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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.

An intriguing new idea involves "feeding" surplus power to the microorganisms instead, which combine it with carbon dioxide to create methane.

When living on the cathode of an electrolytic cell, the organism can take in electrons and use their energy to convert carbon dioxide into methane.

There are no noble metals involved, so it should be very cheap

Of the energy put into the system as electricity, 80% was eventually recovered when the methane was burned – a fairly high efficiency.

Several similar techniques use microorganisms to produce >hydrogen fuel rather than methane. But the hydrogen economy is not here yet, Logan points out. "These methods are great, but hydrogen doesn't fit into our existing infrastructure. Methane does."