I knew an ex prisoner of war who when the war ended tried to march from Warsaw to Berlin. He told me they felt lucky when they could spend the night laying on manure because it was warm. I thought he meant marginally warm compared to no manure not comfy. If you had a dairy operation and wanted to use the energy in rotting manure wouldn't you want to capture the methane too?
That is part of what generates the heat...from what little research I have done, if you use the manure for methane you can use the remainder for fertilizer. There are several decent sized operations out in the Midwest and in Australia doing it. So far it is a barely break even proposition, but I think that is going to change. For interesting reading do a search on China and bio-gas generation. The rural Chinese have been doing it for close to a 100 years!
Aaron
