Commerce produces fuel mix disclosure information by combining results from more than 60 utilities to determine an aggregate mix for the entire state. This information is also used to report the greenhouse gas emissions from the state’s electricity sector.

Each electric supplier serving retail customers in Washington must disclose to its customers the mix of fuels used to generate the electricity sold to them. The fuel mix is based on the generating plants and contracts of each utility and the Bonneville Power Administration, and it also includes information on fuel used to generate electricity purchased in wholesale spot markets. Utilities report their sources of electricity to Commerce, and Commerce combines this information with data from wholesale markets to determine a fuel mix for each utility.

Power Source Disclosure (Fuel Mix) 2019 Update

Engrossed Substitute House Bill 1428 changes the fuel mix statute enacted in 2000 (19.29A RCW). The law requires that electric utilities disclose the fuels used to generate their electricity to their customers. Commerce requested this legislation to make much-need updates to the law and to improve the accuracy and timeliness of the reports. We worked with utility and environmental stakeholders to develop the legislation, and the bill was approved without dissent in either legislative chamber.

For utility customers, the biggest change will be a new category on the disclosure label for “unspecified sources.” Utilities do not always know the sources when they purchase electricity, and the existing law required that Commerce assign fuel shares to this power. Instead, unknown sources will be listed as a separate category.

The law makes other changes that are less obvious but important to the integrity of utility power source disclosures. Utilities will be required to include known sources of electricity generation, and utilities are not allowed to make renewable energy claims if they have transferred or sold the renewable energy certificates associated with that electricity.

Utility Data

Utilities provide the following information in megawatt hours (MWh):

  • Total electricity retail sales including power purchases necessary to cover line losses.
  • Reliance on market power to serve retail load (spot market).
  • Amount of electricity purchased from BPA.