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.

Reinstates and expands tax incentives for certain landfills and anaerobic digesters to stimulate investment in biogas capture and conditioning, compression, nutrient recovery, and use of renewable natural gas for heating, electricity generation, and transportation fuel.