Tacoma wants to turn your poop into renewable fuel. Really.
The city would make money from the sale of the gas and renewable-energy “currency,” a type of credit offered by the U.S. Environmental Protection Agency to agencies that use bio-fuel to offset fossil fuels that otherwise would be in the pipeline.
“You’re creating this ability to offset more non-environmentally friendly fuels by creating this,” Environmental Services director Mike Slevin said recently. “We can produce a good environmental outcome. And having worked in this industry for a long time, this is one of the rare opportunities where you can do something really good for the environment, and not only save money, but make some money doing it, so it’s a very unusual opportunity.”
Best-case scenario: The currency from the EPA Renewable Fuel Standard program stays in place and keeps its value, and the project breaks even and maybe even makes money. City officials estimate that a combination of grants, revenue from the sale of the gas and renewable energy currency would allow the project to make about $730,000 in its first year.
Even if the EPA “currency” goes away or loses value, the city estimates the project would break even over its lifetime because it still would make money on the sale of the gas.
Puget Sound Energy spokesman Grant Ringel said the the utility is finalizing an agreement with Tacoma that would allow the city to connect to the PSE pipeline.
“We’re very involved in that renewable project. We’ve been working with the city for a good while and are very supportive of it,” Ringel said. “We’re actually looking at a number of possibilities in the future to provide different renewable gas options for our customers, so down the road it might open some possibilities for that.”
Where is the gas coming from?
Slevin described the wastewater treatment facility as a giant digestive system.
“Our wastewater treatment plant produces methane,” Slevin told the City Council during a recent study session. “It’s the mechanical gut. Everyone in this room, you take in nutrients and you produce methane, and our plant just does it on a much larger basis.”
Some of that methane is being used to help heat the treatment plant’s boilers. The rest is burned off.
Slevin said the project would “displace carbon that’s affecting our climate” with a natural byproduct and would mark an 80-percent reduction in the amount of methane that has to be flared.
The city estimates that converting the methane that the plant flares off each day would yield enough renewable natural gas to equal nearly 450 gallons of diesel per day. In a year, they estimate it could reduce greenhouse gas emissions by 788 tons, and would displace 325,000 gallons of diesel over the course of a year.
Because the end product would be a bio-fuel, retrofitting the plant wouldn’t be subject to the city’s interim land-use regulations for the Tideflats, which prohibit new fossil-fuel businesses from opening shop for at least the next year.
Jim Parvey, the city’s chief sustainability officer, said the project has been in the works since about 2002. Over that time, technology has improved greatly, making the project more viable.
