The future is increasingly bright for renewable energy, with the US aiming to cut the price of solar photovoltaics by 75% between 2010 and 2020. Denmark plans to obtain 50% of its energy from wind just five years from now. But one form of renewable energy – and one which attracts few headlines – manages to create two useful products at the same time, and is making a growing contribution to combatting climate change. The medieval alchemists who sought to turn base metal into gold would have thrilled at chemistry that let them turn waste into both fuel and fertiliser. Their twenty-first century successors have discovered the secret of doing exactly that. Unwanted food, animal waste, municipal rubbish, crop and forestry residues, sewage and dozens of other left-overs of civilisation can and are now being turned into methane to generate electricity, provide district heating and to fuel road vehicles. Usually the methane produced in these digesters is fed into generators or small power stations on site and used locally. But if it is further purified the gas can simply be fed into a pipeline and mixed with natural gas.
Climate News Network 2nd Feb 2016 read more »