Monday, 14 December 2009

Kenya Trip - Methane

Soon after arriving in Kisii, I could be seen rummaging through the Kisii markets and street traders for bits to (finally) build an anaerobic digester, to produce methane, which i believe can be used as a cooking fuel, amongst other things.

I have ranted on about finding a sensible alternative to wood or charcoal for cooking and stating that methane is the best for most people in rural areas, so, I will not go into our reasons again - just yet.

The first component needed is, of course, a large gas-tight container. a 45 gallon oil drum is fine. At Ksh 2,500, it is not too expensive, but as a pale-skinned potential client, the price had risen inexplicably, but I am not a tourist and got the price back down again.

With a bag full of bits, mainly water plumbing fitments, I imagined that I could get the digester working. So we set off for the site and started to build.

Unfortunately, not all the bits fitted each other, other bits failed and yet others had the wrong thread (the hazard of buying in a market), but eventually, we had a sealed drum with an outlet with a gas-tight tap on it.

We loaded it with fresh slurry from the cow shed next door. Getting it through the standard 2" hole in the top of the oil drum was a trial - and very smelly - but we made a funnel from an old plastic container, which made the job easier. We topped up with rotted cow dung, mixed well and cooked at about 35C, the heat provided by the sun, of course.

According to all the reports I have read, an anaerobic digester takes about a week before it starts to produce methane, but maybe they didn't have the advantage of equatorial sun.

Being impatient, we could not wait the allotted week and tried out the gas that was being produced within a couple of days. It was not methane, or at least, it did not burn. We released all the gas out of the drum, hoping that we were releasing any oxygen, leaving only the product of the digestion process.

The next day was a success. The gas produced a flame!

No comments: