I'm not ready to give up on horse potential just yet because if you've ever been at the south end of a dobbin just after it's eaten wet hay, you will know that NOTHING, but nothing can produce that much methane and not explode except a horse ( or possibly my brother after a feed of brussel sprouts).Now with a really BIG wheel, and a few tons of wet hay, I reckon we can heat the whole of Hull...of course, John needs to be living in a biggish flat....and live permanantly in a NBC suit and gas mask...but I think it's worth the sacrifice.