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.