I found a great book "A Chinese Biogas Manual" which was translated from chinese and is a guide on how to build simple, biogas generators from local material in small communities. It even goes into storage and use of the biogas. I know that the reason most dairies are not generating biogas is due to the the high costs of the stainless steel digesters. This book explains how to make suitable digesters in the ground out of stone, brick, clay and concrete for cheap. Does anyone know of any local examples of DIY biogas generation? It seems like a great way to produce energy and compost from waste products, not only for dairies but for communities as well.