Biogas

Or "What I'm Actually Doing With My Summer"

Biogas is an renewable fuel source (mostly methane) that comes from anaerobic decomposition of waste materials; in our case, this waste is cow manure, but most organic trash works too. If purified enough, it can be used just like natural gas, but this level of scrubbing is usually only done for large installations. For our project, we're just using the gas as it is produced.

Our project is the construction of a small biogas system for a single home in a rural village. This system consists of the digester (where the manure sits to decompose), and the usage system (piping and a stove). The digester itself is dome topped cylinder with a volume of 3 cubic meters with a mixing chamber/inlet on one side and the outlet on the other (once digested, the cow manure makes excellent fertilizer). Most of these structures are brick and mortar, sealed with more mortar and possibly lime. We purchased a bunsen burner and built a stove around it, in a local, fuel-saving style. Unfortunately, we have to wait another 4 weeks or so until we can test the stove as the digester has to vent out all of the air first, and then we have to let the pressure build up for a week or two.

Most of the design work on the digester component was done before I arrived by a student from Iowa State University and another from Makerere University (in Kampala). Megan and I have handled a lot of the piping and stove design and construction ourselves, though.

My great hope right now is that I get to see a biogas flame before I leave Uganda; we'll see.

Feel free to ask any questions through comments or e-mail; I'll try to answer them here.

More about biogas:

• Biogas on Wikipedia (of course)
• A complete guide to biogas