In an effort to support regulators, stakeholders and other interested parties, PJM on Friday published a report with data on both marginal and average emissions rates from electric generators in the PJM footprint.
In the future, PJM expects to release this report in the spring following the end of each calendar year.
PJM Environmental Information Services, a wholly owned subsidiary of PJM Technologies, Inc., developed the average emissions rates for electric generators in the region by using its Generation Attribute Tracking System. PJM Technologies, Inc. is a subsidiary of PJM Interconnection.
The GATS is an all-generation data tracking system to enable compliance with state mandates for fuel mix, emission disclosure and renewable energy. Carbon dioxide, nitrogen oxides and sulfur dioxide are among the emissions data tracked in GATS.
PJM EIS calculates emission factors for all generators in the PJM region on an annual basis, using PJM generation data and emission data from a number of publicly available sources:
- U.S. Environmental Protection Agency unit-level annual emissions from Continuous Emission Monitoring Systems for generators in the acid rain program
- EPA Emissions & Generation Resource Integrated Database (eGRID) emission rate
- Fuel-type default factors
For 2015, 97.2 percent of all PJM generation either was a non-emitting resource or was assigned a unit-specific emission rate calculated using the EPA CEMS data. Another 2.6 percent of generation received an emission factor based on EPA eGRID data.
Only a tiny percentage of PJM generation was assigned a fuel-type default emission factor. In general, PJM has visibility only into generation resources that participate in the wholesale electricity market.
The emissions report does not account for other generation sources, including small diesel and behind-the-meter generation.