We discussed this design on a biogas digestion list
http://listserv.repp.org/pipermail/digestion_listserv.repp.org/
(see the July 2008 archive)
It seems the inner methane digester was dedicated to methane
digesting. The compost pile around it provides only heat, no methane.
Probably compost's pile heat speeds up methanogenesis.
Some members considered Pain's methods were rather empirical than
scientific and required a lot of work.
For compost heat only, mabe a smaller scale, insulated and
forced-aeration composter - like the one proposed by C.Johnson -
should be considered http://mb-soft.com/public3/globalzl.html
Labels: Wind Turbine