All valid points, but burning excrement creates fewer toxins than burning coal - and it's only one example of very many sources of energy which are largely wasted.

Applied on a local scale in a heat and power scheme for example, where I live there is a lot of farm waste in addition to the people's contribution. We're talking hedge and verge cuttings, straw, packaging and animal waste. It's not the answer to everything, but a bit of local knowledge could help provide green power to a lot of public buildings and make a significant contribution to several problems.

In the long term, absolutely everything is recycled. For our own personal comfort, it's better if we organise it to happen before we all die.

When you start to look you find there are a great many more potential energy sources than you expect. None of which come close to replacing what we have now. However in combination they could produce a LOT of useful energy. If at the same time we become more energy efficient the future starts to look a little less bleak.

The compressed air storage systems are new to me. I was interested to read the Wiki JJ linked to earlier. Storing compressed air, large scale, in plastic bags down coal mines, genius.