A Methane Digester

This is a methane digester. You feed manure in one end and the manure undergoes anaerobic digestion and produces methane gas that can be used for cooking. The tank can rise up and down to store the gas. That's the concept anyway. This lady lives in Ecuador where they built some of these digesters.... This actually was a black and white pen drawing but I thought it would look nicer in color.

I think it's funny that the Google ads are picking up on the methane digester stuff, so if you want to build one, you can "follow the ads". :)