A Couple weeks ago I added the following to the Free Books Page:
Fuel Gas from Cow Dung
Fuel From Farms
Hydrogen, Wind, Biodiesel and Ethanol
Biogas Plants In Animal Husbandry
Biogas Technology in the 3rd World
Design and Operation of a full scale Anaerobic Dairy Manure Digester
Practical Building of Methane Power Plants
The Anaerobic Digestion of Livestock Wastes to Produce Methane
Biogas and Waste Recycling
Compost, Fertilizer, and Biogas Production from Human and Farm Waste in China
Distillation of Alcohol and De-Naturing
Running a Biogas Program
Village Technology Handbook
I still have more to get on, but would appreciate any more sent my way.