Energy BOG Report
Joint 1st and 2nd IPCC Expert Meetingon Short-Lived Climate Forcers (SLCFs)

Virtual sessions, 13-20 October 2021

BOG ReportParticipantsExperts: Anouk Aimée Bass, Nathan Borgford-Parnel, Komi Akpé Agbossou, Songli Zhu,
Toshihiko Takemura, Naga Oshima, Yugo Kanaya, Ole-Kenneth Nielsen, Aminata Mbow
Diokhane, Maria de Fatima Andrade, Michael Strogies, Gill-Ran Jeong, Nguyen Thi Kim Oanh,
Stefano Decesari, Tami Bond, Amit Garg, Luis Gerardo Ruiz Suárez, Puji Lestari, Xavier Querol,
Veronika Ginzburg, Leonidas Ntziachristos, Noureddine Yassaa, Yugo Kanaya
TFB members: Kiyoto Tanabe (Co-Chair), Dario Gomez, Rob Sturgiss, Fatma Betül Demirok,Riitta Pipatti, Thomas Wirth••••

Facilitator:
Dario Gomez
Rapporteur:
Vincent Camobreco
Consultant to TSU (MURC): Takeshi Enoki
TSU:
Valentyna Slivinska

BOG ReportHighlights of energy cross-sectoral issues 1• Tier 1 EFs for SLCF could be based on the approach for non-CO2
GHG methodologies but would need to include additional details onfuel characteristics (e.g., S content) and abatement technologies
applied (e.g., reduction efficiency and implementation rate)• Methodologies for stationary combustion should allow the possibilityof estimating emissions under co-firing practices and provide thecorresponding guidance, including activity data collection, emission
factors and other parameters• PM2.5 is considered a SLCF, highly heterogeneous spatially andtemporally (varying from positive to negative radiative forcing
depending on sources and meteorological characteristics). The
participants of this BOG decided to include primary PM2.5 in the listof emissions to be estimated not only because it is a SLCF but as anintermediate variable often needed to estimate BC and OC emissions(most BC and OC EFs are expressed as fraction of PM2.5).

BOG ReportHighlights of energy cross-sectoral issues 2• The IPCC methods for SLCFs should include small emissions sources andnonconventional/informal fuels. Combustion and abatement technologies
guidance currently in IPCC categories for GHGs will therefore require
additional analysis when developing SLCF guidance for these smaller
sources and fuels. Critical aspects of developing SLCF methodologies forsmall emission sources include:– EFs vary by several of orders of magnitude as a function of appliances andabatement technologies for a given fuel type. Furthermore, cooking exhaust (meatcooking etc, not from fuel itself) could be considered as small-scale combustion
sources for OC, BC, and PM2.5.
– Emissions from informal combustion normally uses various types of fuels across thesame year. This practice may be difficult to capture in an inventory. The AD of nonconventional fuels are often difficult to obtain and there are issues concerning thereconciliation of AD with the energy balance which may not contain nonconventionalfuels.
– Quality, type, and moisture content of solid fuels may have a large effect onemission factors. Many solid fuels are collected rather than marketed and estimatesof activity data would benefit from diverse inputs.
– Country-specific practices of one country are not always translatable to othercountries therefore there is the need to develop country-specific EFs andparameters.

BOG ReportList of changes / knowledge gaps 1• Category 1.A.1 Energy Industries– The co-firing of fuels could be a major contributor in thiscategory• Category 1.A.2
construction

Manufacturingindustries

and– Small-scale combustion and use of nonconventional andvariable fuels may occur under some facilities in particularfor brickworks– Emissions arising from off-road and other mobile
machinery in industry should, if possible, be broken out
under the corresponding subcategory– The use of product produced as activity data instead offuel used deserves attention for developing T1 factors andpotential omission or double counting with IPPU sector
should be considered

BOG ReportList of changes / knowledge gaps 2• Category 1.A.3 Transport– For aviation sources LTO is critical for SLCFs so if only fuel based T1 approach isused the EF needs to reflect the whole LTO and cruise phase– For on road sources:• The time dependency of technologies is especially relevant for mobile source fleet, includingthat as technology ages it emits differently so EFs may vary over time and that the EFs andother parameters may need to be updated to reflect the evolving nature of future technologies• Engine start-up SLCF emissions may be large for high-mileage fleets, especially in developingcountries• Super emitters might be a large portion of fleet emissions so may need to consider those intechnology or EF development• It is expected that the distance travelled approach would be the appropriate AD to estimate
SLCF emissions, however, it is convenient to have a fuel-based Tier 1 approach as a check• Include category 1.A.3.b.v “Evaporative emissions from vehicles” for SLCF and note any
potential double counting with post meter estimates form fugitive emissions in Category 1.B.2• Include category 1.A.3.b.vi “Urea-based catalysts” there are some SLCF EFs for urea SCR
vehicles available in the literature, failure of urea SCR systems also should be considered• Include a new category of “Non-exhaust emissions” from brake and tire wear for OC, BC etc.
(maybe as fugitive) also important for EVs so EFs not just based on fuel use, there are globally
applicable methodologies• Include a new category (or as new fuel use for existing categories?) for use of lubricants also
note the need for a discussion on avoiding double counting with category 2.D.1 “LubricantUse”, the contribution of lube oil is important for SLCFs (more so than GHGs)• Exclude distinction of 3-way catalysts, also the types of control could vary going forward soneed to be forward looking and not mention specific technology

BOG ReportList of changes / knowledge gaps 3• Category 1.A.3 Transport (cont.)– For waterborne sources:• IPCC factors and technology description for GHGs might be too simple for SLCFs
especially for NOx (e.g., new hybrid types of ships) so flag need to use newinformation• Add a new Tier 3 to the IPCC methodology for NOx and particulates based onengine power (current GHG approaches does not have a T3 for this category)– For off-road sources:• Although the estimation methods for this subcategory are addressed under mobilecombustion, off-road mobile combustion encompasses a wide variety of off-roadvehicles and other machinery used across the different combustion categories,
therefore, the SLCF methodology for SLCFs should be consistent with the wide
spread distribution of off-road combustion across the different categories• Except for SO2, the emissions of SLCFs are highly dependent on the type ofequipment and technology so the EFs need to reflect that• Most alternative methodologies do not cover BC and OC emissions from thesesources.
• Guidance on the collection and/or estimation of AD is required as this may
constitute the main challenge in estimating these emissions.

– Include category 1.A.3.e.i “Pipeline transport” with all SLCF species forcombustion related emissions from the operation of pump stations andmaintenance of pipelines. Note: the EMEP methodology refers to theestimation of these emissions as that of small-scale combustion undercategory 1.A.4.

BOG ReportList of changes / knowledge gaps 4•

Category 1.A.4 Other Sectors•Category 1.B.1 Fugitive emissions from Solid fuels– For this category especially there would be a diverse amount of small source combustion
technologies and difficulties in collecting activity data on fuels which may not be marketed andtherefore not included in traditional energy use data.
– Age of technology and developing age dependent technology factors is especially important forthis category– The category 1.B.1.a was expanded to include sub categories for underground and surface
mines and within each category emissions from mining, post-mining activities and flaring andconversion of gas were included– For coal mining and handling, EFs for underground and surface mines should contain, if
possible, the three level values provided for CH4 EFs (e.g., EFS for low, average and highvalues)– Regarding cross cutting comment on consistency of tier definitions, the EMEP tier 2 approachprovides information for SLCFs at a more aggregated level that is considered a tier 1 IPCC
method for GHG– All SLCFs instead of just NMVOC were included. Mining and post-mining are not combustion
sources so likely there aren’t any NOx or SO2 emissions but leave to further scoping to define– For category 1.B.1.c There could be potential differences in emissions from commercial vsinformal production so development of EFs would need to take that into consideration

BOG ReportList of changes / knowledge gaps 5•

Category 1.B.2 Fugitive emissions from Oil and natural gas
–––––

•

All SLCFs instead of just NMVOC were included. Non combustion sources will not likely have any NOx orSO2 emissions but leave to further scoping to define
The 2019 Refinement to the 2006 IPCC Guidelines provides tier 1 default emission factors for NMVOC for anumber of technologies used under the different oil and natural gas subcategories. In addition, Annex 4A.2
to chapter 4, presents the percent of emissions that are leaked, vented, and flared in the data sets used for
the Tier 1 emission factors. This disaggregation should be kept and, if possible, enriched for NMVOCs andconsidered for the other SLCFs, when applicable. It is expected that the IPCC SLCF methodology
development for estimating NMVOC emissions for oil and natural gas would take as a starting point thedetailed information already available in the2019 Refinement.
If alternative methodologies are used for SLCF estimation, it is important to identify which types ofemissions (leaks, venting or flaring) are estimated.
The category 1.B.2.a.vi “Other” was added with NMVOC to include leakage from the use of LPG inappliances. A methodology similar to that to estimate post-meter emissions from natural gas appliance maybe developed for LPG.
For category 1.B.2.b.vi Gas post-meter, depending on the approach used to estimate emissions from roadtransportation especially evaporative emissions in category 1.A.3.b.v, checks for double counting of AD may
be needed.

Category 1.B.3 Other emissions from energy production––

Add SO2 to potential SLCF emissions from geothermal activities. Some Parties (e.g., Iceland and Italy)
already estimates and report SO2 emissions from geothermal power to the UNFCCC.
Not include (as suggested) categories for civil power generation facilities and combustion due toagriculture/livestock/fishery facilities as they are already covered in other categories

BOG ReportOther Issues Discussed•

For industrial sources, emissions of SO2, PM, and NMVOCs are often due to a
combination of fuel combustion, the materials that are processed, and emission controltechniques. This poses a challenge for SLCF emission allocation between the Energy
sector and the IPPU sector categories because in some cases the only data available
are the sector fuel use or amount of industrial product created by the sector.

– Conclusion was that this is the same as for GHG emissions from similar sources and there isalready existing IPCC guidance on avoiding double counting across sectors (energy and IPPU)
so the existing IPCC guidance on this for GHGs so would also apply to SLCFs•

Waste incineration Method/Activity data/Cross-sectoral: Fuel consumption is used as AD
in J-STREAM method. In the 2006 IPCC Guidelines, amount of waste incinerated isused as AD. According to the 2006 IPCC Guidelines, emissions from waste burnt forenergy are reported under the Energy Sector.

– It was determined that the J-STREAM method should be consistent with the IPCC guidance
and therefore nothing more was needed in terms of SLCF methodology consideration•Cooking exhaust (J-STREAM) - Method: Times of meals multiplied by emissions (Seethe Waste sector compilation table).

– During the discussions it was determined that the cooking category could be captured as partof the small scale emission methodology development discussion above as part of Category
1.A.4 Other Sectors.

BOG ReportCross-cutting issues identified by the BOG• Consistency of tiered-approaches between alternative methodologies

and the IPCC approach• Decision trees and the lack of key category analysis based on GWP• Black carbon / Effective black carbon / Elemental carbon• Organic carbon / Organic material• Estimation of PM2.5 emissions• Precursors of secondary organic aerosols.

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