i can not provide the numbers, but there are several good bio-gas articles on the web, just search biogas, bio-gas, make methane, etc. Simplest is with a few 55 gallon drums, using a rock to regulate pressure. no cleansing or controls needed. I forget what you have to do to homemade methane to make it run an engine, but it must pass through some sort of scrubbing compound, but to just burn it to heat things up, no processing is needed
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"god gave us fuel, greed gave us gas"