David's bad joke about the biomethane plant reminded me that there is a biomethane plant sitting just 30 metres from my office. Only it runs off someone else's excrement. This is the inlet (sewage pipes from 2 toilets and a bunch of organic waste), the dome is where the fermentation / gasification business happens (you can't actually see it now, because it is buried underground), and the last picture is what comes out: clean natural gas. Now how cool is that. Better than trying to light a fart.