Volume 33 • Issue 6 • June 2008
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Turning cow pies into cash
A green energy solution that also benefits local farmers

Cows can , er, “produce” power by just being cows.

By Rachel Robertson

It’s an easy laugh – making power from poop – but more than that, methane digesters are a really clever idea that benefits both the environment and the farmers.

If there is a negative, it is the cost of building one. Western Washington’s only digester, at the Vander Haak Dairy in Lynden, cost $1.2 million when it was built in 2004, and Farm Power Northwest LCC is in the processes of fundraising for a larger digester in Mount Vernon that is projected to cost more than $4 million.
But back to the benefits: Methane digesters eliminate many of the problems of having too much manure around and at the same time produce green power that is renewable. The digester removes methane (a greenhouse gas) that would otherwise be released into the atmosphere. The processing also reduces the smell and creates a fertilizer that is free of weed seeds and is, well – digested.
“It is more valuable as a fertilizer because it’s more broken down,” explained Daryl Maas of Farm Power Northwest. “So when you spread it on your fields it has an impact right away, instead of staying out there for months and possibly running off into the surface water.”
The solids (or fiber) can be used as bedding for the cows – a byproduct, which is rapidly increasing in value. Daryl’s brother and business parther, Kevin Maas said that the farmers they work with at Farm Power Northwest are getting more anxious for the project to be finished so they can have a reliable supply of bedding. Their current bedding, sawdust, is becoming scarce. Not only is it expensive but there are times when they can’t even get it. The fiber can also be used as a soil amendment and Darryl Vander Haak said he sometimes sells it to the nursery industry.
However, power is the biggest commodity of methane digesters – half the projected revenue for the Farm Power digester, according to Kevin Maas. Puget Sound Energy (PSE) has a special rate they use to purchase power from small energy generators that they contract for 10 years.
“That’s wonderful; because that is something that we can take to the bank and say we have got set prices,” Kevin Maas said.
But there are also less obvious sources of income.
The PSE Green Power Program, a separate not-for-profit entity within the power company, purchases renewable energy credits, sometimes known as “green tags.” The credits are bought either directly from the green energy producer, or through Bonneville Environmental Foundation.
“We’re the broker for our 20,000 plus customers who are voluntary customers of that green power,” said Tom Maclean, manager of green power and emerging technologies at PSE.
Additionally, because the digesters significantly reduce methane emissions, they are eligible to sell carbon offset credits to organizations like the Chicago Climate Exchange (CCX). Through the exchange program, member companies of CCX who can’t reduce their own emissions can purchase credits from those that can.
To encourage the diversification of energy, and thus reduce America’s dependence on foreign oil, the federal government gives tax credits for investments in renewable electricity sources, including methane digesters, as part of the Tax Relief and Health Care Act of 2006.
The Washington State Legislature is also lending a helping hand – in March, Gov. Gregoire signed Senate Bill 6806 to include methane digesters in a property tax exemption, previously given to ethanol and biodiesel facilities.

The nitty-gritty: How it works
Andgar Corp. of Ferndale has been working on building methane digesters for the last eight years. The company has completed three so far in Washington and Idaho and has another two in progress.
The systems are also called anaerobic digesters, which refers to the biochemical process that occurs with the help of specific kinds of bacteria in an oxygen-free (hence, anaerobic) environment. There are different kinds of anaerobic digesters, but the one Andgar uses is a plug-flow digester developed by their partner GHD Inc., based in Chilton, Wis.
A cow’s digestive system is a useful metaphor for visualizing how the system works. In the plug-flow system, as new material enters the digester it pushes the old material out, as it travels a u-shaped path.
To make sure the digester doesn’t get plugged, the slurry is made to be 12 percent solid. As it flows into the digester it is heated up to 100 degrees (a temperature similar to a cow’s stomach) and encounters the bacteria that begins breaking down the material and producing methane gas.
“It usually stays in the digester about 22 days, and why 22 days is the magic number, is we found out that the best gas production is 22 days,” said Mike Apol, regional manager for Andgar’s digester technology. He also explained that by then the byproducts that come out are 99.6 percent pathogen free.
The three byproducts – biogas, biosolid and liquid stream – then exit the digester separately. The biogas is piped to an engine-generator set (or genset) where it is burned to produce power that is sent back to the grid. The gensets are often reused engines that have been modified to burn biogas.
Heat is recycled in the system via hot water that is heated at the genset and sent back to warm the digester using hot water pipes placed along the inside walls.
In addition to cow manure, the digesters can handle other animal and food wastes, so the technology is also applicable to other industries such as meat packing plants.
The amount of energy produced is, of course, dependant on the size of the digester. The one at the Vander Haak Dairy produces about 450 kilowatts, but the larger Farm Power digester will be built for 1.5 megawatts – more than three times the size. Three hundred kilowatts powers about 180 homes, so Kevin and Daryl Maas expect the Farm Power digester will power about 1,000 homes – roughly a town the size of La Conner.

Making it a business
Size is an issue for digester technology.
“I would say, to be cost effective, it would be a thousand-cow dairy or bigger. Of course you can do a smaller one, but your payback is not going to be as great, and that’s what the dairy farmers look at. The typical payback on an operation is usually seven to 10 years,” Apol said.
In the Midwest where the dairies are typically larger and power is more expensive, methane digesters have been faster to catch on. Of the 28 in the United States the highest concentration is in or near Wisconsin and Indiana.
At the Vander Haak Dairy where Darryl Vander Haak has about 900 head of cattle, he supplements the fuel for the digester with manure from a neighboring farm, chicken and egg waste, and waste from fish companies.
The growth of digesters in the area has been limited by the relatively small size of dairy farms – in Washington the average herd size is 480 cows (according to the Dairy Farmers of Washington). However, Kevin and Daryl Maas found a way to get around that limitation.
“If you have a group of farmers that you can get to work together, it really can be done,” Daryl Maas said. “And ours really is very efficient at the scale were doing it – we have a little over 2,000 cows, which is where we think it’s efficient.”
Their business began as a graduate school project for Kevin, who was working on his MBA at Bainbridge Graduate Institute where the focus is on sustainable businesses that are environmentally and socially responsible. The plight of Skagit Valley dairy farmers was salient for the brothers who grew up in Mount Vernon, where many of them were their classmates.
“We love our farmers and we want to keep them here ... they’re not a myth, they are real and they have to make a living,” Kevin Maas said. Daryl Maas explained that part of their motivation for preserving dairy farms is that they believe keeping animals on the land is one of the best things for the soil.
“I knew I wanted to do this. I’ve known that for several years, but it was not until we actually put all the numbers down in enormous spreadsheets and went out and visited a bunch of farmers did we know that this could go. So, that was pretty exciting,” Kevin Maas said.
Knowing the farmers has given them a unique edge in a business that requires a lot of cooperation and coordination of many groups. Farm Power Northwest has four participating farmers and the digester will be built on land leased from one of the farmers and situated between two of the farms.
The Maas brothers have been overwhelmed with support from organizations such as PSE, Skagit County, Skagitonians to Preserve Farmland, the Northwest Agriculture Business Center, and the Economic Development Association of Skagit County.
“This is something everybody wants to see happen. It just takes a lot of work, but the support we’ve been getting has been excellent,” Daryl Maas said.
Maclean said that PSE’s interest in renewable energy starts at the very top of the company with CEO Steve Reynolds, and goes through to the customers who are part of the Green Power Program. And although the methane digesters are relatively small scale compared to a big power plant, PSE is interested in capturing such small- and medium-sized resources.
“It all adds up,” he said.
“It is nice for us to be involved in something that is community-based and is local, and brings innovation down to the county level and the neighborhood level,” said Andy Wappler, senior public relations consultant for PSE.

Rustling up some funding
Fortunately, there is support out there for such enormous projects. Vander Haak received $272,000 in grant funds from the U.S. Department of Agriculture (USDA). And funding from the Paul G. Allen Foundation assisted with research performed by Washington State University, which indirectly supports the digester.
Fundraising has been a big part of the job for Daryl and Kevin Maas. Much of the money is coming from Seattle investors, however Sen. Mary Margaret Haugen, D-Camano Island, helped them locate $500,000 in state funding, and they are also applying for a grant from the USDA.
The brothers feel that the project is really well-suited for a grassroots funding effort and hope that they can also make it available to community members as an investment; to that end they are filing the paperwork with Washington state for a Small Company Offering Registration.
Daryl Maas is optimistic about the impact of their venture.
“We’re adding new value that was not being used before. We’re actually creating value here in the county – for our community, for our economy and especially for the farms,” he said.

The engine-generator set at the Vander Haak Dairy is a reused engine modified to burn biogas. Digesters produce a consistent supply of electricity that is sent back to the grid. Photo courtesy of Andgar Corporation.

The digester at the Vander Haak Dairy is coated with white spray-on foam insulation over 8-inch hollow core panels. The digester is 16-feet tall, but only two feet are above ground. Photo courtesy of Andgar Corporation.

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