Creating fuel from thin air with artificial leaves

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Artificial leaves could one day provide fuel

The sun produces more than enough energy for human activities, but we still can’t capture enough of it, points out Erwin Reisner, energy and sustainability professor at Cambridge University.

He heads a team of researchers trying to capture more of that free energy.

While solar panels have made big advances in recent years, becoming cheaper and more efficient, they just provide electricity, not storable liquid fuels, which are still in great demand.

“If you look at the global energy portfolio and what’s needed, electricity only covers maybe 20-25%. So the question is when we have covered that 25%, what do we do next?” asks Prof Reisner.

His answer is to look to nature: “Plants are a huge inspiration, because they have learned over millions of years how to take up sunlight and store the energy in energy carriers.

“I really believe that artificial photosynthesis will be one part of that energy portfolio over the next two decades.”

When plants photosynthesise, they take up water and carbon dioxide, and use light from the sun to convert these raw materials into the carbohydrates they need for growth.

Erwin Reisner, professor of energy and sustainability at Cambridge University
Prof Reisner is optimistic artificial photosynthesis will become an important energy provider

“We want to replicate this, but we don’t really want to make carbohydrates because they make a lousy fuel, so instead of making carbohydrates we try to make something that can be more readily used,” says Prof Reisner.

An added problem is that plants aren’t actually terribly good at photosynthesis, converting only around one or two per cent of solar energy into fuel. The US Department of Energy has concluded that for artificial photosynthesis to be viable economically, efficiency needs to rise to between five and 10%.

Prof Reisner’s team has worked on a number of