Nicolette Hahn Niman’s op-ed in today’s New York Times about the use of manure for electricity reminds me once again that the difference between sustainability and not is often a matter of scale.

Niman contrasts the use of manure on traditional farms, where it plays an important role in maintaining soil health, with the manure-disposal problem faced by large livestock operations. Increasingly, manure from these large operations is being used to produce electricity through various processes, something I like to call “poo-powered power plants” (P4). Niman rightly points out the downsides to using manure on this scale for electricity production.

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But as with many things, you can’t say that capturing methane from manure is always bad. It all depends on the size. For example, this January I helped build a biodigestor on a small farm in Costa Rica as part of a class on Renewable Energy in the Developing World organized by Solar Energy International. (For pictures see the bottom of this page.) Once it is fully operational, the manure from Don Sedro’s pigs will provide methane for cooking — replacing the cylinders of propane that cost him $60 per month — and a liquid that will fertilize his small garden. Is that the sweet smell of sustainability (or just the pigs)?

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