition gas loss in boilers installed in houses in 1990 were greater than in the current boilers installed, as technology has improved. Therefore, it is assumed that the proportion of gas leaked (i.e. % of the total gas use) from domestic heating and water heating appliances per annum is steady across the time series, with the rationale that the sum of greater pre -ignition losses from fewer older -technology boilers in the early part of the time series will be roughly equivalent to the sum of lower pre ignition losses per unit from the greater number of newer-technology boilers in recent years.
Assumptions used to estimate the leakage at point of use for domestic cooking appliances (manual and automatic ignition) and gas fires are as • gas fires use an estimated 2.5% of total gas used for space heating in the domestic sector, with the remainder used in (automatic ignition) boilers; • gas use in cooking hobs is estimated to be 73.6% of the total dome stic gas use in cooking, with the remainder in gas ovens. This is based on data of average annual gas oven fuel use in kWh/yr and average domestic gas hob fuel use in kWh/yr, combined with data on UK stock of gas ovens and hobs, taken from a series of 2011 European Commission Eco-design studies (Bio IS / ERA Technology, 2011); • for manual ignition devices, a conservative estimate of the delay prior to ignition of 2 seconds has been assumed (expert judgement), whilst the average operational cycle times for di fferent types of appliance have been estimated at 900 seconds for a domestic hob (expert judgement) and 5400 seconds for a gas fire (EC Eco-design Lot 20 Task 5, gas stove base case, 2011); and • for automatic ignition appliances, a conservative estimate of the delay prior to ignition of 0.25 seconds has been assumed (expert judgement), whilst the average operational cycle times of domestic ovens has been estimated at 900 seconds (expert judgement). UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 228 Assumptions used to estimate the leakage at point of use for commercial gas appliances (catering and other uses) are as • for commercial catering gas use, a conservative estimate of the delay prior to ignition of 0.5 seconds has been assumed (expert judgement, to reflect a mixture of hobs and oven use), whilst the average operational cycle has been estimated at 900 seconds • for other commercial gas appliances, assumed to be predominantly gas -fired boilers of automatic ignition design, a conservative estimate of the delay prior to igniti on of 0.25 seconds has been assumed (expert judgement), whilst the average operational cycle time has been estimated at 1800 seconds (expert judgement). There are minor recalculations throughout the timeseries, reflecting revisions to the na tural gas net calorific values, updates to NTS leakage data due to the application of Marcogaz model, and some minor updates to the leakage data from the distributors. Improvements (completed and planned) An improvement project is currently planned to evaluate the evidence and consider potential improvements of methods for obtaining emissions as the result of leakage from the downstream low-pressure gas distribution networks. The sector estimates are subject to the same Tier 1 QA/QC routines as all ot her source Checks on data reported by gas network operators are conducted to check consistency across the time-series and also between operators. As recommended during the September 2014 centralised review of the UK inventory, the UK Inventory Agency has also conducted verification checks on the UK GHGI estimates, by deriving separate emission estimates for methane using the Tier 1 default methods outlined in both the 1996 GLs and the 2006 GLs. The method in the 1996 GLs uses max and min default factors based on the pipeline length of the transmission and distribution network, whilst the 2006 GLs Tier 1 method uses max and min default factors based on the total volume of delivered natural gas. The results are summarised below for 1990 and 2013 1990 UK GHGI total (transmission plus distribution) = 378.8 kt CH4 Using IPCC 1996 GLs Tier 1 method, the range for emissions is derived as 155 to 215 Using IPCC 2006 GLs Tier 1 method, the range for emissions is derived as 67 to 105 kt Therefore, compared to both Tier 1 methods, the 1990 UK GHGI estimate is higher than the 2013 UK GHGI total (transmission plus distribution) = 168.5 kt CH4 Using IPCC 1996 GLs Tier 1 method, the range for emissions is derived as 155 to 215 Using IPCC 2006 GLs Tier 1 method, the range for emissions is derived as 95 to 148 kt

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 229 Therefore, compared to the Tier 1 methods, the 2013 UK GHGI estimate is within the range of values for the 1996 GLs method and higher than the r ange of values for the 2006 GLs The comparison against the IPCC Tier 1 methods indicates that the UK GHGI estimates are of a similar order of magnitude as the Tier 1 defaults. The 1990 UK GHGI value appears to be high, as it is above the range of values derived from the IPCC Tier 1 methods, whilst the 2013 UK GHGI value is also higher than the range for the 2006 GLs Tier 1 method. However, the UK estimates are derived from a country -specific method and we note that the uncertainty estimates provided in the 2006 GLs for the default EFs provided for gas network distribution (which is by far the greatest contributor to overall methane leakage) are cited as -20 % to +500% for factors for developed countries. Therefore, given the large uncertainty range, the UK data are consistent with the IPCC Tier 1 estimates. As far as possible, consistent source data and methods are used across the time series. However, we note the following limitations of the current • The available data on methane leakage from the high pressure gas transmission system is limited. Data are not available for all years of the time series and therefore gap-filling techniques (extrapolation and interpolation) are used; • The calibration of the UK gas leakage model used by all natural gas network operators in based on two in -depth studies of the leakage rates from different constituent elements of the UK gas network – one in 1992, another in 2002.
These studies have been used to establish estimated leakage rates in the UK model that are then applied to activity data gathered annually through surveys and from gas network renewal • The derivation of the UK average natural gas composition uses the best available data for every year of the time series, as the factors are critical for the UK GHGI estimates as a whole (not just for the leakage estimates, but also for natural gas combustion estimates). Since 2007 the weighted average has been calculated using actual data available on gas throughout for each L DZ; prior to 2007 these data are not available and the LDZ gas throughput estimates used in the calculation of the UK average gas composition use Local Authority level gas use estimates, aggregated up to LDZs. These earlier data at Local Authority level we re regarded as “experimental statistics” by DECC until the 2005 dataset were published as national statistics, and as such are regarded as more uncertain than the more recent data. Uncertainties are presented in Annex 2. Uncertainties in the emission estimates from leakage from the gas transmission and distribution network stem predominantly from the assumptions within the industry model that derives mass leakage estimates based on input data such as network pipe replacement (plastic replacing old metal pipelines) and activities/incidents at Above Ground Installations; for these sources the methane content of the gas released is known to a high degree of accuracy, but the mass emitted is based on industry calculations. As noted in the section a bove, the uncertainties for the estimates of gas leakage at point of use are high due to the lack of source data, an IPCC method and the need to use a series of assumptions and expert judgement to estimate the leakage from different gas appliance types. The Inventory Agency considers that the assumptions provide a conservative estimate of gas leakage at point of use across the time series. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 230 MS 20 Other solid fuel transformation Relevant Categories, source names 1A1ci: Solid smokeless fuel production 1B1b: Solid smokeless fuel production Coke oven coke, petroleum coke, solid smokeless fuel production, charcoal production Solid smokeless fuels (SSF) are products which are designed to be suitable for use in smoke control areas. These are manufactured by combining products (often with low volatile content, such as anthracite or coke) using binding agents such as waxes and ref orming them into brickettes. Charcoal production and some SSF production involves processes similar to those DUKES (BEIS, 2022), FAOSTAT Forestry Production and Trade Statistics Emission Inventory Agency mass balance calculations, EIPPCB, 2000, IPCC, An accompanying spreadsheet “Energy_background_data_uk_2023.xlsx” lists all emission information for common activity data sources. Emissions of carbon from SSF production are based on a carbon balance approach. For other pollutants, estimates are either made based on a mass balance approach (for sulphur dioxide) There are a number of SSF production processes used in the UK ranging from processes similar to coking which convert coal into smokeless fuels, to briquetting of anthracite dust and other naturally smokeless fuels. Given the range of processes in use, emission estimates will be very uncertain. It is possible that some emissions from SSF manufacture could arise from the combustion of off -gases produced during SSF manufacturing processes e.g., gases evolved from retorts used to manufacture some fuels, similar to the use of coke oven gas as a fuel in the coke manufacturing process. However, combustion of this type is not identified in the energy statistics and so emissions from SSF manufacture are treate d as fugitive and In addition to coal, the manufacture of SSF involves the consumption of small quantities of coke oven coke in some years. This coke oven coke is treated as a fuel rather than a feedstock and the carbon within the coke is assumed emitted and reported under 1A1c. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 231 Activity data for coal use in SSF manufacture are taken from UK energy statistics, DUKES (BEIS, 2022), combining the sum of fuel used in SSF manufacture. The emission factor is derived from the carbon balance approach which calculates total carbon lost (i.e., emitted) during the SSF manufacturing process, by subtracting the carbon retained in the SSF product from the sum of carbon inputs. The methane emission factor of 0.0802 kt per Mt coke produced is taken f rom the EIPPCB, Best Available Techniques Reference Document on the Production of Iron & Steel, March 2000 (EIPPCB, 2000) and applied to the SSF production. Emissions from charcoal production are based on UK activity data on charcoal production from FAOSTA T Forestry Production and Trade Statistics (FAO, 20 22). These data were available for the UK and the Falkland Islands but not for and other overseas territories or crown dependencies. The methane emission factor is derived from the default emission factors in Note that any fugitive emissions of CO 2 from charcoal production would be considered biogenic, and therefore does not contribute to the GHGI national total. There have been no major changes to estimates for these sources in the 2023 submission. Improvements (completed and planned) The UK is considering reviewing the mass balance methodology for SSF, in particular to better capture the wide range of SSF products with varied feedstocks, and an increasing range of biomass being used for SSF production. This source category is covered by the general QA/QC of the greenhouse gas i nventory in The UK believes that the estimates are time -series consistent, although the data reported under sector 1B1b (including coke oven coke manufacture described in MS 4) are a diverse group of sources with highly variable implied emission factors, particularly when aggregated. For example, solid smokeless fuel production sources dominate emissions for 2015–2019 and are mainly responsible for some large inter-annual variation in the CO2 IEF during this period.
The IEF variation is driven by fluctuations in the ratio of coal to petroleum coke inputs and by the ratio of inputs to solid smokeless fuel outputs . The activity data and emission factors for these sources can be found in the accompanying spreadsheet “Energy_background_data_uk_2023.xlsx” help explain the underlying data for these Due to the nature of the mass balance approach used for SSF manufacture, uncertainty in both the estimated carbon content of input products and the carbon content of SSF delivered to market both contribute to a substantial uncertainty in the difference (i.e., the carbon assumed to be emitted during manufacture). This uncertainty is further increased by the range

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 232 of SSF products, including SSF products which include biomass inputs, introducing an uncertainty on the proportion of the carbon which might be biogenic. Non-CO2 emissions for this category only contribute a small proportion of the total emissions, and therefore do not make a major contribution to overall uncertainty

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 233 4 Industrial Processes and Product Use (IPPU; the Approach 1 and Approach 2 analyses. The uncertainty estimate has been taken from Monte Carlo analysis. Emission trends are presented for 1990-2021 and 2020-2021. A description of the trends and the main drivers behind these can be found in processes 32.33 -61% -5% 0% 3% A. Mineral industry 6.08 -41% 10% -2% 1% 1. Cement production CO2 (L1) 3% 4.22 -42% 8% 0% 0% CO2 4.2 T2 CS 3. Glass production 5% 0.34 -17% 5% 0% 0% CO2 4.4 T2 CS

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 234 B. Chemical industry CO2, N2O, HFCs production N2O (T1) 10% 0.03 -99% -36% 0% 0% N2O 4.7 T2 CS production N2O (L1, T1) N/A 0.00 -100% N/A N/A 0% N2O 4.8 T2 CS 5. Carbide production N/A 0.00 N/A N/A N/A N/A N/A 4.10 N/A N/A production 10% 0.16 48% 15% 0% 0% CO2 4.11 CS CS 7. Soda ash production 6% 0.13 -41% -7% 0% 0% CO2 4.12 CS CS carbon black production CO2 (L1) 30% C. Metal industry 8% 10.73 -59% -1% 1% -4%

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 235 production 0.00 N/A N/A N/A N/A N/A 4.17 N/A N/A production 0.06 -92% 6% 0% 12% CO2, production 0.04 -90% 37% 0% 0% HFCs, 5. Lead production 0.00 N/A N/A N/A N/A N/A 4.20 N/A N/A 6. Zinc production 0.00 -100% N/A N/A 0% CO2 4.21 CS CS 1. Lubricant use 0.32 -39% 9% -3% 0% CO2 4.22 T1 CS 2. Paraffin wax use 0.02 -30% -5% 0% 0% CO2 4.23 T1 D

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 236 E. Electronics industry 46% 0.02 75% -7% 0% 0% semiconductor 0.02 75% -7% 0% 0% HFCs, 2. TFT flat panel display 0.00 N/A N/A N/A N/A N/A 4.26 N/A N/A 3. Photovoltaics 0.00 N/A N/A N/A N/A N/A 4.27 N/A N/A 4. Heat transfer fluid 0.00 N/A N/A N/A N/A N/A 4.28 N/A N/A substitutes for ODS(2) HFCs (L2, T2) 10% 10.80 1247% -6% 0% -2% 2. Foam blowing agents 0.35 111% -7% 0% 0% HFCs 4.30, 4.31 T2 CS 3. Fire protection 0.29 19873% -9% 0% 0% HFCs, 5. Solvents 0.02 N/A -1% 0% N/A HFCs 4.34 T1a OTH 6. Other applications 0.03 28% -6% -15% -34% HFCs 4.35 CS CS

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 237 manufacture and use N2O (L2, T2) 59% 1.12 -28% -1% 0% 1% 1. Electrical equipment 0.33 -60% -3% 0% 1% SF6 4.36 T3 CS 4. Other 0.07 N/A N/A 0% 10% N2O, 4.42 CS CS * CH4 emissions from fletton brick production are reported under 2H in the CRF tables, as not possible to report in 2A4 alongside CO2 emissions from this source. ** N2O emissions from 2B8 are reported under 2B10 in the CRF tables ***N2O emissions from 2C1 are reported under 2C7 in the CRF tables

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 238 The industrial processes and other product use sector (IPCC Sector 2) contributes 7.6% to total greenhouse gas emissions. Emissions from this sector include non -energy related emissions from mineral products, chemical industry and metal production and prod uct use, including emissions of F -gases. Since 1990, this category has seen a 60% decline in emissions, mostly due to changes in the emissions from the chemical production and halocarbon and SF6 production industries. The step-change in emissions between 1998 and equipment at the UK’s only adipic acid production plant (this plant has since closed). UK have been declining since 1990. While this is partly due to the closure of some small er sites, perhaps with growth in capacity at remaining sites, it is predominantly a reflection of decreasing production of many industrial materials in the UK. A large number of closures in the period 2007 -2009 were due to decreased demand for many products as a result of the general economic situation in the UK and elsewhere, with falling demand for steel, cement, bricks and aluminium, for example, leading to plant closures. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 239 Emissions of CO 2 from fuels burnt in cement kilns are reported under CRF category 1A2f, whilst emissions from calcination of non-fuel feedstocks are reported under category 2A1. Fuel combustion also gives rise to emissions of nitrous oxide, reported under 1A2f. Emissions of methane also occur, both due to fuel combustion but also due to the evaporation of organic components present in the raw materials.
The current GHGI methodology for estimating emissions of methane does not allow emissions from fuels and from raw materials to be quantified separately so all emissions are reported under 1A2f. Emission estimates for 2005 onwards are available from the annual UK production of clinker and emission factors provided by the Mineral Products Association (MPA, 2022), formerly the British Cement Association (BCA). These AD and EFs are based on site-specific data generated by UK cement clinker producers for the purposes of reporting to the EU Emission Trading Scheme, and therefore the methodology is effectively Tier 3. Data from the MPA are cross-checked against the EU/UK ETS data set supplied directly by regu lators for use in the inventory. The EU ETS data are incomplete for 2005 -2006 as several kilns were reporting within a different trading system, and therefore EU ETS-MPA data comparisons for those two years are not useful. From 2007 onwards, the scope of t he two datasets are the same, and they are closely consistent, particularly from 2008 onwards where there is an average difference of 0.08%. In each year, the inventory estimates are based on the higher of the two figures, i.e. MPA data for 2005-2007, 2010, 2015-2017 & 2019, and EU ETS for 2008 -2009, 2011-2014, 2018 and 2020. The EU ETS and MPA/BCA data include emissions associated EU ETS and MPA data are available for 2005 onwards only, and are regarded as the best available data to represent the emissions performance of UK cement kilns. Therefore, the

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 240 emission factor value for 2005 has been extrapolated to all earlier years, as it is the most during the economic down -turn of the late 2000s , meaning that emission factors for 2007 onwards are less representative of the period before 2005. Period Activity data Emission factor, kt C / kt carbonate Method Use of the 2005 emission factor derived from emissions from all UK cement plant, from the British Cement Factor derived from annual, site-specific data compiled from EU ETS data by Mineral Products Association (since higher than EU ETS-based CEF for that Factor derived from site-specific EU ETS returns for all UK sites (since higher than MPA-based CEF for that Uncertainties and Time Series Consistency The time-series consistency of the activity data used in the UK GHGI emission calculations is very good across all years, as the Inventory Agency has a complete, consistent dataset from the UK trade association (BCA then MPA) from 2001 onwards, and routine statistical datasets for the earlier years from BGS. Furthermore, since 2005 there is a comprehensive sector-wide dataset for emissions and the EFs applied for carbonisation emissions. Cross-checks with EU ETS data received directly from UK regulators ind icate only very small differences. The extrapolation of the EF from 2005 back to 1990 is the best available data to use for the UK cement sector, but does lead to higher uncertainties for the emissions total in the base year. It is important to note that t here is a distinction to be made (i) the data used to estimate emissions in the UK methodology; and (ii) the data that can be released into the public domain for the purposes of reporting the national inventory. The data used to estimate

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 241 emissions are a complete dataset (of emissions and production) from all UK cement kilns. These data can be provided to a UNFCCC Expert Review team on request. The data reported in the CRF and NIR, however, are limited by commercial confidentiality. Statistical publications of cement production since 2001 are routinely made for Great Britain only, i.e. excluding production in Northern Ireland. Throughout the rece nt time series either one or two cement kilns have operated in Northern Ireland. Their emissions and production data are provided to the Inventory Agency and used in the inventory calculations. However, to release the complete UK clinker production statist ics would be disclosive for the sites in are presented from 2001 onwards. This is the reason for the step-change upwards in IEF over the time series between 2000 and 2001. The underlying calculations do not exhibit any such A large drop in clinker production after 1990 can be explained by a sharp drop in construction activity. This initial drop and a less pronounced downward trend in production over the period 1994-2007 may, in part, also be due to increased use of slag cement, production of which is likely to have risen sharply over the same period; the Inventory Agency estimates that capacity for slag cement production increased from 0.75 Mtonnes in 19 90 to 2 Mtonnes by 2007. A sharp decrease in clinker production between 2007 and 2009 is linked to the recession, which caused a decline in construction and therefore demand for cement. A number of kilns were closed or mothballed during those years, and no ne have subsequently been re -opened. However, there has been a slow and uneven increase in clinker production since 2009, and production in Great Britain in 2016 was at the highest level since 2008, before falling back are for the whole of the UK. The CO2 emission factors are therefore a mixture of those based entirely on UK data (for 1990 -2000) and those that mix UK emissions and GB activity data (2001 onwards), but are shown to give an indication of the trend in the factor over time. CO2 emitted (kt) CO2 emission factor, a Figures in italics exclude production in Northern Ireland

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 242 The UK -specific emission factor for cement clinker production is constant for 1990 -2000 because no year-specific data are available, and a UK factor from the EU ETS reporting period is extrapolated back to UK production data.
Factors presented above for the period 2005 onwards are all higher than the factor for 1990 -2000, because of the change in the activity data from UK to GB in 2001, as explained above. Since the later activity data exclude a small number of sites in Northern Ireland, the activity data are lower, and the implied emission factors for CO2 are therefore higher. The emission factors in the period 2001 onwards do vary from year to year, from a minimum va lue of 0.562 t CO2 / t in 2020 and a maximum value of 0.600 t CO2 / t in 2013. The reason for the large increase in the IEF in 2013 compared with the previous year is not known, although the inconsistency between the activity data (excluding Northern Irela nd) and emissions (including Northern Ireland) may be at least Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Emissions reported to the Inventory Agency by the Mineral Products Association are cross checked with plant specific data reported in the EU /UK ETS to ensure complete coverage of Source Specific Recalculations No recalculations have been made to emissions from this category. Source Specific Planned Improvements Emission factors and activity data will be kept under review. Lime (CaO) is manufactured by the calcination of limestone (CaCO 3) and dolomite (CaMg(CO3)2) in kilns fired mainly by coal, coke or gas, though some wastes and other fossil fuels are also used . The calcination results in the evolution of carbon dioxide. However it is necessary to distinguish between merchant lime processes where the purpose is to produce lime for use off -site and where carbon dioxide is an unwanted by -product emitted to atmosphere, and those captive lime processes where lime is produced so that both the carbon dioxide and lime can be used on-site in the process. In these latter processes, which include sugar refining, none of the carbon dioxide is emitted to atmosphere, apart from the exception listed in the next section. Emissions from li me kilns used in the manufacture of sodium carbonate are, in line with IPCC Guidelines, reported in 2B7. The UK method uses EU and UK ETS data to determine emissions from 2005 onwards, Pollution Inventory (PI) data from 1994 to 2004 and British Geological Survey (BGS) data from 1990 to 1993. The UK ETS data consist of CO 2 emission estimates (including emissions associated with lime kiln dust) and activity data. The activity data takes various forms e.g. feedstock or product, depending upon site, and so it is not possible to generate UK activity data simply by summing the activity data in UK ETS. Therefore, the emissions data have been adopted, with the lime activity data then being back-calculated using a default emission factor of 121.5 t carbon/kt limestone or dolomite. This emission factor is derived by assuming that 85% of UK lime production is from limestone and the remaining 15% is from dolomite (based

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 243 on a recommendation from the EU’s UNFCCC review). For limestone, an emission factor of 120 t carbon/kt limestone is then assumed, based on the stoichiometry of the chemical reaction, and for dolomite, a corresponding emission factor of 130 t carbon/kt dolomite is used. UK ETS returns do provide some indication of site -specific activity data although this is a mixture of data on carbonate inputs and lime outputs. Nevertheless, it would be possible to generate an approximate time-series of lime production for merchant lime producers from UK ETS returns for the period from 2008 onwards and while these cannot be published due to the confidential nature of the data, the figures could be provided on request to a UNFCCC Expert Review Team. There are no suitable data in UK ETS for captive lime processes so we are unable to provide any similar lime production estimates for those sites. Prior to 2005 there are no EU /UK ETS data at all, and data are incomplete for 2005-2007 because of UK exemptions from the EU ETS for some sites in those years. Therefore, between 1994 and 2004, CO 2 emission estimates for lime production are based on emissions data published for each site in the Pollution Inventory (PI), and these data are also used for those sites that were exempt from EU ETS before 2008 . The PI data are mostly for total CO 2 i.e. include emissions from both decarbonisation and fuel combustion on a site, but estimates of the CO2 from decarbonisation only are made using EU ETS data and PI data for 2006 -2008, both of which give fuel combustion emissions separately from decarbonisation. For the period 1994-1997, there is less reporting of CO 2 in the PI and so site -specific CO2 emissions are estimated based on other site-specific data such as emissions data for particulate matter from those sites in the relevant years. The PI data are assumed to cover the same scope as the later EU ETS data i.e. to include emissions from lime kiln dust as well as lime product. There are no PI data for the period 1990 -1993 so BGS activity data are the only data available to calculate emissions. As emissions estimates based on BGS data are consistently lower than emissions from PI and EU ETS sources for the period from 1994 onwards, it is assumed that BGS data for 1990-1993 would also underestimate emissions and the Inventory Agency has therefore applied a ‘correction’ factor of 1.08 to the BGS data for those years. The methods used for each part of the time series are summarised below.
1990-1993 BGS x 1.08 121.5 AD x EF 1994-1997 (back-calculated) 121.5 PI CO2 + estimates extrapolated from later PI data on basis of other data such as emissions data for other pollutants 1998-2004 (back-calculated) 121.5 PI CO2 2005-2007 (back-calculated) 121.5 EU ETS & PI CO2 2008-2020 (back-calculated) 121.5 EU ETS 2021 (back-calculated) 121.5 UK ETS The calculated emissions and activity data exclude carbonates calcined in the chemical industry since this is all used in the Solvay process, for which emissions are reported in 2B7. The UK ETS data for UK sugar producers do not include any emissions from calcination, and consultation with the industry in the past confirmed that the industry considers there to be no

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 244 CO2 emissions from this source - all of the lime used in the carbonatation p rocess (whereby lime and carbon dioxide are used to remove impurities in sugar solutions) is considered to be converted back to calcium carbonate at the end of the process , meaning no net emission in CO2. However, the UNFCCC centralised review of the 2013 submission of the UK GHG Inventory recommended that CO 2 emission estimates were needed and that it should be assumed that some unreacted lime was present in waste sludges at the end of the carbonatation process. Emission estimates are therefore included using a default percentage (24%) of unreacted lime as advised by the ERT. This ERT default is based on data from other countries since UK-specific data indicate zero emissions. Due to the confidentiality of the lime production data at the sugar production si tes, further details of the methodology are not presented here, but can be provided to a UNFCCC Expert Review Team. The calcium carbonate produced by the sugar industry is marketed as a soil liming agent and is assumed to be wholly used by UK agriculture. Emissions associated with this usage are included in the estimates for agriculture as described in Section 5. Uncertainties and Time Series Consistency Uncertainty in the emission estimates for merchant lime plants is low for recent years but higher for earlier years in the time series. EU and UK ETS provide a full dataset for UK facilities from 2008 onwards, and the uncertainties associated with these verified data are low. EU ETS data for 2005 -2007 provide partial coverage of the sector and are used in conjunction with other data sources to derive inventory estimates, and hence these estimates are also regarded as subject to low uncertainty. Uncertainty is higher for the estimates before 2005, because of the need for assumptions to be made in deriving the estimates (for example, assumptions regarding the split between combustion and process emissions in the PI data used between 1994 and 2004). Estimates for the years 1990 to 1993 are the most uncertain, because no reported CO2 emissions data are available, and emissions have therefore to be based on the BGS data that are known to be inaccurate for later years. An adjustment is made to the BGS data to try to deal with the expected underestimating of activity by BGS, but a comparison of BGS and other data for later years indicates that the BGS underestimates are not consistent and so the scale of any underestimation in 1990-1993 is difficult to predict with any confidence. The estimates for lime kilns used in sugar production are highly uncertain since EU ETS data for those sites suggest no CO2 is emitted. In addition, a study for the European Commission on EU ETS emission allowances for the lime sector (Ecofys, 2009b) states that it can be assumed that “there are no process -dependent CO2 emissions released from the limestone that is used”. The UK prod ucer has also indicated that they consider the conversion of lime back to calcium carbonate as being complete (Personal British Sugar, 2013). Source-specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Cross comparison of the BGS data with the EU ETS data as a means of verification has indicated a potential under report in the BGS data. This has led to a change in the methodology to ensure completeness of the inventory reporting. Source Specific Recalculations No recalculations have been made to emissions from this category. Source Specific Planned Improvements Emission factors and activit y data will be kept under review. In response to the ERT recommendation (2017 ARR, item I.14) to collect lime production data to enable the UK to derive and report a production -based IEF, the UK Inventory Agency has consulted with the

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 245 Office of National St atistics (ONS) to seek any data that are available from the industry on production of lime, via the Prodcom surveys and database. The Inventory Agency research has found that there is no complete, consistent time series of annual production data from UK producers from ONS. This is due to the nature of the periodic surveys conducted by ONS, the combination of production data from several mineral sectors (e.g. cement with lime aggregated) and the commercial sensitivity of reported production data. The Inventory Agency notes that the EU/UK ETS emissions reporting is known to cover all existing UK lime works and therefore is complete and accurate for recent years, and that to gather any further activity data from the industry is not practicable given the competi ng priorities for inventory improvement resources.
As discussed in Section 4.3.2, it would be possible to provide an ERT with an approximate timeseri es of lime production estimates for 2008 onwards for merchant lime sites only, which could then be used to generate an approximate IEF for those Emissions from glass manufacture include emissions of carbon dioxide resulting from the use of limestone, dolomite and soda ash as sources of CaO, MgO and Na2O respectively in soda- lime and other glasses. Emissions from fuels used in glass furnaces are reported in 1A2g. The UK had 23 large sites making glass at the end of 2021, producing container glass (12 sites), flat glass (4 sites), continuous filament glass fibre (1 site), glass wool (4 sites), and stone wool (2 sites). A fifth site producing flat glass by the float proces s closed in November 2013. There is also a small site producing ceramic fibres. Ballotini are produced at three sites, but production is small - output was less than 1% of UK glass production in 2021. Special and non-lead domestic glasses are no longer manufactured in the UK, and production of lead glass is only on a very small scale. The last producer of frits closed in 2014. It is assumed that limestone and dolomite are used in the production of container, flat, and special glass, and in glass and stone w ool. Any use of carbonates in frits and lead glass is assumed to be trivial because of the small-scale production of these in the UK (together, both sectors account for about 0.1% of UK glass production). EU ETS data for the sole UK site making ceramic fibres indicate that this process does not involve the use of the three carbonate minerals . The ballotini processes are not covered by EU /UK ETS but are based almost exclusively on the use of recycled glass (cullet) and so carbonates are not used in significa nt quantities. Since the production of ballotini is a trivial fraction of UK glass production and the use of carbonates for ballotini is also trivial, emissions are not estimated. Due to the very small number of sites involved, and the confidential nature of the EU/UK ETS data used to generate the emissions data, reporting the stone wool sector separately would be problematic. The UK therefore combines the data with emissions for other glass industry Process emissions of N2O are not estimated for glass production because suitable methods or data have not been found. Operators of UK plant regulated under the Industrial Emissions Directive do not report any emissions data to the regulators and so any releases of N2O from these sites (including N2O from combustion of fuels) must be below the reporting threshold of 10 tonnes and therefore any process emissions will be very low for the UK as a whole. Emissions from the use of carbonates in glass production are calculated using data from two

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 246 • A detailed, site by site survey of raw material usage in the glass industry, carried out in 2006 (GTS, 2008). This report covered the flat, container, and fibre sectors; • Data reporting under the EU/UK Emissions Trading System (EU/UK ETS) from 2008 In the case of the survey of raw material usage, data are available on the quantities of each type of carbonate used by each sub -sector of the industry during 2006. Emissions must be estimated, and this is done based on the stoichiometric relationship between carbon and the related carbonate, and assumes all of the carbon is released to atmosphere i.e. The EU/UK ETS data are for CO2 emissions, disaggregated by the source of the emission e.g. use of natural gas, use of limestone etc. The data have to be analysed so that emissions can be separated into those that occur due to use of fuels, and those that are due to use of the three carbonates. Data are available for the period 2008-2021 for all sites manufacturing flat glass, container glass, continuous filament glass fibre, glass wool and stone wool. Carbonate use is back-calculated using the stoichiometric relationships given above. Since ETS data are available on a site -by-site basis, the emissions data and the derived activity data can be agglomerated to give estimates for each sub-sector of the glass industry. The two data sources can be used to derive estimates of carbonate use / CO 2 emissions for each sub-sector of the glass industry as 2008-2021: flat, container, glass fibre, glass wool, stone wool; 2006: flat, container, glass fibre/glass wool (combined in the survey). These data indicate some changes over time in rates of carbonate use for flat, container and glass wool, and partial EU ETS data for 2005 -2007 also support this. Therefore the 2006 survey, rather than the later EU ETS data, is assumed to be more reliable as a guide to the rates of carbonate usage in the three sectors in the years 1990-2005 and usage for that period is therefore extrapolated from the 2006 figures on the basis of production in each sub -sector in each year. For stone wool, data are only available from the EU/UK ETS for 2008-2021, so the average consumption rate calculated for those years is then applied to the period 1990 - 2007 using stone wool production estimates for each year. The data indicate that some glass industry sub-sectors in the UK do not use all three carbonate minerals, or on ly use small quantities of some. Neither of the two data sources contains information on special or domestic glasses because the only UK sites producing either type of glass closed before the end of 2006.
Therefore, carbonate usage for both types of glass has been assumed to be equal to the average rate for container, flat and glass wool in 2006, as given in the raw material usage Glass production data are available on an annual basis for container glass only (British Glass, 2022), and a full time-series of production for other types of glass has therefore to be estimated based on the partial time series of production data covering a limited years (e.g. data for late 1990s from EIPPCB, 2000; flat glass data for 2003 onwards from British Glass). These are then extrapolated to other years on the basis of estimated plant capacity. In the case of flat and container glass, the glass production data used to estimate carbonate usage are corrected for the amount of cullet used in each year, so the estimates do take into account changes over time in recycling rates and use of cullet. This is not possible for other types of glass, and so the calculation of carbonate usage for these glass types is based on total production. Therefore, the estimates for glass wool, special glasses and domestic glass implicitly assume that the rate of recycling in these sectors remains constant over the time series. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 247 for CO2 emissions from carbonate use Glass wool 104 302 Yes Yes Yes Ceramic fibres 14 14 No No No The EU/UK ETS data also includes extremely small CO2 emissions (<1 tonne) occurring due to use of barium or potassium carbonate by the glass sector, and somewhat larger though still relatively trivial emissions from other process sources. The largest of these is emissions that occur when waste wool at one site is recycled through the process, and it is assumed that the carbon results from oxidation of organic coatings that were applied to the wool as part of the finishing process. Waste generated during cutting of the wool following the coating process is recycled to the glass kilns. A time-series of emission estimates has been added for this version Uncertainties and Time Series Consistency For the years 2008-2021, the methodology is based on the use of highly accurate emissions data reported under the EU and UK ETS for all significant UK glass producers. The emission estimates for 2006 are based on activity data given in a detailed industry study. These emission estimates should be assumed to be slightly more uncertain than the EU and UK ETS data of 2008 -2021 since the source gives carbonate usage figures only, and emissions have to be calculated assuming that these figures refer to pure carbonates and that all carbon in the minerals is released to atmosphere. While the emissions d ata are therefore conservative, the uncertainty is still considered to be low since fairly pure carbonate minerals For the remaining years in the time -series, the methodology relies upon the extrapolation of highly accurate activity/ emissions data for one year to all other years based on glass

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 248 production. The glass production data are, however, a mixture of actual production data from the glass industry, and Ricardo Energy & Environment estimates, which are far more uncertain. The emission estimates for 2A3 are therefore subject to far greater uncertainty for the earlier part of the time -series than for recent years, because of the greater reliance on extrapolation, and the lower quality of the glass production estimates for these years. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Source Specific Recalculations There have been no significant recalculations. Source Specific Planned Improvements Emission factors and activity data will be kept under review. The UK has a large number of site s involved in the production of heavy clay goods such as bricks, roofing tiles, and similar items. These sites range from the smallest operations where bricks are hand-made, to bigger sites where bricks are manufactured on a large scale, using automatic production methods. The brick industry can also be divided into fletton and non - fletton types. Fletton bricks are manufactured using the Lower Oxford Clay, found in South - East England only. This clay has an exceptionally high content of carbonaceous material which acts as an additional fuel when the bricks are fired, but also produces a characteristic appearance in the finished bricks. Non -fletton bricks are made from other clays and shales and these have much lower carbon contents. For all bricks, firing lea ds to emissions of CO 2 from the carbonaceous material in the clay. Limestone, dolomite and barium carbonate can also be used in brickmaking, leading to further releases of CO 2 during firing. Finally, many brick manufacturers add crushed coke ("colourant") to some bricks to change the final appearance of the bricks. Coke oven coke is known to be used in this manner, and it is assumed that petroleum coke is as well. Colourant is added at rates of up to 15% of the raw material weight. A high proportion of the carbon in the colourant is known not to be oxidised during firing and remains in the for Emissions Trading Scheme ( ETS) reporting use of carbonates, the UK inventory estimates include carbon emissions from the use of colourants in bricks here as well, in the absence of anywhere more appropriate to report them. Also included are emission estimates for the use of clays to produce ceramics other than The 2006 GLs draws attention to other sources of CO 2 emissions from use of soda ash and other carbonates. These other uses include Flue Gas Desulphurisation (FGD), magnesia production, and use of soda ash in soaps & detergents, and other applications.
The UK inventory includes CO2 emissions that occur during the manufacture of soda ash and from the use of soda ash by the glass sector and detailed descriptions of those source categories are provided in Sections 4.12 & 4.4 respectively. The inventory also includes emission estimates for the use of soda ash in applications other than glass production, and these emissions are reported in 2A4b. These estimates are based on a review (Passant et al, 2019) which found that soda ash is used in the UK for a wide range of applications but that

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 249 most is used for one of three purposes – manufacture of glass, manufacture of chemicals (including sodium bicarbonate) and manufacture of detergents and soaps. Not all uses of soda ash are likely to result in CO 2 emissions and so this review also considered the potential for emissions. Emissions also occur from the subsequent use of sodium bicarbonate and these emissions are reported in 2A4d. Limestone is used i n FGD systems for abatement of SO 2 emissions at most remaining UK coal-fired power stations and emissions are reported under 2A4. The power stations at Drax and Ratcliffe were the first to get FGD (in 1994), followed by West Burton A in 2004, Eggborough an d Cottam in 2005, then Ferrybridge C, Fiddlers Ferry and Rugeley B in 2008/2009. The Ferrybridge C and Rugeley B stations were both closed during 2016 , Eggborough closed in September 2018, and Cottam in September 2019. Various small, predominantly waste and/or biomass-fired stations also report CO2 emissions from limestone scrubbing in the ETS. In all of these processes, limestone reacts with the SO2 present in flue gases, being converted to gypsum, with CO 2 being evolved. Uskmouth B has a dry lime - injection system, so there is no potential for CO 2 emissions at this site. Seawater scrubbing systems are used at Aberthaw and Kilroot and was also used at the now -closed Longannet power station but CO2 emission estimates are not included in the GHGI for this type of FGD there is no estimation method for this process. Some MSW incinerators are believed to use the dry lime injection process to remove SO2 as with Uskmouth B, there will be no CO2 emissions from this type of FGD technology. Magnesia production in the UK is thought to be limited to a single plant that closed in 2005. This site produced magnesia from seawater, with magnesium salts in the seawater precipitated as magnesium hydroxide, fol lowed by conversion to magnesia in kilns. No process emissions of CO2 occurred at this site. CO2 emissions from production of bricks and tiles are based on data reported in the UK and EU ETS. ETS provides site by site emissions, with data in most cases broken down by source (e.g., from clays, fuels, colourants etc.). The ETS data from the producers of bricks and tiles are representative of the sector from 2008 onwards, when all significant manufacturing sites were included in ETS. The ETS dataset is documented and reported at a level of resolution such that the Inventory Agency can readily apportion the emissions data between fuel combustion and non-fuel sources (i.e., process emissions). However, it is more difficult to divide the non -fuel data into sub -types such as emissions from clays, colourants, or 'pure' carbonates like limestone, dolomite, and barium carbonate since some of the information on the source of the CO2 is presented as aggregated data and not resolved per specific material input to the process. The information presented by UK operators confirms that the emissions from the colourant (coke oven or petroleum coke) are included within the aggregated process The ETS data are calculated by each brick and tile producer using site -specific activity data, and industry -wide emission factors, compiled by the industry trade association (British Ceramic Confederation, 2014). These inclu de factors for simple carbonates based on the stoichiometric relationship of carbon to the carbonate, as well as measured emission factors for different types of clay e.g. , Keuper Marl, Weald Clay, and Lower Oxford Clay. A high proportion of the carbon in the colourant is known not to be oxidised during firing and remains (British Ceramic Confederation, 2013). Consultation with the brick industry indicates that the E TS data for 2008-2012 covered 93% of sector production. A single further site joined ETS in 2013, bringing coverage to 95%. The remaining 5% of production is at small sites that are outside the scope of ETS. The ETS emissions data for 2008 onwards are therefore increased using these figures to reflect non -

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 250 reporting brickworks, assuming that emission rates at non-reporting sites will be the same as on average at reporting sites. With the exception of the large site that joined in 2013, the non- reporting sites over the period since 2008 are much smaller producers and it is not known how representative the industry factors will be for these atypical sites. In the absence of better data, it is assumed that emission rates are the same. ETS data are incomplete bef ore 2008, and therefore are not used to derive a national total. Instead, annual brick production data are used, available in Government Statistics (Monthly Statistics of Building Materials and Components, September 2022, available from to extrapolate back from the ETS data. These data are for total numbers of bricks produced, and it is necessary to consider what proportion of these bricks are of the fletton type, since this type of brick is associated with higher process emissions. Fletton bricks have had a declining share of the UK brick market for many years and are no longer used in the construction of new buildings.
Information on the market share is however Ove Arup (1990) puts it at 25%, Blythe (1995) states it is 20%, and by 2011, following the announcement that the last but one fletton brickworks was being closed, local media reports all stated that fletton bricks now accounted for less than 10% of the UK market. The inventory method therefore assumes a 25% share in 1990, falling to 20% in 1995, then falling to 10% by 2010. ETS data for the fletton works suggest production has fallen further since 2010 and so is used to estimate the trend for fletton bricks since 2010. Using these data and assumptions, it is possible to then gener ate estimates of the numbers of fletton bricks and non -fletton bricks produced each year . For 2021, it is estimated that 5% of UK bricks produced were of the emission estimates for 2008-2013, and then the estimates of non-fletton bricks produced can be used to generate emission estimates for the period 1990-2007 using this emission factor. In the case of fletton bricks, the PI provides additional data to suppl ement the information in the ETS for 2008 onwards. Total CO 2 emissions are reported for the Stewartby and Saxon/Kings Dyke sites for each year between 1998 and 2007. The later ETS data at these sites is used to separate the PI data for 1998 -2007 into a fue l component and a process component. This gives a time series of process emission estimates back to 1998, and this is further extrapolated back to 1990 on the basis of the estimates of fletton brick production. operating and the data available for emission estimates over the time series. Years Number of sites and fuels Availability of data 8 fletton works operating in 1990; only 5 still in operation by 1993. Those in 1993 burnt coal, or a mixture of coal and natural gas. Unknown number of non -fletton No emissions data available, annual production (numbers) of all bricks available and fletton and non- fletton brick production estimated from this. Emission estimates require use of emission factors generated 1998/1999. Both used only coal as a fuel so by the end of 1999, 3 coal, the other two (Saxon/Kings Dyke), both in the same area in Annual emissions of CO 2 and methane available in the Pollution Inventory for each fletton site until 2004, when emissions for the two gas -burning sites, which are located about 1.5 km apart start to be reported as combined totals. Reported emissions have to be split between ener gy- and process -related emissions . Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 251 Years Number of sites and fuels Availability of data England, now b urn natural gas fletton brickworks in early 2000s. Estimates for non-fletton bricks have to be generated using emission factors from later ETS data Annual production (numbers) of all bricks fletton and non-fletton brick production estimated. 2008 Closure of coal -burning fletton works at end of 2008, leaving only 63 non-fletton brickworks report in Annual emissions of CO 2 and methane available in the Pollution Inventory for Stewartby, and for ETS data for the same two fletton brickmaking units, and also for non -fletton brickworks. These data are detailed, allowing fuel -related and process -related emissions to be separated. Emission estimates can be based directly on ETS data. fletton brickworks in operation. brickworks, with 49 reporting in ETS by 2011. In 2013, final large site joins ETS, with total of 46 non-fletton sites then reporting. Annual emission of CO2 and methane available in the Pollution Inventory for the Saxon/Kings Dyke works. ETS data for all significant fletton and non -fletton works for all years except for one site that joins ETS in 2013. Emission estimates can be based directly on Other types of ceramics are manufactured in the UK, including wall and floor tiles, refractories, sanitary ware, household ceramics etc. No suitable national data on the levels of production for these types of ceramic goods have been found. However, the UK Minerals Yearbook (BGS, 2022) gives production, imports, and exports for 4 types of clay (ball clay, china clay, fireclay, other clays & shales), and these data can be used to estimate total UK demand for each type of clay. These figures can then be compared with ETS data for clays used in brick production, and then the difference can be assumed to be clay usage for non-brick manufacture. ETS data only extend back to 2005 but clay usage for bricks in 1990 -2004 can be estimated by extrapolating back from 2005 using the brick production data. Significant quantities of clays and shales are used in the manufacture of cement clinker, and emissions from this usage will already be reported in 2A1. BGS reports separate figures for this usage, so clay usage in other ceramics can then be calculated using the following ClayOther ceramics = ClayTotal (from BGS) - ClayBricks (from ETS) - ClayCement (from BGS) There are likely to be other, possibly non-emissive uses of clay, for instance some china clay may be used in paper production. But we assume these other uses are either trivial or emissive. The calculations suggest that, on average over the 1990 -2020 period, about two thirds of UK clay consumption is used for bricks, and the remaining third is used for the manufacture of other ceramics, cement clinker or other uses. The trends in the total clay and brick clay estimates are fairly similar in the 1990 -2014 p eriod, so that this pattern of approximately two thirds bricks to one third other uses is broadly true for all years within that period. But this pattern has changed since 2015, and the total clay figures for 2015, 2018 & 2019 are only slightly higher than the estimates for brick clay, suggesting that hardly any clay was used in those years for other uses.
BGS data for clays used for cement confirm that consumption by this sector reduced by about 90% after 2014. It is therefore assumed likely that UK production of other ceramics has declined significantly in the last five years. BGS data are never available for the latest year in each inventory submission, and therefore we have to assume the same total clay consumption in the latest year as the year prior. T he figures for

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 252 the latest year will be revised in the next submission once BGS data for the year become No emission factors are available specifically for clays used in other ceramics, therefore we apply the emission factors used by brickworks to estimate their emissions in the ETS dataset. Separate factors are available for ball clay and fire clay, whereas emissions from china clay and ‘other clays and shales’ are estimated using the generic ‘other clay’ factor also used for ETS reporting by bri ck producers. A few non -brick ceramic processes do report in ETS and so the emissions data for these sites are used directly. For non-glass use of soda ash, consultation with the only UK producer of soda ash identified application has been assumed to be emissive i.e., leading to emissions of CO2. The UK emission estimate s are based on UK demand estimates supplied by the sole UK producer for soda ash, who estimated consumption in 1990 and 2019 (Tata Chemicals Europe, 2019). Consumption in 1991-2018 was then estimated by the Inventory Agency, with one of three methods being used to estimate consumption in each • For most sectors, the overall demand for soda ash/sodium bicarbonate was similar in 1990 and 2019, so intervening years were estimated on the basis of a linear change. • For the chemical sector, a linear change w ould not be realistic since consumption would have been dominated by a small number of sites, many of which are now closed. Therefore, the processes operating each year were identified, and annual consumption then estimated based on the likely consumption at each site. The overall consumption figures then reflected the closure of key sites and the commissioning of new o Closure of the tripolyphosphate works in 1999 o Closure of the Ultramarine Blue works in 2008 o Closure of the sodium chromate works in 2009 o Commissioning of the sodium percarbonate works in 2000 and closure in 2014 • A breakdown of the sodium bicarbonate market is only available for 2019 (for 1990 we have only the total market). Therefore, we have estimated the market split for sodium bicarbonate by extrapolation back from the 2019 figures. However, one of the key markets is flue gas treatment and we consider it unlikely that this market existed until fairly recently. This type of flue gas treatment is likely being used in recently commissioned Energy from Waste (EfW) plants, and since many have been built since 2010, we assume that consumption for flue gas treatment was zero up until 2009. Figures for 2019 were extrapolated to 2020 onwards assuming no change in demand. We expect that some uses such as detergents might have been affected by the pandemic and demand in sectors could have also increased or decreased for other reasons. However, we believe that any year-on-year changes will be relatively small because of the nature of these uses. Future submissions may be able to incorporate new data if soda ash suppliers can Soda chemicals Used in production of various chemicals or chemical

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 253 Soda detergents Used as a builder to emulsify oil; to reduce the deposit of dirt during cleaning; to provide alkalinity, and to soften Soda other Fertilizers, production of bentonites, organic and inorganic colourings, enamelling, petroleum industry, Used in poultry & cattle feeds 0% Sodium bicarbonate used where a milder detergent is required. Used in hard surface cleaners where its limited water-solubility is advantageous. Used for treatment of acidic flue gases. 100% Used as a raising agent for a wide range of bakery and Sodium bicarbonate can be used in foam blowing, soda blasting, explosion suppressants and fire extinguishing. Sold to distributors (so end use is unknown) 75% a Rather than being emissive, conversion of soda ash to sodium bicarbonate requires CO 2 so the process consumes some of the CO 2 generated in the production of soda ash. This consumption of CO 2 to convert from soda ash to sodium bicarbonate is taken into account in the emissions reported in 2B7. Emissions were then estimated assuming that uses were emissive or non-emissive as shown industry, except those for named chemical processes, where the assumption was based on the chemical reactions taking place. For emissive processes, it is assumed that all of the carbon in the soda ash was converted to CO2 which was then emitted. So, an emission factor of 0.4151 ktonne CO2 / ktonne soda ash consumed was used for emissive applications. In the case of sodium bicarbonate use, the activity data used in the UK inventory are expressed as soda ash converted to bicarbonate. The conversion from soda ash requires reaction with So, it follows that for any emissive uses of sodium bicarbonate, an emission factor of 0.8302 kt CO2 / kt soda ash is appropriate i.e., double that of soda ash used for other applications. Further detailed discussion of the methodology is included in the report by Passant et al Emissions from Flue Gas Desulphurisation (FGD) are either calculated using an emission factor of 69 t carbon/kt gypsum produced or based on EU ETS emissions data. The factor is based on the stoichiometric relationship between gypsum and carbon dioxide formed in the FGD plant.
Data on gypsum prod uced in FGD plant are available from the UK Minerals Yearbook (British Geological Survey, 2016 and earlier versions), but these data are not always

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 254 consistent with site-specific emissions data available from ETS, and so a composite series of emissions data is used with BGS activity data , and the emission factor used for 1994 -2004, and ETS emissions data for 2005 -2019. Four small biomass -fired power stations were no longer in ETS after 2012, and so we have obtained CO 2 emissions data for the scrubbing systems at these sites from the operator. Emissions at these non -ETS sites have averaged about 2% of the total emission in recent years. applications in the inventory for 1990 -2021. The provided activity data correspond to the 1990 170.4 10.8 0.0 59.2 5.7 3.8 1995 179.1 11.2 0.0 59.0 5.9 3.9 2000 146.5 11.6 0.0 58.8 6.1 4.1 2005 146.5 12.0 0.0 58.6 6.3 4.2 2008 146.5 12.2 0.0 58.5 6.5 4.3 2009 109.6 12.3 0.0 58.5 6.5 4.3 2010 78.0 12.4 2.8 58.4 6.6 4.4 2015 67.9 12.8 17.1 58.3 6.8 4.5 2020 67.9 13.1 28.5 58.1 6.9 4.6 2021 67.9 13.1 28.5 58.1 6.9 4.6 Non Energy chemical feedstock, soda Bread baking, sodium bicarbonate Sodium food Flue gas treatment, sodium bicarbonate Sodium flue gas treatment Other emissive applications of soda ash Soda other Unknown applications, sodium bicarbonate Sodium distributors Other emissive applications, sodium Sodium miscellaneous

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 255 Uncertainties and Time Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC source category and fuel type. In the case of FGD plant there is a change in methodology between 2004 and 2005. However, BGS and EU ETS-based emission estimates for 2005 are very close, and for 2006 -2014 are within 6% of each other (with the EU ETS numbers usually higher). No data are available from BGS for 2015-2019 and so no comparison can be made with the EU ETS based figures. Emission estimates for soda ash are relatively uncertain, for a number of • The time-series of estimates rely on estimates for UK demand in 1990 and 2019 only and a linear interpolation is generally used to estimate demand in the years in - between. The UK manufacturer was unable to provide further data, so alternative sources would probably need to be identified in order to refine the time-series. • No data could be obtained for 2020 onwards, so we assumed the same consumption as in 2019. In reality some uses such as detergents might have been affected by the Covid pandemic and demand in sectors could have also increased or decreased for other reasons. However, we believe that any year -on-year changes will be relatively small because of the nature of many of the sectors that use soda ash and sodium bicarbonate, and so assuming no change in usage is unlikely to introduce large errors providing this is only done over a very short period. Future submissions will be able to incorporate new data if soda ash suppliers can provide this, alternatively it will be necessary to obtain alter native data to allow a better long -period timeseries (for example, estimates of consumption of bread and other baked products could be considered as a means to extrapolate forward the estimates for bicarbonate usage by • Estimates are also sensitive to assumptions regarding the operation of certain chemical processes. However, since these plant closed in the years from 1999 to 2014, this uncertainty does not affect the estimates for recent years. • While it is certain that some uses of soda ash are emissive (e.g., glass and certain chemical processes), for other uses it is less so. Soda ash seems to be used for a wide range of minor applications, including both emissive and non -emissive ones. In the absence of any detailed breakdown of individual uses, we assume 50% emissive. Estimates for bricks are considered to be highly reliable for the period 2008 onwards where ETS data are available for almost all sites. For earlier years, the emission estimates rely upon extrapolation of the 2008 emissi ons data using brick production estimates and this will introduce uncertainty within the earlier part of the time series. Emission estimates for methane from fletton brickworks are, similarly, based on reported data in later years and extrapolation using brick production for the early part of the time -series, so the uncertainty will again be greatest in the earlier part of the time series. Emission estimates for other ceramics are derived using the difference between total UK consumption of clays, and consu mption of clays by the brick and cement sectors. Emission factors specifically for other ceramic processes do not exist, therefore we use factors developed by the UK brick industry for the purpose of reporting to ETS. Emission estimates for other ceramics are more uncertain than those for bricks because of this. The figures for 1990-2004 are also more uncertain than later figures, because the estimates for clay usage for brickmaking are more uncertain. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 256 Source Specific Recalculations The methodology for extrapolating bricks activity data for 1990-97 has been refined to use an average of several years’ reported data instead of only 1998 data. Source Specific Planned Improvements Emission factors and activity data for bricks, ceramics , soda ash use and FGD will be kept under review .
We will continue to seek updated data on soda ash consumption from the We are aware that one sodium bicarbonate site has recently started using captured CO2 from combustion as a feedstock fo r the process, and it is on the improvement programme to consider how best to estimate and report this process. Ammonia is typically produced using the Haber process, which starts with the steam reforming of natural gas to make hydrogen. The simplified reactions The hydrogen is then reacted with nitrogen to form ammonia. If the by -products CO and CO 2 are not captured and used, then these are emitted to atmosphere. Ammonia plants can be integrated with methanol manufacture for greater efficiency, since the carbon oxides can be used to manufacture Over the time period covered by the UK greenhouse gas inventory, ammonia has been manufactured at four locations in the UK. CO 2 emissions are reported from three of those at the remaining site (Hull), the ammonia is produced with hydrogen supplied as a by- product from another chemical process operated on a neighbouring site. At one of the remaining three sites where CO2 is reported, some carbon from the steam reformer was, until 2001, exported for use in the manufacture of methanol. At least one ammonia plant sells CO2 to the food industry and nuclear industry. Because this CO2 is still ultimately emitted to atmosphere, it is included in the emissions reported here. This is considered more reliable than trying to identify carbon emissions at the po int of final use since CO2 will also be emitted from other processes within those sectors, for example from fermentation. Potential applications for exported CO2 might include (but are not limited to): • use in carbonating drinks (emitted on consumption of the drinks, which is not reported • use as a cover gas for the brewing industry (emitted during brewing or consumption of drinks, not reported elsewhere in the inventory); • use as a refrigerant (emitted from leakage during the manufacture, use and disposal of the product, not reported elsewhere in the inventory, although it is modelled as part of wider refrigerant modelling);

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 257 • use as a feedstock for other chemical industries (emitted on oxidation of those chemicals, this is accounted for in the case of methanol; we don't currently hold data on the extent to which other chemical processes might use this feedstock); or • by slaughterhouses to render animals unconscious (emitted during use, and not reported elsewhere in the inventory). It is also worth noting there is cross-border activity for some CO2-containing products, such as soft drinks. So, it is expected that some of the CO2 is emitted outside the UK, and some CO2 will be emitted in the UK which ultimately derives from by-product CO2 generated outside the UK. For simplicity, we assume that by-product CO2 generated in the UK is emitted in UK and that net imports of CO2 in products is zero. Methane emissions from the steam reforming processes and the associated ammonia production facilities are reported partly under 2B1 and partly under 2B10, with the latter including methane emissions from other chemical manufacturing sites as well. Nitrous oxide emissions from natural gas combustion are also estimated. UK ammonia manufacturers do not report any emissions of this pollutant and so any additional process emissions are assumed to be negligible or not occurring. Urea production was occurring in the UK at one site as recently as 1986, but this facility closed soon after. No other urea production facilities have been commissioned in the UK, and throughout the records from UK environment regulation and permitting of production plant (whereby individual plants operate under agreed permits, which in England was implemented from 1993 onwards) there is no mention of urea production in any IPC/IPPC/IED permits. The main company that currently manufactures ammonia in the UK has three urea production facilities (one in each of France, Germany and Netherlands) that they use to supply th e UK market. Therefore the Inventory Agency is confident that there has been no production of urea in the UK since 1990, and the UK ammonia production estimates throughout the time series need not take any account of urea production. Ammonia production processes require natural gas both as a feedstock and as a fuel to produce heat required by the steam reforming stage of the ammonia process. The emissions from both feedstock and fuel use of natural gas are both reported under 2B1, in l ine with the requirements of the 2006 Guidelines. Emissions of CO2 from both fuel and feedstock use of natural gas are calculated by combining reported data on CO2 produced, emitted and sold by the various ammonia processes. Where data are not available, t hey have been calculated from other data such as plant capacity or total natural gas consumption. The ammonia plant utilising hydrogen by-product from chemical manufacture does not need to be included as there are no process emissions of CO2. production and emissions etc. by the sector. Billingham Natural gas Yes Some production Severnside Natural gas Yes Closed in 2007

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 258 CO2 emission factor, (t / t NH3) (all UK production plant)* where there are no CO2 emissions). Due to the limited market for ammonia production in the UK, to present detailed technology - specific data on production and emissions would be disclosive. Full details of the installation- specific production, fuel use and emissions will be provided upon request to a UNFCCC Expert of ammonia (which is partly based on operator data and partly on Inventory Agency estimates based on plant capacity), total estima ted 2B1 CO 2 emissions and ammonia IEF on a production basis, as presented in the CRF.
The operator of the Ince and Billingham UK ammonia plants has provided information on reasons underlying the year on year variation in emission factors. Firstly, plants a re typically shut down for routine maintenance every two years, and start -up and shut-down procedures increase the emission factors overall. Secondly , plant production rates are varied by the operator during times of high gas prices or low demand, which reduce efficiency and increase

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 259 emission factors. In addition to these operational variables, each plant will have a different intrinsic efficiency, which will in part reflect the age of the plant and the technology used. The IPCC 2006 Guidelines suggests a Tier 1 default emission factor of 1.694 tonnes CO 2 / tonne NH3 for a ‘modern’ European plant, but a higher Tier 1 default of 2.104 tonnes CO 2 / tonne NH3 for a ‘typical’ plant i.e. based on a mix of modern and old plant. The overall UK IEF the UK plant where there are no CO2 emissions; Aggregate UK factors for the three sites with CO2 emissions show an average of 1.51 tonnes CO 2 / tonne NH3 for production across the whole 1990-2021 time-series, and averages for individual years would mainly be within the range suggested by the two IPCC defaults, the exceptions being 1990-1993 & 1998 when the factors were marginally below 1.694 tonnes CO 2 / tonne NH3, and 2002 when the emission factor was slightly higher than 2.1 tonnes CO 2 / tonne NH3. [Note that fully detailed data are to an ERT.] All of the UK plants have b een in operation since before 1990; the fact that the average UK factor lies between the 2006 IPCC Guideline defaults for modern plant and mixed modern/old plant indicates that the performance of the UK ammonia plants is broadly typical of European ammonia production facilities. Methane and nitrous oxide emissions from natural gas burnt at ammonia plant to produce heat are estimated by applying IPCC default factors for industrial combustion of natural gas ( 1 kg methane / TJ & and 0.1 kg N2O / TJ), and these emissions are reported in 2B1. It is assumed that there are additional emissions of methane from the ammonia process itself, for example from fugitive leaks. Therefore in the UK inventory, methane emissions from ammonia production also include estimates p rovided from plant operator reports to the UK regulators; these emissions are reported, together with process emissions from other chemical sites, in 2B10a. These operator -reported emissions may include estimates of methane from fuel combustion and hence there is potential for a small double-count in emissions reported across 2B1 and 2B10a. Because it is not at all certain that the methane reported by the operator would include methane from fuel combustion, we have retained the estimates in both 2B1 and 2B10a on the basis that a potential double -count is preferable to a potential gap, particularly since we believe that the latter is more likely were we to remove one of the estimates. Uncertainties and Time Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC source category and fuel type. The uncertainty associated with this source is low, since the carbon content of natural gas is well known and plant specific data are received from the A consistent time series of activity data has been reported from the manufacturers of ammonia, and this results in good time series consistency of emissions. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6 and the source emissions data from plant operators is subject to the QA/QC procedures of the Environment Agency’s Pollution Inventory. Source Specific Recalculations There have been no significant recalculations to this category. Source Specific Planned Improvements Emission factors and activity data will be kept under review. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 260 Emissions sources Sources included Method Emission 2B2: Nitric Acid Production T3, T2 CS Key Categories 2B2: Nitric acid production - N2O (T1) Completeness No known omissions. A general assessment of completeness for the inventory is No major improvements to the data and methods. Further information on the abatement technology applied at UK installations has been added below. Nitric acid is produced by the catalytic oxidation of Nitrous oxide is also formed by oxidation of Nitrous oxide is emitted from the process, as well as a small percentage of the NOx that cannot be recovered for conversion into nitric acid. At the end of 20 21, nitric acid was being manufactured at 2 UK sites with a total of 4 production plants. At one site, the nitric acid production plant has had NO x/N2O abatement fitted to all units since commissioning (pre - 1990), whilst at the other UK production site, all three production lines have had nitrous oxide abatement retrospectively fitted during 2011 Quarter 1. This has led to a notable reduction in the UK IEF for nitrous oxide emissions from nitric acid production in the UK between 2010 and Across the 1990 -2021 time-series the availability of emissions and production data for UK nitric acid plant is inconsistent, and so a range of methodologies have had to be used to provide estimates and derive emission factors. Where possible, emission estimates are based on site-specific data provided by process operators. Site -specific production estimates are largely based on production capacity reported directl y by the plant operators. This approach may overestimate actual production. No data are available for three sites operating between 1990 and 1993, and production at these sites is calculated based on the difference between estimates of total production and the sum of production at the other sites.
Emission estimates for N2O are derived for each nitric acid site using one of the

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 261 a) Emissions data provided by the process operators directly or via the Pollution Inventory (1998 onwards for plant in England, 2001 onwards for plant in N Ireland); b) Site-specific emission factors derived from reported emissions data for the same site for another year (1990 -1997 for some plant in England, 1994 -1997 for other plant in England, 1990-2000 for plant in N Ireland); and c) A default emission factor of 7 kt N 2O /Mt 100% acid produced in cases where no emissions data are available for the site (some sites in England, Scotland, 1990-1993). This default factor is the default factor provided in the 2006 IPCC Guidelines (IPCC , 2006) for medium pressure plant. production and N 2O emissions fo r the UK inventory and the methods used by operators to derive the emissions data they report to regulators and the inventory team. The emissions monitoring at the two sites still in operation was originally based on periodic (at least quarterly, if not mo re frequent) sampling, but from 2010 onwards has been continuous, using on -line infra-red monitoring systems. The continuous monitors at both sites are certified to MCERTS, installed and maintained to EN14181, and subject to UK ETS Permit. MCERTS (Monitoring Certification Scheme) was set up by the Environment Agency to ensure good quality environmental measurements. The scheme is based on international standards and provides for the product certification of instruments, the competency certification of perso nnel and the accreditation of laboratories. The European Standard EN14181 covers quality assurance for automated measuring systems. The details of monitoring at the closed sites are not known, but it is assumed to have been the same as the sites that remain in operation i.e. periodic prior to 2010. The closed sites were shut before the fitting of continuous monitoring devices was required for EU ETS reporting purposes; the N 2O monitoring systems at these sites comply with the requirements of UK ETS reportin g, and are subject to low uncertainty (5 -10%). Therefore, the emissions data reported by operators are associated with low uncertainty, and are representative of the technology and abatement in the UK installations. a One site closed at end of January 2008 which submitted emissions data for that month based on emission factors having used monitoring to quantify emissions the previous year. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 262 Year Number of sites Production (Mt 100% The larger of the two remaining UK plants fitted control equipment to reduce N 2O emissions in early 2011, and this has decreased NOX emissions from that plant as well, leading to the large decreases in the aggregate EFs for both pollutants in 2011 compared with the previous year. A large increase in N 2O emissions between 1998 and 1999 resulted from a change in the NOX abatement system at one plant from NSCR to SCR. NSCR reduces emissions of N2O as well as NOX, whereas SCR only abates NOX and can actually increase N2O emissions. Since 2011 all of the UK nitric acid production facilities are fitted with EnviNOx SCR abatement (Alexander, 2 019) which includes heating of the tail gases from the production vessels, followed by NOx and N2O destruction in a catalyst bed using ammonia gas and hydrocarbon inputs to mitigate the NO X and N2O. The technology is described in a reference document (Groves and Sasonow, 2010)68. The UK installations apply the technology in process variant 2 design, which achieves N2O mitigation performance of around 99.5%, and this is the reason for the very low IEF of the UK nitric acid production sector since 2011. The N 2O emissions from all UK plant are monitored (since 2009 for all plant) using Continuous Emission Monitoring systems, and the annual operator submissions to the Environment Agency (the environmental regulatory agency for both UK nitic acid facilities) are subject to quality checks by the Site Inspectors to validate that the annual data reported to the PI and used in the UK Uncertainties and Time Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty accor ding to IPCC source category and fuel type. Emissions from nitric acid production are estimated based on a combination of emission factors and reported emissions data. The methodology used to estimate N 2O for this sector does vary through the time-series depending upon the availability of data. The calculated N2O

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 263 EF for UK nitric acid production facilities varies quite significantly across the time series, which is a reflection of nitric acid production patterns across UK sites that utilise different proces s conditions. Successive closures have changed the average N2O EF, as plants with generally above-average emission rates cease production. Abatement of N 2O using catalytic decomposition technology at the remaining UK production plants has also played a par t in reducing the UK emission factors over time. The changes in EF may also partially reflect the lack of availability of a consistent time-series of emissions data. Emission estimates for recent years have been based partially (1998-2008) or wholly (2009-2021) on continuous monitoring, and therefore will be subject to low uncertainty . The monitoring systems used at the 2 sites currently in operation are subject to an uncertainty of 5-10%. The nitric acid plant emissions data reported by operators since 19 98 are considered to be complete and accurate, since they are subject to internal QA/QC checks by the plant operators and the Environment Agency before being reported in the Pollution Inventory. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Source Specific Recalculations There have been no significant recalculations to this category.
Source Specific Planned Improvements Emission factors and activity data will be kept under review. Adipic acid is manufactured in a multi-stage process from cyclohexane via oxidation with nitric acid. Nitrous oxide is produced as a breakdown product from the nitric acid. There was only one company manufacturing adipic acid in the UK, but this closed in early 2009. Production data are not provided in the NIR because of commercial confidentiality. Production data and emission estimates have been provided by the process operator (Invista, 2010). The emission estimates are based on the use of plant -specific emission factors for unabated flue gases, which were determined through a series of measurements on the plant, combined with plant production data and data on the proportion of flue gases that are unabated. In 1998 an N2O abatement system was fitted to the plant. The abatement system was a thermal oxidation unit and was reported by the operators to be 99.99% efficient at N2O destruction. The abatement unit was not available 100% of the time, and typically achieved 90-95% availability during adipic acid production. A small nitric acid plant was associated with the adipic acid plant, and both the adipic and nitric acid plants emitted NOx. From 1994 until the plant’s closure in 2009, the NOx emission from the nitric acid production is reported under 2B2, but prior to 1994 it is included under adipic acid pro duction because separate emissions data for the different processes on that site were not available for those years. Therefore, the N 2O emissions from nitric acid production and adipic acid production were reported together for 1990 – 1994 under category 2B3 (adipic acid production). This discrepancy in reporting will cause a variation in the reported

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 264 effective emission factor for these years for 2B2 and 2B3 but overall emission estimates are Uncertainties and Time Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC source category and fuel type. Emissions data for N2O from adipic acid production are provided by the process operator, but can be cross -checked against emissions reported in th e Pollution Inventory. The level of uncertainty associated with reported emissions is not known, but the data are considered to be reliable as they are subject to QA/QC checks by the operator, and the related Pollution Inventory data are also checked by th e regulator. A higher uncertainty is assumed for 1990 than for later years. Emissions no longer occur from this source since the plant has closed. Fluctuations in the N2O EF from this plant are apparent since the installation of the abatement plant. Following direct consultation with the plant operators, it has been determined that the variability of emissions is due to the varying level of availability of the abatement plant. A small change in the availability of the abatement system can have a very signif icant impact upon overall plant emissions and hence upon the annual IEF calculated. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. During summer 2005, consultation between Defra, AEA, plant operators and the UK Meteorological Office was conducted to discuss factors affecting emissions from the adipic acid plant, plant design, abate ment design, abatement efficiency and availability, emission measurement techniques, historic stack emission datasets and data to support periodic fluctuations in reported emissions. The meeting prompted exchange of detailed plant emissions data and recalculation of back-trajectory emission models. Source Specific Recalculations There have been no significant recalculations in this category. Source Specific Planned Improvements Emission factors and activity data will be kept under review. Caprolactam was made at one site in the UK in the early 1970s. The site was destroyed in a serious explosion in 1974, and no other production sites have been built since. Glyoxal and glyoxylic acid have not been produced on an industrial scale in the UK at any time. A literature search of documents from the last 25 years on chemical production in Europe as well as consultation with the Chemical Industries Association has confirmed that these sources should This source category includes silicon carbide and calcium carbide. Neither chemical is known to have been manufactured on an industrial scale in the UK since the 1960s, when calcium carbide plants at Kenfig and Runcorn closed. As above for 2B4, literature searches and

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 265 consultations with UK chemical industry representatives have confirmed that this source should be reported as not occurring in the UK. Titanium dioxide has been produced in the UK by two i) from ilmenite, using the sulphate process; and ii) from rutile, using the chloride process. Only the chloride process leads to process emissions of greenhouse gases. In 1990, there were two sites each using the chloride and the sulphate process, but the two sulphate processes closed in 1997 and 2009, so all titanium dioxide in the UK is now produced using the chloride process at the two sites at Stallingborough and Greatham. The chloride process involves the chlorination of rutile ore in a reducing atmosphere to produce titanium tetrachloride (TiCl 4), followed by oxidation of the TiCl 4 to titanium dioxide. The reducing atmosphere is produced by combus tion of petroleum coke or coke oven coke. The 2006 GLs recommend the use of either a Tier 1 method involving a default emission factor and national activity data, or a Tier 2 method using installation-specific data on reducing agent usage. For the UK, neither of these methods are feasible options due to limited data; there are no UK activity data (i.e. annual production statistics) for any individual chemical product, and the only site -specific data for the UK plant is in the form of C O2 emissions data.
These emissions data are available from two regulatory reporting sources, however the scope of reporting has varied over the utilities. However, for three years (2006-2008), the process operators were required to report thermal CO2 and chemical CO2 separately, so the latter could be assumed to cover emissions from coke use only; • From the ETS, detailed data covering fuel use for energy production in site boilers during phase II (2008-2012), extended to cover fuels burnt in furnaces, driers etc. as well as use of reducing agents (coke) for phase III (2013 onwards). From these data it is possible to obtain the emissions from the chemical p rocess for some 2006-2008 (using the PI data for chemical CO 2 emissions), and 2013-2021 (from the detailed ETS data). The fuel/process split in emissions for these years can be calculated, and the PI provides total CO2 emissions at each site back to 1998. Prior to 1998, there is no data on either emissions or production, and therefore it is assumed that emissions in 1990 -1997 are at the same level as in later years (the production capacity at all UK sites producing TiO2 by the chloride route is the same for all years). In order to avoid a potential double -count in emissions in the UK GHGI, it is necessary to ensure that the reductant used in the processes is not included as a fuel and emissions reported in 1.A. The method adopted by the inventory team addresses this issue by back - calculating the coke oven coke/petroleum coke used as a reductan t from the emissions data using UK carbon emission factors for the feedstock, and discounting this amount from the

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 266 Uncertainties and Time Series Consistency The country-specific method used is regarded as the best available method for the UK, given the lack of any production activity data. The use of site -specific UK ETS and PI data, even if not relating to input materials as required by the Tier 2 method in the GLs, ensures that emissions data are quite certain for the period from 1998 onwards. Estimates for 1990-1997 are more uncertain due to the need to extrapolate 1998 data backwards in the absence of any specific information on production, materials usage or emissions in those years. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Source Specific Recalculations There have been no significant recalculations in this category. Source Specific Planned Improvements Emission factors and activity data will be kept under review. Soda ash has been produced in the UK using the Solvay process at two sites operating since the start of the time period covered by the inventory. The Solvay process involves the conversion of limestone (calcium carbonate) and brine (sodium chloride) to soda ash (sodium carbonate) and calcium chloride. The initial stage in the process is the calcination of limestone in a kiln to produce lime and CO2 gas, both of which are used in the process. Coke oven coke is used to fire the lime kilns and CO2 from the coke is included in the gases used in the soda ash plant. In theory, if limestone and brine are converted completely to soda ash and calcium chloride, then that part of the soda ash process is carbon-neutral and the CO2 emitted should be equal just to those emissions occurring from the coke. In practice, the process is not 100% efficient so emissions of CO2 are actually higher than would just be due to the coke use. Soda ash production at one of the two UK sites (Winnington) ceased in February 2014, although the site is still being used to make sodium bicarbonate from sodium carbonate solution & CO 2, which we assume is sourced from the neighbouring Lostock plant. The sodium bicarbonate process will consume CO2 some of which is subsequently emitted since some uses of sodium bicarbonate are emissive. However, these emissions from sodium b icarbonate usage are reported elsewhere. EU/UK ETS data suggest that the sodium bicarbonate process does emit some CO2 – presumably unreacted CO2 that passes through the process and, since this CO2 probably originates with the soda ash process at Lostock, it is included in the emission Emissions from soda ash (sodium carbonate, Na2CO3) used in the manufacture of soda-lime glasses is reported under source category 2A 3 and emissions from other uses of soda ash and sodium bicarbonate are reported in 1B2d and 2A4d. The 2006 GLs suggest that emissions should be based "on an overall balance of CO2 around the whole chemical process”. In the UK, soda ash has been produced at two sites and both began to report under the EU ETS in 2013, although one is now closed. The EU ETS emissions data for the two sites is calculated using a carbon balance approach with inputs in

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 267 coke and limestone balanced against soda ash and waste products. The 2013 -2021 EU and UK ETS data therefore meets the requirements for the method suggested in the GLs. Prior to 2013, no data for the UK plant were reported in EU ETS, but CO 2 emissions have been reported in the PI from 1998 onwards. Comparison of the PI and EU ETS data for 2013- 2020 shows that EU ETS d ata were 3 4% higher than emissions in the PI in 2013 and, on average, 60% higher in the years from 2014-2020. The reason for this is not known, but since the PI data for 1998 -2013 are fairly consistent, it is assumed that there is a systematic underestimate in the PI data across the entire time -series (possibly they represent CO 2 releases from just part of the process, rather than the whole-process balance used in the EU ETS).
We have assumed that the level of underestimation in 1998 -2012 is at the same level as in 2013 and we have therefore used the PI data for 1998-2012 but multiplied by a factor of 1.34 to give estimates of emissions in those years. The difference in 2014 -2020 was consistently higher and so a more conservative approach would be to use a factor based on data for all years after 2013 (1.65). However, the Winnington plant was closed in early 2014 and so the years from 2014 onwards are atypical compared with the 1990-2013 period of full operation of both processes. For 1990-1997, no data of any type are available, but since the same two sites have been in operation in the UK across the entire time -series, emissions in 1990-1997 are assumed to be at the same level as in later years. Uncertainties and Time Series Consistency The method used is regarded as the best available given the lack of any production activity data, or a time-series of coke consumption. The use of site-specific EU and UK ETS data for 2013-2021 should ensure that the emission estimates for those years are quite certain. The poor agreement between the PI and EU ETS data in 2013 -2020 means that the emission estimates for 1998-2012, based on PI data, are far more uncertain. The difference between EU ETS and PI data is even greater (in percentage terms) in 2014-2020 than in 2013, however both sites only operated fully throughout 2013, Winnington having closed in February 2014. We have therefore treated the 2013 EU ETS/PI ratio of 1.34 (based on both plants operating throughout the year) as a more reliable guide to the potential underestimation in the PI data in earlier years. Estimates for 1990-1997 are more uncertain still due to the need to extrapolate 1998 data backwards in the absence of any specific information on pro duction, materials usage or emissions in those years. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Source Specific Recalculations No recalculations have been made to emissions from this category. Source Specific Planned Improvements Emission factors and activity data will be kept under review. This category includes emissions from the following 2B8a Methanol, 2B8b Ethylene, 2B8c Ethylene Dichloride, 2B8d Ethylene Oxide, 2B8e Acrylonitrile, 2B8f Carbon Black and 2B8g Other. The UK has a large petrochemical industry, with manufacture of all the chemicals

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 268 explicitly mentioned in the 2006 IPCC Guidelines for at least part of the period 1990 -2021, although a series of site closures in recent years has reduced the number of products Methanol was manufactured in the UK until 2001 in a process which was integrated with ammonia production. Ethylene was produced at five sites in 1990, although the closure of the two works in 1993 and 2010 reduced this to three at the end of 2021. The UK ethylene crackers use either naphtha or natural gas liquids as feedstocks, and off -gases from the ethylene crackers are used as fuels on -site. Ethylene dichloride (EDC) has been produced at 4 sites over the period covered by the GHGI, although only 1 is still in operation, and only 2 of those processes used the oxychlorination route that causes process emissions of CO 2. Ethylene oxide (EO) was produced at a single UK plant between 1990 and closure in January 2010. There is also a single site producing acrylonitrile (ACN): this has operated since 1990 and is still in operation. Two sites produced carbon black, until their closure at the very start, and in the middle of 2009 respectively. Most of the production was of furnace black. A number of other chemical sites also emit CO2 due to the use of off-gases as fuels. Emissions of CO2 at these sites are very small relative to the emissions from ethylene production. All emissions of CO 2 from use of off -gases as fuels is reported under 2B8g, i ncluding the emissions from ethylene production. Many chemical processes emit small quantities of methane, either as a result of fugitive releases from equipment, or as a component of tail gases released from vents. The inventory includes separate emissions data for production of ethylene, methanol, ACN, EO, and carbon black. Emissions of methane from other chemical processes are reported under 2B10. Details of the methodologies used for petrochemical and related processes are shown in Ethylene 2B8g 2B8a Site specific emissions data from EU ETS (CO2 only), PI and from process operators. Where no emissions data are available, these are estimated by extrapolation from data available for later years, taking into account Methanol 2B8b 2B8b See below for CO2 methodology. Emission estimates for methane are based on operator -reported data from the 2B8c - Emissions estimated using IPCC Tier 1 emission factor for process CO2 assuming production is 500,000 tonnes

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 269 Ethylene Oxide 2B8d 2B8d CO2 emission estimates for 1995 -2009 from the PI, emissions in 1990-1994 assumed same as in 1995. CH4 estimates for 2004-2009 from the PI. No emissions data are available for 1990 -2003, so the Tier 1 IPCC default is used, combined with estimates of EO production at the plant derived from the CO2 emitted, and assuming a CO2 emission factor of 0.663 t CO 2 / t EO (IPCC default for oxygen process, default catalyst sensitivity). Acrylonitrile 2B8g 2B8e CO2 emission estimates for 2008-2021 from EU ETS. No data on emissions for earlier years, but the capacity of the plant is thought to have been unchanged since 1990, so the average emission for the 5-year period 2008-2012 is used for 1990 -2007.
The operator reports methane emissions to be be low the 10 tonne threshold for reporting in the PI, so an emission of 5 tonnes/annum is Carbon black 2B8f 2B8f CO2 emissions are reported in the PI for 1998 -2009 for one site, and 2003-2008 for the other (this site closed at the start of 2009, so emissions in 2009 are assumed zero). The PI emissions are assumed to be from process sources, and emissions in earlier year s are assumed to be the same as in the earliest year for which data exist. Emission estimates for methane are also based on PI data for later years, but no data are available for the period 1990-2003, and so the IPCC Tier 1 default is used 2B8g 2B10 Emissions data for other petrochemical processes are taken from EU ETS (CO 2 only), and the PI (English/Welsh sites) or SPRI (Scottish sites). For those years where operator -reported emissions data are not available, then emissions are assumed to be the same as for later years where data are available. There are no petrochemical processes located in Northern Ireland a – production is not known but capacity of two plant in 1987 was 500,000 tonnes and one subsequently closed so 500,000 tonnes is considered a conservative estimate. Methanol production, like ammonia, requires hydrocarbon fuels both as a source of raw materials and as a fuel. The UK methanol process used natural gas . Whereas in ammonia processes, natural gas is reformed to produce hydrogen for the process and carbon dioxide as a waste by -product, in the methanol process reforming of natural gas generates carbon dioxide for the process with hydrogen as the waste product. The UK’s only methanol plant was integrated with one of the ammonia plants, so that carbon dioxide produced by the ammonia plant could be exported and used to synthesise methanol. This CO 2, and additional CO 2 produced in the methanol plant’s own reforming process is assumed stored. The plant closed in 2001 and there is limited information on emissions and none at all on natural gas consumption at the plant. The nominal capacity of the plant was 500 ktonnes but analysis of European production data for the 1997-2001 period indicate that the UK plant production fell sharply between 1997 and 1998 as new capacity came on stream elsewhere in Europe, and

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 270 the plant was closed as uneconomic in 2001. For the period 1990-1996, it has been assumed that the UK plant was running at 98% of capacity, as in 1997. The various estimates of production have then been combined with the IPCC Tier 1 emission factor for methanol using conventional steam reforming of natural gas with integrated ammonia plant (1.02 t CO 2 / t methanol) to give the emission reported in 2B8b. The production estimates are also used to calculate the CO2 stored, and finally, both emitted CO2 and stored CO2 are also converted into estimates of natural gas consumed so that we can ensure there is no double-counting of that The methodology for CO 2 emissions from 2B8g was developed through an inventory improvement research project in 2013-14 (Ricardo-AEA, 2014b), with a review conducted of available data on industrial use of process off -gases and waste residues as fuels, including consultation with operators of several of the installations that were known to use process off- gases as a fuel. The research included a review of data within the EU ETS. In addition, installation-specific (but anonymised) data from the chemical industry C limate Change Agreement (CCA) data reported for 2008 and 2010 were also reviewed. CCA data was used primarily to quality check the number of sites in the chemicals sector that reported the use of waste-derived fuels, and this dataset confirmed that there w ere a very small number of sites reporting waste-derived fuel use. It is not possible with the current data available to distinguish between feedstock-derived off-gases that are used directly as a fuel and those used in other process-related activities tha t result in emissions, such as flaring, and therefore the total emissions reported for those sites are allocated to 2B8g. Uncertainties and Time Series Consistency For the use of waste residues and process off -gases as fuel in the chemical industry, the emissions estimates are somewhat uncertain as the level of completeness of the data over the whole time-series is hard to verify; the 2014 inventory improvement study, however, has confirmed that the inventory covers all high-emitting sites in the UK that have been in operation in recent years, and therefore the overall uncertainty on the UK inventory estimates, at least for the period covered by EU ETS data, is not regarded as significant. Energy and environmental experts within the UK trade association for the chemical sector, the Chemical Industries Association, also confirmed that they were not aware of any other sites in the UK that used process off -gases, over and above the sites included in the UK GHGI (Personal communication, Chemical Industries Associ ation, 2014). These are dominated by the four ethylene production sites and a handful of other sites producing organic chemicals, typically Emission estimates for other sources are mostly based on a mixture of PI and/or EU ETS data with estimates for earlier years then based on the assumption that emissions are as in later years. Tier 1 IPCC default emission factors are used for the minor sources 2B8c (for CO 2), 2B8d and 2B8f (both CH4, part of time-series only). No UK-wide activity data (production data)

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 271 are available with which to generate a better time series for any of the sub-sectors within 2B8, so the earlier part of the time -series for all of the chemical industry sectors is particularly uncertain.
EU ETS-based emissions are considered the most reliable basis for estimates in the GHGI and the uncertainty is estimated to be +- 5%. PI data are more uncertain, because it is not clear what methods are used and the emission sources (combustion, process, other) are not transparent. Uncertainty for GHGI estimates based on the PI data is estimated to be +- 15%. Emissions data for methane are likely to be more uncertain than those for CO2 since the former are often fugitive in nature, or minor components in stack emissions (thus requiring stack monitoring to quantify). Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Source Specific Recalculations No recalculations have been made to emissions from this category. Source Specific Planned Improvements It is noted that this sector has been identified as a key category, and that not all of the estimates within this sector use a tier 2 or higher approach. The UK has recently reviewed this sector and included some additional sources using what is believed to be the best currently available data. The UK will review this position should further information come to light. Emissions arise from the UK manufacture of HFCs, PFCs and HCFC -22. HFC-23 is a by - product of HCFC -22 manufacture. There are two single manufacturers of HFCs and PFCs respectively in the UK, and two companies were operating HCFC-22 plants. Both HCFC plants closed in 2008/9; one reopened in 2013 and was shut down again in 2016. HFC production There is no UK production of SF6. A full description of the emission model and associated methodology used for this sector is contained in AEA (2008). Within the model, manufacturing emissions from UK production of HFCs, PFCs and HFC-23 (by-product of HCFC-22 manufacture) are estimated from reported data from the r espective manufacturers. Manufacturers have reported both production and emissions data, but only for certain years, and for a different range of years for different manufacturers. Therefore, the emissions model is based on implied emission factors, and production estimates are used to calculate emissions in those years for which reported data are not available. Two of the three manufacturers were members of the UK greenhouse gas Emissions Trading Scheme. As a requirement of participation in the scheme, the ir reported emissions were verified annually via external and independent auditors. For PFC production, emissions are now reported to the Environment Agency’s Pollution Inventory, and these emissions are directly used within the GHG inventory. The operator of the HFC and (now closed) HCFC-22 plant provides speciated emissions data directly to the Inventory Agency, based on vent analysis and flowmeter readings, or on weighbridge differences. The other

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 272 HCFC-22 plant, which closed in 2008, also reported to the Pollution Inventory and these emissions were used within the GHG inventory. Uncertainties and Time-Series Consistency The uncertainty analysis in Annex 2, provides estimates of uncertainty according to IPCC source category and fuel type. The uncertainty estimate for emissions from HFC manufacture has been revised for this submission, based on information from the plant operator. There is a significant decrease in HFC emissions in 1998/1999. This step-change in emissions is due to the installation of therm al oxidiser pollution abatement equipment at one of the UK manufacturing sites. Fugitive HFC emissions from both an HCFC -22 plant and HFC manufacturing plant (run by the same operator) are treated using the same thermal oxidiser unit. Emissions also decrea se in 2004, reflecting the installation of a thermal oxidiser at the second of the UK’s HCFC-22 manufacturing sites. This was installed in late 2003, and became fully operational in 2004. HFC-23 emissions decreased in 2009 and 2010 following the closure of both HCFC-22 manufacturing sites. A small emission of HFC-23 remains, which arises from the production of HFC -125, most likely due to impurities in the feedstock. HCFC-22 manufacture restarted in 2013 and was shut down in 2016. A significant increase in PFC emissions from the production of halocarbons is observed from 1992 to 1996 (with the trend changing after 1996). The increase in emissions was due to increasing production levels at the single UK manufacturing plant during this period. Since 1996, the level of emissions has changed each year which broadly reflects the demand (and hence production levels) for PFCs. In 2004 and 2005, emissions reported by the company increased compared with the preceding 3 years of fairly stable emission levels 2001 -2003. Emissions declined sharply in 2007-2009, before increasing again in 2010 and 2011 and then Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6, and details of verification of emissions are given in Annex 6. Data reported via the Pollution Inventory are also further checked by the Environment Agency. Source Specific Recalculations There have been no significant recalculations in this category. Source Specific Planned Improvements There are currently no planned improvements for this sector, however data sources will be The UK has a large chemical manufacturing sector and emissions of methane are reported elsewhere in 2B for emissions from specific chemical processes, but also reported in 2B10 in the case of emissions from other, general petrochemical processes. Methane emissions from ammonia production sites are included in 2B10, rather than being reported separately in 2B1. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 273 Site-specific emissions data for chemical processes located in England and Wales are available in the Pollution Inventory (Environment Agency, 20 22) and Welsh Emission Inventory (NRW, 20 22) respectively. Reporting generally started in 1994 or 1995, and few data exist for the years prior to 1994. Site specific emissions data for processes in Scotland have been obtained from the Scottish Pollutant Release Inventory (SEPA, 2022).
All of the data available are in the form of emission estimates generated by the process operators and based on measurements or calculated based on process chemistry. Emission factors and activity data are not available, but emission factors are estimated using the best available ‘surrogate’ activity data that are available across the time series; this approach then enables estimates of emissions to be made for the years prior to ope rator-reported emission estimates (typically pre-1994). For most commodities, the extrapolation is linked to changes in the level of output from the chemicals manufacturing sector as measured by the 'index of output' figures published by the Office for National Statistics (2022). Uncertainties and Time Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC source category and fuel type. Estimates for 1994 onwards are mostly based on data reported by process operators through the regulatory agency data management and checking systems that govern UK industrial emissions data within the PI, WEI, SPRI and NIPI. The dataset is evidently incomplete in some years, due to the variations through time in the reportin g thresholds for different pollutants. The Inventory Agency has used good practice techniques to address these reporting inconsistencies, and therefore the completeness of the data is good through the time series. Unfortunately, UK production data are not readily available for chemicals and other products from the sites reported under 2B8. This inhibits the Inventory Agency’s ability to conduct data validation tests on the reported emissions data against a reliable time -series of production estimates. Emission estimates for the period prior to 1994 are also more uncertain due to the need for extrapolation of emissions data for 1994 or some other year backwards, using general indicators of chemical industry output. Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6. Emissions data taken from the Pollution Inventory are subject to additional QA/ QC by the Environment Agency before being used in the inventory. Source Specific Recalculations There are recalculations for the years 2010 to 2021 due to revisions to the ONS index of production figures in the most recent publication. Source Specific Planned Improvements Minor revisions to emission estimates may be required periodically in order to deal with changes in the data available e.g. revisions to emissions reported to UK regulators. The Inventory Agency will continue to review the ava ilable operator-reported data and seek to derive a consistent time series of emissions. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 274 Emissions sources Sources included Method Emission Basic oxygen furnaces - dolomite Following for indirect gases Rolling Mills (Hot & Cold Rolling) Iron and steel production may be divided into integrated steelworks, electric arc steelworks, downstream processes such as continuous casting, and iron & steel foundries. Integrated steelworks convert iron ores into steel using the three processes of sintering, pig iron production in blast furnaces and conversion of pig iron to steel in basic oxygen furnaces. For the purposes of the inventory, emissions from integrated steelworks are estimated for these three processes, as well as other minor processes such as slag processing. Sintering agglomerates the raw materials for the production of pig iron by mixing these materials with fine coke (coke breeze) and placing it on a travelling grate where it is ignited. The heat produced fuses the raw materials together into a porous material called sinter. Blast furnaces are used to reduce the iron oxides in ore to iron. They are continuously charged with a mixture of sinter, fluxing agents such as limestone, and reducing agents such as coke. Hot air is blown into the lower part of the furnace and reacts with the coke, producing carbon monoxide, which reduces the iron ore to iron. Gas leaving the top of the furnace has a high heat value because of the residual CO content, and is used as a fuel in the steelworks. Molten iron and liquid slag are withdrawn from the base of the furnace. The most significant greenhouse gas emissions to occur directly from the blast furnace process are the combustion gases from the 'hot stoves' used to heat the blast air. These generally use blast furnace gas (BFG), together with coke oven gas and/or natural gas as fuels. Emissions are reported in CRF cate gory 2C1. Gases emitted from the top of the blast furnace are collected and emissions occur when this BFG is subsequently used as fuel. Pig iron has a high carbon content derived from the coke used in the blast furnace. A substantial proportion of this mu st be removed to make steel and this is done in the basic oxygen furnace. Molten pig iron is charged to the furnace and oxygen is blown through the metal to oxidise carbon and other contaminants. As a result, carbon mono xide and carbon dioxide are emitted from the furnace and are collected for use as a fuel. As with blast furnace gases, some losses occur and these losses are reported with blast furnace gas losses in 2C1. Limestone and dolomite are used in steelmaking, typically being added to sinter where t hey are calcined, releasing CO2 which is emitted. Some of the limestone or dolomite used may be added directly to blast furnaces without being sintered first, which would mean that the CO 2 released would be emitted from the blast furnace stage of steelmaking rather than the sintering stage. However, this distinction is not important for GHG reporting and the practice is ignored

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 275 for the GHGI with all additions and, therefore, emissions being reported as from sintering. Dolomite is also an important addition as a fluxing agent in basic oxygen furnaces and CO 2 evolved from the dolomite is reported as a separate category under 2C1.
Electric arc furnaces produce steel from ferrous scrap using electricity to generate the high temperatures necessary to melt the scr ap. Carbon dioxide emissions occur due to the breakdown of the graphite electrodes used in the furnace. The UK had 2 integrated steelworks (at Port Talbot & Scunthorpe) in operation at the end of 2021, following the closure of the Teesside works in September 2015. In 1990, five sites had been in operation, with the steelworks at Ravenscraig in Scotland closing in 1992, followed by the closure of Llanwern in Wales in 2001. Teesside was mothballed between January 2010 and April 2012 due to the loss in demand for its steel products. Electric steel is manufactured in 3 large steelworks, in Rotherham, Sheffield and Tremorfa, and a few smaller works. Other large electric arc steelworks once operated in Sheerness, and Newport. The methodology for estimating CO2 emissions from fuel combustion, fuel transformation, and related processes at integrated steelworks is based on a detailed carbon balance (this methodology is described in more detail within the section on CRF sector 1A2a). C arbon emissions from integrated steelworks are reported under 1A1c, 1B1b, 1A2a, 2A3 and 2C1, depending upon the emission source. Emissions from sintering (from use of both coke breeze and limestone & dolomite), flaring of blast furnace gas and basic oxygen furnace gas, use of dolomite in oxygen furnaces, and from arc furnaces are all reported under 2C1. Flared losses of blast furnace gas (including basic oxygen furnace gas) are given in DUKES and carbon factors are derived using the carbon balance described previously. Usage of limestone and dolomite for steel production is available from the Iron & Steel Statistics Bureau (2021). The carbon content of limestone and dolomite used at steelworks is available from operators via the EU ETS data. Separate values are available for the years 2007-2021. These data show close consistency across the time series and therefore the 2007 value has been extrapolated back to 1990. The carbon emissions from electric arc furnaces cover electrode emissions, as well as CO2 emissions from the addition of scrap metal, alloys, carbonate minerals and other additives. The methodology also takes account of carbon stored in by -products, such as steel, slag, scales etc., produced during the steelmaking process. Electric arc furnace operators including Liberty Steel and Outokumpu have provided additional information regarding the fuels used, process inputs (e.g. other carbon sources, reductants, electrodes, wastes, slags, carbonates) that underpin the carbon emissions data for their electric arc furnaces as reported via the EU ETS. [A UK GHG Inventory research paper was drafted in 2021 to summarise research in the sector and describe the development of the inventory methodology; that report (Passant and Gorji, 2021) is commercial in confidence but can be shared with an Expert Review Team on request.] The comparison between the operators and EU ETS data allows for calculation of a more detailed timeseries of emission factors for those individual sites. Further analysis was then required for the purpose of gap-filling for the periods where no or limited data were available due to the changes in the reporting procedures in different EU ETS phases. There are a number of electric arc furnace plants that have been closed over the years, and therefore further gap -filling exercise was required to estimate emissions from such plants. Based on the revision of the operations of such plants, the emission factors obtained from the first phase of the currently operational plants were deemed suitable for es timating their

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 276 emissions. This method therefore allowed to account for emissions from the plants that have stopped production over the timeseries. The Inventory Agency has developed a time series consistent method by applying IPCC good practice methods to address data gaps, as • Identification of (22) EAF sites operating in the UK across the time series; this includes several EAFs that operated only prior to the start of the EUETS in 2005 and for which there are very scarce data on activity and emissions; • Analysis of the ISSB production statistics on EAF steel production since 1990, including annual UK-wide statistics and also regional production data; • Analysis of the Regulator Inventory data, to identify all available emissions data, including for smaller EAF sites that are evidently omitted from the ISSB statistics; • Use of EU ETS emissions data and ISSB regional production data to derive a time series of IEFs for production for the larger (8) EAF sites that report within EU ETS; • Development of a hyb rid approach to apply operator emissions data per installation where available and to gap -fill for the remaining UK production using the IEF across the sector from the EU ETS reporting, with the 2005 data back-cast to earlier years. Emissions from the use of coke oven coke in foundries and other iron & steel industry processes are included in category 1A2a but any other process emissions from foundries of methods used for emissions reported under 2C1. Source Category Method Activity Data Emission Factors UK-specific factor from UK-specific based on reported AD x EF ISSB UK-specific from EU ETS Iron & steel - flaring AD x EF BEIS energy UK-specific factor from Electric arc furnaces AD x EF ISSB UK-specific factor Ladle arc furnaces AD x EF ISSB UK-specific factors Uncertainties and Time Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC source category and fuel type. Much of the activity data used to estimate emissions from this source category come from the Iron and Steel Statistics Bureau and from DUKES. Time -series consistency of these activity data is very good due to the continuity in data in these publications. Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 277 Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the inventory in Section 1.6.
The UK inventory carbon balance method uses the best available industry data across the time series, including EU ETS data from integrated steelworks from 2005 onwards. The comparison in recent years between the UK GHGI method and the EU ETS data for individual installations indicates that the GHGI method is somewhat conservative, as the GHGI data are generally slightly higher than installation data. The Inventory Agency will continue to keep the method and input data under review to ensure that the carbon balance model delivers estimates that are as accurate as possible for the UK. Source Specific Recalculations Due to a methodology update to further utilise the EU ETS data, a more complete timeseries of operator data has been developed. The result of this is an increase in total emissions across the timeseries, specifically an increase of 18kt in 1990 and an increase of 8kt in 2019. For further information on recalculations, see Section 10. Source Specific planned Improvements It is noted that this sector has been identified as a key category, and that not all of the estimates within this sector use a tier 2 or higher approach. The UK uses what is believed to be the best currently available data, and that tier 1 methods are only used for very limited parts of this sector. The UK will review this position should further information come to light. Emission factors and activity data will be kept under review. Where appropriate, fuel characterisation data from verified EU ETS datasets will be considered in future GHGI cycles. The term ferroalloy cove rs a wide range of products, manufactured by various means, only some of which lead to industrial process emissions of greenhouse gases. Potential sources of • Use of reductants such as coke oven coke; • Consumption of carbon electrodes in furnaces used for melting raw materials; • Decarbonisation of limestone or dolomite used as a fluxing agents; • Decarbonisation of any carbonate ores used. The UK has been a minor producer of ferroalloys. The previous version of the BREF note (Best Availabl e Techniques Reference document) for the non -ferrous metals industry, produced by the European IPPC Bureau69 estimated UK production in 1993 as 55 ktonnes out of a European total production of 2,620 ktonnes while the updated version of that document, published in 2017, does not identify any production of ferroalloys at all in the UK in the period Other than the estimate for 1993 given in the BREF note, the Inventory Agency has not found any data on UK production of ferroalloys. The absence of the UK as a European producer in the recent update of the BREF note suggests that UK production is either zero or insignificant; through consultation with trade associations and industry statistics experts (ISSB) the Inventory Agency has only been able to identify a few small-scale manufacturers of specialist ferroalloys such as ferro-molybdenum and ferro-vanadium. The production data for 1993 lists 45,000 tonnes of ferromanganese production in a blast furnace (where emissions would arise 69 downloadable from

Industrial Processes (CRF Sector 2) 4 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 278 from use of reductant s), and 10,000 tonnes of other ferroalloys in electric furnaces. The ferroalloy producers identified as in operation in recent years either carry out exothermic processes only (for ferro -molybdenum alloys) or use electric induction furnaces for melting. None of the processes report any CO2 emissions in the Pollution Inventory, or are included in the EU/UK ETS; the Inventory Agency has not identified any process currently in operation that would cause any industrial process emissions of direct GHGs. The estimated production of 45,000 tonnes of ferromanganese in 1993 would use coke oven coke or coal as a reductant, and therefore the emissions are already included in the inventory as all UK consumption of these fuels is assumed to lead to emissions of CO2. Any emissions associated with ferroalloy production would therefore already be included in 1A2a or 1A2b for coal, or 1A2g or 2C6 for coke oven coke. Given the lack of a time-series of production data, or information on the type or quantities of any reductant u sed in the ferromanganese production, the Inventory Agency has not made any re-allocation of emissions from 1A or 2C6 to 2C2. There is no evidence of any current use of electric arc furnaces, or the use of limestone or dolomite fluxes or carbonate ores. Th erefore, UK emissions from ferroalloys are i) Included Elsewhere in the case of any emissions from use of reductants; ii) Not Occurring in the case of emissions from other sources. Aluminium was produced by the electrolytic reduction of alumina at two UK sites at the end of 2011, although the larger of these two sites subsequently closed in early 2012, leaving just one small smelter operating in the UK. A third site had closed during 2009, and a fourth closed in mid-2000. The operational site and the recently -closed processes all use or used the pre - baked anode process, whereas the plant closed in 2000 used the Soderberg Cell process. This distinction is important because of large differences in emission rates for some pollutants. Both process types make use of carbon anodes and these anodes are consumed as the process proceeds, resulting in emissions of CO2. The PFC species tetrafluoromethane (CF4) and hexafluoroethane (C2F6) are formed if the alumina content of the electrolyte falls too low. Computerised control of alumina addition to the cells is a feature of modern plant and has helped to reduce PFC emissions from aluminium production. Emissions of methane are not estimated as there is no methodology available and emissions are considered to be negligible. The smelter design has a large effect on the rate of PFC emissions, and point feeder prebake technology is regarded as the best option for feeding aluminium oxide into the electrolytic cells, allowing addition at controlled intervals, resulting in fewer anode effects.