ENERGY LEAVES

April 2021

Harvesting solar energy has always been a fantastic approach to reducing carbon emissions, but it has been limited and tricky. Now scientists at Cambridge University have developed a prototype for a renewable energy device that works like an artificial leaf.

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

The new artificial leaf mimics this action – immersed in a bath of water containing carbon dioxide, it converts sunlight into a liquid energy carrier.

“I really believe that artificial photosynthesis will play a key part in the energy portfolio over the next two decades," says Erwin Reisner, the research paper’s senior author and energy and sustainability professor at Cambridge University.

Different to conventional solar panels, which only provide an electric current, the photosynthesis device produces a liquid fuel meaning its energy can be stored and more easily transported than hydrogen.

Reisner points out that the breakthrough is important because the device can be used in two ways – either scaled up into an energy farm, or individual leaves could be attached to homes.

The slim device is made of photocatalysts – materials that absorb light to create a reaction. It is coated in a semiconductor powder and immersed in water and carbon dioxide. When the sunlight hits it, a chemical reaction takes place – the device absorbs the light, which ignites electrons that then join with the carbon dioxide and protons released from the water. This reaction results in formic acid, which can be stored and used as a fuel on its own, or turned into hydrogen or other fuels. Ants and bees produce formic acid in their venom.

What makes this so remarkable is that the device doesn’t require wires or an external power source, it is a stand-alone object that is powered by the sun.

The Cambridge team say that the device works better than they anticipated as it produces formic acid cleanly. The next important step is improving its efficiency and stability before scaling can start on the path to commercial deployment. Reisner says that his team will address these challenges in the next five to 10 years and also work on the production of other liquid fuels and chemicals from sunlight.


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Artificial Leaf for solar energy conversion to produce renewable fuels.
Artificial Leaf for solar energy conversion to produce renewable fuels.
Artificial Leaf for solar energy conversion to produce renewable fuels.
Artificial Leaf for solar energy conversion to produce renewable fuels.
Artificial Leaf for solar energy conversion to produce renewable fuels.
This article appeared in DAM78. Order your personal copy.