Ember’s calculations for emissions are frequently enhancing, however could also be conservative or in any other case unsure in methods we describe beneath. These figures goal to incorporate full lifecycle emissions together with upstream methane, provide chain and manufacturing emissions, and embrace all gases, transformed into CO2 equal over a 100 12 months timescale.
Emissions can differ over time as energy station effectivity modifications, and as totally different gasoline qualities are used. Therefore, we report emissions values by gasoline kind, and emissions depth by nation. These values are calculated by multiplying our technology numbers by emissions elements taken from quite a lot of sources, detailed beneath. We goal the place attainable to seize variance between geographies and over time in emissions depth from totally different fuels. We have lately up to date this strategy and are actively working to enhance it; when you’ve got any feedback or recommendations for enchancment please electronic mail [email protected].
Our sources and methodology for various fuels is described beneath. All elements we use are for internet technology; the place we report gross technology we alter our elements by 6% for thermal gasoline sources and 1% for others.
Coal
Data is taken from Gibon et al. 2022 (UNECE) and the Global Energy Monitor Coal Plant Tracker (GEM). UNECE supplies lifecycle emissions elements for various gasoline sorts for the 12 months 2020 for every REMIND region. UNECE stories values for various applied sciences utilizing bituminous coal; we derive elements for various coal grades primarily based on IPCC 2005 direct combustion emissions elements. Using country-level annual expertise and coal grade mixes from GEM capability information, we estimate blended emissions elements per nation per 12 months for exhausting coal and lignite. The vary of things used within the EU from 2000-2023 is
- Hard coal: 952-1045 g/kWh
- Lignite: 1033-1080 g/kWh
Gas
Country-level elements are taken from Jordaan et al. 2022, and are for technology for the 12 months 2017. Two units of things are offered; we use those that try to account for mixed warmth and energy. For smaller international locations the place no information is offered, a world common quantity is used. The vary of things used within the EU is:
Nuclear and wind
We use region-level information from UNECE. The values used are:
- Onshore wind: 12 g/kWh
- Offshore wind: 15 g/kWh
- Nuclear: 5 g/kWh
Bioenergy, hydro, photo voltaic, different renewables and different fossil fuels
We use information from the IPCC AR5 WG3 Annex III (2014). These are international estimates for the 12 months 2020; we use midpoint lifecycle elements. These are:
- Bioenergy: 230 g/kWh
- Hydro: 24 g/kWh
- Solar: 48 g/kWh
- Other renewables: 38/kWh
- Other fossil: 700/kWh
Caveats
This strategy makes an attempt to account for some geographical and temporal variance in emissions elements. It is a piece in progress, and figures might differ from actuality for quite a lot of causes. Some of those are listed beneath:
- Coal: UNECE base elements are for coal vegetation within the 12 months 2020. They don’t seize operational effectivity losses related to older vegetation or intra-technology effectivity variations. Finally, we make assumptions to derive elements for coal grades apart from lignite, together with similar combustion efficiencies and upstream emissions per MWh generated.
- Gas: our gasoline elements are particular to the 12 months 2017, so don’t account for temporal variations in plant efficiencies or methane leakage charges. The methodology in Jordaan et al. 2022 additionally prefers to underestimate methane emissions the place there’s doubt. In basic there’s very vital uncertainty round methane emissions charges, even in international locations that prioritise gathering this information. Some authors consider that emissions charges are considerably increased than assumed in our elements.
- Time horizon: upstream methane emissions for gasoline and coal technology are calculated on a long-term foundation assuming methane is 21 occasions as potent as CO2. However, the short-term impression of methane is definitely 4 occasions increased, at 86 occasions the efficiency of CO2 over the primary 20 years within the ambiance. See this page for extra info.
- Solar and wind: current effectivity enhancements have seen wind and photo voltaic emissions depth drop, as vitality output has elevated relative to emissions from manufacturing. Our numbers might due to this fact be increased than actuality. We additionally don’t presently seize geographical variation in emissions depth inside REMIND areas; this may be vital, as international locations with decrease annual photo voltaic capability elements may have proportionately increased lifecycle emissions.
- Bioenergy: our worth could be very prone to be a big underestimate of the particular emissions brought on by bioenergy technology. The emissions depth of bioenergy is very depending on the feedstock, the way it was sourced, and what would have occurred had the feedstock not been burnt for vitality. The IPCC determine we use is for devoted vitality crops and crop residues, somewhat than the rather more generally used woody or forest biomass, which has been proven to hold a greater risk of high-carbon outcomes. In sure circumstances, bioenergy can have a carbon depth significantly greater than coal. Bioenergy can be continuously cofired with fossil fuels; we now have disaggregated these wherever attainable, however in sure circumstances recorded bioenergy technology might embrace some cofiring. In these circumstances, precise emissions will likely be increased than we estimate.
- Hydro and different renewables: hydropower emissions are typically very low, however can differ primarily based on emissions throughout building and biogenic emissions, and so in a small variety of circumstances may be a lot increased than our worth. Similarly, different renewable sources resembling geothermal can in rare outlier cases have excessive emissions.
- Gross and internet technology: within the EU, we report internet technology for month-to-month information and gross technology for yearly information. For gross technology, we carry out the conversion described above, which can introduce some error.
- Combined warmth and energy (CHP): in lots of circumstances, thermal energy vegetation produce each warmth and electrical energy. Our coal elements are primarily based on solely the electrical energy produced by such vegetation, ignoring warmth. It might not due to this fact be truthful for our dataset to incorporate all emissions attributed to cofiring vegetation, which even have better effectivity than reported when contemplating complete helpful vitality output. Our gasoline elements account for CHP.
