Power plant greenhouse gas standards

We set emissions standards for power plants in Washington. Power plants covered by our rule are required to meet greenhouse gas emission performance standards and carbon dioxide sequestration conditions.

About this regulation

Ecology and local clean air agencies regulate small plants that generate more than 25, but less than 350, megawatts of electricity (MWe) by rule. Plants are required to meet greenhouse gas emission standards and offset, or mitigate, their carbon pollution under this regulation.

The Energy Facility Site Evaluation Council (EFSEC) regulates plants larger than 350 MWe.

All power plants in Washington or a power plant with an agreement with a retail utility serving customers in Washington to purchase power must meet a greenhouse gas emission performance standard. Renewable and nuclear-powered electricity, and long-term contracts with the Bonneville Power Administration are exempt from our rule's requirements.

TransAlta, a power plant in Centralia, has special requirements set by the state Legislature. The TransAlta plant must comply with the greenhouse gas emission performance standard for one boiler by Dec. 31, 2015 and a second boiler by Dec. 31, 2020.

Greenhouse gas emissions performance standards

The 2008 law establishes the greenhouse gas emissions performance standards and requires new plants to emit greenhouse gas at a rate of no more than 1,100 pounds per megawatt-hour.

The Washington Department of Commerce is also required to review and revise this number every five years. The revision is based on the average rate of greenhouse gas emissions from new combined-cycle natural gas thermal electric generation turbines. Commerce revised the rate in 2013 to 970 pounds per megawatt-hour. We are currently in the process of revising our rule to be consistent with the lower rate.

The standard applies to electric generating plants or electric cogenerating plants that are designed and permitted to operate at 60 percent or greater capacity (known as their baseload generation).

When does the standard apply?

  • A new power plant starts operation.
  • Ownership change at existing power plants.
  • An existing plant installs a new unit.
  • An existing plant or unit gets modified and increases fuel usage.
  • An investor-owned or consumer-owned utility signs a long-term contract (5 or more years) with a baseload generating or cogenerating plant. 

Sequestration plans

A power plant using non-geologic sequestration of greenhouse gases must submit a sequestration plan to Ecology or EFSEC for approval to comply with the emissions performance standards.

  • Non-geologic plans should include financial requirements, technical evaluation, post closure requirements, and monitoring plans according to Washington law. 
  • Geologic sequestration requirements according to Washington law. 
  • A  public comment period and a hearing are required.

Permanently-sequestered greenhouse gas emissions do not count toward compliance.

Carbon dioxide mitigation

New or modified thermal power plants larger than 25 megawatts must mitigate or offset their carbon dioxide emissions. 

A fossil-fueled thermal electric generation unit must mitigate or offset the equivalent of 20 percent of the potential carbon dioxide (CO2) emissions that could be emitted over 30 years. Examples of these types of units are:

  • Boilers that run on coal, oil, natural gas, or coke.
  • Combustion turbines.
  • Coal gasification units that produce synthesis gas or hydrogen for a fuel cell.
  • Hydrocarbon reformer emissions where the hydrogen produced is used in fuel cells.

Mitigation plans may include any combination of:

  • Payment to a third party to provide mitigation.
  • Direct purchase of a permanent carbon credit.
  • Direct investment in an applicant-controlled carbon dioxide (CO2) mitigation project including cogeneration.

When does a mitigation plan apply?

  • A new power plant starts operation.
  • An existing plant increases its carbon dioxide emissions by 15 percent or more.
  • An existing plant modifies its operations to increase its capacity by at least 25,000 kilowatts.