900 Cows, 600 Homes


The New York Times has a cheerful story today about farmers using the methane in cow waste to generate natural gas, instead of just bulldozing the manure into hideous and dangerous brown lagoons, as most dairy farmers do today.

According to Lee Jensen, general manager of a 900-cow dairy in Elk Mound, Wis., "We’re not taking any risk, the reduction in odors is huge, and we’re powering 600 homes with 900 cows," he said. "You’ve got to admit, that’s pretty efficient."

Methane is a greenhouse gas.  By capturing it and using it to generate energy, you’re winning on two fronts: avoiding the emissions from the coal or oil you would have burned, plus taking care of the cows’ contribution to global warming.  The gardeners don’t even lose out here–the leftover liquid from the bio-digestion process used to generate the gas is apparently still good as fertilizer.

In Vermont–an enlightened place where most people have actually seen a manure lagoon and probably noticed that it is not the ideal way to dispose of cow manure–a utility called Central Vermont Public Service offers its customers a choice.  They can pay more, if they want, for "cow-powered" electricity.  More people have signed up for the program than Central Vermont Public Service has cow power to offer.

Why don’t our president and vice president understand that a lot of ordinary people are willing to pay more for clean power, if it means saving the world around us from an ugly climate shift, not to mention war in Iraq?  We don’t need to be treated like toddlers who want what they want and to hell with the consequences.   A lot of Americans are willing to be a little less comfortable today, if it means we can avoid ending up at the bottom of a brown lagoon tomorrow.


  1. Burning methane releases water and carbon dioxide, itself a greenhouse gas. It won’t reduce the cows’ “contribution” to global warming. It does reduce other emissions, such as particulates, sulfur compounds, and so on, from “dirty” fuels such as coal and oil.

    When you consider how much cows eat, and how much energy goes into growing the feed which cows consume, then the available energy from cow waste is not so surprising. Unless we can grow all that feed without consuming fossil fuels, it’s still a net loss.

  2. Xris, I need to gently correct your calculation of greenhouse gases. It is true that burning methane (aka natural gas) releases CO2, but the quantities are comparatively small. What’s important about methane digesters is that they reduce the amount of methane that is released into the air. When it comes to trapping heat in the atmosphere, methane is roughly 20 times as potent as CO2. Thus, methane digesters do indeed reduce the cows’ “contribution” to global warming.

    As for the fossil fuel consumption of farms, that is indeed a more complex issue. Methane digesters get a bad rap from some because if they catch on, it is feared that they will encourage more factory farming — it’s not easy to capture methane from cows roaming in open fields. And that’s true enough. On the other hand, on a recent trip to China, I visited a poor villager who was lighting his family house with gas from a methane digester fueled by the wastes from two cows and, truth be told, two humans. So I guess it’s all a question of scale. And motivation.

  3. Jeff: Thanks for the feedback. I wasn’t trying to do a deep calculation of greenhouse gases; I’m not qualified to do so. In the context of the original post, I only wanted to point out that burning methane does not eliminate environmental concerns. It shifts them, and we still need to consider *those* impacts.

    My understanding is that every molecule of methane – CH(4) – burned results in one molecule of carbon dioxide – CO(2) – and two of water:

    CH(4) + 2*O(2) => CO(2) + 2*H(2)O

    So the number of molecules, or the volume, of CO(2) released will be the same as that of the CH(4) used as fuel. The mass/weight of resulting CO(2) is *greater* than that of the CH(4) used as fuel, since CO(2) has a greater molecular weight (a little less than 2.8x) than CH(4).

    I wasn’t considering the relative greenhouse impact of CO(2) versus CH(4). Your note about a “20 times” difference led me to read up on this. I didn’t find anything about that figure, but I learned that the global warming potential of methane is greater than carbon dioxide (of the same mass). The factor ranges from 62 over the next 20 years to 7 over the next 500 years, dropping over time because CH(4) is removed from the atmosphere more quickly than CO(2). Even considering the mass ratio, substituting carbon dioxide for methane reduces the greenhouse impact.

    Mind you, we switched our heating system from oil to natural gas when we bought our house last year. So I agree that methane is a preferable fuel source!

    Thanx – Xris

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