Rebecca Norman wrote:Yes biogas is fairly common in India, or has been in the past. It's generally given as a rule of thumb, that it takes about 3 cows, who stay at home all day (no pasturing), to provide enough gas for a family.
Human manure has much less biogas producution value than cow manure, for some reason, beyond the obvious huge difference in volume. Food scraps are said to be high value, so if you can collect scraps from a restaurant it could be good, but you'd have to make sure there aren't big long things that can clog up the works.
It works best when kept as warm as an animal's gut, so much warmer than the ambient temperature for most of the year in the US, though India has many places that are warm enough for most of the year. Here in the Himalayas at our school we tried it, with solar heating the tank, but we ran into other problems (we made it out of the cheapest possible materials and it didn't last). We'll do it eventually. We've got 4 cows, and are cooking for like, 100 people most of the time, but we've got solar cookers and wood burning stoves too so the biogas would be an effort to reduce or eliminate our commercial bottled gas.
It's might be a good idea to get a separate burner for the biogas in the kitchen, and keep your propane range. The burners are different, and you might want to keep the propane as a backup. I read about various ways to scrub the sulfur compounds and moisture to make your flame more efficient and your appliance last longer without rusting out too fast.