we all know it exists (much of it for free) but almost nobody uses it! on this earth are millions of head of livestock, farmed for all kinds of needs, each producing natural waste. many commercial farms mechanically clean the animal pens at regular intervals, placing the waste produced by the animals in large containers called digesters. the product is then left to rot and ferment for fertilizer. the gas produced during this process is pure methane, which is released through a valve at the top into the atmosphere. (methane is one of the main causes of ozone damage). this gas can be easily compressed into gas cylinders for use in combustion engines cooking or any number of applications. why do we not use it?