Updated Default Emissions Values

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We are excited to announce the following changes to REopt's default emissions rates:

Climate Emissions Rates

Grid Emissions Rates for Sites in the Contiguous U.S. now from Cambium

• Before: Default grid climate emissions were hourly historical CO2 emissions from the EPA's AVERT database (v3.2), at the AVERT regional resolution.
• Now: Grid climate emissions data is obtained from NREL’s Cambium 2022 database, which contains modeled emissions projections for a range of possible futures of the U.S. electricity sector through 2050 (see the documentation and Scenario Viewer). The default grid climate emissions factors in REopt are hourly, long-run marginal emissions rates (LRMERs) for CO2e averaged over the analysis period at a resolution of “generation and emission assessment (GEA) regions” (similar to eGRID regions). CO2e values are calculated using 100-year (AR6) global warming potential values (GWP) from the IPCC’s Sixth Assessment Report, with GWP values for CO2, CH4, and N2O of 1, 29.8, and 273, respectively. The default emissions rates include precombustion and combustion emissions and T&D losses. Users can opt to change the geographic resolution, emission metric type, future grid scenario, emissions years, and inclusion/exclusion of T&D losses to obtain customized grid emissions rates from Cambium. For users of the codebase, these inputs are all under the ElectricUtility key.

Grid Emissions Rates for Sites in Alaska and Hawaii

• Before: Default grid climate emissions were annual 'non-baseload' CO2 values, including T&D losses, from the EPA's eGRID 2016 database.
• Now: Default grid climate emissions are annual 'non-baseload' CO2e values, including T&D losses, from the EPA's eGRID 2021 database. (CO2e values are calculated using 100-year (AR6) global warming potential values (GWP) from the IPCC’s Sixth Assessment Report (2023).

Emissions Rates of On-Site Fuel Burn

• Before: Fuel climate emissions factors were CO2 values from the EPA's GHG Emissions Factors Hub 2018 release
• Now: Fuel climate emissions factors are CO2e values from the EPA's GHG Emissions Factors Hub 2023 release (CO2e values are calculated using 100-year (AR6) global warming potential values (GWP) from the IPCC’s Sixth Assessment Report (2023).

Health-Related Emissions Rates (NOx, SO2, and PM2.5)

Grid Emissions for Sites in the Contiguous U.S.

• Before: Default grid health emissions rates were hourly historical emissions from the EPA's AVERT database (v3.2), at the AVERT regional level
• Now: Default grid health emissions rates are hourly historical emissions from the EPA's AVERT database (v4.1), at the AVERT regional level

Grid Emissions Rates for Sites in Alaska and Hawaii

• Before: Default grid health emissions were annual 'non-baseload' values, including T&D losses, from the EPA's eGRID 2016 database. (PM2.5 not included)
• Now: Default grid health emissions are annual 'non-baseload' values, including T&D losses, from the EPA's eGRID 2021 database. (PM2.5 not included)

Emissions Rates of On-Site Fuel Burn

• Before and Now (no change): NOx, SO2, and PM2.5 emissions factors for each fuel type are calculated from the EPA’s WebFIRE database.

For more information on emissions calculations within REopt, please see the User Manual. For more information on these changes in the codebase, please see the REopt.jl CHANGELOG.