At sites and inventory years for which robust data on landfill gas flaring are not available, it is conservatively assumed that no landfill A high standard of gas collection and combustion efficiency is achieved by compliance with the Landfill Directive requirements for gas collection, and by implementing national guidance on landfill gas collection. This is enforced via the landfill permitting and regulatory processes. Large-scale passive venting of landfill gas is no longer accepted under permitting conditions and impermeable barriers are required as best practice to prevent the migration of landfill gas Power generation is currently the dominant use for landfill gas in the UK and good data are available on this from official sources. The method for calculating methane combusted in landfill gas engines is as reported in the 2 013 UK NIR. In summary, the quantity of methane combusted was calculated as Mass of methane combusted (kT) = Electricity generated (GWh) / Net calorific value of methane (50,000 GJ/kT) The assumed efficiency of landfill gas engines in these calculations was calculated in accordance with research carried out for the UK Government (Golder Associates, 2014). Engine efficiency was assumed to be 30% up to 1996, and 36% from 2012 onwards. Between 1996 and 2012, engine efficiency was assumed to increase linearly from 30% to 36% Current data on the amount of methane used for power generation in England, Scotland, Wales and Northern Ireland, calculated from the electricity generated from landfill gas as 3,313 GWh renewable electricity was generated from combustion of landfill gas. Carbon dioxide emitted from the combustion of landfill gas is biogenic in origin and is therefore not Since 2009, operators of landfills in England and Wales permitted under the Integrated Pollution Prevention and Control (IPPC) Directive have been required to report the annual quantity of methane flared at the regulated sites under the terms of their operating permits. As

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 456 it has been obtained under the terms of IPPC operating permits, this data has documentation and quality control built in via the permitting procedures and operator obligations at an individual site level . The use of this dataset is therefore a robust and appropriate basis on which to evaluate the quantities of methane flared by operators. Based on guidance from the Expert Review of the 2013 GHG Inventory (para 98 of the 2013 Annual Review Report), this dataset was used to estimate the quantity of methane flared at landfill sites in England and Similarly, landfill site operators in Scotland have been required to compile a similar annual report on the quantity of landfill gas flared since 2013. This dataset was used to evaluate the quantity of methane flared by operators at landfill sites in Scotland from 2013 onwards. Further work was commissioned by BEIS (then DECC) to identify all reasonably available data on the quantities of methane flared at landfill sites in England, Scotland and Wales for other years (DECC, 2015). This project identified some additional site-specific data which was also taken into account in compiling the inventory. Additionally, landfill operators voluntarily provided further site-specific data on the quantities of methane flared at older sites without a reporting requirement set in permit conditions for 2010 to 2015. The landfill methane flaring data provided represents information for approximately 365 individual sites in 2021. Data checking/validation therefore relies on the regulatory authorities and processes, rather than comprising additional checks on individual operators. The information on landfill gas flaring is provided via under the Environmental Permitting (England/Wales) and Pollution Prevention and Control (Scotland/Northern Ireland) regulatory processes. This information is consequently subject to quality obligations under these regulations, as with any other information reported to the regulatory authorit ies by regulated process operators under the terms of their operating permits. The data is then forwarded to the compilation agency by each regulatory authority. At all other sites and inventory years, robust data on landfill gas flaring was not available, and it was conservatively assumed that no landfill gas was flared. generation added to the estimated quantity of methane flared. The minor proportion of landfill gas used for non -electricity generation purposes such as direct use and as a vehicle fuel is neglected in these calculations due to a lack of data, and assumed to be emitted to the atmosphere as a conservative assumption. 7.2.3.4 Overseas Territories and Crown Dependencies The IPCC landfill model is used for all landfill estimates. Where available, country -specific waste generation and composition data have been applied and appropriate defaults have been chosen e.g. taking into account climatic variation. There are n o landfill emissions for Gibraltar as waste is exported. Parameters used in these calculations are shown in Annex Uncertainties and time-series consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC source category and fuel type. There are many uncertainties in estimating methane emissions from landfill sites. The model is sensitive to the values assumed for the degradable organic carbon (DOC) present in different fractions of waste, and the amount of this that is dissimilable (i.e. is converted to methane and carbon dioxide), as well as to the quantity of methane combusted in engines and flares, and the oxidation factor. The uncertainty estimates in Annex 2 are intended to reflect the current uncertainties in data and model parameters. The estimates for all years have been calculated from the MELMod model and thus the methodology is consistent throughout the time series. Estimates of waste composition and

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 457 quantities have been taken from different sources as described in Section 7.2.3. The new sources of data on waste receipts from 2005 – 2008 onwards are considered to be more robust and consistent than the previous combination of data sources. The approach to calculating DDOC, the main driver behind methane formation, was reviewed and updated in 2011, and was endorsed by peer reviewers.
Uncertainty in the quantity of methane collected is also an important contributory factor to uncertainty in the calculation of overall landfill methane emissions. Uncertainties in the key components of this calculation are as follows. • Current and historical combustion of methane in landfill gas Reliable data on methane collected for power generation are available, based on national statistics for energy generated from landfill gas engines (BEIS , 2022). The methane to carbon dioxide ratio of gas burnt in landfill gas engines is assumed to be 50:50, following the IPCC default approach. Gas engine efficiency is assumed to be 30% up to 1996, increasing linearly to 36% in 2012 and thereafter, following peer review (Golder Associates, 2014). This is considered to be a reasonably reliable calculation of the quantity of methane combusted in landfill gas engines; and • Combustion of methane in flares. These data are based on site-specific records where available and are considered to be accurate for the sites where d ata exist. However, records of the quantity of landfill gas are incomplete, particularly for the years prior to 2008. In cases where records of landfill gas flaring are not available, the quantity of methane flared was assumed to be zero. This means that t he landfill methane inventory is subject to greater uncertainty for the years prior to 2008, although because of the conservative approach adopted in respect of landfill gas flaring, it is considered that the inventory represents an over-estimate of methane emissions from landfill sites in the UK, particularly for the years prior to 2008. Landfill permit conditions are designed to deliver a high standard of gas collection and combustion efficiency. Requirements to design and operate landfills in order to minimise gas escape have strengthened considerably since the 1990s. In this context, the calculated collection efficiencies of 46% to 58% for the period 20 09 to 202193 derived in this analysis appear reasonable. Lower collection effi ciencies in the years between 1990 and 20 08 are likely to be more conservative. Oxidation of methane in the surface layers of landfills i s a further source of uncertainty in overall emissions. In the absence of better data, the IPCC oxidation default factor of 10% is applied to the estimated quantity of gas released as a fugitive emission. A pilot survey carried out on behalf of the UK Gove rnment and Environment Agency included measurements of surface methane oxidation. This study did not support a move away from the IPCC default position. A particular challenge in deciding oxidation rates for use in a national landfill model is the high level of variability in field measurements, reflecting a wide range of factors such as nature and porosity of the surface layers, moisture content and temperature, along with methane production rates in the underlying waste. Source-specific QA/QC and verification This chapter provides the information described in IPCC (2006) Section 3.8 “QA/QC, Methodological data are described in Section 7.2.2 above, with quantitative data in Annex 3.5.1. Activity data are described in Section 7.2.3 above, with quantitative data on annual waste amounts and the quantities of landfill gas collected in Annex 3.5.1. A breakdown of

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 458 waste composition for each year is available but as noted in IPCC (2006) Section 3.8, it is not practical to provide all documentation in the National Inventory Report. In relation to specific recommendations of IPCC (2006) Section 3.8: • “Countries using other methods or models should provide similar data (description of the method, key assumptions and parameters)” – this is provided in Section 7.2.2. • “If country -specific data are used for any part of the time series, it should be documented.” – country-specific data on DOC, DOCf and MCF are used, as • “The distribution of waste to managed and unmanaged sites for the purpose of MCF estimation should also be documented with supporting information. ” This is • “If CH 4 recovery is reported, an inventory of known recovery facilities is desirable. Flaring and energy recovery should be documented separately from each other.” Data on methane recovery for ele ctricity generation is based on national statistics on electricity generation from landfill methane combustion, rather than reports of recovery at individual facilities. Data on methane recovery and flaring in 2019 is based on records from a total of 186 individual facilities in England, 40 in Scotland, 17 in Wales, and 3 in Northern however, it is not practical to provide documentation for all these facilities in the National Inventory Report. Methane recovery for flaring and energy recovery are separately documented in Section 7.2.3 and Annex 3.5.1. • “Changes in parameters from year to year should be clearly explained and referenced.” There was no change in parameters between 2017 and 2019. The landfill methane model has been subject to peer review in 2011 and 2014 (see Eunomia Consulting and Research, 2011; Golder Associates 2014). The landfill methane model is subject to normal quality assurance procedures, as described in Section 1.6. IPCC (2006) guidelines, section 3.8 suggests that calculated emissions can be compared with those of similar countries.
Relatively few countries have a similar history of landfill use to the UK, but in 2017 emissions for the period 1990-2015 were compared to data taken from NIRs recently produced by Ireland and Italy where landfill use has been extensive in the past, and 1990 93.3 1.9 25.2 2709 53 726 1% 0% 15% 1995 104.5 2.0 28.5 2939 64 677 5% 0% 21% 2000 84.9 2.1 27.4 3028 74 776 17% 32% 28% 2005 72.6 2.3 21.2 2870 90 787 32% 55% 40% 2010 51.4 1.6 19.1 2278 98 701 53% 89% 60% 2011 52.5 1.4 16.7 2159 96 678 55% 84% 65% 2012 49.6 1.2 14.4 2041 93 680 55% 87% 61% 2013 48.4 1.0 13.8 1929 89 612 60% 79% 76% 2014 48.2 0.8 12.6 1820 84 600 63% 69% 74% 2015 51.0 0.6 11.4 1716 80 565 62% 63% 81%

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 459 There is no more than a very approximate connection between the amount of waste landfilled in any year, and the amount of methane generated. The connection is stronger in cases where the quantities and composition are constant over a longer period of time. Nevertheless, for the majority of years, the reported quantity of methane generated in all three countries was in the range 24 to 50 kT methane per Mt waste landfilled. The UK was in the range 28 to 44 k t methane per Mt waste landfilled throughout the time series, with both higher and lower values exhibited by Italy and Ireland. This indicates that there are no causes for concern regarding any obv ious inconsistency in the overall results for methane generation with the values reported by these other countries. Since 2013, the UK has reported an estimated methane collection efficiency of between 59% and 63%. This is comparable with, and, if anything, lower than the collection efficiencies reported by Ireland and Italy. This indicates that there are no causes for concern regarding any obvious inconsistency in the estimated methane collection efficiency with the values reported by these other countries. This onetime comparison was specifically performed to compare the methane collection efficiencies between the countries but was not carried out for the purposes of verification of For the 2019 submission, an ad -hoc verification of the MELMod model was also carried out by comparing the estimation of emissions for 1990-2017 from the UK (Tier 2) model with the IPCC Tier 1 model. The IPCC model was set up in two firstly, to reflec t the UK Tier 1 model inputs so far as possible, and secondly, to reflect IPCC default inputs . The key methodological differences between MELMod and the IPCC-waste model with IPCC defaults • The MELMod model contains a more detailed breakdown of waste types with different categories to those used in the IPCC model. Hence it was not possible to accurately represent the MELMod inputs in the IPCC default model. • The UK model allows for different waste types to have a range of rapidly, moderately and slowly decaying wastes, compared to the single value for each waste type used • Additionally, the IPCC model includes a category of “Industrial waste” whereas the UK model is based on the EWC codes for every waste consignment, and so does not have an equivalent to the “industrial waste” category. This category was therefore not used in the IPCC model, further restricting the range of inputs available. The model results are compared with each other, and with results derived from analysis of

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 460 results and estimates derived from environmental measurements The following conclusions were drawn from this a) In view of the similarity between the UK model and the IPCC Model Configuration 1, the UK model does not appear to have significant errors in how it is set up. b) The results obtained using the UK Tier 2 model and IPCC Tier 1 Model set up to reflect UK waste and landfill management practices are more reliable than the results obtained using the IPCC Tier 1 Model default inputs. c) The UK landfill methane model provides a reliable calculation of landfill methane emissions for the period 2010 to 2016. d) The UK landfill methane model diverges from the estimated quantities calculated from environmental measurements for the period 1990 to 2005. This is currently under review via a separate initiative. e) The IPCC Tier 1 model using default inputs d oes not provide a robust estimate of UK landfill methane emissions. The MELMod outputs have been compared to the outputs that would result from applying the IPCC Tier 1 methodology to the available data on UK waste receipts. This process indicated that the UK model does not have significant errors in how it is set up, and the use of UK - specific inputs to the UK Tier 2 model or the IP CC Tier 1 model gives more reliable results than the use of the IPCC Tier 1 model with IPCC default inputs. In conclusion, this analysis provides confidence in the UK greenhouse gas inventory for Sector 5.A. The verification of MELMod has been described in the 2008 NIR. The update undertaken by Eunomia (Eunomia, 2011) in 2010 resulted in the updating of input data to the model only,

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 461 with no changes implemented as to calculation methodology other than where indicated. The changes to the model input data recommended by Eunomia were peer reviewed by independent experts from academia, industry, regulators and consultants in late 2010, before their incorporation into the UK inventory. The implementation of the recommended changes within the model has now also been reviewed, and the changes arising from this review were MELMod was subject to a further peer review process in 2014 (Golder Associates, 2014).
In the light of this peer review, changes were made to the assumed efficiency of landfill gas As described in Section 1.6.3, the UK GHGI is verified against data measured from the InTEM network of measurement masts. These measurements indicate good agreement with the UK inventory for the period 201 0 onwards, during which time there has been no strong trend in the landfill methane inventory, the total UK methane inventory, or the estimated inventory derived from the InTEM measurements . However, over the period 1990 – 2010, the InTEM measurements indicate a reduction of about 30% to 40% in the total UK methane emissions, whereas the GHGI for sector 5A indicates a more significant reduction of up to 60%. The trend in the UK GHGI is driven mainly by reductions in landfill methane emissions. The reasons for this discrepancy are currently under review, as discussed in Section 7.2.7. Source-specific recalculations Changes to the UK landfill methane inventory for 2021, as • Data on waste landfilled for Wales and Northern Ireland in 2020 was updated following a revision to waste allocation based on EWC codes • Revision of methane flaring data for England and Wales for 2019-2020. As a result, slight changes to the landfill methane inventory for England, Scotland, Wales and Northern Ireland were calculated. The UK inventory of methane emissions from this combusted in engines and flares, oxidised by the landfill surface and emitted to the Source-specific planned improvements The Inventory Agency is working on improvements to the spatial distribution of landfill methane emissions data. This will enable verification of the calculated inventory against the InTEM field measurements to be carried out in more detail (InTEM is discussed in Annex 6). UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 462 Emissions sources Sources included Method Emission 5B: Composting (non-household) Anaerobic digestion (non-agricultural) Mechanical biological treatment Key Categories 5B: Biological treatment of solid waste - CH4 (T1, T2, L2) 5B: Biological treatment of solid waste – N2O (T2) Estimates have been made for OT and CD emissions from 5B1, composting of municipal solid waste, where data on the total amount of waste composted is available. In these cases, 2006 IPCC default EFs are applied. These estimates are included within 5B for CRF reporting. Completeness No known omissions. A general assessment of completeness for the inventory is No major improvements have been made since the last Emissions of methane and nitrous oxide from composting of MSW (Category 5.B.1) and anaerobic digestion and Mechanical Biological Treatment (MBT) (Category 5.B.2) are estimated using a Tier 2 methodology. This was identified as an appropriate approach in view of the scale of emissions from this sector (DECC, 2015b). Activity data for composting and anaerobic digestion relies on the approaches used in the GHG and ammonia inventories. Activity data f or composting was derived from Devolved Administrations’ data on organic waste fractions. Inputs to household composting were calculated by using population statistics and district level analysis for home composting in the Activity data for MBT and whether the MBT is aerobic or anaerobic is based on a nnual organics recycling reports, published between 1998 and 2013 The Waste and Resources Action Programme (WRAP, 2009 to 2014), The Association for Organics Recycling (2006 to 2008), The Composting Association (1998 to 2005). Some extrapolation and interpolation are required to generate a complete and consistent time series. Activity data for anaerobic digestion was derived from a site information database recorded in the National Non-Food Crops Centre ( NNFCC 2021). The reported inputs to each site in NNFCC reflect the actual tonnes inputted by feedstock category. [The UK activity data are summarised in Annex 3.5.2]

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 463 Emissions from the anaerobic digestion of agricultural residues are not considered in the waste sector. These emissions are reported in the agriculture sector (CRF Sector 4), as it is suggested by the IPCC 2006 Guidelines. Emission factors for source categor y 5.B.1 and the anaerobic digestion component of 5.B.2 were taken from IPCC (2006) default emission factors. IPCC 2006 Guidelines published an update for the waste sector in July 2015. This update is related to the default CH 4 and N2O emission factors proposed for composting and anaerobic digestion and it has been applied to the complete time series. CO2, in line with the IPCC methodology, is not included in the Inventory calculation as it comes from material of biogenic origin. The emission factors for the anaerobic digestion component of mechanical biological treatment were assumed to be t he same as for anaerobic digestion. 7.3.2.1 Overseas Territories and Crown Dependencies Emissions from 5.B.1 have been estimated, however due to data availability, only estimates for Guernsey and Bermuda can be derived. Within Guernsey, composting has only occurred on the Island since 2008, due to creation of a new national composting scheme. The total amount of waste composted within this scheme has been supplied by Guernsey. Official statistics provide the amount of waste composted in Bermuda. IPCC 2006 default emission factors for both CH4 and N2O have been applied. Uncertainties and Time Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC source category and fuel type. Activity data for industrial activities over the time series were taken from relevant publications and are considered to provide robust and accurate data. Activity data for home composting is less reliable, but now represents a small proportion (approximately 3%) of total composting activity carried out in the UK. IPCC Tier 1 default emission factors were used for this analysis. These are considered to be less reliable, and hence subject to greater uncertainty. This is the key source of uncertainty in emissions from the 5.B sector. Time series consistency is based on activity data and is considered to be reasonably representative of activity in this sector between 1990 and 2021.
Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the greenhouse gas inventory in Source Specific Recalculations The inputs to anaerobic digestion plants have been revised and the historic timeline updated based on a new methodology to calculate composting emissions (UKCEH 2022).This resulted in an decrease in the quantity of waste assumed to be processed at permitted composting facilities (~-6% in the latest year), and associated methane and nitrous oxides emissions. For information on the magnitude of recalculations, see Section 10. Source Specific Planned Improvements Emission factors and activity data will be kept under review. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 464 Emissions sources Sources included Method Emission 5C2: Accidental dwellings Accidental other buildings Gases Reported CO2, CH4, N2O, NOx, CO, NMVOC, SO2 Key Categories None identified Included in the CRF with the UK MSW incineration, since the same emission factors are applied, apart from 5C2.1b, incineration of waste from small scale burning, where estimates are now made for Guernsey using IPCC default Completeness A general assessment of completeness for the inventory is No major improvements have been made since the last This source category covers the incineration of wastes (excluding waste -to-energy facilities which are reported in X ). The UK also reports indirect GHG emissions from various other sources including crematoria, small-scale waste burning, accidental fires, and fireworks under 5C2. Methane emission estimates are included for accidental fires. In the UK, all MSW incineration plants have recovered energy since 1997, and so emissions are reported under CRF source category 1A1a. For the years 1990-1996, at least some MSW was incinerated at plants with no energy recovery, so emissions are split between 1A1a and 5C for those years, in proportion to the waste burnt with and without energy recovery respectively. All incineration of chemical wastes, clinical wastes, sewage sludge and animal carcasses is reported under 5C1, since we have no information on any recovery of energy from these processes. In -situ burning of agricultural waste e.g. crop residue burning is The numbers of chemical waste, clinical waste and sewage sludge incinerators in the UK are not known with certainty, although that number has almost certainly decreased significantly between 1990 and 20 21. A total of 26 incinerators regulated under the Industrial Emissions Directive (IED) have been identified as operating in 20 21 - 2 burning sewage sludge, 15 burning clinical wastes, and 9 burning chemical wastes. It is possible that a few very small incinerators, outside the scope of IED, may also exist. Approximately 2600 animal carcass

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 465 incinerators were believed to be in use in the early 2002 (estimated in AEA Technology, 2002) and in the absence of updated data, we assume this is still the case. Animal carcass incinerators are typically much smaller than the incinerators used to burn other forms of waste. Numbers of crematoria are slowly increasing in the there were 312 in 2021 compared with 239 in 1999 (based on statistics published by the Cremation Society of Great Britain, website at This source category also includes emissions from the open burning of wood waste in Emissions of CO 2, CO, NO x, SO 2, and NMVOC from chemical waste incinerators are estimated based on analysis of emissions data reported to the Pollution Inventory (Environment Agency, 2021), the Welsh Emissions Inventory (NRW, 2021) and the Northern Ireland Pollution Inventory (NIEA, 20 21). These data so urces cover England, Wales and Northern Ireland respectively. There are not thought to be any plants in Scotland. Emissions data are not available for all pollutants for all sites and so some extrapolation of data from reporting sites to non-reporting sites occurs, using estimates of waste burnt at each site as a basis. The gaps in reported data are usually for smaller plants but the need for extrapolation of data may contribute to significant variations in the quality of the estimates. Emissions of N2O from chemical waste incinerators are estimated using the 100 g N 2O / t waste default factor for industrial waste incineration given in the IPCC guidelines (2006 ). Waste tonnages burnt at the largest individual chemical waste incinerators for the period 2006 – 2018 have been obtained from the Environment Agency, but the overall quantity of chemical waste burnt must then be estimated by the Inventory Agency, with estimates for the smaller plant based on their capacity. For the earlier part of the time series, we use the following estimates of total 1993 290,000 tonnes (HMIP, 1995) 2002 284,000 tonnes (Entec, 2003) the HMIP and Entec figures for the years 1994-2001. For the period 2003-2005, we interpolate use of reported emissions data for pollutants other than N2O avoids the need to rely upon the highly uncertain activity data. Emissions of CH4, CO, N2O, SO2 and NMVOC from sewage sludge incineration are estimated using literature-based emission factors, while emissions of NOx are estimated using Pollution Inventory data. The factor for N2O is the average of the range of emission factors given in the 2000 IPCC good practice guidance for UK sewage sludge incineration. Emission factors for other pollutants are taken from the EMEP/EEA Emission Inventory Guidebook. The quantity of waste burnt annually is estimated using data from various sources, 1991-1998 Digest of Environmental Statistics (Defra, 2004) 2006-2021 Environment Agency, waste disposal data for individual sites in England 2004-2021 Inventory Agency estimates for Northern Ireland, based on design capacity of incinerator plant at only site. 2013, 2015-2018 Scottish Environment Protection Agency, estimates of total sewage sludge Interpolation between the various estimates is used to fill the gaps in the activity data time

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 466 Emissions of CO2, CH4, CO, N2O, NOx, SO2, and NMVOC from clinical waste incineration are estimated using literature-based emission factors. The factors for CO2 and N2O are 2006 IPCC and 2000 IPCC default factors respectively.
Emission factors for other pollutants are largely taken from the EMEP/EEA Emission Inventory Guidebook. The quantity of waste burnt annually is also estimated, these estimates being based on information given in the following 2006-2021 Environment Agency, waste disposal data for individual sites in England 2004-13, 2015-21 Scottish Environment Protection Agency, estimates of total clinical waste Interpolation between t he various estimates is used to fill the gaps in the activity data time Emission estimates for animal carcass incinerators are taken directly from a Defra -funded study (AEA Technology, 2002) and are based on emissions monitoring carried out at a cross section of incineration plants. No activity data are available and so the emission estimates given in this report are assumed to apply for all years. Emissions of CO, NO X, SO 2 and NMVOC from crematoria are based on literature -based emission factors, expressed as emissions per corpse, and taken from US EPA (2008). Data on the annual number of cremations is available from the Cremation Society of Great Britain Emissions from MSW incineration for the period 1990 -1996 are reported as a split between 1A1a and 5C, in proportion to the tonnages of waste burnt with and without waste recovery respectively. The same methodology is used to estimate emissions for both types. Estimates for accidental fires are based on statistics from the Fire Service of Great Britain, available from the Department for Communities and Local Government (Home Office, 2022). These statistics give the number and severity of fires in dwellings and other buildings, and the number of fires in road vehicles by type. The statistics have then been converted into masses of material burnt by applying country -specific assumptions for each type of fire e.g. for the many fires in dwellings that are limited to just a single item, the mass of material combusted is assumed to be 1 kg. The total material burnt is then combined with emission factors to obtain emission estimates for methane, CO, NOX and NMVOC. The methane factors are taken from AP 42 (USEPA, 2014) and relate to open burning of municipal waste (for dwellings and other buildings) and automobile parts (for vehicle fires). Factors for other pollutants are taken from the same source, or from UK -specific literature. The UK is not aware of any source of appropriate emission factors for carbon or nitrous oxide emissions from this source, but emissions of these pollutants from this source are expected to be small. The tonnage of MSW burnt in incinerators in the Cayman Islands and the Falklands is provided by their respective local governments. UK GHGI EFs were then applied to these activity data to estimate emissions from this sector. Emissions from waste incineration in Jersey and the Isle of Man are reported under 1A1a. Data are available for the amount of waste open-burned in Guernsey, so these are used to estimate emissions for 5C2 using IPCC 2006 default EFs. It is assumed that this source is not occurring in the remaining territories. The inventory also includes estimates for emissions • CO, NO X & NMVOC f rom small -scale burning of domestic and garden waste, for example on domestic grates and on garden bonfires;

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 467 • CO from open fires lit as part of 'bonfire night' celebrations; and All of these estimates are very uncertain, because of the ne ed for expert judgements and assumptions in order to derive any activity data from waste arising data, and the need, because of a lack of suitable emission factors, to instead use factors that were designed for other types of emission source such as domestic fires. Uncertainties and Time-Series Consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty according to IPCC Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the greenhouse gas inventory in Source Specific Recalculations The following recalculations apply to the estimates submitted in this compilation • Analysis of installation-level reported data in the early 1990s has led to the addition of methane estimates for a number of chemical waste facilities, e.g. to fill gaps for sites that reported methane in later years. In addition, a minor revision to clinical waste incineration estimates due to an improved EF. • Update to the Crown Dependency incineration data. Estimates based on emissions data from regulators have been revised. The regulators’ data does contain gaps, generally because operators consider that emissions are below reporting thresholds so need not report an actual emission. This does not mean that there are no emissions at all, just that they are less than the threshold. This year, we have improved the systems for processing all of the regulator data and for filling in these gaps and this has led to some relatively trivial revisions to UK GHGI estimates. For information on the magnitude of recalculations to Source Category 5C, see Section 10. Source Specific Planned improvements Emission estimates for chemical waste incineration cu rrently do not include the burning of chemical wastes in flares and it is unclear whether these emissions might be included in the estimates reported in 2B10. As recommended in the 2014 Expert Review and associated report, if data on flaring becomes availa ble within the pollution inventory for chemical waste incineration this data will be included in the GHG inventory. No evidence has been found for any chemical waste incineration processes carried out in Scotland or Northern Ireland, and so emissions in these regions are assumed to be zero. The need to deal with significant gaps in the reported data means that estimates are quite uncertain. Emission estimates for clinical waste, animal carcass and sewage sludge incineration are also quite uncertain and idea lly would be improved. However, all incineration processes are relatively minor sources of greenhouse gases and further development of the methodology is not a priority.
UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 468 Emissions sources Sources included Method Emission 5D1: Domestic Waste-water treatment 5D2: Industrial Waste-water Treatment Key Categories 5D: Wastewater Handling - N2O (L2, T2) 5D: Wastewater treatment and discharge - CH4 (L1, L2) Emissions from wastewater handling within OTs and CDs are included in 5D1. Estimates are based on 2006 IPCC Guidelines and EFs with country-specific parameters applied, where Completeness No known omissions. A general assessment of completeness for the inventory is Revised estimates for 5D2, industrial wastewater treatment, based upon a new Tier 1 approach. Emissions reported in 5D2 arise from wastewater handling in a number of industry sectors in the UK where organic content of effluent is high. Emissions reported in 5D1 arise from wastewater handling, sludge treatment and disposal in the UK’s municipal waste -water treatment system and private waste -water management systems. The UK’s municipal waste -water treatment system encompasses the treatment of effluent and sludge from residential and commercial sectors as well as trade waste from many Methane is released from handling of wastewater and its resid ual solid by -products (i.e. sludge) under anaerobic conditions, due to the decomposition of organic matter by Nitrous oxide is released from human sewage during wastewater handling due to the release of nitrogenous material from proteins and from treatment of industrial wastewaters which The emissions from 5D1 and 5D2 are estimated for the following sources in the • 5D1 Domestic and Commercial Wastewater. Which consists of 4 main o UK CH 4 emissions from municipal wastewater treatment. UK-specific method, using activity data for the municipal waste -water treatment volumes, organic content and sludge treatment and disposal routes. Emission factors are derived from water operators reported data since 2013 and extrapolated back o UK CH4 emissions from private wastewater management. Default IPCC methodology using UK-specific per capita Biochemical Oxygen Demand (BOD) and estimated population using private waste-water management systems;

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 469 o UK N2O emissions. Default IPCC methodology applied to UK time series of population and protein intake estimates from food surveys; o OT and CD Sewage Treatment . For the majority of overseas territories and crown dependencies, wastewater emissions are estimated using UK data and scaled by population. Data specific to Bermuda were provided by the territory and used within the time series, interpolating and extrapolating where • 5D2 Industrial Wastewater Treatment. Default IPCC methodology94 applied to U K production data from a range of wastewater generating industrial sectors. 7.5.2.1 5D1: UK CH4 emissions from municipal waste-water treatment The UK estimates for methane from municipal domestic and commercial wastewater and sewage sludge treatment and disposal a re derived from a time series of activity data for (i) total mass of sewage sludge disposed, and (ii) population equivalent of effluent treated in the municipal water treatment systems. These data cover most of the UK water operator activity since 1990, which reflects shifts in UK water sector regulation and management. 7.5.2.1.1 UK Industry Overview The UK wastewater treatment industry is a highly-regulated sector that has undergone a high level of investment in infrastructure and improvement of management practice s over several decades in order to deliver a service that achieves high environmental standards and meets key performance indicators (e.g. treatment parameters and volumes, economic and water quality standards). Even prior to 1990 the UK network of wastewater treatment plants were at the forefront of engineering and technological development globally, and this has been strengthened by the impacts of successive and more stringent regulations in the intervening years, notably the Urban Wastewater Treatment Directive in the late 1990s / early 2000s which banned dumping of sewage to sea. The UK water sector was previously publicly owned and is now comprised of over a dozen individual companies and a statutory cooperation that operate regional networks and infrastructure. There is a long history of UK -wide research and co -operation across these operators, and in response to the challenge to monitor and report environmental performance, all major UK water operators engage via a central body, UK Water Industry Resea rch (UKWIR), through which common reporting frameworks and systems are researched, developed and updated to reflect latest science and industry practices. In the UK, a typical Wastewater Treatment Plant (WWTP) involves a number of interrelated processes each of which have different emissive behaviour. The different combinations of treatment options and the local wastewater arising characteristics (especially where high volumes of industrial waste are combined and treated together with municipal wastewater, altering the wastewater input characteristics away from “typical” municipal wastewater arisings) lead to a range of performance in the management of organic waste and the emission performance of the treatment works. The UK tools to monitor WWTP performance , estimate the input water characteristics (which in the UK is linked to regulatory and charging regimes for industrial customers, often based on periodic sampling of industrial effluents that pass into the predominantly municipal system), and to estimate the GHG emissions from these activities have been developed through research focussed on the UK wastewater sector and the existing infrastructure. This research underpins the UK GHGI estimates of methane emissions, as the country -specific model uses operator-reported data via the Carbon Accounting Workbook (CAW) which accounts for plant specific processes using CS emission 94 Note that in the case of N2O this means a 2019 refinement to the 2006 IPCC guidelines default methodology, as there is no method presented in the 2006 IPCC guidelines. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 470

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 471 7.5.2.1.1.1 Preliminary Treatment All wastewater is initially filtered for large objects and particulate matter. The filtering process is not emissive, and the screened material is largely inert. Any emissions associated with the disposal of non-inert content of the screened waste are included in estimates for other sectors 7.5.2.1.1.2 Settlement (Primary, Secondary and Tertiary) After preliminary treatment all wastewater undergoes primary settlement.
Primary settlement involves allowing suspended solids to settle at the bottom of the tank to form a sludge. The sludge can then be extracted for separate sludge treatment. The process is relatively short, and hence there is no time for methane generating bacteria to proliferate. Methane emissions from process are therefore insignificant. During Secondary and Tertiary treatment, the biological processes can lead to the conversion of dissolved solids to suspended solids. When this occurs, additional settlement stages are typically used to extract more solids from the water. The process of secondar y and tertiary settlement is otherwise the same as primary settlement. 7.5.2.1.1.3 Secondary Treatment The standard secondary treatment in the UK is an aerobic treatment which reduces the biological dissolved solids by allowing bacteria to proliferate and process the dissolved solids. The dissolved solids are converted to suspended solids which are separated from the water This process was made compulsory for large WWTP s in 2001 under the Urban Wastewater Treatment Directive. Before 2001 this treatment practice was widespread but was not implemented at all UK WWTPs. As a result, the effluent to UK waterways prior to 2001 would typically have had a higher biological load. For this reason, the UK GHGI method applies the IPCC default methodology for wastewater disposed to waterways, to account for the increased biological load of this water. The additional biological load is estimated by finding the difference between the sludge generated per capita before and after 2001. Secondary treatment is a source of nitrous oxide emissions, and a small amount of methane emissions (primarily due to potential disruptions in the process which may allow anaerobic conditions to occur). Emissions of nitrous oxides are included in the operator reported data; the Inventory Agency does not use this as we do not have sufficient information to determine what impact this process has on downstream nitrous oxide emissions. Emissions of methane are reported with mechanical treatment and short-term storage of sludge in the CAW, and the Inventory Agency uses these values as part of the emissions estimates. 7.5.2.1.1.4 Tertiary Treatment(s) In many UK WWTPs, there is a requirement for tertiary waste water treatment, in order to meet the regulatory permit conditions and/or to meet water quality criteria for the water-ways receiving the WWTP effluent outflow. There are a number of tertiary processes that can occur depending on what products require removal from the water. The most common tertiary treatments are nitrification and denitrification which aim to reduce the nitrogen load of effluents. These processes can be a significant source of nitrous oxide within the WWTP, but they also reduce the level of nitrous oxide emissions occurring downstream due to the removal of nitrogen from the effluent. Similar to secondary treatment, the UK cannot estimate nitrous oxide emissions from this source (using the directly reported emissions from WWTP operators) without introducing a potential double count with downstream emissions, as the data are not available to establish the impact of these tertiary treatments on the residual nitrogen loads in WWTP effluent. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 472 Similar to secondary treatment processes, methane emissions from tertiary treatments do not occur through routine operation and are considered negligible by the UK industry. 7.5.2.1.1.5 Mechanical Treatment and Short-Term Storage All sludge extracted from wastewater goes through an initial mechanical treatment and to short term storage. This process thickens, dewaters and homogenises the sludge to reduce the volume of the sludge and prepare it for further treatments. The gravity thickening process and storage of sludge under anaerobic conditions leads to methane emissions which are reported by wastewater operators via the CAW, and these data are used to derive t he UK inventory In the UK the vast majority of sludge undergoes anaerobic digestion after mechanical treatment, particularly in recent years. This process allows anaerobic bacteria to process the sludge, reducing the volume of sludge and generating methane. WWTPs collect the generated methane and burn it in engines to generate electricity; this generation of electricity by the industry using sewage gas is reported within the UK energy statistics. Emissions from the burning of sewage gas are reported in the UK inventory within sector 1A1a Power generation, whilst emissions from the disposal of sludge is reported according to the water operator reporting of sludge fate, to landfills (5A), incinerators (5C) and agricultural soils (3D). There is an increasing trend in the UK to pre-treat the sludge before digestion to improve the efficiency of digestion; this is known as advanced digestion. There are two main advanced digestion processes; Cambi’s patented Thermal Hydrolysis Process (CambiTHP™ ) which involves high pressure steam to improve anaerobic digestion conditions and Acid Phase Digestion (APD) which involves creating two sets of conditions which suits two distinct groups of microbes. These processes increase higher biogas yields and asso ciated reductions in sludge volume, relative to conventional anaerobic digestion. Digestion is the main source of methane emissions in UK WWTP as methane is intentionally generated but not all methane is collected. The data reported to the UK inventory tea m by wastewater operators via the CAW accounts for the types of digestion occurring and whether or not the digestion is enclosed. Nitrous oxide emissions from digestion are negligible, due to the lack of oxygen in the system. In some cases, UK W WTPs may compost the sludge after mechanical treatment, instead of digestion. This is a source of methane and nitrous oxide emissions. These emissions are reported by wastewater operators in the UK through the CAW, the method for which applies default meth ane and nitrous oxide emission factors for composting from the 2006 IPCC 7.5.2.1.2 Waste-water Treatment and Sludge Disposal Activity Data Activity data are available at an aggregated level (across England and Wales, Scotland, Northern Ireland, and with no detail on treatment) for the early part of the time series within EPSIM data published by UK Government (Defra, 2006).
In recent years, each of the UK’s 12 water and sewerage operators report annual activity data on water trea tment, sewage sludge arising and the ultimate fate of sewage sludge, to UK industry regulators. The activity data reported by each operator includes data that are used to estimate operator GHG • Total volume of sludge disposed (kt total dissolved solids (tds)); and

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 473 • Population Equivalent (PE) Served (‘000), this is the estimated resident and non-resident (e.g. tourist) population served which acts as an alternative indicator of In addition, each operator provides a detailed split of sewage sludge disposal routes, including data (kt tds per year) for the following • Disposal at sea (up to the year 2000, when this activity was banned); and For the 201 3 inventory cycle the Carbon Accounting Workbook (CAW), developed by UK Water Industry Research (UKWIR), was the tool used by the water industry for reporting emissions to Defra and OFWAT. It was adapted to provide detailed data for the inventory. The inventory team was provided with a methodology report that included a number of the underlying assumptions and emission factors and activity (in PE for secondary treatment, m3 for biogas use and kt tds otherwise); CH4 and N2O emissions were reported for the • Mechanical treatment and short -term storage of sludge (activity and CH 4 emissions • Secondary treatment (activity and N2O emissions only); • Digestion (activity and CH4 emissions only); • Advanced digestion (activity and CH4 emissions only); • Composting (activity and CH4 emissions only); • Advanced digested sludge to land; • Raw and limed sludge to land; • Raw and composted sludge to landfill (activity and CH4 emissions only); • Digested sludge to landfill (activity and CH4 emissions only); • Sludge to incineration (activity and N2O emissions only); • Biogas used in CHP for energy generation (activity only); and • Biogas used for combustion other than by CHP (activity only). From 2000 to 2009, each of the 10 water operators in England and Wales reported sludge disposal activity to the industry regulator, OFWAT, broken down across 8 sludge disposal incineration, composting, landfill, land reclamation, farmland untreated , farmland conventional, farmland advanced and other. After 2009 the requirements of data reported to OFWAT changed, and data was no longer publicly available. For 2013 onwards, operator reported data from the CAW has been available. For 1991 to 2005, the EPSIM data present a breakdown of sewage sludge disposal data across five farmland, incineration, landfill, sea disposal and other, and for 1986-2005 this data set gives total estimates sewage sludge arising. No additional information is available, such as the BOD loading of the municipal sewerage system, treatment methods, or the population equivalents treated by UK water operators. The overlap in time-series between the EPSIM data and operator reported data confirms that the total and split of di sposal methods are largely consistent with each other. In Scotland the same level of detailed activity data as outlined above for operators in England and Wales have been available since 2002 and continues to be published, from the Water

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 474 Commissioner for Scotland; EPSIM data are used for 1990 -2001. The totals reported in the EPSIM data fit the operator reported data very well, but because the disposal split fits very poorly in the overlapping years the operator reported split from 2002 is used with the EPSIM total for the earlier part of the time series. In Northern Ireland, data are only available from the water regulator, UREGNI, for 2006-9 and 2012. Northern Ireland Water, the sole provider of water and sewerage services in Northern Ireland have reported data for 2013 onwards. The Defra EPSIM statistics are used to provide activity data for the early part of the time series to 2005, whilst the gap between these data sets are interpolated. The EPSIM time-series trend fits well with the operator reported trend in later years, as the disposal split is similar in the 2013 reported data and at the end of EPSIM time-series it is reasonable to assume a similar split for the intervening years. 7.5.2.1.3 Emission Use of UK-specific Factors The UK GHG inventory mo stly follows the UK water industry GHG emission estimation methodology developed by UKWIR and used by all UK water operators to generate their annual emission estimates from all sources / activities. UKWIR have not provided an approach for estimating emissions associated with waste to sea in the 1990s, so to avoid an omission the 2006 IPCC default approach using the Methane Correction Factor (MCF) for sea, river and lake discharge has been used. Discharges would have only been to the cold seas with low organic loadings around the UK, so this is likely to be a very conservative approach for Methane emissions from sewage sludge disposed to landfill and incineration are accounted for in 5A and 5C, and hence no estimates are included in 5D1 to avoid a double count. Waste disposed of via ‘other’ means has been given a weighted average emission factor based on the emissions from other disposal methods. Where the treatment before disposal isn’t specified, the treatment split is estimated based on the profile given in CAW reported data for since 2013; for example, it was only after 2013 that the sludge disposed to landfill has been disaggregated based on treatment, this split has been used to estimate the treatment split for the earlier years where none is specified. UK-specific emission factors are applied to the treatment and disposal methods reported in the CAW, outlined above. Most of these factors are derived from UK water industry emissions data reported to the Inventory Agency, through use of the UKWIR estimation spreadsheet tool that all UK water operators utilise.
The UKWIR tool provides emission factors for sub - processes within the industry, enabling water operators to calculate their methane emissions based on their stock of water treatm ent equipment and effluent inputs to individual water treatment works. From the aggregated industry reported emissions and activity data, implied emission factors for each of the treatment and disposal approaches can be derived. The emission factor for com posted sewage sludge treatment is derived from the 2006 IPCC Water operator reporting of emissions to the Inventory Agency is not comprehensive; emissions data are only available from 2009 onwards, and only from up to 9 of the 12 UK water operators in any one year before 2013; for example, in 2009, emission reporting by water operators was estimated to cover around 53% of total UK water treatment. During 2013 the Inventory Agency met with all UK water operator carbon managers and the authors of the UKWIR reporting tool that all operators use under a voluntary mechanism for GHG emissions reporting. Through this consultation, 9 out of 12 water operators provided 2012 emissions data, covering around 65% of UK water operator activities. In addition, a reporting template has been drafted for inclusion within the UKWIR tool, which means that since 2013 we have received data from all 12 of the water operators in most years. In future

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 475 we should continue to receive this much more comprehensive data from th e industry, and therefore have much more confidence in emissions estimates. Despite limitations to data collection in previous years, there is good consistency across the emission factors derived from the different water operators and the data are based on UK- specific water treatment facilities, effluent inputs and treatment / disposal activities, and therefore are regarded as the best available data upon which to derive inventory estimates. 7.5.2.1.4 Reporting of Methane Recovery from Sewage Treatment As part of th e data supplied by water operators through the CAW, volumes of sewage gas captured are reported, including whether the sewage gas is flared, burned for energy on site, or exported to be upgraded and injected into the natural gas network. However, this is only available for years where CAW data are reported, i.e., for 2013 onwards. Data on the annual amount of sewage gas being produced are provided in DUKES (BEIS, 2022), and in combination with older publications of DUKES, there is a timeseries of sewage gas utilisation for 1990 onwards. These data are used to extrapolate the data reported in the Note that these data are not used as part of methane emissions estimates, so are presented in the CRF for information only. 7.5.2.2 5D1: UK CH4 emissions from private waste-water management An estimate of the number of households that are likely to be using off-grid systems in the UK in 2013 has been made based on data provided by the Environment Agency (EA), the Scottish Environmental Protection Agency (SEPA), the Northern Ireland Department of the Environment (NIEA) and Natural Resources Wales (NRW). A time series of emissions has been developed using population data. This time series of number of households has been combined with ONS data for average household occupancy and the calculated volume of waste produced per person per year based on water operator statistics to produce an estimate of total wastewater being disposed of via off-grid systems. The emissions are then calculated following the method set out in the IPCC 2006 guidelines Volume 5, Chapter 6: Wastewater treatment and discharge. Equation 6.2 in the GLs, reproduced below, calculates the emission factor. EFj= emission factor, kg CH4/kg BOD (Biochemical Oxygen Demand) j = each treatment/discharge pathway or system B0= maximum CH4 producing capacity, kg CH4/kg BOD the default factor for septic tanks. The team did not have enough data to establish the activity by waste treatmen t process. As the vast majority of private waste management systems observed were septic tanks, and the septic tank factor is conservative when compared to other systems that could be used, it was decided that it would be the most appropriate factor to

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 476 Parameter Description Units Value Bo Maximum CH4 producing capacity kg CH4/kg BOD 0.6 MCF Methane correction factor Fraction 0.5 EF Emission factor kg CH4/kg BOD 0.3 The emission factor is then combined with total amount of organically degradable material in the wastewater (TOW), expressed as kg BOD/year, which is calculated using Equation 6.3 in TOW = total organics in wastewater in inventory year, kg BOD/yr P = country population in inventory year, person BOD = country-specific per capita BOD in inventory year, g/person/day 0.001 = conversion from grams BOD to kg BOD I = correction factor for additional industrial BOD discharged into sewers (for collected the default is 1.25, for uncollected the default is 1.00). BOD value is assumed to be similar to the BOD per capita implied by the data provided by the major water operators. Data on BOD values applied and estimated population connected to private wastewater management systems are presented in Annex 3.5.4. 7.5.2.3 5D1: UK N2O emissions from Domestic and Commercial Waste-water Nitrous oxide emissions from the treatment of human sewage are based on the 2006 IPCC default methodology. The most recent average protein consumption per person is based on the Expenditure and Food Survey is not available in time, and therefore the latest year is assumed to be the same as the year before. Population estimates are from the Office for National Statistics (ONS, 2021). In previous years, the protein consumptions used to estimate emissions were “household intakes”. However, Defra now produce a time seri es of the estimates of the small amount of additional protein from consuming meals eaten outside the home; this intake is called “eating out intakes”. This time series is only available from 2000 onwards. For values between 1990 and 2000 an average of the data available is applied.
The sum of the “household intakes” and “eating out intakes” then provides the total protein consumption per year per person. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 477 Nitrous oxide emissions are calculated by 2. annual total protein consumption per person; 3. the fraction of nitrogen in protein (0.16kg N/kg protein); 4. the fraction of municipal nitrogen load from unconsumed protein (1.16; Henze and 5. the fraction of municipal nitrogen load from commercial and industrial sources, as per the 2006 IPCC guidelines (1.25); and, 6. The default emission factor (EFEFFLUENT) for N2O-N (0.005 kg N2O-N/kg –N) 7. The conversion factor 44/28, from kg N2O-N into kg N2O. This derives a total for the UK nitrous oxide emissions from sewage sludge, but not all of those emissions are allocated to 5D1. The nitrous oxide emissions from sludge spread on agricultural land are reported under IPCC source category 3D Agricultural Soils , emissions from waste incineration are included in 5C , and some sewage sludge is disposed to landfill sites, where N2O emissions do not generally occur due to the anaerobic conditions. Therefore, to avoid a double-count in the UK GHG inventory, the estimated nitrogen content of sewage sludge disposed via these other routes is removed from the total N estimated to be in 7.5.2.3.1 Use of UK-Specific Protein Consumption Data instead of FAO Data The FAO estimate of per capita protein consumption is based on supply balance sheets for all commodity items. For each commodity supply balance sheet, factors are applied to the estimate of supply for human consumption to derive total protein consumption and a per capita balance sheets to derive a total protein consumption estimate for a country. The FAO estimate is therefore an aggregate calculation based on aggregate commodity supply data. It uses common conversion factors (not specific to an y country) to derive food, protein and fat per capita consumption estimates. It also relates to quantities available for consumption and does not account for losses (e.g. fat trimmed from meat) beyond the farm - gate through to retail. These methodological l imitations of the FAO estimates are more significant for developed countries such as the UK where a greater proportion of consumption is in the form of processed products. The UK GHGI estimate of protein consumption is derived from the Expenditure and Food Survey (Defra, 20 20). This is a sample household survey in which households record the actual purchases of food they make. UK-specific conversion factors are then applied to these individual food items to estimate consumption of protein and other nutrients. The UK-specific conversion factors are based on a detailed analysis of the individual types of food purchased and contrasts to the more broad -brush factors used by the FAO. The Expenditure and Food Survey estimate is also net of any losses through the food chain through to retail as it is based on actual purchases. The only limitation to the Expenditure and Food Survey is that it may have an element of under-recording due to purchases of some food items not being included in the diary of survey participa nts, but the Inventory Agency considers that it is more representative of UK protein consumption per capita than the FAO estimate. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 478 7.5.2.4 5D2: Industrial Waste-water Treatment In the UK, a high proportion of industry trade wastewater is disposed to the municipal sewer system and treated by water operators together with the sewage and effluent from domestic In the data reported by the water operators and used to generate methane emission estimates in 5D1 (see above), some of the annual reporting to water regulators includes explicit data on the COD from “trade waste” and the total COD treated (i.e. including domestic and commercial effluent) in the municipal systems. The share of total BOD that is attributable to the industry sector (i.e. “tr ade waste”, managed via contracts between water operators and industry operators) is variable across the UK and across years. This is removed from estimates of COD generated by industrial activity, to mitigate double -counting and leave only the COD treated through on-site treatment systems within the industrial sector. It is this source of emissions considered under IPCC category 5D2. In addition to the above, where large industrial sites that have on -site waste-water treatment plant are regulated under IPPC/EPR, the annual IPPC/EPR reporting to regulator inventories (PI/SPRI/NIPI) includes the requirement to report any methane emissi ons from the waste - water effluent plant. The PI/SPRI/NIPI data on methane emissions are used within the UK GHGI, and included within many IPCC source categories, but the lack of source-specific detail in the PI/SPRI/NIPI reporting does not enable the waste -water treatment emission estimates from these industrial facilities to be split out and reported separately in the CRF. In practice it is not straightforward to ascertain the extent to which emissions from waste-water treatment are consistently included in operator estimates across different industry sectors, as the IPPC/EPR data are not presented ‘by source’, but rather ‘by installation’. Within sector - specific guidance to plant operators on pollution inventory data preparation, emissions of methane from wastewater treatment are not highlighted as a common source to be considered, whilst in guidance for several industrial sectors, wastewater treatment is singled out as a potentially significant source of ammonia and nitrous oxide emissions. Therefore, some industrial waste-water treatment methane emissions are already reported within a range of IPCC source categories, but cannot be quantified explicitly due to the lack of transparency of available source data from UK environmental regulatory reporting systems. In 2020, Ricardo Energy & Environment developed a new tier 1 estimate and timeseries for both methane and nitrous oxide emissions from industrial waste-water treatment, with regard to previous review comments (Section 10.4) and in preparation for the 2019 Refinement to the 2006 IPCC Guidelines yet to be formally adopted.
This was part of a larger research project, funded by BEIS, to improve the GHG emission estimates from wastewater handling. The previous approach was thought to be an overestimate owing to the use of a ‘methane correction factor’ (MCF) originating from the 1996 Guidelines, representative of the factor for Australia, Canada and USA, and was assumed representative of UK treatment practices. This factor was likely too high given the degree of aerobic treatment occurring in the UK. This new tier 1 estimate employs the methodology detailed in the 2006 IPCC Guidelines, which includes MCFs per treatment pathwa y (or treatment technology) , therefore offer ing a more refined approach, provided data describing treatment pathways/technologies can be sourced. 7.5.2.4.1 Summary of Estimation method for UK 5D2 Estimates The new Tier 1 approach uses production data for each of th e specific industries identified within the 2019 Refinement as wastewater intensive. Production data was sourced from Eurostat’s ‘Prodcom’ database, which provides a detailed disaggregation of UK production by product. This enables a bottom up approach to defining the coverage of each industry specified within the 2019 Refinement, by combining the production estimates for various products. In total, data for 481 individual products was sourced and allocated to industry

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 479 sectors. As this data is used as the fundamental activity data for both Tier 1 estimates of CH4 and N2O emissions, this was a joint exercise for both pollutants. Industries highlighted as emissive for CH4 emissions It should be noted that the P rodcom database typically includes production estimates for the UK from 1995 onwards, meaning production data prior to 1995, back to 1990, has been estimated using the ‘splicing’ techniques described in Section 5.3.3 of Volume 1, Chapter 5 of the 2006 IPCC Guidelines. A ‘surrogate’ approach is used, where a proxy dataset, related to the specific industry, is used to simulate the trend in activity data. Surrogates selected pertain to value indexes from the UK’s Blue Book, an official dataset published by the ONS, describing economic activity in the UK. Specific indexes were mapped onto specific industries above (e.g. the ‘Manufacture of chemicals and chemical products’ index was applied to the ‘organic chemicals’ sector) and the Blue Book dataset provides a timeseries back to 1990. [The UK activity data are summarised for selected years across the time series in Annex In addition to the production data detailed above, the remainder of the estimation methodology for CH4 is based on the combination of the following data and • Default values for Chemical Oxygen Demand (COD) per unit of wastewater , and of the 2019 Refinement to the 2006 IPCC GLs; compl emented where possible by country-specific values derived from permits supporting the Industrial Emission Directive (IED) or values identified from literature research; • The Factor B 0 (0.25 kg CH4/kg COD), representing the IPCC COD -default factor for the maximum methane producing capacity of Industrial Wastewater; • Default Methane Correction Factors for each type of treatment and discharge pathway • The percentage utilisation of treatment or discharge pathways sourced through analysing the Environment Agency’s Discharge Consent Database. These are presented by industry, so that each industry has a specific treatment split, generating an industry specific weighted EF. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 480 • There is no information currently available on how much sewage sludge is removed and sent to landfill or applied to agricultural land. Although it is likely that this act ivity does take place, due to the absence of information, the default value of zero has been • There is no information on the amount of methane recovered, so the default value of zero has been used, although it is likely that this activity also takes p lace. There is some evidence from the EU ETS dataset that several UK food and industry facilities collect methane from anaerobic digestion systems and use the gas as a fuel source. CH4 emissions from Industrial wastewater treatment are calculated using the above data and assumptions in accordance with equations 6.4, 6.5 and 6.6 of Volume 5, Chapter 6, of the N2O emissions from Industrial wastewater treatment are based on the same Prodcom data and wastewater generation factors detailed above, following equations 6.13 and 6.11 of Volume 5, Chapter 6, of the 2019 Refinement. For these • Parameter TNi, the t otal nitrogen in untreated wastewater for each industrial sector, 6.8A of Volume 5, Chapter 6, of the 2019 Refinement; and, • The percentage utilisation of treatment or discharge pathways per industry, or parameter Tij in equation 6.11, is the same as that used above for CH4, for the purposes The Inventory Agency considers that these new emission estimates are an improvement upon the previous approach and likely to be more representative of actual emissions. There remains uncertainty within this approach owing • Whether wastewater generation factors are appropriate, relative to wastewater practices in the UK. As a result, these should be periodically reviewed in compilation. • The percentage utilisation of treatment or discharge pathways. This is currently based upon a one-off exercise and held constant for the timeseries but should be periodically updated when and if new data is made available. In addition, efforts should be made to determine changes in the percentage utilisation of treatment or discharge pathways over time, to represent improvement in treatment practice relative to legislation. 7.5.2.5 Overseas Territories and Crown Dependencies Estimates from the OTs and CDs are calculated using the Tier 1 approach from the 2006 IPCC Guidelines and default EFs. Country -specific parameters have been chosen based on information provided through a waste survey (distributed in 2014) and through expert judgement.
Per capita protein consumption data were ta ken from FAOSTAT with data for Bermuda applied to all OTs other than Gibraltar, and data from the UK applied to all CDs and Uncertainties and Time-Series Consistency As outlined in Section 7.5.2, the method for deriving methane emission estimates for 5D1 uses activity data from across the time series, and applies emission factors that are derived from reported emissions data from 2009 onwards. The method uses a published national set of activity statistics that reflect the changing fate of sewage sludge treatment and disposal; the UK water industry has undergone a marked shift in treatment and disposal practices since the Urban Waste-water Treatment Directive of 1999 banned the dumping of sewage to sea and in 2001 the same directive required all large WWTP to conduct secondary treatment; the sludge disposal trends are consistent with this regulatory change. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 481 Not all UK water operators reported their emission estimates in all years since 2009, and the available dataset for deriving country-specific factors is limited in some cases to only around 50% coverage of UK water treatment and sludge treatment / disposal activity. The Inventory Agency has continued to develop working relationships with the 12 UK water operators and from 2013 onwards obtained activity and emissions data from all of the 12 water operators. Therefore, we have a much more complete, consistent set of activity and emissions data reported from across the UK. This helps to further develop the UK-specific dataset from which estimates can be derived, improving accuracy through accessing more complete, representative data which reflects the range of waste -water quality and the design / stock of waste-water treatment facilities across the UK. The reported emissions and activity by UK water operators since 2013 has been used to derive country-specific emission factors for water treatment, methane capture, sludge treatment and most disposal routes, and these factors are applied to the activity dataset back to 1990. We are therefore using the best available data to estimate the emissions back to 1990. The use of the IPCC default for methane emissions from waste disposal to sea introduces a significant uncertainty to the early part of the time series where the activity is known to have taken place. This is because the IPCC default factor is for a wide range of situations including stagnant lakes with high organic loads in temperate climates, which would have very different emissive behaviour to the cold, low organic load seas around the UK. Furthermore, the limited activity data time series for 5D1 due to changes in data reporting across the time series limits the accuracy and time series consistency of the estimates for the early part of the time series; however it is observed that the overlaps in trend between the data sets typically show strong See Annex 3.5.4 for further details on the activity data, implied emissions factors and emissions estimates, and Section 7.5.6 below for an insight into the planned improvements Source Specific QA/QC and Verification This source category is covered by the general QA/QC of the greenhouse gas inventory in The 2016 UK GHGI reviews under the EU ESD and the UNFCCC Expert Review Team (ERT) concluded that the UK should carry out a verification of the methodology by comparing it with a tier 1 default methodology set out in the 2006 IPCC guidelines. Below this comparison is The UK currently uses a 2006 IPCC default methodology to estimate emissions from waste water disposed to waterways and private waste management systems. The verification calculations below compare the emission estimates using the IPCC 2006 GLs Tier 1 method against the UK’s country-specific model for all other waste water sources, i.e. from emission sources at UK WWTP where the 2006 IPCC Guidelines are not directly applied. As outlined in Section 7.5.2.1.1.3 the UK uses well -managed centralised aerobic treatment for waste water treatment. The UK also has a well -managed, flowing, closed sewer system. The 2006 IPCC default MCF for these sources is “0”, which means that should the UK follow the 2006 IPCC default methodology it would be reporting zero emissions of methane. We note, however, that the MCF of “0” may be due to a rounding of a small number rather than inferring that zero methane emissions would occur. It is likely that some methane emissions will occur. Even at well -managed WWTPs there will be incidences that lead to temporary anaerobic conditions. At an EU Working Group 1 meeting in February 2016 it was flagged that having an MCF of “0” for some sources in the 2006 IPCC guidelines meant that some countries will be under-reporting emissions. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 482 The UK uses a country specific factor which accounts for several processes that occur at UK WWTPs including aerobic treatment95. Unfortunately, because it includes processes that are out a comparison of parameters used to estimate methane emissions in the guidance with the not assume equivalence between BOD and raw dry solids (DS), but rather serves to preface the comparison in total magnitude of emissions relative to the IPCC default method. UK industries use dry solids (DS) as units and emission factors linked to the CAW, originate in the report ‘Carbon accounting in the water non-CO2 emission’ (UKWIR, 2009). While the UK estimate comes out close to the lower estimate of methane emissions based on IPCC default methodology, the higher value is d ependent on the assumption that methane emissions are not captured in anaerobic digestion of sludge. This appears to be very conservative when even compared to the IPCC Volume 5 Chapter 4 factor (which does account for methane capture), which is more than 2 orders of magnitude smaller and comparable to the UK’s CS factors. Note that the conclusions of this verification should apply to the latest estimates as the methodology has not meaningfully changed since. IPCC MCF is 0 for Centralized, aerobic treatment plant.
UK factors from the CAW, which additionally includes emissions from sewage treatment processes associated with temporary storage and Flowing sewer (closed) 0 kg / kg BOD Not Estimated This is not included in the CAW, and the UK has not investigated further as the IPCC default is 0. While strictly speaking there probably are non-0 emissions from this source it is likely very close to 0 in the UK’s well developed, managed, closed UK uses IPCC default methodology for this source. UK uses IPCC default methodology for this source. UK factors from the CAW, this accounts for several different methods of digestion. The Chapter 4 IPCC Digestion factor includes the impact of methane recovery; the Chapter 6 digestion factor does not. Given that anaerobic digestion is rarely done without methane recovery it is very conservative to assume it does not occur. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 483 UK uses IPCC default methodology for this source. This source is included in the CAW, but they additionally used the 2006 IPCC guidelines. This is a parameter that the guidance gives to derive activity data. Value chosen from the IPCC guidelines is in the mix of other Western European countries presented. The UK value presented is the implied factor based on reported data via the CAW and other waste water reporting systems. 1.25 Not Estimated This is a parameter that the guidance gives to derive activity data. The reported data via CAW and other waste water reporting systems should already account for industrial co-discharge. 57 to 174 kt 59 kt The range of IPCC Default emissions is dependent on which digestion factor is used; note that the higher value does not account for methane capture, which we know is occurring The UK’s estimate remains within the range of emissions estimates based in IPCC methodologies for both 1990 and 2015. The only notable differences between the UK’s method and the default method is the use of a non-0 UK factor for well-managed, centralised aerobic treatment, and using specific factors for different methods of anaerobic treatment. Source Specific Recalculations As part of integrating a change to the format of CAW data received from water operators, there has been a revision to the approach to splicing and gap -filling the various datasets used to generate complete, time -series consistent and process -specific estimates for centralised municipal wastewater treatment data. A large number of small changes have been made throughout the time-series, with some of the larger changes • Revising assumptions about the uptake of ad vanced digestion in the early 1990s; previously as assumption based on data for later years was used, but now the strong increasing trend in the available data has been utilised to justify assigning much less advanced digestion in early years. • Interpolations, extrapolations, and splicing is now done at an operator level first where available, and then a regional level. Previously some of these data were aggregated further before splicing, extrapolating or interpolating, which might have lost some of the operator, or region-specific features. This has a particularly large impact on how

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 484 the approach to gap filling approach to estimating untreated wastewater disposed to While these data are primarily used for methane emissions reported in sector 5D1, some of the data are utilised for refining the estimates for nitrous oxide 5D1 emissions (specifically around the nitrogen balance calculations), and these data also include the industrial co - discharge, which is removed from 5D2 to avoid a double count, and therefore most emissions estimates for wastewater have been impacted by these revisions. Estimates for CH4 and N2O emissions from industrial wastewater treatment for 5D2 have been revised in this submission. This is primarily due to the adjustment to the activity data (e.g. the industrial production estimates for various products allocated to industry ) and to a m ethod improvement to extrapolation from 1990 to 1995, which previously was flat -lined backwards from 1995 and now uses the ONS Industry indices . Moreover, CH4 and N2O emissions for 2020 have decreased between this submission and the previous in the 2021 NIR, as a consequence of updated 2020 Prodcom data for refinery production and for alcohol refining production, which not available last year and therefore were extrapolated. For information on the magnitude of recalculations, see Section 10. Source Specific Planned improvements It is noted that N2O emissions from wastewater has been highlighted as a key category, and we are currently using a tier 1 method. It should be noted that the 2006 IPCC GLs do not provide a higher tier method , however the 2019 Refinement to the 2006 IPCC Guidelines does. This is, however, yet to be a formal requirement towards the UK GHGI. The BEIS research project detailed in Section 7.5.2.4 considered, in addition to industrial wastewater treatment, improvements to both domestic wastew ater handling and emissions from the OTs and CDs. For domestic wastewater handling, it was noted the 2019 Refinement now considers emissions from the discharge of effluent into water bodies as a potential source of N 2O. Work has been undertaken to explore the provision of a country specific method already part of the CAW, that would characterise this source. This work will continue with UKWIR, and water operators as part of stakeholder engagement. Aether, as partner to the research project, liaised with a range of contacts in the OTs and CDs, to explore further data provision, and to characterise the further sources in the 2019 Refinement (such as emissions from discharge). Data supplied as part of this contact may results in minor revisions in future cycles, but the inclusion of new sources is largely contingent on the progress of the 2019 Refinement.
Similarly, estimates have been developed for emissions from the discharge of effluent of industrial wastewater, which will be included based upon the progressi on of the

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 485 No emissions are reported in Sector 6. Indirect CO2 and Nitrous Oxide Emissions 9 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 486 9 Indirect CO2 and Nitrous Oxide Description of Sources of Indirect Emissions in GHG The calculation of indirect CO 2 and N 2O is not mandatory. The UK calculates indirect emissions of N 2O from emissions of NO X and NH 3 from non -AFOLU sources. These are The methods and data sources for the calculation of NOX and NH3 emissions are described in the UK’s Informative Inventory Report (IIR), as submitted under the Convention on Long Range Transboundary Air Pollution. Emissions of indirect N2O are calculated using Equation 7.1 of Volume 1 of IPCC, 2006. EF4 within the equation is the IPCC default of 0.01 kg N2O-N/kg NH3-N or NOX-N emitted. Uncertainties and Time-Series Consistency No formal uncertainty or trend analysis for indirect N 2O emissions has been carried out. Uncertainties and trends for NOX and NH3 are described in the IIR. Category-Specific QA/QC and Verification Emissions of NOX and NH3 reported under the GHG inventory a re cross checked with those reported under CLRTAP and are consistent. Category-Specific Recalculations Indirect nitrous oxide emissions will change in line with changes made to the NO x and NH3 inventories. These are described in the IIR. Category-Specific Planned Improvements Indirect nitrous oxide emissions will change in line with changes made to the NO X and NH3 inventories. Air quality pollutants are subject to a separate improvement programme to the GHG inventory, this is described in the IIR. Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 487 10 Recalculations and Improvements This section of the report summarises the recalculations and improvements made to the U K GHG inventory since the 2022 NIR submission (1990-2020 inventory), including responses to reviews of the inventory. It summarises material that has already been presented and discussed in more detail in Chapter 3 to Chapter 7. Each year the UK greenhouse gas inventory is updated, extended and may be expanded. Updating often entails revision of emission estimates, most commonly because of revision to the core energy statistics presented in the Digest of UK Energy Statistics (DUKE S). The be revised. Updating also covers adoption of revised methodologies. Updating, particularly involving revised methodologies may affect the whole time series, so estimates of emissions for a given year may differ from estimates of emissions for the same year reported previously. Therefore comparisons between submissions should take account of whether there have been • the emission estimation methodology, including revisions to assumptions or • the reporting guidelines under which the submissions are made (for this sub mission, the IPCC 2006 guideline); the emission factors applied; and/or The time series of the inventory is extended by including a new inventory year. For example, the previous report covered years up to and including 20 20. This report gives emission estimates for 20 20 and also includes estimates for the year 20 21. The time series of the inventory may also be expanded to include emissions from additional sources if a new source has been identified within the context of the IPCC Guidelines, there are sufficient activity data, and suitable emission factors. CO2, CH 4, N 2O and F -gases since the 20 22 NIR submission (1990 -2020 inventory). The changes in emissions are net changes (the sum of any increases and decreases) in the source category, for each GHG in the Base Year (1990) (1995 for F -gases) and latest recalculated where these descriptions can be found in the main text of this document. All revisions to source data and methods, and all recalculations that are reported in the latest UK GHG inventory are conducted by the Inventory Agency in agreement with the DESNZ GHG inventory management team; all major recalculations and systematic improvements to the UK GHG inventory are approved and managed via the National Inventory Steering Committee (NISC), with new outputs approved through the UK’s system for pre -submission review. The inventory improvement process that manages the prioritisation and implementation of revisions to inventory data and methods uses the guiding principles of the 2006 IPCC Guidelines to govern the decisions over whether to implement changes to

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 488 inventory estimates or not. The most common justifications for implementing changes that ✓ Improved accuracy of the estimates, e.g. where underlying data from data providers has been revised (e.g. revisions to energy statistics), where less uncertain data are now available (e.g. use of EU ETS activity data to inform energy allocations, in preference to UK energy statistics data sources), or where the Inventory Agency has applied more representative (ideally country-specific) EFs in estimation methods; ✓ Improved transparency of the inventory estimates, e.g. the restructuring of inventory data reporting to improve the level of detail of the UK inventory (e.g. the reporting of F- gas estimates by species wherever this is achievable); ✓ Improved comparability of the inventory estimates, e.g. the restructuring of inventory data reporting to enable UK estimates to align more closely with IPCC Guidelines and Good Practice Guidance , (e.g. re -allocations of limestone and dolomite data in the glass sector from 2A3 and 2A4 to 2A7, which was implemented in the 2012 submission to enable more harmonised data reporting across EU Member States); ✓ Improved completeness of the inventory estimates, e.g. the addition of emission estimates for new sources that come to light in the UK, or where new data for an existing source indicates that the activity data previously used in the method omit ted some portion of the source emissions. ✓ Improved consistency of the inventory estimates, e.g.
to implement new or revised methods that deliver estimates based on more consistent underlying data or assumptions across the time series. Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 489 % Explanation for recalculations A. Fuel combustion activities 550069.21 550928.41 859.20 0.16% see explanations below in individual categories 1. Energy Industries 238058.47 238059.49 1.02 0.00% No significant recalculations 2. Manufacturing industries and construction 77047.10 75237.16 -1809.93 -2.35% Reallocation from 1A2gvii and 1A2gviii to 1A4ai based 3. Transport 119750.59 120222.30 471.71 0.39% No significant recalculations 4. Other sectors 109919.62 112116.02 2196.40 2.00% Reallocation from 1A2gvii and 1A2gviii to 1A4ai based 5. Other 5293.44 5293.44 0.00 0.00% No significant recalculations B. Fugitive emissions from fuels 6787.08 6787.09 0.01 0.00% see explanations below in individual categories 1. Solid fuels 1698.56 1698.56 0.00 0.00% No significant recalculations 2. Oil and natural gas 5088.52 5088.53 0.01 0.00% No significant recalculations 2. Industrial Processes and product use A. Mineral industry 10133.32 10234.92 101.61 1.00% Methodological update to extrapolate back to 1990 using more representative data for process emissions B. Chemical industry 6975.59 6975.59 0.00 0.00% No significant recalculations C. Metal industry 25429.25 25429.25 0.00 0.00% No significant recalculations D. Non-energy products from fuels and solvent use 552.81 552.81 0.00 0.00% No significant recalculations G. Other product manufacture and use NO NO

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 490 % Explanation for recalculations G. Liming 1016.78 1019.16 2.38 0.23% No significant recalculations H. Urea application 327.68 293.75 -33.93 -10.35% Revisions of application rates of urea-based fertiliser. 4. Land use, Land-use change and A. Forest land -13992.50 -13940.16 52.34 -0.37% No significant recalculations B. Cropland 15947.46 14230.88 -1716.59 -10.76% Incorporation of new EF for cropland on wasted peat and revised organic soil areas C. Grassland 114.65 -618.75 -733.41 -639.67% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas D. Wetlands 571.12 668.77 97.65 17.10% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas E. Settlements 5427.63 5426.53 -1.09 -0.02% No significant recalculations G. Harvested wood products -2087.72 -2096.17 -8.45 0.40% No significant recalculations C. Incineration and open burning of waste 1360.37 1445.17 84.80 6.23% Latest submission now includes GHG emissions from % Explanation for recalculations A. Fuel combustion activities 300819.52 300902.16 82.64 0.03% see explanations below in individual categories 1. Energy Industries 76089.41 75904.16 -185.25 -0.24% No significant recalculations

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 491 % Explanation for recalculations 2. Manufacturing industries and construction 38946.24 40301.99 1355.76 3.48% DUKES revision to natural gas use 3. Transport 96405.28 97035.93 630.65 0.65% No significant recalculations 4. Other sectors 87974.70 86285.57 -1689.13 -1.92% DUKES revision to natural gas use 5. Other 1403.89 1374.51 -29.38 -2.09% Revision to DUKES data for gas oil use in shipping B. Fugitive emissions from fuels 3442.60 3440.39 -2.21 -0.06% see explanations below in individual categories 1. Solid fuels 197.11 197.11 0.00 0.00% No significant recalculations 2. Oil and natural gas 3245.49 3243.28 -2.21 -0.07% No significant recalculations 2. Industrial processes and product use A. Mineral industry 5659.21 5542.54 -116.67 -2.06% Revision to clay production and consumption activity B. Chemical industry 4513.43 4513.43 0.00 0.00% No significant recalculations C. Metal industry 10672.94 10732.34 59.40 0.56% No significant recalculations D. Non-energy products from fuels and solvent use 379.49 373.26 -6.23 -1.64% Revision to vehicle engine use of lubricants G. Other product manufacture and use NO NO G. Liming 950.29 1119.74 169.45 17.83% Adjustment in the application of BSFP data to Northern H. Urea application 234.27 234.12 -0.15 -0.06% No significant recalculations 4. Land use, land-use change and forestry A. Forest land -17933.72 -18195.11 -261.39 1.46% Updates to the provisional Forestry Statistics and

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 492 % Explanation for recalculations B. Cropland 14403.93 12696.55 -1707.38 -11.85% Incorporation of new EF for cropland on wasted peat and revised organic soil areas C. Grassland -1873.95 -2659.79 -785.83 41.93% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas D. Wetlands 605.99 613.59 7.60 1.25% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas E. Settlements 4032.04 3804.91 -227.13 -5.63% Revised organic soil areas and updated deforestation G. Harvested wood products -2128.72 -1994.14 134.58 -6.32% Updated activity data for afforestation and deforestation C. Incineration and open burning of waste 248.95 306.22 57.28 23.01% Latest submission now includes GHG emissions from % Explanation for recalculations A. Fuel combustion activities 3624.30 3630.42 6.11 0.17% see explanations in individual categories 1. Energy Industries 261.17 261.17 0.00 0.00% No significant recalculations 2. Manufacturing industries and construction 128.49 114.70 -13.80 -10.74% Implementation of new NRMM model 3. Transport 1419.08 1423.29 4.21 0.30% No significant recalculations 4. Other sectors 1811.58 1827.28 15.70 0.87% No significant recalculations 5. Other 3.98 3.98 0.00 0.00% No significant recalculations B. Fugitive emissions from fuels 38269.25 38281.98 12.74 0.03% see explanations in individual categories 1. Solid fuels 24446.08 24446.08 0.00 0.00% No significant recalculations 2. Oil and natural gas 13823.17 13835.90 12.74 0.09% No significant recalculations

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 493 % Explanation for recalculations 2. Industrial processes and product use A. Mineral industry 34.84 34.84 0.00 0.00% No significant recalculations B. Chemical industry 248.23 248.23 0.00 0.00% No significant recalculations C. Metal industry 43.92 43.92 0.00 0.00% No significant recalculations A. Enteric fermentation 27644.97 27680.22 35.25 0.13% No significant recalculations B. Manure management 4657.83 4646.15 -11.68 -0.25% No significant recalculations F. Field burning of agricultural residues 209.47 209.47 0.00 0.00% No significant recalculations 4. Land use, land-use change and forestry A.
Forest land 98.04 99.49 1.45 1.48% Revised organic soil areas B. Cropland 326.98 332.36 5.39 1.65% Incorporation of updated Tier 2 analysis of organic soil C. Grassland 2672.17 2807.05 134.87 5.05% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas D. Wetlands 2197.10 2313.24 116.14 5.29% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas E. Settlements 18.26 19.03 0.77 4.19% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas A. Solid waste disposal 67636.28 67633.35 -2.93 0.00% No significant recalculations B. Biological treatment of solid waste 20.31 21.89 1.58 7.79% Revision to composting at permit sites in Jersey C. Incineration and open burning of waste 152.68 213.78 61.11 40.02% Latest submission now includes GHG emissions from

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 494 % Explanation for recalculations D. Waste water treatment and discharge 2558.25 2365.31 -192.94 -7.54% Methodological change to extrapolate data back to % Explanation for recalculations A. Fuel combustion activities 1350.11 1317.79 -32.32 -2.39% see explanations in individual categories 1. Energy Industries 427.90 424.82 -3.07 -0.72% No significant recalculations 2. Manufacturing industries and construction 150.27 131.70 -18.57 -12.36% Implementation of new NRMM model 3. Transport 85.92 87.16 1.23 1.43% Revision to DUKES data on natural gas use 4. Other sectors 684.98 673.08 -11.90 -1.74% Implementation of new NRMM model 5. Other 1.05 1.04 -0.01 -0.86% No significant recalculations B. Fugitive emissions from fuels 5245.48 5311.24 65.77 1.25% see explanations in individual categories 1. Solid fuels 531.67 531.67 0.01 0.00% No significant recalculations 2. Oil and natural gas 4713.81 4779.57 65.76 1.40% Incorporation of revised gas leakage timeseries

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 495 % Explanation for recalculations 2. Industrial processes and product use A. Mineral industry 2.94 2.94 0.00 0.00% No significant recalculations B. Chemical industry 75.27 75.26 -0.01 -0.01% No significant recalculations C. Metal industry 12.24 12.24 0.00 0.00% No significant recalculations A. Enteric fermentation 23450.11 23448.29 -1.83 -0.01% No significant recalculations B. Manure management 4269.45 4251.08 -18.37 -0.43% No significant recalculations 4. Land use, land-use change and forestry A. Forest land 115.50 117.44 1.93 1.67% Revised organic soil areas B. Cropland 312.85 318.42 5.57 1.78% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas C. Grassland 2711.40 2849.26 137.86 5.08% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas D. Wetlands 2288.85 2380.39 91.54 4.00% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas E. Settlements 33.81 27.87 -5.94 -17.56% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas A. Solid waste disposal 14461.60 14463.06 1.46 0.01% No significant recalculations B. Biological treatment of solid waste 1362.80 1289.45 -73.36 -5.38% Methodological improvement for household composting C. Incineration and open burning of waste 8.28 58.46 50.18 606.35% Latest submission now includes GHG emissions from D. Waste water treatment and discharge 1916.51 1814.26 -102.26 -5.34% Revisions to municipal and industrial waste water data

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 496 % Explanation for recalculations A. Fuel combustion activities 3246.14 3226.70 -19.44 -0.60% see explanations in individual categories 1. Energy Industries 1277.73 1277.73 0.00 0.00% No significant recalculations 2. Manufacturing industries and construction 280.46 260.45 -20.01 -7.13% Implementation of new NRMM model 3. Transport 1282.63 1289.90 7.28 0.57% Revision to DfT data for minor roads 4. Other sectors 355.41 348.71 -6.71 -1.89% Implementation of new NRMM model 5. Other 49.91 49.91 0.00 0.00% No significant recalculations B. Fugitive emissions from fuels 39.82 39.82 0.00 0.00% see explanations in individual categories 1. Solid fuels 0.08 0.08 0.00 0.00% No significant recalculations 2. Oil and natural gas 39.74 39.74 0.00 0.00% No significant recalculations 2. Industrial processes and product use B. Chemical industry 21162.10 21162.10 0.00 0.00% No significant recalculations C. Metal industry 18.43 18.43 0.00 0.00% No significant recalculations G. Other product manufacture and use 529.93 533.61 3.68 0.69% No significant recalculations B. Manure management 3053.54 3038.90 -14.63 -0.48% No significant recalculations D. Agricultural soils 12940.81 13428.41 487.60 3.77% Methodological improvement to use Tier 2 EFs for histosols from cropland and intensive grasslands F. Field burning of agricultural residues 51.40 51.40 0.00 0.00% No significant recalculations 4. Land use, land-use change and forestry

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 497 % Explanation for recalculations A. Forest land 669.53 438.95 -230.58 -34.44% Incorporation of updated Tier 2 analysis of organic soil emission factors and updated forest areas B. Cropland 653.25 653.25 0.00 0.00% No significant recalculations C. Grassland 180.00 134.86 -45.15 -25.08% Incorporation of updated Tier 2 analysis of organic soil emission factors and revision to intensive grassland areas revised organic soil areas D. Wetlands 18.94 18.90 -0.04 -0.21% No significant recalculations E. Settlements 392.27 392.31 0.05 0.01% No significant recalculations H. Other (Indirect N2O) 271.66 271.94 0.28 0.10% No significant recalculations B. Biological treatment of solid waste 11.53 12.36 0.83 7.20% Revision to composting at permit sites in Jersey C. Incineration and open burning of waste 45.29 61.44 16.15 35.67% Latest submission now includes GHG emissions from D. Waste water treatment and discharge 794.31 796.37 2.06 0.26% No significant recalculations % Explanation for recalculations A. Fuel combustion activities 1887.92 1898.21 10.29 0.54% see explanations in individual categories 1. Energy Industries 623.44 621.99 -1.45 -0.23% No significant recalculations 2. Manufacturing industries and construction 222.87 222.02 -0.85 -0.38% No significant recalculations 3. Transport 863.88 876.66 12.78 1.48% Implementation of new NRMM model causing increase in DERV allocated to road transport 4. Other sectors 164.57 164.72 0.15 0.09% No significant recalculations 5.
Other 13.15 12.81 -0.35 -2.64% Revision to MoD data

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 498 % Explanation for recalculations B. Fugitive emissions from fuels 27.49 27.47 -0.02 -0.07% see explanations in individual categories 1. Solid fuels 0.01 0.01 0.00 0.00% No significant recalculations 2. Oil and natural gas 27.47 27.45 -0.02 -0.07% No significant recalculations 2. Industrial processes and product use B. Chemical industry 45.43 45.43 0.00 0.00% No significant recalculations C. Metal industry 6.33 6.33 0.00 0.00% No significant recalculations G. Other product manufacture and use 669.30 668.63 -0.67 -0.10% No significant recalculations B. Manure management 2501.98 2477.82 -24.16 -0.97% No significant recalculations D. Agricultural soils 10358.49 10666.61 308.12 2.97% Methodological improvement to use Tier 2 EFs for histosols from cropland and intensive grasslands 4. Land use, land-use change and forestry A. Forest land 633.38 386.80 -246.58 -38.93% Incorporation of updated Tier 2 analysis of organic soil emission factors and updated forest areas B. Cropland 354.35 354.35 0.00 0.00% No significant recalculations C. Grassland 164.29 127.61 -36.68 -22.32% Incorporation of updated Tier 2 analysis of organic soil emission factors and revision to intensive grassland areas and revised organic soil areas D. Wetlands 22.06 21.82 -0.24 -1.10% Incorporation of updated Tier 2 analysis of organic soil emission factors and revised organic soil areas E. Settlements 261.39 255.56 -5.83 -2.23% Methodological revision to align settlement organic soil H. Other (Indirect N2O) 152.75 153.42 0.67 0.44% No significant recalculations

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 499 % Explanation for recalculations B. Biological treatment of solid waste 635.83 618.01 -17.82 -2.80% Methodological improvement for household composting C. Incineration and open burning of waste 23.45 35.93 12.48 53.20% Latest submission now includes GHG emissions from D. Waste water treatment and discharge 904.17 894.17 -10.00 -1.11% Revisions to municipal and industrial waste water data % Explanation for recalculations 2. Industrial processes and product use 2.C.4. Magnesium production 399.06 399.06 0.00 0.00% No significant recalculations 2.G.1. Electrical equipment 821.58 828.89 7.30 0.89% Revision due to latest data becoming available 2.G.2. SF6 and PFCs from other product use 62.92 62.92 0.00 0.00% No significant recalculations % Explanation for recalculations 2. Industrial processes and product use 2.C.4. Magnesium production 28.29 28.29 0.00 0.00% No significant recalculations 2.G.1. Electrical equipment 339.43 340.30 0.87 0.26% Revision due to latest data becoming available 2.G.2. SF6 and PFCs from other product use 51.72 51.68 -0.04 -0.08% Revised proxy data in latest year % Explanation for recalculations 2. Industrial processes and product use

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 500 % Explanation for recalculations 2.B.9. Fluorochemical production 14807.32 14807.32 0.00 0.00% No significant recalculations 2.E.1. Integrated circuit or semiconductor 10.84 10.84 0.00 0.00% No significant recalculations 2.F.1. Refrigeration and air conditioning 201.37 201.39 0.02 0.01% No significant recalculations 2.F.2. Foam blowing agents 167.84 167.80 -0.03 -0.02% No significant recalculations 2.F.3. Fire protection 1.01 1.01 0.00 -0.02% No significant recalculations 2.F.4. Aerosols 407.72 407.71 -0.01 0.00% No significant recalculations 2.F.6. Other applications 35.87 23.59 -12.29 -34.26% Methodological improvement to use HFC Outlook data % Explanation for recalculations 2. Industrial processes and product use 2.B.9. Fluorochemical production NO NO 2.C.4. Magnesium production 1.34 1.34 0.00 0.00% No significant recalculations 2.E.1. Integrated circuit or semiconductor 20.46 20.46 0.00 0.00% No significant recalculations 2.F.1. Refrigeration and air conditioning 9661.49 9665.24 3.76 0.04% No significant recalculations 2.F.2. Foam blowing agents 380.36 192.57 -187.79 -49.37% Revision to OT and CD activity data 2.F.3. Fire protection 323.39 323.57 0.18 0.06% No significant recalculations 2.F.4. Aerosols 1113.99 1086.54 -27.46 -2.46% Methodological revision removing assumption that HFC-152a is used as a replacement for HFC-134a 2.F.5. Solvents 16.44 16.44 0.00 0.00% No significant recalculations 2.F.6. Other applications 37.59 31.84 -5.75 -15.30% Methodological improvement to use HFC Outlook data

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 501 Explanation for recalculations 2. Industrial processes and product use 2.B.9. Flurochemical production 78.94 78.94 0.00 0.00% No changes. 2.C.3. Aluminium production 0.00 0.00 0.00 0.00% No changes. 2.F.3. Fire protection 0.00 0.00 0.00 0.00% No changes. 2.G.2. SF6 and PFCs from other product use 0.00 0.00 0.00 0.00% No changes. Explanation for recalculations 2. Industrial processes and product use 2.B.9. Flurochemical production 1.53 1.53 0.00 0.00% No changes. 2.C.3. Aluminium production 0.00 0.00 0.00 0.00% No changes. 2.G.2. SF6 and PFCs from other product use 0.00 0.00 0.00 0.00% No changes. Explanation for recalculations 2. Industrial processes and product use 2.E.1. Integrated circuit or semiconductor 0.26 0.26 0.00 0.00% No changes. Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 502 Explanation for recalculations 2. Industrial processes and product use 2.E.1. Integrated circuit or semiconductor 0.34 0.34 0.00 0.00% No changes. A. Fuel Combustion (sectoral approach) Y Y Chapter 3 1. Energy industries Y Y Chapter 3 2. Manufacturing industries and construction Y Y Chapter 3 B. Fugitive emissions from fuels Y Y Chapter 3

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 503 2. Oil and natural gas and other emissions from energy C. CO2 transport and storage N N 2. Industrial processes and product use Y Y Chapter 4 A. Mineral industry Y Y Chapter 4 B. Chemical industry Y Y Chapter 4 C. Metal industry Y Y Chapter 4 D. Non-energy products from fuels and solvent use Y Y Chapter 4 E. Electronic industry Y Y Chapter 4 F. Product uses as substitutes for ODS Y Y Chapter 4 G. Other product manufacture and use Y Y Chapter 4 A. Enteric fermentation Y Y Chapter 5 B. Manure management Y Y Chapter 5

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 504 D. Agricultural soils Y Y Chapter 5 E. Prescribed burning of savannahs N N F. Field burning of agricultural residues N N Chapter 5 H. Urea application Y Y Chapter 5 I.
Other carbon containing fertilisers Y Y Chapter 5 4. Land use, land-use change and forestry Y Y Chapter 6 G. Harvested wood products Y Y Chapter 6

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 505 A. Solid waste disposal Y Y Chapter 7 B. Biological treatment of solid waste Y Y Chapter 7 C. Incineration and open burning of waste Y Y Chapter 7 D. Wastewater treatment and discharge Y Y Chapter 7 6. Other (as specified in Summary 1.A) N N

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 506 all recalculations is a decrease of 0.9 Mt CO2 equivalent in 1990, and a decrease of 2.5 Mt in the current and the previous NIR, according to IPCC source sector. Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 507 changes in total net GWP emissions, between the inventory presente d in the current and the previous NIR. There has been a very minor change in the reported trend in emissions. The reported trend from 1990 to 20 20 in the 20 22 inventory sub mission was a decrease of 49.6%. The recalculated trend from 1990 to 20 20, as presented in the 2 023 submission is a decrease of

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 508 All recalculations to the inventory, including those made in response to the review process and other recalculations e.g. due to data revisions are described in detail within Chapters 3 to 8, recommendations from the review process, including where these have led • changes in reporting in the NIR; • changes in reporting in the CRF; and • planned improvements for future submissions. The UNFCCC conducted desk review of the 2022 UK greenhouse gas inventory submission from the 19th September to the 24th September 2022, in accordance with the Article 8 review guidelines of the Kyoto Protocol (adopted by decision 22/CMP.1 and revised by decision 4/CMP.11). The final output of this review, the 2022 Annual Review Report, was published on the 10th of February 2023.T he expert review team (ERT) did not identify any issues that required a resubmission of the 2022 submission. Each review report reconsiders items raised during the previous review (in this case the 2021 UNFCCC review) , updating the item as to whether it has been resolved or not reso lved, or whether the item is being addressed. The

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 509 10.16 details updated responses to the last UNFCCC review , for legacy items that also those items new to the 2022 UNFCCC review. Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 510 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Make information related to the national registry publicly available and provide the correct link in the Resolved. The Party reported in its NIR (p.584) that publicly accessible information is available from the United Kingdom’s registry via the Kyoto Protocol Public Reports page at registry.service.gov.uk/kp-reports. Section 12.4 Clearly indicate the geographical coverage of the Digest of United Kingdom Energy Statistics and demonstrate how fuel consumption data at the subcategory level for each overseas territory and Crown dependency are obtained and incorporated into the national totals for that subcategory. Addressing. Text has been added to Section 1.1.2.1 and A3.6 explaining that where the data is available, activity data on fuel consumption at the subcategory level is included for each overseas territory and Describe in the NIR how much biogas is blended with natural gas, consider ways of reporting AD on and related CO2, CH4 and N2O emissions from biogas separately under biomass, ensuring that any changes do not affect the accuracy of the reporting on CH4 and N2O emissions, and update the NIR section on biomass (section 3.2.5) and the relevant method Not resolved. The UK improvement programme includes an item to consider this recommendation. Enhance the transparency of allocation and reporting of recovered CH4 originating from the waste sector that is used in the energy sector. Resolved. The Party reported in its NIR (p.437) how waste management, waste disposal and waste utilization are considered and interact among the waste, energy and agriculture sectors, and where waste management, disposal and utilization are reported in the inventory. Specifically, the United Kingdom has introduced a new section to the NIR (pp.437–446, “Waste Related Activities Reported In Section 7.1.1

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 511 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Other Sectors”), which includes a discussion of how CH4 recovery data related to biogas fuel use are Evaluate the relevance of the current equipment data used in the 2004 model for estimating off-road emissions, and on the basis of the results of the evaluation, either document in the NIR how the model still reflects current circumstances or make efforts to update the model and report on progress in the NIR. Resolved. Databases and information for the new model were provided by industry trade associations and stakeholder groups including the Off Highway Engine and Equipment Group (OHEEG) the Agricultural Engineers Association (AEA), Department for Transport (DfT) and the Construction and Agriculture Equipment Security and Registration (CESAR) database. Machinery or engine-specific fuel consumption and emission factors (g/kWh) in the new model are based on stakeholder consultation and the 2019 EMEP/EEA Guidebook. The AEA were able to provide fuel consumption rates for different agricultural machinery types in litres per hour based on telemetry data. Exception were agricultural telehandlers which were adjusted to align with fuel consumption rate implied by Guidebook factors.
Model includes detailed activity from base year 2018, various proxy statistics are used as activity drivers for different groups of machinery types to estimate fuel consumption across the full time-series, EMEP/ EEA Guidebook (2019), up to Stage V. The new model considers hours of use in two Firstly, the new NRMM model allows hours of use assumptions for a given machinery type to vary by the sector in which it is used. This is to recognise that different sectors may have different hours of use for the same machinery type. Secondly, it also has the provision to adjust for decreasing operating hours with increasing age. Fuel reconciliation adjusts all bottom-up off-road estimates, including agricultural off-road. MS 6

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 512 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Describe in the NIR the coverage of the AD, methods and EFs for estimating emissions from well drilling, well testing and well completions in oil and natural gas exploration and clarify whether these emissions are reported under category 1.A fuel combustion activities) or 1.B (fugitive emissions from fuels). Resolved. The Party included in its NIR a new annex 3 section (p.789), which has a description of the AD, methods and EFs for estimating upstream oil and gas production emissions. The description covers the split between fuel combustion and fugitive emissions, including emissions from well drilling, well testing and well completions in oil and gas exploration. Method Statement 18 summarizes the data, methods and results from the recently completed United Kingdom Oil and Gas Inventory Improvement project (Thistlethwaite et al., 2022). Further methodological details by category are provided in annex A3.1.6, including details of each source reported under category 1.B.2.a.1 (oil exploration) and category Estimate and report CO2 and CH4 emissions from exploratory activities or, if they are considered insignificant, report them as “NE” and justify that the likely level of emissions is below the significance threshold established in paragraph 37(b) of the UNFCCC Annex I inventory reporting guidelines. Resolved. A new minor source was added under category 1.B.2.a.1 (oil exploration) across the entire time series incorporating the method from the 2019 Refinement to the 2006 IPCC Guidelines (vol. 2, chap. 4, pp.49–51) to estimate emissions from onshore oil well exploration (NIR p.229). The Party also estimated fugitive CO2 and CH4 emissions from unconventional gas well drilling activities during the period in which they occurred (2010–2020). For 2020, 0.07 kt CH4 emissions and 6.26 kt CO2 emissions were estimated for this category. On page 236 of the NIR, correct the information stating that N2O emissions from nitric acid production and adipic acid production were reported together for 1990– 1994 under category 2.B.3 (adipic acid production) to clarify that these emissions have been reported separately for the entire time series in CRF 2021 ARR) Resolved. The text in the NIR has been amended Section 4.8

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 513 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Report recalculations or reallocations of emissions in accordance with paragraphs 43– 45 of the UNFCCC Annex I inventory reporting guidelines. Resolved. The ERT reviewed the explanations of the recalculations provided in the NIR of the 2022 submission and noted that the issues identified as not reported in compliance with the UNFCCC Annex I inventory reporting guidelines in the NIR of the 2021 submission (according to document FCCC/ARR/2021/GBR) have been fully addressed. This concerns documentation of recalculations in sections 4.5.5, 4.13.5, 4.34.5, 4.35.5, 4.36.5 and 4.42.5 of the NIR. The ERT noted that the Party documented significant recalculations in the “Source specific recalculation” sections of the NIR and used the wording “no significant recalculations” rather than “no recalculations” for minor recalculations. Furthermore, the Party summarized its explanations of non-minor recalculations in NIR tables 10.1–10.14. During the review, the Party expressed its intention to continue to review how recalculations are presented Report CO2 emissions from stone wool production under subcategory 2.A.4.d (other) along with emissions from other sources currently reported under that category to avoid disclosing confidential data, or, if the number of facilities reporting under that category is insufficient to enable the confidential data from stone wool producers to be masked, report them at an aggregated level under one of the other categories under the mineral industry and use the appropriate notation key under subcategory 2.A.4.d, if needed, providing a relevant explanation in the NIR as to where emissions are reported. that an analysis of alternative approaches for reporting CO2 emissions from stone wool production found that the number of facilities is too small to mask confidential data, if reported under category 2.A.4.d (other (other process uses of carbonates)), therefore, the Party continues to report these emissions under category 2.A.3 (glass production). Taking into consideration other options for following the recommendation and reporting emissions from stone wool production at an aggregated level under one of the other categories of the mineral industry (2.A.1 (cement production), 2.A.2 (lime production), 2.A.4.a (ceramics), 2.A.4.b (other uses of soda ash) or 2.A.4.c (non-metallurgical magnesium production)), the ERT agrees with the Party’s judgment that Section 4.29.2

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 514 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section reporting of emissions from stone wool production under category 2.A.3 is the most sensible option. The NIR (pp.254 and 515) clearly specifies that emissions from stone wool production are reported under Complete the ongoing study on the non-glass uses of soda ash in the country and estimate and report CO2 emissions from sodium bicarbonate use under subcategory 2.A.4.d (other) as well as update the NIR to include the relevant AD, EF and methods used for Resolved.
Activity data for soda ash and sodium bicarbonate have been added to the NIR Section 4.39 Estimate CO2 emissions from ceramic products other than bricks either by using the assumption that the clay consumption of these products is on average 11 per cent of the clay consumption of brick production, according to the available data for 2008– 2012, or by applying a country-specific method (e.g. based on the AD for clay consumption for different applications as provided in the United Kingdom Minerals Yearbook 2018), and report these emissions under subcategory Resolved. The Party reported CO2 emissions from the use of clay for the production of ceramics other than bricks under category 2.A.4.a (ceramics) in CRF provides details on the method applied to estimate the emissions and the EFs used. The resulting increase in CO2 emissions for 2019 for category 2.A.4.a is 33.17 kt (9.8 per cent) compared with the level of emissions reported for 2019 for this category in the Update the descriptions of the emissions from sodium bicarbonate use and their allocation in the inventory. Resolved. The Party corrected the text about allocation of emissions from sodium bicarbonate use. In the NIR (pp.258 and 264) it explained that these emissions are included partly under category 2.A.4.d (other (other process uses of carbonates)) and partly under category 1.B.2.d (flue gas desulfurization Use the standard splicing techniques in the 2006 IPCC Guidelines (vol. 1, chaps. 5.5.3.1–5.5.3.4) to fill the gaps of AD and CO2 emissions for categories 2.B.6 (titanium dioxide production) for 1990–1998, Resolved. An improvement item has been raised to evaluate the potential application of splicing techniques to the categories identified by the ERT. This work is currently in draft form awaiting Section 4.12

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 515 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section 2.B.7 (soda ash production) for 1990–1998, 2.B.8.a (petrochemical and carbon black production (methanol)) for 1990–1997, 2.B.8.d (petrochemical and carbon black production (ethylene oxide)) for 1990–1995 and 2.B.8.f (petrochemical and carbon black production (carbon black)) for 1990–1998, revise the CO2 emission estimates accordingly, and explain in the NIR which techniques were used to fill the gaps (e.g. the ERT considers that the surrogate data or overlap approach may be appropriate for developing a consistent time series). If it is not possible to apply the standard splicing techniques, follow the 2006 IPCC Guidelines (vol. 1, chaps. 5.3.3.5–5.3.3.6) and apply an alternative technique for splicing, providing an explanation in the NIR as to why the standard techniques are not valid, documenting the alternative technique applied and comparing the results with one of the standard techniques contained completion, however currently no changes are proposed to the categories identified by the ERT due to the lack of appropriate data. It should be noted, however, that many of the splicing techniques described in volume 1 of the 2006 IPCC Guidelines are not suited to the categories described as the gaps in activity data are within the early time series, from 1990 onwards, not between data points, as in the use of interpolation. Nor do they represent a higher tier methodology for a portion of the timeseries, as in the application of the ‘overlap’ technique described in section 5.3.3.1 of volume 1 of the IPCC guidelines. Two standard splicing techniques do apply, the use of ‘surrogate data’ to simulate the trend in emissions and trend extrapolation, although it should be noted that trend extrapolation should not be used if the change in trend is not constant over time. For each category, available surrogate datasets were evaluated, and the implications of trend extrapolation were considered. For the identification of surrogate datasets, the following order of preference was • Financial data of specific chemical sector • General financial/physical indices of chemical This order of preference aimed to prioritise surrogate datasets that are most indicative of the chemical process accounted for by the category. Other considerations pertain to the coverage and completeness of the surrogate dataset, in comparison to the existing time series for each category. As described in section 5.3.3.2 of volume 1 of the IPCC guidelines, regression analysis is used to select appropriate surrogate data, specifically the use of

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 516 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section common diagnostics like the Pearson correlation coefficient. The applicability of each surrogate is defined in the IPCC 2006 Guidelines as the indicative dataset ‘most strongly correlated’ with the emission factors, activity data or other estimation parameters in question. Surrogates evaluated included data pertaining to specific chemical production quantities, export quantities or export values from Eurostat or in the case of titanium dioxide (2.B.6), data from the British Geological Survey. General financial indices of chemical production from the UK's Office for National Statistics (ONS) was also evaluated. Ultimately none of these datasets were more correlated when tested against the current approach, involving the use of plant capacity as a surrogate. Trend extrapolation was considered, however the trend was thought to be non-linear and the change between years not constant over time, as observed in reported data. The UK approach therefore continues to consider plant capacity to be the best surrogate dataset, and the UK considers the current estimates to be consistent with the 2006 IPCC guidelines for splicing techniques when using plant capacity as a surrogate even if the surrogate is coincidentally constant over the period that the ERT have highlighted. Either avoid the double counting between categories 2.B.1 and 2.B.10 other (chemical industry) or explain in the NIR that double counting of the emissions may occur between these categories Resolved. The Party clearly explained in its NIR (pp.265–267) the nature of the potential double counting between categories 2.B.1 (ammonia production) and 2.B.10 (other (other chemical production)), stating that CH4 emissions from steam reforming processes are reported partly under category 2.B.1 and partly under category 2.B.10. N2O emissions from natural gas combustion in ammonia production are estimated and reported under category 2.B.1.
According to the NIR (p.281), the Party reports CH4 emissions from general petrochemical processes Section 4.5.2

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 517 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section under category 2.B.10; data on these emissions are obtained from the plant operator reports submitted to national regulators (NIR p.267). CH4 emissions are reported together with process emissions from other chemical plants; these operator-reported emissions may include estimates of CH4emissions from fuel combustion and hence there is a small risk of double counting in emissions reported between categories 2.B.1 and 2.B.10. The Party has decided that removing the CH4 emissions from category 2.B.1could lead to a possible omission in reporting CH4 emissions, as it is not certain that operators would include CH4 emissions from combustion in their reports to national regulators, so the approach used in the 2022 submission was deemed most conservative given the available information. Provide in the NIR a description of the methodology used for estimating CH4 and N2O emissions from ammonia production reported under category 2.B.1 and provide the correct reference (i.e. to category where these emissions are reported. Resolved. The Party provided in the NIR (p.267) a detailed description of the methodology used for estimating emissions of CH4 and N2O from ammonia production and correctly identified under which categories they are reported (2.B.1 and 2.B.10). Section 4.5.2 Reallocate CO2 emissions from iron and steel production related to the use of blast furnace gas, coke oven coke, fluxing agents, fuel oil and coal from the energy sector to the IPPU sector in accordance with the 2006 IPCC Guidelines (vol. 3, chap. 4) in Method Statement 3 and Method Statement 4 that CO2 emissions from blast furnace gas and coke oven gas used at integrated iron and steel plants and fuel used in blast furnaces (except for fuel oil and coal, which the Party has concluded are used for energy purposes) have been reallocated from category 1.A.2.a (iron and steel) of the energy sector to category 2.C.1.b (pig iron (iron and steel production)) of the IPPU sector. The ERT considers that this allocation is in accordance with the 2006 IPCC Guidelines (vol. 3, chap. 4) in terms of the

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 518 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section transparency of reporting for iron and steel Include in the NIR the tier level of the methodology for estimating emissions for subcategory 2.F.1. Resolved. The Party reported in its NIR (p.301) that a tier 2a approach is used for estimating emissions for Continue to include in the improvement plan the need for an update of the AD, based on actual consumption, for the estimation of SF6 and PFC emissions from semiconductor manufacture and report any progress thereon in the NIR. Resolved. The Party explained in its NIR (p.332) that it has recently revised a semiconductor model with the primary purpose of improving the AD needed for estimating SF6 and PFC emissions from semiconductor manufacture. As a result of this revision, SF6 and PFC emissions for category 2.G.2 have been recalculated for the entire time series. The methodology used to estimate emissions for the 2022 submission is described in the NIR (pp.327–331) and the assumptions made about the AD (sector growth rates) are explained (p.328). In particular, in the 2022 submission, it is assumed that semiconductor production is constant from 2001 onward (p.328), while in the previous version of the semiconductor model a 10 per cent growth rate after 2010 was assumed (p.332); this, together with updated assumptions on abatement rates, justifies the increasing differences in emissions from 2010 to 2019 between the 2021 and 2022 submissions. The assumptions in the current version of the model have been revised and updated on the basis of consultations with stakeholders in the semiconductor industry and other stakeholders such as trading bodies. During the review, the Party provided a very detailed explanation of the assumptions made in the updated model, as well as of the recalculations and Section 4.6.2

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 519 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section on the trends in the SF6 and PFC emissions. The ERT concludes that the assumptions made are reasonable, and that the recalculations are justified. The ERT acknowledges the improvements made to the model, the reporting on progress in the NIR and the Party’s intention to continue with stakeholder consultations in order to make further improvements over time. The ERT concludes that with the existing update to the model, the recommendation is resolved. Estimate and report emissions for categories 3.F, 3.G and 3.H for overseas territories and Crown dependencies or, if they are considered insignificant, report them as “NE” and provide a detailed explanation in the NIR on the likely level of emissions for categories 3.F, 3.G and 3.H for overseas territories and Crown dependencies in accordance with paragraph 37(b) of the UNFCCC Annex I inventory Addressed. Text has been added to section 5.10 outlining the significance of emissions sources for has been added to this section to present the agricultural areas and emissions for the UK, Isle of Man, the Falkland Islands (Malvinas), and remaining overseas territories and Crown Dependencies. Section 5.10 Update the uncertainty analysis for all categories, including enteric fermentation, for which significant data or methodological changes have occurred since the previous uncertainty analysis was conducted. Resolved. A full uncertainty run has been carried out for the 2023 annual submission including uncertainty analysis for enteric fermentation, the results of which are presented in the NIR. The uncertainty parameters will be kept under review in subsequent submissions but the uncertainty method does now reflect the higher Tier methodologies used in the UK GHGI.
Improve the accuracy of emission estimates for enteric fermentation, manure management and agricultural soils reported for the Crown dependencies by applying a splicing technique (e.g. extrapolation) from the 2006 IPCC Guidelines (vol. 1, chap. 5) to estimate the IEFs for the Crown dependencies instead of maintaining a constant IEF in years for which updated United Kingdom IEFs are not available Addressing. The IEFs were updated in the 2023 submission. The accuracy of emissions estimates for reporting years where updated United Kingdom IEFs are not available in sufficient time will be improved by using extrapolation to estimate the IEFs for the Crown Dependencies. Section 5.4.2.2

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 520 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section in sufficient time to apply them to the emission estimates for the Crown dependencies. Implement general QC procedures in accordance with the QA/QC plan to avoid errors in future annual submissions such as the error found in the 2021 submission in the conversion of the uncertainty estimates for categories 3.B (manure management) and 3.D (agricultural soils) to percentages, where the value was divided by the range maximum rather than by the mean, causing these estimates to be Resolved. The Party reported in its NIR (p.533) that the model used to transpose uncertainty parameters from the agriculture sector uncertainty outputs to the United Kingdom approach 1 uncertainties model has been corrected. Furthermore, the Party stated in its NIR (p.724) that within-model documentation has been added to minimize the risk of such errors. The ERT confirms that the error found in the 2021 annual submission has been corrected, suggesting that general QC procedures have been implemented. Section 5.5.2.2 Clearly report the methodology used to estimate emissions for each of the overseas territories and Crown dependencies in the relevant section of the NIR and ensure that this information is consistent across the NIR, including clearly stating that there are no agriculture activities in Gibraltar Addressing. The UK continues to implement improvements in the agriculture sector for the OT and CDs. A separate chapter for the OT and CDs has been added within the agriculture sector, in order to clearly and transparently report the methodology used to estimate emissions for each of the overseas territories. Added information on the lack of activity data for the relevant OTs for sectors 3F-H are reported within this OT and CD agriculture chapter. being a Tier 1 methodology. A note has been added to this chapter to clarify that there are no agricultural activities in Gibraltar. Section 5.5.2.4 Until a more transparent way of reporting emissions for overseas territories and Crown dependencies in the CRF tables is determined, enhance the references in the agriculture section of the NIR (the N2O emissions from agricultural soils were said to be Resolved. The Party added in its NIR a new section (section 5.10, pp.378–380) on agriculture emissions in the overseas territories and Crown dependencies. Therein, the Party reported that in the CRF tables, all emission data for overseas territories and Crown dependencies are reported under category 3.J

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 521 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Estimate the animal distribution in composting and digester MMS to estimate CH4 and N2O emissions from manure management, using expert judgment to estimate the animal distribution in both MMS until such time that country-specific data are available for Addressing. The UK team has not as yet found any activity data pertaining to composting on UK farms; we continue to work with the organisations that design farm surveys to seek to add more questions to try to determine whether this activity is "NO" or "NE" within the UK. To date we are very confident that this is a very low level (or "NO") activity in the UK, so we have retained the current approach to reporting. As the previous ERT noted, this does not lead to an underestimation of emissions that would be significant for the UK, and all waste manures are accounted for within the current UK model. CRF tables Include the methane conversion factor for anaerobic details on and a reference for the methane conversion factor used for manure managed in digesters for cattle, pig and poultry manure provided during the Resolved. The Party reported in its NIR (p.354) and factors used for anaerobic digestion of livestock manure are based on the values used in the German inventory. The methane conversion factors for anaerobic digestion for cattle, pig and poultry manure Include a summary in the NIR of the research and justification used to determine the different MMS used in the United Kingdom, together with the relevant Resolved. The Party provided in its NIR (pp.356–357 and 864–865) a comprehensive summary of the research, including relevant references, and justification applied in determining the MMS used in the United Kingdom. CRF tables Clarify the data source, methodology used and references for the country-specific N2O EFs in the NIR Resolved. The Party reported in its NIR (pp.356–357) and in NIR tables A3.3.6(c–d) the data sources, methodologies and references used in developing the country-specific N2O EFs for manure management. United Kingdom data relating to direct N2O emissions from manure management were reviewed as part of a Department for Environment, Food and Rural Affairs Section A2.1

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 522 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section project (AC0114) (Topp et al., in preparation). Country-specific EFs are derived from United Kingdom measurements, as described in documents available on request and summarized in N2O Emission Factors for Manure Management in UK Agriculture (Misselbrook, 2017) Include in the NIR an explanation of the poultry manure management practice and the final Resolved.
The Party reported in its NIR (p.357) an explanation of the poultry manure management practice and the final destination of the manure. Manure types going to incineration are assumed to be broiler and turkey litter and the reported quantities incinerated are converted to a proportion of the total manure for these poultry categories on the basis of estimated manure output per bird. Quantities quantities exported from Northern Ireland to England incinerated are deducted from the AD prior to the calculation of emissions from manure spreading on Include in the NIR references for all assumptions made for managed manure N applied to grassland and cropland, whether it be a published reference, a reference or report under preparation, or simply Resolved. The Party provided in its NIR (pp.364– 365) references for the sources of data underpinning the assumptions applied in the United Kingdom inventory regarding managed manure N applied to grassland and cropland. Section 5.10 Include in future annual submissions a summary of how the country-specific N2O EFs for sheep urine and dung were determined, including references. Resolved. The Party reported in its NIR (p.367) a summary of how the country-specific N2O EFs for sheep urine and dung were determined. According to 11.1), the N2O EF for sheep excreta is 50 per cent of the value of the EF for cattle excreta. This EF is supported, for sheep urine, by mean EF values in the 2019 Refinement to the 2006 IPCC Guidelines (vol. 4,

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 523 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section of the value of the EF for cattle dung (0.04 per cent for sheep compared with 0.13 per cent for cattle). On the basis of this information, the United Kingdom derived N2O EFs for sheep urine and dung by halving the country-specific values for cattle urine and dung Provide in the NIR an explanation and further supporting evidence for the classification of organic soils in the Falkland Islands (Malvinas) as unmanaged and explain why the areas of organic soils in overseas territories and Crown dependencies are not included as a contributing source to N2O emissions from the cultivation of organic soils Addressing. Peat organic soils occur in the Falkland Islands and Isle of Man but not in the other Overseas Territories and Crown Dependencies. Emissions from the drainage and rewetting of organic soils on the Isle of Man were reported in this years inventory submission, with text included in the NIR text. There is a longer term research project into organic soils and emissions in the Falkland Islands (funded through the UK Government Darwin Initiative project DPLUS083), the results of which will feed into the Report emissions from overseas territories and Crown dependencies in the respective categories (3.A (enteric fermentation), 3.B (manure management), 3.D (direct and indirect N2O emissions from agricultural soils), 3.G (liming) and 3.H (urea Resolved. The documentation boxes in the CRF for categories 3.A-H have been updated to transparently clarify that the data for OTs and CDs are reported Provide an explanation in the NIR for the discrepancies between areas of organic soils reported Resolved. The Party reported in its NIR (pp.368 and grassland. The area of grassland on organic soils

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 524 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section and non-intensive/semi-natural grassland condition categories, hence the differences in areas of organic soils reported in CRF tables 4.B, 4.C and 4(II). Calculate SOC change values for each soil type, under each land-use category and for each devolved administration and use those values to calculate SOC changes associated with land-use changes. Addressing. The implementation of the land-use tracking vector approach will enable the UK to move towards resolving this issue, by analysing areas of stable land-use. This needs to be combined with an updated assessment of SOC estimates by land use type to ensure that the most accurate and robust soil information is used in the inventory modelling. Both of these items have been proposed for addition to the Implement methodological changes to avoid any artefact trends in SOC changes in mineral soils associated with land-use changes or identify how the accumulation of land that has undergone a land-use change but not yet reached a new equilibrium, rather than a change in the rate of land-use changes, contributes to the trend in total SOC changes Addressing. Work has been commissioned to explore the effect of an extended land use change time series (beginning in 1900 vs beginning in 1950) on the resulting soil carbon stock change from 1990 onwards. Results of this will be reported in the 2024 Include information in the NIR on the verification of all carbon stock changes estimated using tier 3 methods and/or models (CARBINE, C-Flow and BSORT Addressing. The results from the second cycle of the NFI are not yet available, but will be used as part of verification efforts once the data has been analysed. Estimate and report carbon stock changes in biomass from forests not used for timber production in accordance with the 2006 IPCC Guidelines (vol. 4, chap. 4) owing to biomass losses associated with harvesting and/or gathering (e.g. fuelwood) or provide transparent information justifying that such losses are

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 525 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Provide in the NIR verification information consistent with the 2006 IPCC Guidelines (vol. 1, chap. 6.10, p.6.19) on estimates of emissions and/or removals prepared using tier 3 models, in accordance with paragraph 41 of the UNFCCC Annex I inventory reporting guidelines, and continue the model soil carbon stocks and flux verification exercise and report Addressing.
We will continue efforts to verify the changes is soil carbon estimated by the SCOTIA model and publish the results, along with identifying any potential additional data for verification. Allocate rural hedges to settlements or grassland, ensuring time-series consistency of the accounting of these areas to a single land-use category, and clearly indicate in the NIR where they are included. Resolved. The Party reported in its NIR (pp.409 and 520) that the land-use change methodology has been revised to assimilate multiple sources of information on land use and land-use change, removing the inconsistency in the definition of hedgerows arising from the use of data on broad habitats from the UK Centre for Ecology & Hydrology Countryside Survey. The biomass carbon stock changes were calculated from a different (linear) Countryside Survey source (Haines-Young et al., 2000) and all carbon stock changes were reported under grassland. Collect the necessary data to enable reporting of emissions/removals from peat extraction remaining peat extraction in overseas territories and Crown Resolved. Estimates of peat extraction remaining peat extraction for domestic fuel use in the Falkland Islands are included in the 1990-2021 inventory. This was based on a new data source (household census repeated every 5-6 years from 1991) on households using fuel peat combined with expert local knowledge to produce an activity time series using interpolation between census values. It is assumed that abandoned peat extraction areas have not been Provide in the NIR detailed information to describe that land conversion to peat extraction in overseas territories and Crown dependencies is not occurring. Resolved. Estimates of land converted to peat extraction for domestic fuel use in the Falkland Islands are included in the 1990-2021 inventory. This

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 526 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section was based on a new data source (household census repeated every 5-6 years from 1991) on households using fuel peat combined with expert local knowledge to produce an activity time series using interpolation between census values. It is assumed that abandoned peat extraction areas have not been Assess the areas of and emissions from wildfires on forest land remaining forest land, land converted to forest land, grassland remaining grassland and land converted to grassland for all overseas territories and Resolved. To address this issue, the United Kingdom information on wildfires in the overseas territories and published government data on fire occurrence, and contacted local experts in all overseas territories and Crown dependencies (NIR annex, p.934). This assessment found no occurrence of fires and zero burned areas for 2002–2019 for the Cayman Islands, Guernsey, the Isle of Man and Jersey. Bermuda fire statistics show either forest land or grassland. For the Falkland Islands (Malvinas), the Global Wildfire Information System recorded 11 fires between 2002 and 2019 on an estimated total area of 5,024 ha based on pixel size, although the total burned area is recorded as zero. Owing to the lack of publicly available data for wildfires in the overseas territories and Crown dependencies, a geographical proxy burning rate was used to estimate wildfire Include verifiable production data from the CARBINE model and the corresponding factors used to convert the production data to carbon, and report those data Resolved. In the 2021 submission, the Party reported a truncated time series of production data from the converting production data to carbon were absent

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 527 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section verification of the HWP estimates series is reported (1960–2020) and the values for converting production units to carbon are provided. Implement the proposed improvements of the emission estimates for SWDS in overseas territories and Crown dependencies by providing further information on the methodologies used to estimate the emissions and by completing the CRF tables with specific parameters such as AD, methane correction factor and degradable organic carbon. Resolved. The Party provided in its NIR the AD for total MSW disposal for Crown dependencies (NIR parameters used for estimating emissions for SWDS in addition to defaults provided in the IPCC landfill model. The United Kingdom indicated in the reported are for mainland United Kingdom only, while the emissions reported include contributions from overseas territories and Crown dependencies. During the review, the United Kingdom confirmed that in CRF mainland United Kingdom only, while emissions include activities in mainland United Kingdom as well as in overseas territories and Crown dependencies. The Party explained that it considers this approach (in combination with the documentation box pointing readers to the section of the NIR where parameters for the overseas territories and Crown dependencies are documented) to be pragmatic. The Party noted that the alternative to presenting modified AD and other non-emission data in the CRF tables reflecting specific overseas territories and Crown dependencies that fall within the scope of each of the United Kingdom’s three different CRF submissions (i.e. Convention, Kyoto Protocol and European Union) would lead to a disproportionate effort for little value. The ERT agrees that the reporting is sufficiently transparent, and that emissions are not affected by the choice of reporting approach. The ERT considers that this recommendation has been fully addressed in

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 528 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section accordance with paragraph 73 of the UNFCCC review Investigate the availability of alternative data sources for the composition of mixed waste and update the waste composition data used for estimating emissions from this category accordingly, or, if this is not given annual submission, provide a justification in the NIR that the waste composition data used are representative of current national circumstances. Addressing. A project is underway to sample and characterise the composition of mixed wastes disposed to landfills.
This should also provide a methodology to estimate the composition in historic Report CH4 recovery consistently with the energy Resolved. The Party revised the data on CH4 (pp.441–445) how data reported by operators compare with energy statistics on sewage gas utilization for 2013 onward. Prior to 2013, CH4 recovered is extrapolated on the basis of United Kingdom energy statistics. The ERT concludes that Exclude N removed with sludge in the calculation of the emission estimates for the waste sector, as suggested by equations 6.7 and 6.8 in the 2006 IPCC Guidelines, and report the AD in the relevant CRF Resolved. The Party reviewed the calculations for N2O emissions from domestic wastewater and updated them by applying an N-balance-based calculation reflecting the estimated N content of sewage sludge removed and used in agriculture, p.476), in accordance with equations 6.7 and 6.8 in the 2006 IPCC Guidelines. The Party revised the AD

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 529 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Report on any progress in collecting the data needed to report AD and emissions from industrial wastewater separately from domestic wastewater. Resolved. As described in the 2nd paragraph of Section 7.5.2.4, data from municipal wastewater operators on industrial co-discharge referred to as 'trade load' are reported by water operators, and these data are used to remove the expected proportion of industrial wastewater which is treated via municipal wastewater systems rather than in-situ. Section 7.5.2.4 Collect information on the proportions of aerobic and anaerobic treatment systems and revise the methane correction factor used accordingly. Resolved. The Party deployed a revised methodology developed in 2021 for estimating CH4 emissions from industrial wastewater that involves estimating the proportions of aerobic and anaerobic treatment systems and using a revised methane correction factor. As indicated in the NIR (p.478), default methane correction factors from the 2006 IPCC Guidelines are used for each type of treatment and discharge pathway or system, taking into account aerobic and anaerobic treatment (2006 IPCC Collect the necessary data to complete the estimates of CH4 recovery from industrial wastewater. Not resolved. The United Kingdom environmental reporting system does not include yet the amount of CH4 recovered nor data allowing to estimate CH4 recovery within the industrial wastewater treatment plants. This issue will be considered for action alongside all other potential inventory improvements and acted upon subject to data and funding Include specific information on how land under CM, GM and WDR is identified, especially related to the report developed as part of the ongoing project on Resolved. The Party reported in its NIR (pp.553–562 and 574) and confirmed during the review that the land-use tracking project is being implemented in two phases, and that the phase one results are available, allowing the Party to use, in the 1990–2020 inventory, spatially explicit data to track land-use change across the United Kingdom that are then simplified to non- Section 11

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 530 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section spatial information for use in the LULUCF and KPLULUCF models. During the review, the Party also clarified that implementation of phase two of the project will not change the land representation as the same underlying set of land-use vectors will be used Estimate and report, in accordance with the 2006 IPCC Guidelines (vol. 4, chap. 4), carbon stock changes in biomass from forests not used for timber production owing to biomass losses associated with harvesting and/or gathering (e.g. fuelwood) or provide transparent information justifying that such Resolved. The ERT has assessed that this issue does not influence the Party’s ability to fulfil its commitments for the second commitment period of the Kyoto Protocol. This same issue will be tracked for convention reporting as issue L.5. (a) Estimate the background level and margin using a consistent and initially complete time series containing emissions for 1990–2009, in accordance with decision 2/CMP.7, annex, paragraph 33, using, if appropriate, methodologies from the 2006 IPCC Guidelines (e.g. vol. 1, chap. 5); (b) Report in the NIR detailed information on the background level of emissions associated with annual natural disturbances that have been included in the FMRL, on how the background levels and margins for AR and FM have been estimated, on how the Party avoids the expectation of net credits or net debits during the commitment period, and on how the FMRL technical correction addresses emissions from natural disturbances for which the provision (e.g. substitution of natural disturbances emissions in the FMRL by the background level estimated) is intended to be applied. (a) Resolved. The Party recalculated the background level and margin and reported in emissions from wildfires (the only natural disturbance considered) for 1990–2009, in Gg Kingdom and the overseas territories and Crown dependencies, in accordance with decision 2/CMP.7, annex, paragraph 33, using methodologies from the 2006 IPCC Guidelines (e.g. vol. 1, chap. 5). (b) Resolved. The default method in the Kyoto Protocol Supplement was used for estimating the background level of emissions and margins. The annual emissions from wildfires on FM and AR land reported in the United inventory were used for the calibration period, applying the same methodology for assigning the wildfire emissions. Avoidance of the expectation of net credits or net debits was achieved in the background level calculation by Section 11

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 531 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section including only the emissions from natural disturbances explicitly included in the GHG inventory (namely, from wildfires) and, as noted by the ERT, the absence of an observable trend in the background time series.
The United Kingdom calculated a technical correction to the FMRL for the current annual submission and one of the elements in the technical correction comprised the revised estimates of emissions from natural Correct the identified inconsistencies in the technical correction and all the information required by the Resolved. The Party corrected the inconsistencies in the FMRL technical correction by including the estimates of emissions from FM land for overseas territories and Crown dependencies. The accounting quantity is reported and justified in the NIR (pp.577– 580) in accordance with the requirements of the Kyoto Protocol Supplement. Section 11 Resolve the inconsistency resulting from the assumption that dead organic matter was instantaneously oxidized and recalculate the technical correction accordingly by using a recalculated and consistent background level of emissions. Resolved. The Party recalculated the background level of emissions to ensure consistency with the estimates included in the GHG inventory, thus eliminating the inconsistency identified by the previous ERT (NIR pp.563 and 574). The technical correction was recalculated on the basis of the latest inventory and assumptions about the level and type of management that would be consistent with policies in place in 2009. These assumptions were based on the method detailed in the United Kingdom National Forestry Accounting Plan, 2021 to 2025. Among the changes in data and assumptions since the FMRL was calculated are a correction to double counting in the calculation of deadwood and the inclusion of estimates of emissions from FM land in overseas

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 532 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section contains the FMRL and technical correction for 2013– Clarify in the NIR how the automated algorithm is used to prepare timber production statistics for the CARBINE model used to produce the technical correction on the one hand, and FM estimates during the second commitment period on the other. Resolved. The Party reported in its NIR (pp.577–580) that the assumptions for FM in the FMRL technical correction were revised to be consistent with the methodology described in the United Kingdom National Forestry Accounting Plan, 2021 to 2025. The resulting divergence between the technical correction and FM estimates is documented in the NIR and explained as part of the accounting quantity. The Party switched from using the CARBINE model to using the C-Flow/CARBINE models, which can represent a wider range of tree species and management practices, though the Party informed the ERT during the review that the methodologies of both models are consistent with each other. The FMRL for the United Kingdom was calculated using the same methodology for estimating forest carbon stock changes and GHG emissions as the methodology used for the Convention LULUCF inventory, the KP- LULUCF inventory and national projections of LULUCF emissions and removals, but with assumptions about the level and type of management that would be consistent with policies in place in 2009. Section 11 Provide an assessment of whether and to what extent differing application of the algorithm to adjust the assumed FM harvest to harmonize with timber production statistics results in a divergence between the technical correction and the FM estimates during Resolved. The Party reported in its NIR (pp.577–580) that the assumptions for FM in the FMRL technical correction were revised to follow the methodology described in the United Kingdom National Forestry Accounting Plan, 2021 to 2025. The resulting divergence between the technical correction and FM estimates is documented in the NIR and explained as part of the accounting quantity. For further details, see

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 533 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section Define the category of land under which hedges are to be accounted, ensure that corresponding GHG emissions and removals are estimated, and report consistently thereon for the entire time series. Resolved. The Party stated in its NIR (p.906) that managed and unmanaged hedges are all reported under grassland and that biomass carbon stocks are estimated as the median of values relevant to the United Kingdom in the published literature, as determined from a literature review, supplemented by more recent data, for the entire time series. Full details of these values and data sources are included in the Party’s Grassland Management Biomass total biomass carbon stocks, the uncertainties and the root-to-shoot ratios for managed and unmanaged hedges applied in estimating emissions and removals for the 2022 submission. Section 11 Develop the necessary AD on controlled burning throughout the year and in land areas smaller than 1 ha and estimate and report the associated CO2 and non-CO2 emissions for the entire territory. Resolved. During the review of the 2021 submission, information regarding controlled burning on grassland was provided to the ERT, including a preliminary assessment supporting the view that emissions from controlled biomass burning are insignificant (approximately 163 kt CO2 eq without accounting for post-fire vegetation regrowth). The previous ERT considered that including a summary of this information in the next annual submission would resolve the recommendation. The Party reported in the NIR (pp.916–917) of the current annual submission a summary of the information, as

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 534 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section The Party reported in its NIR (p.585) the CPR value of 90 per cent of the assigned amount as 2,470,443,559 t CO2 eq. The ERT noted that according to the Party’s report to facilitate the calculation of the assigned amount for the second commitment period of the Kyoto Protocol, and through its own calculation of the information documented in the NIR (p.585), this value should be 2,470,443,599 t CO2 eq.
The ERT also noted that in the NIR (p.585), the comparison of 90 per cent of the assigned amount was made with eight times the total GHG emissions of the inventory for 2018 contained in the 2020 submission instead of with eight times the total GHG emissions of the inventory for the 2020 contained in the 2022 submission, as required by decision 11/CMP.1, annex, paragraph 6. During the review, the Party confirmed the CPR value to be an editorial error and that the correct value is 2,470,443,599. Regarding the comparison of the assigned amount, the Party clarified that it believes it should have used the total GHG emissions for 2019 contained in the 2021 submission. However, the ERT noted that as the 2022 submission will be the latest available reviewed annual submission at the time of publication of the 2022 annual review report, the comparison should have been made with the total GHG emissions for 2020 contained in the 2022 submission, which is equal to 404,834,197 × 8, or 3,238,673,576 t CO2 eq. This value is higher than the value of the CPR as contained in the report to facilitate the calculation of the assigned amount for the second commitment period of the Kyoto Protocol. The ERT concludes that the final CPR is 2,470,443,599 t CO2 eq. The ERT further concludes that this potential problem of a mandatory nature does not influence the Party’s 2022 ARR G.2 Resolved. The ERT recommended that the calculation of the commitment period reserve in the 2022 submission should have used eight times the total GHG emissions of the inventory for 2020 contained in the same submission. The emissions total in the CPR calculation in the 2023 submission has been updated to use the ERT’s recommended value of 2020 emissions from the 2022 submission, excluding KP LULUCF. Our rationale for continuing to emissions from the 2023 submission) is that the 2022 submission is the UK’s most recently reviewed inventory submitted to fulfil reporting obligations under the Kyoto Protocol, and the final inventory to be compiled using the geographical scope of the Kyoto Protocol second commitment period. In addition, 2020 is the last year of the second commitment period of the Kyoto Protocol. Section 12

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 535 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section ability to fulfil its commitments for the second commitment period of the Kyoto Protocol and therefore this issue was not included in the list of potential problems and further questions raised. In several cases, the Party reported in its NIR (annex 2) uncertainty for aggregated categories (e.g. 1.A (coal) (CO2) and 2.B (chemical industry) (CO2)) instead of for each subcategory. The Party reported in its NIR (p.525) that it will consider the encouragement from the previous ERT to transparently explain in the NIR its rationale for estimating uncertainties for aggregated categories during future updates of annex 2 to the NIR. During the review, the Party clarified that according to the 2006 IPCC Guidelines (vol. 1, chap. 3), aggregation should be used as a means to make the uncertainty analysis more accurate by reducing unaccounted for correlations and dependencies. According to the Party, the biggest challenges with disaggregation are that (1) subcategories can have positive or negative correlations to one another that are either not accounted for in approach 1 or require additional work to adequately account for in approach 2 and (2) disaggregation without consideration of the 2022 ARR G.3 Resolved. The UK has added 2 sentences to the opening section of Annex 2 in the NIR in order to be more transparent about the rationale for not estimating uncertainties at higher levels of sectoral

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 536 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section correlations changes the results of the uncertainty analysis in ways which make the results less valid. The ERT agrees with the Party’s views. The ERT recommends that the Party explain in the NIR its rationale for aggregating category uncertainties to account for correlations and dependencies, rather than reporting uncertainty by subcategory. The Party reported in its NIR (p.141) fuels that are excluded from the United Kingdom’s reference approach but are included in its sectoral approach, namely, waste oils, fossil-containing waste, scrap tyres and waste solvents. The Party also reported that the reference approach does not include emissions from these fuels because the reporting of the fuels is not complete in the United Kingdom energy statistics. discrepancy in AD between the reference approach and the sectoral approach for other fossil fuels, specifically, for 2020, 69.85 PJ other fossil fuels are reported under the reference approach and 113.05 PJ are reported under the sectoral approach. The ERT noted a lack of transparency regarding which other fossil fuels are included in the reference approach and the main reasons for the observed differences. During the review, the Party clarified that the data on other fossil fuels used for the reference approach are data on MSW used as a fuel from the United Kingdom energy statistics and also that the MSW data in the energy statistics do not include all waste products accounted for under the sectoral approach. For 2022 ARR E.7 Resolved. The UK has updated Section 3.2.1.1.5 of the NIR to include a brief discussion of the comparison between the sectoral approach and reference approach for other fossil fuels Section 3.2.1.1.5

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 537 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section example, while some scrap tyres are included in the United Kingdom energy statistics as part of the MSW data, the Party is aware that some scrap tyres used as a fuel are not included in these statistics and, therefore, does not include these in the reference approach.
The ERT recommends that the Party clarify in the NIR which fuels are included in the other fossil fuels portion of fuels considered under the reference approach, including, for example, what percentage of total MSW is captured by the United Kingdom energy CO2 emissions associated with residual fuel oil use in fishing, which resulted in a CO2 IEF of 535.00 t/TJ. The ERT noted that the reported IEF is higher than that for all other reporting Parties (maximum of 77.95 t/TJ for 2020) and higher than the default IPCC EF IPCC Guidelines). During the review, the Party clarified that the AD for this category are for mainland United Kingdom only while the emission data include the overseas territories and Crown dependencies. The use of these data resulted in an unrepresentative IEF, but the CO2 EF used by the Party for residual fuel oil is 76.50 t/TJ, which is in line with the default 2022 ARR E.8 Resolved. After the ERT's review, it was noted that reporting residual fuel oil use in fishing is unusual since fuel oil is normally used by larger ships. After review by the Party, residual fuel oil use in overseas territories and Crown dependencies has been estimated as 0 and the equivalent energy use and associated emissions have been moved to gas oil activity instead. This results in IEFs that are

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 538 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section IPCC EF and those of the other reporting Parties. The Party explained that the AD for the overseas territories and Crown dependencies for this source are in a different format to those for mainland United Kingdom and cannot be aggregated and included in the CRF tables without manual intervention. The Party noted that it is working towards recording AD for overseas territories and Crown dependencies in a format consistent with that of the mainland United Kingdom AD, therefore making it easier to identify and aggregate these data and transpose them into the CRF tables. The ERT recommends that the Party continue to work to gather AD for residual fuel oil use in fishing (category 1.A.4.c.iii) for the United Kingdom’s overseas territories and Crown dependencies in the appropriate format and report of the IEF with the other reporting Parties or describe in the NIR the differences in these AD from mainland United Kingdom AD and the reason for not including CO2 IEFs associated with solid fuel transformation. The interannual change in the CO2 IEF is significant for several years, for example, between 2015 (150.97 kg/t) and 2016 (217.23 kg/t), representing a 43.9 per cent increase, and between 2018 (214.75 kg/t) and 2019 (108.04 kg/t), representing a 49.7 per cent decrease. Methodological information on category 1.B.1.b was not provided in the NIR and the reasons for the inter-annual changes were not reported. During the review, the Party clarified that category 1.B.1.b (solid fuel transformation) covers three distinct coke oven related sources at steelworks, and the use of coal and petroleum coke in the production of solid smokeless fuel (i.e. two sources). The two solid smokeless fuel production sources 2022 ARR E.9 Resolved. The UK has introduced a new method statement (MS 20, in chapter 3 of the NIR) which describes the methodology used for other sources reported in 1B1b, and included commentary on the time-series fluctuations in IEF and a reference to the energy background data that would help future reviewers see the justification for these IEF

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 539 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section dominate emissions for 2015–2019 and are mainly responsible for the inter-annual variation in the CO2 IEF. The Party confirmed that emissions for these two sources tend to vary from year to year because their estimation is based on a simple carbon balance method and is affected by the ratio of coal to petroleum coke inputs and by the ratio of inputs to solid smokeless fuel outputs. The ERT recommends that the Party include in Method Statement 4 of its NIR information on solid smokeless fuel production (currently only coke oven related sources at steelworks is covered) and reference the relevant background spreadsheet for each year of the inventory, which includes the AD and CO2 EFs for the input and output streams of solid smokeless fuel production and explain any inter-annual differences in the CO2 IEF for category 1.B.1.b (solid fuel The Party reported in its NIR (p.265) that some of the CO2 recovered from ammonia production is sold by the production facilities to other industrial plants, without specifying whether the emissions associated with the CO2 sold are included elsewhere in the inventory. The ERT noted that according to the 2006 IPCC Guidelines (vol. 3, chap. 3, equation 3.3 and certain applications should be subtracted from emissions under category 2.B.1 (ammonia production) if reported elsewhere in the inventory. During the review, the Party clarified the applications of the CO2 sold, stating that it is used, for example, in the production of carbonated drinks, as a refrigerant, as a cover gas for the brewing industry, as a feedstock for other chemical industries, and at slaughterhouses. The Party confirmed that emissions from CO2 used in these applications are included in the GHG inventory. The ERT did not identify any 2022 ARR I.13 Resolved. The UK has expanded the text of exported CO2 from ammonia production in Section 4.6.1 of the NIR, including listing likely uses for the CO2 and discussing how those are reported in the UK

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 540 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section underestimation of CO2 emissions resulting from the accounting for CO2 sold.
The ERT recommends that the Party include in the NIR (section 4.6.1 or 4.6.2, for example, in tabular or list format) the applications of CO2 that is recovered from ammonia production and sold to other industrial plants, clearly specifying for each application whether the associated emissions are reported under categories other than 2.B.1 (ammonia production), and if so, which categories. For the 2022 submission, in response to a reallocated a large part of the emissions occurring at integrated iron and steel plants from category 1.A.2.a (manufacturing industries and construction (iron and steel)) to category 2.C.1.b (iron and steel production (pig iron)). Specifically, all blast furnace gas and coke oven gas used at integrated iron and steel plants and all fuel used in blast furnaces were reallocated. The ERT noted that the description of the methodology to estimate emissions from iron and steel production in the NIR (pp.282285) has not been updated accordingly; in particular, on page 283, the Party states that emissions from the use of blast furnace gas and coke oven gas are reported by the process in which they are used (i.e. under category 1.A.2.a) rather than under category 2.C.1. The ERT noted the lack of consistency between the actual allocation of emissions to categories 1.A.2.a and 2.C.1.b (as reported in CRF tables 1.A(a)s2 and 2(I).AHs2 respectively) and the text explaining that allocation in the NIR (pp.282–285). During the review, the Party 2022 ARR I.14 Resolved. The text in Source Category 2C1 has been amended in the 2023 submission. Section 4.16

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 541 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section noted the error on NIR page 283 identified by the ERT, but clarified that this reallocation of emissions between categories 1.A.2.a and 2.C.1.b is documented (NIR Method Statement 3, Method Statement 4 and p.517).The ERT recommends that the Party correct the text in the NIR (pp.282-–285 in the 2022 annual submission) regarding the allocation of emissions from the use of blast furnace gas and coke oven gas at integrated iron and steel plants to ensure that it reflects the allocation of these emissions between category 1.A.2.a (manufacturing industries and construction (iron and steel)) and category 2.C.1.b (iron and steel production (pig iron)). Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 542 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section emissions from lubricant use while it reported the AD for this category as “NO”. The Party reported AD on 2020). During the review, in response to a question raised by the ERT, the Party provided the ERT with the complete set of AD (amounts of lubricants used, in kt) covering the entire time series. The ERT recommends that the Party report AD on lubricant use UNFCCC Annex I inventory reporting guidelines. 2022 ARR I.15

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 543 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section The ERT conducted an N balance check for manure management from the point of Nex entering MMS to the point of land application on the basis of data available in CRF tables 3.B(a)s2, 3.B(b) and 3.D. The amount of N leaving manure storage estimated by the ERT was lower than the reported amount of N applied to soils for 1990–2013 and higher than the amount reported for 2014–2020. During the review, the Party clarified that the values calculated by the ERT differ from the reported values owing to several factors not taken into account by the (1) consideration of emissions of N (dinitrogen/nitrogen gas) throughout manure management, (2) removal of poultry manure N going to incineration, (3) categorization of manure processed through anaerobic digestion as digestate when applied to land, with this manure therefore being included under category 3.D.2.c (other organic inclusion of bedding N in the N amounts reported in these factors into account, the ERT considers that the approach applied by the United Kingdom for calculating the N balance along the manure cascade is correct; however, it is not transparently described in the NIR. The Party also clarified that the structure of the CRF tables for reporting emissions from manure management do not align well with the more disaggregated nature of the United Kingdom’s agriculture model and stated that it will therefore provide more detailed output in the NIR and the annex to the NIR, including a full N balance check from the point of Nex entering MMS to the point of land application. The ERT recommends that the Party provide in the NIR information on all N flows from the point of Nex entering MMS to the point of land application in order to allow a transparent assessment of the N balance. 2022 ARR A.18 Resolved. A full balance check for manure management has been provided as a supplementary file to the NIR, including a full N balance check from the point of Nex entering MMS to the point of land application as requested by the previous ERT. Supplemental file

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 544 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section During the review, in response to the issue raised by the ERT under ID# A.20 below, the Party noted that incorrect values for poultry Nex were entered in CRF throughout). The United Kingdom emphasized that this error has no impact on reported emissions for this category for those years. The ERT agreed that the reported emissions are not affected by the incorrect values for poultry Nex. The ERT recommends that the Party provide the correct values for poultry Nex in values have been corrected across the time series and the UK has strengthened its QAQC of the data submitted within the CRF.
CRF tables

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 545 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section The ERT noted the following information relevant to information item for reporting HWP in SWDS was reported as “IE”, with the comment “included with 4.Gs1, the documentation box contains the note that “the amount of HWP in SWDS are not currently the annual change in the long-term carbon storage in HWP waste is reported as “NO”. These three pieces of information are inconsistent with one another and present different potential issues depending on which of the entries is correct. During the review, the Party clarified that the information in the documentation box in SWDS are not currently estimated, allowing the ERT to have confidence that neither an underestimation of CH4 emissions for the waste sector nor a problem in KP-LULUCF reporting regarding the fulfilment of the requirements of decision 2/CMP.7, annex, paragraph 32, has occurred. The Party informed the ERT that it was unable to identify wood entering SWDS from domestic production as distinct from imports, consistent with the elected production approach, and therefore was unable to estimate the potential emissions from HWP in SWDS. The ERT recommends that the Party (1) follow the guidance in the 2006 IPCC Guidelines (vol. 4, chap. 12, section 12.2.1), which advises using the methods of the waste sector (which are consistent with the consumption approach for HWP) to assess whether emissions from HWP in SWDS are likely to be significant (i.e. larger than any other key category), and include information consistent with this assessment in its reporting for the LULUCF sector; and (2) if the likely emissions from HWP in SWDS are found to be significant, develop a methodology 2022 ARR L.12 Resolved. The CRF has been corrected for the 2023 submission to report HWP in SWDS as NE in all relevant tables. Investigation of the significance of the emissions/removals relating to HWP in SWDS has been added as a potential improvement item and will be discussed by the Scientific Steering Group. Any progress will be documented in the NIR. CRF tables

Recalculations and Improvements 10 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 546 category/issue Recommendation made in previous review report Review report / paragraph Response Chapter / section consistent with the 2006 IPCC Guidelines that is appropriate to its national circumstances for estimating the emissions/removals of HWP in SWDS and include these emissions/removals in its reporting

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 547 All reporting of information required under Article 3, paragraphs 3 and 4 of the Kyoto Protocol for the purposes of the second commitment period of the Kyoto Protocol has now taken place. This information is available in the UK's 1990 -2020 greenhouse gas inventory, published in 2022, which will be used to assess compliance with the UK’s targets under the Doha Amendment. The 2022 N IR submission is available at

Information on Accounting of Kyoto Units 12 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 548 12 Information on Accounting of The UK’s Standard Electronic Format report for 2022 containing the information required in paragraph 11 of the annex to decision 15/CMP.1 and adhering to the guidelines of the SEF has been submitted to the UNFCCC Secretariat electronically – RREG1_GB_2022_2_1.xls At the end of 2022, the total CP2 holdings for the UK Registry was 33,243,067 CERs, of which 10,894,859 were in the voluntary cancellation account and 22,061,304 in entity holding accounts. There was also a total of 12,275,645 ERUs. In total for 2022, the UK Registry received 19,298,577 CERs and 0 ERUs. Conversely, 11,987,502 CERs and 15,509 ERUs were externally transferred to other national registries. No other CP2 units were transferred or acquired. 0 CERs or ERUs were cancelled. Full details are available in the SEF tables. Information on legal entities authorised to participate in mechanisms under Articles 6, 12 and 17 of the Kyoto Protocol can be found on the UK Emis sions Registry website in the Kyoto Protocol Public Reports area at Annual Submission Item Reporting Guidance 15/CMP.1 Annex I.E paragraph 11: Standard electronic format (SEF) UK’s Standard Electronic Format report for 2022 containing the information required in paragraph 11 of the annex to decision 15/CMP.1 and adhering to the guidelines of the SEF has been submitted to the UNFCCC Secretariat electronically. RREG1_GB_2022_2_1.xlsx (Commitment Period 2 only). Information on Accounting of Kyoto Units 12 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 549 Annual Submission Item Reporting Guidance 15/CMP.1 Annex I.E paragraph 12: List of discrepant transactions No discrepant transactions occurred in 2022. No CDM notifications occurred in 2022. Refer to Separate Electronic Attachment “SIAR Reports 2022 -GB 15/CMP.1 Annex I.E paragraph 15: No non-replacements occurred in 2022. Refer to Separate Electronic Attachment “SIAR Reports 2022-GB 15/CMP.1 Annex I.E paragraph 16: No invalid units exist as at 31 December 2022. Refer to Separate Electronic Attachment “SIAR Reports 2022 -GB 15/CMP.1 Annex I.E paragraph 17 Actions and changes to address Actions and changes are addressed in Chapter 14: Information on Changes to National Register under section Change of The following information is deemed publicly accessible and as such is usually available via the homepage of the UK registry via the Kyoto Protocol Public Reports link at emissions-trading-registry.service.gov.uk/kp-reports/ In accordance with the requirements of Annex E to Decision 13/CMP.1, all required information for a Party with an active Kyoto registry is provided with the exceptions as outlined

Information on Accounting of Kyoto Units 12 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 550 Account Information (Paragraph 45) Certain information listed in paragraph 45 of the Decision is considered confidential.