A team of Cambridge scientists have developed a new kind of solar energy producing “artificial leaf”, that recreates the process of photosynthesis to create green energy from sunlight, carbon dioxide and water. The artificial leaves are still in the prototype phase but have shown significant promise as a major breakthrough in the quest to realise artificial photosynthesis – the energy creation process that natural life is founded upon.

The big advantage of the artificial leaf technology is that, unlike standard solar cells, the leaves produce a storable liquid fuel as opposed to an electrical current. As a result the Cambridge University team behind the research are confident their technology will eventually be scalable. That could see the leaves combined in large numbers as solar energy plants or even installed on buildings such as residential properties and office facilities.

At the moment, the devices convert around 1% of the energy they come into contact with. That’s record efficiency for an attempt at artificial photosynthesis and is almost at the same level as some plants. It is, however, some way short of traditional solar power cells, which can convert up to 15% to 20% of sunlight they come into contact with. But the fact the artificial leaves create storable energy is an important competitive edge.

Qian Wang, who works in Cambridge University’s chemistry department thinks that the artificial lead technology could even work alongside traditional solar panels.

The device can convert sunlight, CO2 and water into oxygen and formate, a kind of liquid fuel that can be either stored or used directly in a fuel cell to produce power. Alternatively, formate can also be converted in hydrogen, which can be used to power boilers.

Source: The Times

Scientists have been convinced for some time that artificial photosynthesis could offer an efficient means of producing carbon neutral energy but have so far run into challenges in achieving the process without also creating unwanted and potentially volatile by-products.

Commenting on the newly developed technology, Erwin Reisner, senior author of the research paper that documents the breakthrough, said:

“In addition, storage of gaseous fuels and separation of by-products can be complicated — we want to get to the point where we can cleanly produce a liquid fuel that can also be easily stored and transported.”

Despite the fact there are still challenges to overcome, the promise shown by the device gives ground for optimism. When sunlight comes into contact with the artificial leaf’s semiconductor powder-coated panel, it absorbs the light, which ‘excites’ the electrons in the panel. These activated electrons then combine with the CO2 and protons released from the water which is also present, reducing the CO2. The result is a chemical reaction that creates storable formic acid.

Dr Wang comments:

“We were surprised how well it worked in terms of its selectivity — it produced almost no by-products. Sometimes things don’t work as well as you expected, but this was a rare case where it actually worked better.”

The researchers still have work to improve their device’s efficiency before there is a real prospect of the technology being commercially viable, but are optimistic. Professor Reisner hopes the new technology “will pave the way toward sustainable and practical solar fuel production.”

The University of Michigan’s Kate Adamala, who was not involved in the research commented on the new technology’s promise:

“It can be easily deployed, doesn’t require complex substrates and it doesn’t cost much to make, so it’s possible to actually use it on a large scale”.