Single-celled organisms that can convert electricity into methane could help solve one of the biggest problems with renewable energy – its unreliability compared to the steady output of polluting fossil-fuel power stations.

Wind power is capricious, while solar cell output drops off at night or on cloudy days. That fluctuating output poses big problems for electricity grids that rely on steady levels throughout the day. Proposals to deal with the ups and downs of green power supply have included better batteries or redesigning the electricity grid.

An intriguing new idea involves "feeding" surplus power to the microorganisms instead, which combine it with carbon dioxide to create methane. That could then be stored and burned when needed. The method is sustainable too, as the carbon is taken from the atmosphere, not released from long-term storage in oil or coal.

Logan is optimistic about the method's potential: "Commercial applications could be just a few years down the road," he says.