Biogas contains a lot of methane, or natural gas. Percentages vary, but according to the Wikipedia article it can range from 50-75%. While researching biogas I came across the following video from the Urban Farming guys. They demonstrate how to build a methane biodigester (or anaerobic composter).
It looked easy enough. So I thought I'd build my own. First, acquire a barrel. I found mine on craigslist. They are all over on there. I think I picked mine up for $15.
Then cut the top off of it and wash it out. I don't know what was in the one I got, but it was strong. It had a real strong--like burn your nose strong--peppermint odor. I washed it out good with the hose and let it dry.
I picked up the cheapest trash can that I could get at Home Depot.
It was actually a really nice trash can. I felt bad about cutting the top inch or so off with the Dremel. I had to do this so it'd fit in the blue barrel.
Then I got out my handy-dandy 1-1/4" drill bit and put a hole in the bottom of the trash can.
Then it was time to install the Uniseal. These things are great. They go right into the drilled hole and then the PVC pipe gets inserted through making a watertight seal. I can't remember where I bought them. It was either here or here. The one pictured here is for 1/2" PVC pipe.
Here's the Uniseal inserted into the hole in the bottom of the trash can.
That's as far as I've gotten for now. I'll post more updates as I make them.