The project follows a long-running controversy over how clean hydro-electric power really is, with some estimates indicating that the methane produced from rotting organic matter, in the oxygen-poor reservoirs behind hydro dams, is greater than an equivalent power station burning the gas. Like opening a bottle of soda, a large part of the methane dissolved in the water, bubbles off and is released to the atmosphere when it runs through the turbines.

While there is still great uncertainty about the precise amount of methane added to the atmosphere in this way, a statistical analysis carried out by the INPE has estimated that large dams could be responsible for worldwide annual emissions equivalent to some 800 million tonnes of carbon dioxide. To put that in perspective, last year’s total greenhouse gas emissions from the UK were around 660 million tonnes.

The INPE scientists are proposing that with relatively simple technology, this unwanted by-product of hydro-electric power generation could be turned into an extra source of clean, renewable electricity.

Full story at BBC news, Science