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October 26, 2006
Moooore power
Methane from cow manure makes new energy
Eight-hundred dairy cows help power many farms and homes.
By Vincent Staupe
niversity researchers are studying a peculiar source of energy on a dairy farm about an hour north of the Twin Cities.
The energy is derived from methane gas produced by the manure of the 800-plus dairy cows that inhabit Haubenschild Farms located near Princeton.
Richard Huelskamp, a scientist with the University's bioproducts and biosystems engineering department, studies anaerobic digestion, a process that produces biogas from decomposing manure. The gas can be used to create energy.
"Basically, the philosophy of the farmer is 'if it's a waste, let's figure out what we can do with it to get something out of it,' " Huelskamp said.
Around 1999, Dennis Haubenschild, the owner of the farm, decided to do just that. He installed an internal combustion engine with a 135-kilowatt electrical generator that runs on the methane captured from the breakdown of manure.
"I believe that agriculture has got to be supplying 25 to 50 percent of our domestic energy," Haubenschild said. "We need to maintain sustainability."
Behind the cow barns at his farm are several linear concrete troughs, called digesters, which channel the manure slowly for 30 days, allowing it to decompose and eventually release gas. A flexible white cover bulges over the trough, revealing the amount of gas generated by the manure below, Huelskamp said.
Once the manure works its way through the digester, and the biogas is captured and stored, the less pungent waste is pushed to a nearby holding pond where it can eventually be used for agricultural purposes such as fertilizing fields, Huelskamp said.
The farm lacks the strong smell of what might be expected from a farm of more than 800 cows because the majority of the gas is extracted and sent through the generator.
"That gas is basically 60 percent methane and a little less than 40 percent carbon dioxide," Huelskamp said.
Though the generator has powered the farm compound and several homes nearby for about six years, there are some drawbacks, including the release of greenhouse gasses, associate professor Philip Goodrich said.
"It's a very noisy, high maintenance generator set," he said, "And it's not clean."
The University, along with sponsors like the Initiative for Renewable Energy and Environment, the previous legislative commission on Minnesota resources and the Minnesota Department of Agriculture, produced a fuel cell system in 2005 that worked to extract the hydrogen from the biogas to create electricity without combustion.
While the fuel cell system is much quieter and cleaner than the combustion engine, it is much more expensive to operate, leading researchers to consider other ways of converting biogas, Goodrich said.
"We're looking at different ways to market the energy," Goodrich said.
Options include exportation of the hydrogen and methane. Haubenschild is currently exploring the use of methane to fuel vehicles.
Graduate student Ananth Sundareshwar, who worked on the project, said the importance of the research is looking at renewable energy sources that may not have been previously studied.
"Biomethane as a fuel hasn't been looked at in detail as
has ethanol," Sundareshwar said. "This is a new alternative, which is why it is important."
Whether the technology involves using manure to produce electricity, methane or hydrogen, the importance, Huelskamp said, is who is producing it.
"Are we going to get our energy from the Middle East or are we going to do it ourselves?" he said. "This is one guy who did."
© Copyright 2006 The Minnesota Daily