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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

MAILING ADDRESS: 1120 SW 5th Ave, Room 1000, Portland, OR 97204

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Renewable Natural Gas: Turning waste methane into clean energy

It turns out that sewage isn’t just waste to be treated, but a source of clean, renewable energy.

Environmental Services has been harvesting biogas (a byproduct of sewage treatment that is mostly methane) for many years, generating heat and electricity to power the treatment plant while selling a portion to a nearby roofing manufacturer. But even with this reuse, some methane was still burned off, released to the environment as carbon dioxide.

Now, Portland is on its way to harnessing virtually all the methane produced at the treatment plant and turning this waste into a valuable resource - renewable natural gas (RNG) to replace dirty diesel in commercial vehicles.

Infographic 

Environmental Services’ aims to create a triple win for the public: eliminating 21,000 tons a year of climate-altering emissions, generating upwards of $3 million a year in revenue for ratepayers, and replacing over one million gallons of vehicle fuel with clean renewable natural gas.

That makes Portland a national leader in turning poop into power. Instead of energy from fossil fuels, the anaerobic digesters at Portland's main wastewater treatment plant are creating a clean, local fuel that can be produced year after year from the waste of Portland's more than 600,000 residents. 

How we’re doing:

Before 2017 - Environmental Services had captured 77 percent of biogas from its anaerobic digesters, turning the waste methane into electricity and heat for use at the City’s wastewater treatment plant in North Portland and selling a portion to a nearby roofing company for its manufacturing process. The rest was flared - released to the environment as carbon dioxide.

2017 - City Council authorized Environmental Services to build the infrastructure to capture and clean almost 100 percent of the plant’s biogas, and to enter into a partnership with NW Natural to distribute the resulting renewable natural gas (RNG). Funneling the RNG into NW Natural’s pipeline allows a wider distribution. To maximize the environmental, community and revenue benefits, the RNG will be marketed as truck fuel to displace dirty diesel. Some of the RNG also will power City trucks at a natural gas fueling station to be built at the wastewater treatment plant.

2018 - Environmental Services opens the natural gas fueling station at the plant. It will run on conventional natural gas until RNG production begins in 2019, creating clean air benefits immediately by displacing dirty diesel. Climate benefits will be realized when the switch is made to RNG.

2019 (projected) - RNG production begins.

Information contact: Diane Dulken (503)823-5328 diane.dulken@portlandoregon.gov 

This page created October 2018