Washington County a Growing Leader in Providing RNG for Area Fleets

At its South Treatment Plant in Renton, King County is now purifying biogas—which it has produced for more than 30 years—into renewable natural gas (RNG) for use as an alternative vehicle fuel that generates revenue for the county while reducing greenhouse gas emissions, according to a news release.

The purified RNG produced at the South Treatment Plant can replace diesel fuel in commercial vehicles, capitalizing on a federal program designed to power more transportation with renewable energy. Renewable natural gas sales last year yielded more than $6 million in revenue for King County’s Wastewater Treatment Division.

“We are demonstrating to the rest of the country how local governments can work together to build a sustainable clean-energy economy,” said King County Executive Dow Constantine. “By producing renewable natural gas at our treatment plant, we are reducing greenhouse gas emissions and the region’s reliance on fossil fuels.”

The environmental benefits of renewable natural gas are significant. Biogas is a byproduct of the wastewater treatment process and is often burned off.  By converting this waste gas to a transportation fuel, the emissions profile of both wastewater treatment and transportation is significantly lowered. Each year, the volume of renewable natural gas produced at the South Treatment Plant is the energy equivalent of about 1.7 million gallons of diesel fuel.

Clean Energy is currently delivering the renewable natural gas produced from South Plant to its Washington fueling station network. The five stations fuel about 1.5 million gallons of renewable natural gas annually, sourced from this local production facility. One of the largest local end users is Recology, an employee-owned waste management company that uses the renewable natural gas for their garbage trucks that roam the region’s neighborhoods.

In addition to renewable natural gas production at South Treatment Plant, King County’s Cedar Hills Regional Landfill in Maple Valley is also a large producer of renewable natural gas. Collectively, King County’s efforts to convert waste products into resources resulted in more than $14 million of revenue from the sale of RNG and renewable electricity generated in 2017.