Entrepreneurial farmer uses manure to make electricity
by Joy Powell / Star Tribune

As Minnesota edges closer to a potential electricity shortage, farmer Dennis Haubenschild is testing a new source of power: cows.

At his family's dairy near Princeton, the Haubenschilds are converting manure to electricity and simultaneously reducing odor in an experiment they say will improve air quality near feedlots.

In January, the coldest month of the year, the Haubenschild farm produced enough methane from its 850 cows to power the dairy operation and 78 homes.

The farm -- the only one in Minnesota with a fully operational anaerobic digester -- demonstrates how farmers can help the state become more energy self-reliant, Haubenschild said.

Manure is heated to 95 to 105 degrees to speed up its digestion by bacteria. The process produces "biogas" that contains 55 to 70 percent methane.

Alternative energy isn't the only benefit. Haubenschild and others say the digester process greatly reduces the manure's stink, greenhouse gases and pathogens, while boosting the fertilizing value of manure.

State officials are looking for a hog farm where the same kind of experiment can be conducted to biologically treat manure while improving air, soil and water quality near feedlots.

"In farming, you have to work with Mother Nature," Haubenschild said. "If you're not an environmentalist, you're not going to be successful."

He recently testified in support of a state bill to create a $10 million revolving loan fund for manure-processing and odor-control projects. Under the legislation sponsored by Sen. Dan Stevens, R-Mora, and Rep. Howard Swenson, R-Nicollet, a farmer could seek an interest-free loan for up to $200,000.

Haubenschild testified that his digester process enabled him to save 35 tons of coal and 1,200 gallons of propane that he otherwise would have used in January. During spring planting, he won't have to use 34 gallons of propane or natural gas per acre to make anhydrous ammonia, he said.

How it works

Every day, about 20,000 gallons of manure are pumped to collection flumes beneath two barns and then into the digester, a 400,000-gallon tank that looks like a small, oblong Metrodome.

The anaerobic digestion of the manure is accelerated by heating it for 20 days before it moves into a lagoon for later application as field fertilizer.

Before the Haubenschilds began using the digester in 1999, the smell of freshly mixed and spread manure would drift 2 or 3 miles and last four days. Now, a much milder smell from the digested effluent disappears overnight after spreading, said Marsha Haubenschild. She and husband Dennis own the 1,000-acre farm with their sons, Bryan and Tom.

In the silvery-colored digester, biogas builds up. It's routed to an engine and generator, which convert it to electricity and hot water. The electricity flows to a transformer and the water heats the digester and barn floors.

A third of the electricity returns to the farm to power the milking parlor and other operations. Two-thirds is sold to East Central Energy, a cooperative serving about 43,000 customers in east-central Minnesota. In January, the Haubenschilds earned $4,380 selling electricity.

Electric cooperatives are excited about the project, which is exceeding expectations, said Henry Fischer, business and community development manager for East Central Energy. He serves on an advisory task force that prepared a report on the digester project.

"It's an excellent example of sustainable agriculture," Fischer said. "By using the digester, the Haubenschilds not only end up with high-quality compost -- a liquid slurry that they can use for fertilizer -- but from an environmental perspective, it eliminates all the odors associated with the fertilizer. The electricity is a bonus."

Cow's life

Everything at the farm is designed for the cows' comfort, Tom Haubenschild said. They are milked three times a day, fed constantly and bedded on 5-inch mattresses covered with rubber liners and recycled newspaper. Keeping each 1,400-pound Holstein contented leads to high production, the Haubenschilds say.

"That cow is producing our milk and our electricity and enough manure to do it all over again," Dennis Haubenschild said. "That's a real conversion."

He began researching digesters 25 years ago while studying microbiology in college. After years of trying, he received state and federal financing for the $355,000 construction of the digester and generator system. It began operating in September 1999.

The Haubenschilds now have 30 employees working three shifts, running electric milkers and maintaining the farm. Dennis Haubenschild figures the system will pay for itself in five years.

European 'digesters'

Today, he and Marsha Haubenschild are headed to Uppsala, Sweden, where the city's buses are powered by methane. More than 450 farm-based digesters are used in Europe. About a million small-scale digesters have been used in China and India for decades.

In the United States, at least 32 digesters are operating on swine and dairy farms.

"I would love to see people using digesters on all sizes and types of waste,' said John Lamb of the Minnesota Project. That nonprofit organization worked with the advisory group to report on the Haubenschild farm, the only one of its kind this far north in the nation.

Its methodology has proved successful in disposing of cow manure, controlling odor and generating electricity in a cold climate, said Janet Streff, manager of the Energy Office of the Minnesota Department of Commerce.

The Haubenschild operation was selected as one of the nation's 13 charter farms of AgSTAR, a joint program of the Environmental Protection Agency, Department of Energy and U.S. Department of Agriculture. AgSTAR provided the Haubenschilds with $40,000 in technical assistance.

The Minnesota Department of Agriculture offered a $150,000 no-interest loan. The state Department of Commerce and Office of Environmental Assistance granted $87,500 for construction. The family paid $77,500.

University of Minnesota economists are evaluating the digester's feasibility. Some experts say dairy farms need at least 400 cows and must earn at least six cents a kilowatt hour to operate digesters profitably.

This spring, scientists will begin researching whether plants can more easily absorb nutrients from the farm's digested manure than from conventional dung or commercial fertilizer.

"The belief is that the nitrogen in the digested manure is more available to plants, eliminating the need for starter fertilizers for forage crops, so it saves money on fertilizer," Lamb said.

Beginning next year, farmers will be invited to field days at the farm to see how the digester operates, how crops respond to the digested manure and if weed seeds survive. They also will see a comparative financial analysis.

Published Monday, March 12, 2001© Copyright 2001 Star Tribune. All rights reserved