Manure-to-Methane Plan Picks Up Steam

It’s a little bit like the old saying, “When life gives you lemons, make lemonade.”

Dairies have given the Yakima Valley an abundance of cow manure and, one day, it might be used to make methane.

To that end, Energy Northwest, the public power group that owns the region’s only nuclear power plant, is looking at the possibility of teaming up with dairy farms in Washington, Oregon and Idaho to develop this form of “green” power.

The goal is to build a 3- to 4-megawatt electrical power plant fueled with “biogas,” or manure-derived methane.

“We’ve been working with the dairy industry for 10 to 15 years, trying to solve the manure waste problem,” said Ivan White, president of Sunnyside Inc., the economic development group for this central Washington city of 14,000.

Sunnyside in Yakima County is one of the locations Energy Northwest is looking at, along with northwestern Washington’s Whatcom County, Boise and Twin Falls, Idaho, and Tillamook, Ore.

Yakima County alone has 85,000 head of dairy cows, and tons of manure. That’s a very renewable resource.

And it’s no bull that biodigester technology today makes it possible to get about 0.3 kilowatts of electricity per cow, as much as 0.9 kilowatts in some European studies, said Stan Davison, business development specialist for the Richland-based utility. One kilowatt is enough to power 10 100-watt lightbulbs.

The manure-to-methane project would work like this:

A big digester tank, acting essentially as a mechanical stomach, is filled with a slurry of manure and water. Bacteria, already present in the waste, process the manure into methane while thriving in the 130-degree temperature of the tank.

The methane rises to the top--it’s lighter than air--and is piped off to power a pair of modified diesel generators outfitted with spark plugs.

While the generators make electricity, the remaining fiber in the tanks settles to the bottom. Liquid squeezed out of the fiber makes fertilizer and the dry fiber makes compost.

The Northwest accounts for 8% of the nation’s dairy farm business. A biomass power plant would need access to a dairy or dairies, room to build the power plant and access to transmission lines.

“The real issue is high capital costs,” Davison said. “If you ignore the capital costs, the fuel is free--it’s a byproduct of milk. It’s something you’re going to be producing anyway. You might as well handle it as fuel as handle it as waste.”

The rough estimate for building such a plant is about $2,800 dollars a kilowatt. Wind power runs about $1,000 per kilowatt.

But on average, a wind farm only produces about 30% of capacity over the course of a year, while a cow-powered plant can produce at 90%. That just about evens up the costs, Davison said.

“Over the years, there have been a number of people promoting methane digesters. The one thing they’re always lacking is capital,” said Jay Gordon, a Lewis County dairy farmer and director of the Washington State Dairy Federation, which represents about 650 family dairy farms in the state.

The margin is thin, Davison said. So Energy Northwest’s next step is to approach utilities to see if there’s enough interest in such a project to pay for it.

It could be a nice fit for a lot of dairy farms, if it doesn’t cost the farmer money, Gordon said.

“We know the technology works. We know it’s a great concept. We know it’s renewable. We know it’s green,” he said.

But the construction and capitalization of the facilities and the issue of return on investment could make a good idea in theory difficult to execute, he said.

In Oregon, Portland General Electric is working cooperatively with dairies in Boardman and Salem, Ore., on digester projects, and it doesn’t cost the farms anything, said Joe Barra, director of distributed energy for the utility.

Manure management has been a problem for dairies, faced with more environmental regulation and suburban expansion into agricultural areas.

The actual percentage of reduction in manure is small, Gordon said, but the leftover fiber and liquid are more sanitary and less aromatic.

“If the energy utility comes in and says it won’t cost anything, and you get a little less smelly product, a little more usable product, it fits with the nature of the farm,” Gordon said.