Plying Poop Power in Portsmouth

12/19/07Follow @wroush

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have someone take manure away, according to Hall. (In fact, in some cases the company can collect “tipping fees” for getting the manure off of a farmer’s property.)

Another is that clean-energy projects like anaerobic digestion plants allow their owners to participate in the magical pseudo-economy of renewable energy certificates and carbon credits. An REC, also called a renewable energy credit or a “green tag,” is a tradeable commodity certifying that one megawatt-hour of electricity was generated using a renewable energy source. If a utility generates one megawatt-hour of electricity using natural gas that it bought from Environmental Power, it is then entitled to sell one REC.

Since natural gas from a renewable source generates this extra value, Environmental Power is able to charge the utility a premium for it. But get this: Because methane is a potent greenhouse gas—trapping heat in the atmosphere even more effectively than carbon dioxide—Environmental Power is also entitled to a separate carbon credit or “certified emission reduction” by virtue of the fact that it captured the methane in its digesters, rather than allowing it to dissipate into the atmosphere as it would have if the manure had gone into one of the lagoons found on most dairy farms. The company can sell that credit directly to anyone looking to buy “carbon offsets”—pledges that one person or organization has reduced its greenhouse-gas emissions by a certain amount in order to counterbalance someone else’s emissions.

Opening Day at Environmental Power’s Stephenville Plant“It’s a triple whammy,” says Hall. “We sell the gas, we get the added value for the REC, and we sell the carbon credit.”

It’s really a quadruple whammy, since, as noted above, the raw material is free. But it doesn’t stop there. Believe it or not, the liquid waste left over from Environmental Power’s process can be sold back to farmers as nitrogen-rich fertilizer, and the solid material—mostly undigested grass—can be dried and re-used as animal bedding. “It’s light and fluffy and the cows are pretty comfortable in it,” says Hall.

Prospects are so bright that Environmental Power is designing and breaking ground on several new facilities in Nebraska, California, and Texas even before the Stephenville plant has been completed. Of course, there are plenty of complications that could reduce or delay the profitability of Environmental Power’s project. For one thing, high-temperature digestion is an unstable process that’s tricky to manage correctly, especially in tanks holding almost a million gallons of manure, Hall says.

And the company can’t build its facilities just anywhere: they have to be adjacent to a large manure source (i.e. a large dairy or cattle herd or hog farm), close to a gas pipeline, and not too far from a metropolitan area with lots of grease-rich restaurants. The lack of large herds in New England means Environmental Power won’t be building any facilities near its Portsmouth headquarters, but Hall says upstate New York could become home to anaerobic digestion facilities, as could Virgina, the Carolinas, and other Southeastern hog havens.

Just how big is Environmental Power’s potential market? “It’s hard to quantify,” says Hall. “It’s like a map with many layers—you have to overlay where the farms are, and where the pipelines are, and the relative value of energy commodities in different areas of the country. But 3 billion pounds every day—that’s a lot of manure. We think the market is very significant.”

Wade Roush is a contributing editor at Xconomy. Follow @wroush

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  • Carl Hansen

    Intrepid Technology of Idaho Falls, Idaho is already producing pipe-line quality gas from manure at their facility near Rupert, Idaho. The facility is on a 6000 cow dairy North of Rupert (see

  • todd dorset

    Great idea. I have been told that cows are serious producers of methane in the UK at least and a potential threat to the environment.
    best of luck with your project.