Requires the Washington State University extension energy program and the department of commerce, in consultation with the utilities and transportation commission, to submit, by September 1, 2018, recommendations to the governor's office and the legislative energy committees on how to promote sustainable development of renewable natural gas in the state.

Requires the department of commerce to: (1) In consultation with the department of ecology, the utilities and transportation commission, and the department of health, explore development of voluntary gas quality standards for the injection of renewable natural gas into the natural gas pipeline system; and

(2) Consult industry groups and identify industry best practices.

Provides a sales and use tax exemption for equipment necessary to process biogas from a landfill into marketable coproducts.

Addresses property tax and leasehold excise tax exemptions with regard to land, buildings, machinery, equipment, and other personal property used primarily for the operation of an anaerobic digester.