A company called Farm Power Northwest is building two new methane digesters in Tillamook that will turn dairy cow poop into power. One will start up next month, taking manure from cows on five dairies and turning it into 1 megawatt of electricity – enough to power about 700 homes for a year. The second, yet to be built, will use the manure from one farm to produce 750 kilowatts of electricity –enough to power about 500 homes a year.*
Methane digesters are not new. The Port of Tillamook Bay has been operating a community digester since 2003. But the technology is getting more efficient, and it’s sprouting up in more and more locations around the Northwest as farmers and power producers realize it offers many other benefits in addition to renewable energy.
The digesters essentially cook the methane out of cow manure and then burn the gas to generate electricity.
In the process, they reduce greenhouse gas emissions by burning the methane that would naturally be released from the manure. That reduction makes them eligible for some hefty carbon offset credits because methane is a greenhouse gas that is 23 times more effective at trapping heat in the atmosphere than carbon dioxide.
That’s not all. The digesting process also cleans the manure so dairy farmers can use it on their pastures with much less odor and less risk of polluted water runoff. And the leftover fibers can be used to make a clean mulch that farmers can use for cheap cow bedding.
Digesters are usually too expensive for small farms to install on their own. So Farm Power Northwest is making a business out of pooling the poop from several small farms to feed one mid-sized digester.
Here’s how it works: The company will pay Tillamook farmers around $60 a year per cow for their manure. The manure is piped into a receiving pit and fed into the digester, which acts like a cow’s stomach to warm up bacteria in the manure to about 100 degrees.
The bacteria eat the remaining sugars and proteins in the manure and produce methane gas. The gas is captured in a pipe above the digester and fed into a generator, where it is burned to make electricity.
“It’s like our own little natural gas well except we’re not taking it out of the ground,” said Daryl Maas, a co-founder of Farm Power Northwest. “We’re harvesting it from manure.”
Water pipes running through the generator capture the waste heat from the process and send it back into the digester to warm up the incoming manure.
The power will be sold to the Tillamook People’s Utility District, and the carbon offset credits from the reduced methane emissions will be sold to Puget Sound Energy or Climate Trust.
“It’s like our own little natural gas well except we’re not taking it out of the ground. We’re harvesting it from manure.” — Daryl Maas, a co-founder of Farm Power NorthwestThe process kills the stinky and polluting bacteria in the manure. So, the water leftover can be piped back to the farmers and used as a cleaner fertilizer than they had before. And the leftover solids from the manure can be separated to create much cheaper cow bedding material than the wood shavings farmers have traditionally used (which are getting more expensive because wood waste has market value for power production, too).
The digester arrangement works out well for the farmers and the power producers, said company co-founder Daryl Maas, who grew up in the dairy farming community in Mt. Vernon, Wash.
“Our goal was to make it no impact for the farmer. They usually store the manure in a tank and use it as fertilizer,” he said. “We want the methane, and they want the phosphorous and nitrogen.”
Chad Martin of Martin Dairy said he had been looking into installing his own digester before Farm Power Tillamook proposed to build one near his property. He agreed to send manure from his 900 cows to the Farm Power project because he would get cleaner fertilizer without additional costs.
He already separates and composts the fiber from his cows’ manure to make cow bedding, but the liquid manure he sprays on his grazing pastures is smelly and has to be handled carefully because it can pollute nearby waterways.
“Manure is so expensive to handle,” he said. “You’re kind of limited in what you can do out here because it’s so wet.”
The business model for starting a new methane digester is a little risky. As this article in Sustainable Business Oregon reported, they cost $3 million to $4 million to build and last about 30 years. But if the dairies feeding them facing go under they can lose their feedstock, and the about half the $500,000 in annual earnings from power sales goes back into maintaining operations.
Farm Power’s digester start-ups have relied on help from the U.S. Department of Agriculture to get off the ground. Farm Power Tillamook tapped a $2.65 million loan guarantee and a $100,000 grant from the USDA’s Rural Development Program. But that was enough to allow the company to secure private financing for the rest of $4 million digester.
Jill Rees of the U.S. Department of Agriculture’s Rural Development Program in Oregon said her agency supports digester projects – “just enough to get good projects over the hump.”
The reason is primarily economic development but also to develop a new source of renewable energy, she said. The projects have the added benefits of preventing greenhouse gas emissions and improving air and water quality as well as dairy farm operations.
“In a lot of these cases farmers are interested in the technology but they already have a job to do,” she said. “They’re interested in seeing how can this benefit them, and they’re supportive but they don’t have the ability to do it themselves.”
A report released last year by The Climate Trust and The Energy Trust of Oregon assessed the potential for more biogas, which can come from manure, sewage, garbage, plant and food waste.
It concluded the state’s biogas industry could grow to 12 times its current size and generate 100 megawatts of power. Dairies offer the largest biogas opportunity, the report found, with 140,000 cows on 150 farms offering 46 megawatts of potential energy.
The report said biogas could cut 800,000 metric tons of carbon-dioxide equivalent emissions in Oregon – almost 5 percent of the reductions the state needs to meet its 2020 greenhouse gas goals.
But building the biogas facilities – such as a methane digester – costs money. And tapping their environmental benefits might require additional incentives from state government such as tax credits or requirements for utilities to buy a certain percentage of biogas.
Maas said his company is essentially competing with natural gas, which has been getting cheaper and cheaper as hydraulic fracturing technology unlocks new supplies from shale rock. Low natural gas prices make it harder for new methane digester projects to pencil out.
“We’re fundamentally still a power producer. We compete in a power market,” he said. “Right now the power price we can get for new facilities is falling because of gas prices. Like everything else with renewable energy, it has to compete with fossil fuels.”