I see there's a lot of interest/inquiries regarding biogas, so I wanted to post a link to a unique and convenient biogas opportunity-
HomeBiogas is a company that has been developing household biogas for close to 8 years, with the goal of making them easy-to-use and affordable.
We just launched an extremely successful campaign with the newest model- a "Do It Yourself" kit which was met with overwhelming support, buyers, and enthusiasm from all over the world.
For a bit longer you can still get them at reduced prices-
HomeBiogas is off-grid, and has been built with durability, low-maintenance, and convenience in mind. This model was built as a response to home-made models breaking down easily, not producing optimal yield, and complicated/dirty maintenance procedures. With HomeBiogas you don't have to worry about all that.
I love the idea and wish that my climate worked well for it. Unfortunately the time we do the most cooking is during the winter (eat a lot of salads in the warmer months). I can definitely see this as being a real economic and environmentally friendly option for those in warmer climates.