My understanding from an independent researcher who had tried to develop a
small farm scale biogas system for many years is that temperate climates are
a huge obstacle to small scale biogas systems. The most efficient microbes
are very picky about temperature, so you need a very warm and stable space
for them to do their work. I think thats the reason many have tried and only
a few systems in the warmest climates have actually succeeded...
This researcher attempted below ground, hoop houses, many ideas before giving
up.
If I'm wrong, I'm glad I about it:)
-Jeff Hall, Ames Iowa