Volume 33 • Issue 6 • June
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Turning cow pies into
A green energy solution that also
benefits local farmers
Cows can , er, “produce” power by
just being cows.
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
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
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.
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.
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
The nitty-gritty: How it
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.
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
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
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.
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.
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
“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.
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
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
“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
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
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.
Maas is optimistic about the impact of their venture.
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
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