Methane Digester
Construction and testing of small-scale microbial digester that produces usable methane gas. -Design Various designs exist, some more complicated than others. Essentially is comprised of a sealed digesting vessel in which compost, manure and/or vegetable scraps combined with water and a microbial innoculation produce methane as a by product of microbial metabolism. The gas is then drawn off and burned. Difference in designs mainly revolve around how to accomplish this second step. Some employ a separate gas storage vessel, more simple designs collect the gas above the digesting slurry. Youtube video of a design that I find is sofisticated enough without being difficult for a preliminary effort: http://www.youtube.com/watch?v=l5e_2W71jMM
Other examples: http://www.youtube.com/watch?v=TTdreS_HN2Y
-Materials Based on the above design and others two to three 50 gallon plastic tanks; PVC Tubing, connectors, etc.; manure/vegetable scraps and microbes; and the tools necessary to assemble the system seem like the basic requirements. Refinements to the basic system seem not to require too many extra materials. -Assembly Seems simple enough if done carefully, also potentially fun. -Testing Initial objective here to get combustible gas with a later focus on filtration and clean burning methane.