Back in the seventies we had power problems in the UK and my factory in St Ives was affected like everyone else. At that time I looked into the possibility of a methane digester to produce gas to power a generator to produce our own electricity.
One of our employees at that time mentioned a relative (uncle I think) who had powered his farm in Africa (Northern Rhodesia?) with the use of animal waste. The man was L. John Fry.
http://journeytoforever.org/biofuel_library/MethaneDigesters/MD8.html
See also:
http://journeytoforever.org/biofuel_library/MENintvus/fryintvu.html
which is truly fascinating.
I have always wanted to build methane digesters and that is on my Bucket List.