Ember’s emissions calculations are continually being improved, but may be conservative or uncertain in the ways described below. These figures are intended to include full lifecycle emissions, including upstream methane, supply chain and manufacturing emissions, and include all gases converted to CO2 equivalent over a 100-year timescale. will appear.
Emissions can change over time as power plant efficiency changes or different fuel qualities are used. Therefore, we report emissions by fuel type and emissions intensity by country. These values are calculated by multiplying the number of generations by emission factors obtained from many sources, as detailed below. We aim to capture, to the extent possible, differences between regions and over time in the intensity of emissions from different fuels. We recently updated this approach and are actively working on improving it.If you have comments or suggestions for improvements, please send us an email [email protected].
Various fuel sources and methodologies are discussed below. All elements we use are for net generation. When reporting total electricity generation, adjust the factor by 6% for thermal fuel sources and 1% for all others.
coal
Where does the data come from? Gibbon et al. 2022 (UNECE) and Global Energy Monitor Coal Power Plant Tracker (jewelry). UNECE provides life cycle emission factors for different fuel types for 2020. Made to remember region. UNECE reports values for various technologies that use bituminous coal. Based on the IPCC 2005 direct combustion emission factors, we derive factors for different coal grades. We use country-level annual technology and coal grade mixes from GEM production capacity data to estimate annual country-mix emission factors for hard coal and lignite. The range of coefficients used in the EU from 2000 to 2023 is:
- Hard coal: 952-1045 g/kWh
- Lignite: 1033-1080 g/kWh
gas
Country-level factors are obtained from: Jordan et al. 2022, and for the 2017 generation. Two sets of coefficients are provided. Use one that takes into account the combination of heat and power. For smaller countries where data are not available, global average values are used. The range of factors used in the EU is:
Nuclear and wind power
We use region-level data from UNECE. The values used are:
- Onshore wind power: 12 g/kWh
- Offshore wind power: 15 g/kWh
- Nuclear: 5 g/kWh
Bioenergy, hydropower, solar power, other renewable energies, and other fossil fuels
We use data from IPCC AR5 WG3 Annex III (2014). These are global predictions for 2020. Use the midpoint life cycle factor. these are:
- Bioenergy: 230 g/kWh
- Hydropower: 24 g/kWh
- Solar power: 48 g/kWh
- Other renewable energy: 38/kWh
- Other fossils: 700/kWh
Notes
This approach attempts to account for geographic and temporal variations in emission factors. This is a work in progress and the numbers may differ from reality for a variety of reasons. Some of them are shown below.
- coal: UNECE basic coefficients are for coal-fired power plants in 2020. It does not take into account operational efficiency losses associated with older power plants or efficiency differences within technology. Finally, assumptions are made to derive factors for coal grades other than lignite, such as the same combustion efficiency and upstream emissions per MWh produced.
- gas: Our gas coefficients are specific to 2017 and therefore do not take into account temporal fluctuations in plant efficiency or methane leakage rates.methodology in Jordan et al. 2022 We also prefer to underestimate methane emissions when in doubt. In general, there is a great deal of uncertainty regarding methane emission rates, even in countries that have prioritized collecting this data. Some authors believe that the emission rate is significantly higher than assumed by our coefficients.
- Target period: Upstream methane emissions from gas and coal power generation are calculated on a long-term basis assuming methane is 21 times more potent than CO2. But methane’s short-term impact is actually four times higher, 86 times more potent than CO2 during its first 20 years in the atmosphere.look This page For more information.
- solar and wind: Recent efficiency improvements have reduced emissions from wind and solar power, as their energy output has increased relative to emissions from manufacturing. Therefore, our numbers may be higher than reality. Additionally, we currently do not know the geographic variation in emissions intensity within the country. Made to remember region. This can have important implications because countries with lower annual solar capacity utilization rates also have proportionately higher life-cycle emissions.
- bio energy: Our values are very likely to significantly underestimate the actual emissions caused by bioenergy production. The emission intensity of bioenergy is highly dependent on the raw materials, how they are sourced, and what happens to the raw materials if they are not combusted for energy. The IPCC numbers we use cover dedicated energy crops and crop residues, rather than the more commonly used woody or forest biomass. Increased risk of high carbon outcomes.In some cases, bioenergy can have carbon intensity significantly larger than coal. Bioenergy is often co-combusted with fossil fuels. We have subdivided these as much as possible, but in some cases the recorded bioenergetic production may include some co-combustion. In such a situation, actual emissions will be higher than our estimates.
- Hydropower and other renewable energy: Hydropower emissions are generally very low, but can vary due to construction emissions and biogenic emissions, so they could be much higher than our values in a small number of cases. there is. Similarly, other renewable resources such as geothermal rare outlier cases Emissions are large.
- Gross power generation and net power generation: The EU reports net electricity generation for monthly data and gross electricity generation for annual data. There may be some error in the total power generation due to the above conversion.
- Combined heat and power (CHP): Thermal power plants often produce both heat and electricity. Our coal factor is based only on the electricity produced by such plants, ignoring heat. Therefore, it may not be fair to include in our dataset all emissions attributable to co-firing plants that are actually more efficient than reported when considering the total effective energy output. Our gas coefficients take CHP into account.
