New cogen system triples energy output from biogas at Oregon WWTP

By Katie Fletcher, Biomass Magazine.

On May 4, Clean Water Services, Energy Trust of Oregon and the Oregon Department of Energy formally announced the implementation of a new cogeneration system that converts wastewater and grease into renewable energy. The innovative system, which is part of Clean Water Services Durham Treatment Facility, is the third cogeneration system in Oregon to codigest fats, oils and grease (FOG).

Amongst the people in attendance of the renewable energy facility opening were Andy Duyck, chair of Clean Water Services of Washington County; Michael Kaplan, director of the Oregon Department of Energy; and Betsy Kauffman, renewable energy sector lead of the Energy Trust of Oregon.

Since 1993, Durham has operated a 500-kW cogeneration system using biogas from the communities’ wastewater to offset its own energy usage. By replacing this smaller engine with two new Jenbacher 848-kW engines, Durham now has a 1.7 MW cogeneration system fueled by biogas produced from the anaerobic digestion (AD) of municipal wastewater solids as well as FOG from Washington County restaurants, commercial food processors and others. Average gallons of FOG codigested per week will start at 70,000 gallons and is expected to increase to 100,000 gallons within the next six months. The Durham campus hosts two, 1.3 million gallon digesters. Prior to being fed to the engine, the biogas will need to be treated with a gas treatment system made by Unison Solutions that will remove hydrogen sulfide particulates, siloxane and moisture from the raw biogas.