Renewable Energy from Dairy Farm Manure
A New Methane Digester Comes to Northwest Washington

In a promising development for the agricultural economy, an up-and-coming Washington start-up company, is turning the dairy industry’s huge manure waste problem into a renewable energy solution. After a successful debut with a farm-based anaerobic digester in Rexville, Washington, Farm Power Northwest, with its prime contractor, the Andgar Corporation, is constructing a second methane digester near Lynden in Whatcom County.

The Million Ton Problem

The environmental problem Farm Power Northwest has taken on is not trivial. Each year, dairy cows in Whatcom County alone produce nearly a million tons of manure. Dairy farms store this enormous amount of waste in open lagoons where it can contaminate groundwater, and, as it decomposes through natural anaerobic processes over the course of many months, emits the greenhouse gas, methane, into the atmosphere. When you consider that methane is 21 times more potent as a greenhouse gas than carbon dioxide, the scale of the farm waste problem becomes apparent.

Farm Power, by sending the manure through an enclosed anaerobic digester, is able to accelerate and control that same natural anaerobic process. In just three weeks, the digester breaks down the manure, captures the methane to burn for electricity production, and decontaminates most of the remaining waste byproduct into a valuable nitrogen-rich fertilizer.

“Dairy farming without waste is a piece of cake,” said Mike Douma, whose farm will supply manure to the new Lynden digester. The potential energy locked inside this animal waste is immense.

If all of Whatcom County’s manure could be turned into power it could potentially produce 800,000 kilowatt-hours per day. Since the average U.S. household uses about 30 kilowatt-hours per day, the cows could provide enough methane to power approximately 26,000 homes.

Two Brothers and an Idea 

Brothers Kevin and Daryl Maas organized Farm Power Northwest LLC in 2007 to develop, own, and operate farm-based anaerobic digesters. The idea for the company took root in 2004, when Kevin, at the time a high school teacher, toured the Vander Haak Dairy, the first manure digester in Washington state.

“The next year I was teaching school,” said Kevin, “and I was thinking about manure digesters, but I figured that by the time I could do anything, half the farmers in the county would already be working on their own project. Lo and behold a year later — nothing. Nothing at all!”

“So that’s when we headed down this path,” he said. “If nobody was doing it, yet it was clear that it could be done, that it should be done, then we just had to figure out a better way to do it!”

Kevin enrolled in graduate school in Sustainable Business and thought about the digester some more, hoping to come out with a business plan. “A big plan takes a lot of time,” he said. Joined by his brother Daryl, using a combination of grants, money raised through a public stock offering for middle class investors, and their own capital, Farm Power completed its first digester at Rexville in Skagit County, Washington in August 2009.

Manure Becomes Electricity

At Farm Power Rexville, the digester breaks down manure from two neighboring farms and produces electricity. The process is designed to take advantage of anaerobic bacteria, which thrive in wet, low-oxygen environments and produce methane-rich biogas. Manure from nearby farms flows through underground pipes into concrete pits on the site, where it mixes with food-processing waste, and then goes into the partially buried 16-foot-deep concrete digester tank. Inside the tank, heat exchangers keep the manure at a constant 100º F, while gas injection churns it to allow anaerobic bacteria to flourish.

The digester roof captures the methane which moves through a pipe to the mechanical building. There, Farm Power chills and pressurizes the biogas, injecting it into a sixteen-cylinder spark engine. The engine turns a generator, producing electricity—approximately 700 kilowatts (rated 750 kW) — that Farm Power sells to Puget Sound Energy. Farm Power captures the waste heat from the engine as hot water and uses it to warm the digester.

New Methane Digesters

The new Lynden digester, similar to the Rexville plant, adds a valuable innovation by piping part of the waste heat from the digester to the nearby Van Wingerden greenhouse complex to grow vegetables year-around. Even as Farm Power constructs the Lynden plant, which it expects to complete in November, the company has plans in the works for new anaerobic digesters in Enumclaw, Washington and Tillamook, Oregon.

Each new digester brings advances. With a more efficient engine-generator to boost electrical production from a rated 750 kilowatts to one megawatt, the Enumclaw plant will be able to produce more energy than the previous Farm Power digesters. Also, due to its proximity to Seattle’s food processing industries, the Enumclaw digester will process a greater ratio of food waste to manure, and earn money as a waste composting facility.

The Tillamook project in development is in a renowned dairy area of Oregon. The State of Oregon has granted Farm Power a $1 million dollar energy program grant for construction. This will help finance the estimated $4 million cost for a digester. Once construction is complete, Oregon will give the company a $1 million dollar Business Energy Tax Credit. With the energy program grant, the site secured, committed dairy farmers to provide the manure, and Oregon’s tax credit, Farm Power expects to break ground next year.

Powerful Benefits

The construction of four new methane digesters with their beneficial outputs of renewable electrical energy, waste transformation, and greenhouse gas reduction are great accomplishments for a small start-up company. Farm Power Northwest and the Maas brothers provide one more public service: they remind us of the American entrepreneurial spirit—what we have been and what we can become.


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