Jerry Jennissen, Brooten, Minn.

Jerry Jennissen has proven that you can benefit from a methane digester even when you milk 150 cows.

Since his digester went online in May 2008, electricity revenues have tripled to $1,000/month. While that income doesn't put the operation in the black, he says, it points to the digester's potential.

He's also gained manure bedding from the digester solids, which he values at $1,000/month. And the digester has delivered an intangible benefit. "The public and our community are very much in support of it,” he says.

In addition, Jennissen has partnered with a local cheese plant to take its salt whey, which he adds to his digester to increase methane production.

On the flip side, Jennissen has experienced plenty of frustration. He's burned through two generator engines. His third engine is working properly, pushing electricity output to 24-35 kW/hr.

He hasn't traded carbon credits yet. "Our output just isn't enough to make it worthwhile” to attract serious attention from carbon offset traders, he says.

Jennissen is still looking for ways to improve the digester's benefits. If he can build a new gen-set (combination of generator and engine), he believes he could boost the digester's power output by 50% to 100%. He hopes to expand his milking string to 200 cows and to one day operate an on-farm cheese-processing plant, powered by the digester's energy output.

Without those improvements, Jennissen says, he wouldn't build a digester again. "There's so much potential for digesters,” he says. "Why is it so hard?”

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