Emission Rates in PJM Reach All-Time Low


The average emission rates for carbon dioxide, nitrogen oxides and sulfur dioxide from generators operating in the PJM footprint dropped to a record low in 2023, having steadily declined for nearly two decades, according to annual data compiled by PJM.

From 2005 to 2023, carbon dioxide emission rates fell 43% across PJM’s footprint. Emission rates for nitrogen oxides declined 90%, and the rates for sulfur dioxide dropped 96%.

This decline has occurred as competitive wholesale electricity markets continue to encourage the entry of new technologies, and lower-emitting, more efficient resources replace older, less efficient units.

The PJM system average annual value is a weighted average that accounts for higher loads during the summer and winter months. Emissions are measured in pounds per megawatt-hour (lbs/MWh).

PJM Offers Tracking Tools

PJM’s Emissions page and PJM Now app include a visualization of overall average hourly emissions information for the region PJM serves.

PJM also publishes 5-minute marginal emission rates, hourly marginal emission rates and hourly total emissions on Data Miner.

PJM stakeholders have identified potential uses for marginal emission rates to determine the times each day when electricity use can have the least impact on the environment by drawing on lower-emitting resources.

In addition, PJM Environmental Information Services Inc. in March 2023 began providing hourly, time-stamped certificates for PJM generation, answering the growing demand for procuring and tracking carbon-free energy around the clock.

Advocates of the approach maintain that hourly certificates can help electricity consumers, including large government and business customers, tailor their energy consumption to the availability of carbon-free energy at all hours of the day. Such demand expressed through the market could also incent new carbon-free generation resources to serve the hours of the day when renewable energy production is currently lacking.