The emissions performance standard (EPS) is a set of state-imposed rules to a limit the amount of CO2 that each power station may emit to atmosphere.
The emissions performance standard (EPS) is a set of state-impose rules to limit the amount of greenhouse gas emissions each baseload power plant can release into the air.
Every five years, our office adopts rules on the average available greenhouse gas emissions output by surveying new combined-cycle natural gas thermal electric generation turbines. The turbines need to be commercially available, offered for sale by manufacturers and purchased in the United States. Then we determine the average rate of emissions of greenhouse gases for them.
Baseload generation limits and utility investment restrictions
Baseload generation, which refers to the minimum amount of continuous electricity supply that is needed to meet the basic demand of the power grid over a 24-hour period, is considered to be a generating unit operating at a capacity factor of 60 or greater percent. This means a facility that produces energy each year equaling at least 60 percent of the energy it could produce at continuous full power operation for the same period.
Utilities may not enter into long-term contracts (five or more years) with a baseload generating facility, nor can utilities invest in a facility, when the greenhouse gas emissions of the facility exceed the standard.
The standard applies to all investor and consumer-owned utilities in the state. Renewable and nuclear-powered electricity are exempt, as are long-term commitments with the Bonneville Power Administration.
The performance standard was last updated in January 2025. The new rule lowers the average estimated greenhouse gas emissions rate of combined-cycle natural gas power plants from 925 to 876 pounds per megawatt-hour. This updated emissions rate of greenhouse gas emissions will be used by the Department of Ecology (Ecology) and Energy Facility Site Evaluation Council (EFSEC) to apply Washington’s emissions standard as required by state law (Chapter 80.80 RCW).
Power plants must meet the greenhouse gas emission standards or capture and store their carbon pollution under this rule. The Department of Ecology and local clean air agencies regulate small plants that generate megawatts of electricity (MWe), but less than 350 MWe. The Energy Facility Site Evaluation Council (EFSEC) regulates larger plants that generate more than 350 MWe.
Rulemaking
Commerce began its most recent rulemaking process in February 2024, and since then, the agency held three public workshops and three technical advisory group meetings. Commerce received and responded to comments, incorporating changes based on them into the rulemaking process. The public workshops and advisory team meetings were well-attended. Commerce received two public comments.
The latest rule lowers the average available greenhouse gas emissions output estimate of combined-cycle natural gas facilities from 925 lb/MWh to 876 lb/MWh. The updated average rate of greenhouse gas emissions will be used by the Department of Ecology (Ecology) and Energy Facility Site Evaluation Council (EFSEC) to implement Washington’s baseload electric generation emissions performance standard as provided for under Chapter 80.80 RCW.
For questions related to the rulemaking process, please contact Aaron Tam, Energy Utility Data Specialist, at energydata@commerce.wa.gov or by calling 206-454-2251.