Portland is searching for alternative sources of energy in unlikely places – including the city’s sewage treatment plants. New infrastructure at the Columbia Boulevard Wastewater Treatment Plant will allow the city to produce renewable natural gas (RNG) for use in trucks, instead of diesel. The plan could allow Portland to slash their greenhouse gas emissions by 21,000 tons every year.
Bacteria decomposing solid waste at the sewage plant produce methane, a greenhouse gas that can also be turned into a hydrocarbon fuel. The Columbia Boulevard Wastewater Treatment Plant has been capturing that waste methane since 2008, but, until now, have only been able to collect around 77 percent of it, which is used to generate electricity or sold. The other 23 percent is flared off, emitting climate change-inducing greenhouse gases. Now the city aims to recover 100 percent of the methane.
The captured waste methane will be converted into RNG, replacing 1.34 million gallons of diesel fuel, according to the city. 154 garbage trucks a year are expected to run on that amount of energy. The whole project will cost around $12 million.
City commissioner Nick Fish said in a statement, “We are creating a triple win for the public in terms of revenue, climate action, and cleaner air. The renewable natural gas we will produce is truly local and homegrown, a by-product of the waste from every Portland household that we can now repurpose.”
The fueling station should be complete by the end of this year, and the fuel will be used in city trucks. Then in 2018 the city will start selling the fuel for distribution through utility company NW Natural. By reusing a waste product and cutting pollution, Portland expects to earn $3 million each year.