I have, in the past, given the output of our twa beasties to an organic farm, in exchange for produce. The idea of constructing a methane generator here is intriguing, especially after seeing the documentary "Sweet as a Nut", many years ago.

However, I would expect that the regulations of the municipality, where I live, would prohibit it, unless it was done by someone who was licensed as a gas fitter. This might prove a very expensive undertaking.   

RichardH, have any problems arisen regarding local code requirements, regarding your digestor? How much time and labour is required to keep it up and running?