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An Artificial Leaf: a photo-electro-catalytic cell from earth-abundant materials for sustainable solar production of CO2-based chemicals and fuels

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Artificial leaf taps into full potential of solar energy

An ‘artificial leaf’, sourced from non-critical materials, can turn sunlight into fuel. The key now is to scale this technology up to industrial levels.

Climate Change and Environment

The sustainable exploitation of renewable energy sources is paving the way towards a fossil fuel-free future. “In the 1980s, no one believed that photovoltaics would ever become commercially viable,” notes A-LEAF project coordinator José Ramón Galán-Mascarós, research professor at the Institute of Chemical Research of Catalonia, Spain. “Now, solar power is cheaper than many other energy sources that feed the energy grid. This is the result of a lot of science of course, but also because we have been able to scale the technology up.” As more renewable energy is turned into electricity, storage has emerged as a key issue. “If we really want to transition away from fossil fuels, then we cannot rely on batteries alone for energy storage,” explains Galán-Mascarós. “At the scale of heavy industry for example, batteries become simply too heavy, and are not always reliable.”

Artificial leaves

One solution to this challenge is to transform renewably sourced electricity into ‘green’, carbon-neutral fuel. This would provide an efficient, environmentally friendly means of storing excess solar energy when there is too much sun, for example, and could directly help to replace fossil fuels. To get to this point however, the technology needs to be shown to be both reliable and scalable. This was the purpose of the A-LEAF project, which sought to develop a photosynthesis-mimicking device that produces solar fuels and chemicals. The completed prototype, which looks a little like a soft drink can, absorbs sunlight, just like the leaves of a plant. Adding water and carbon dioxide, it produces formate – which can be used as a solar fuel – as well as oxygen. “This project was tricky from a scientific point of view, because we didn’t necessarily use the best materials possible to build our device,” adds Galán-Mascarós. “We could have used rare materials that might have been more effective, but it would have then been difficult to present this as a sustainable solution that can transform society.” The project combined scientific expertise across a number of domains with industrial know-how. All participants shared in the objective of advancing renewable energy. “We all knew that we needed to develop an artificial leaf that works, that is profitable, and is sustainable,” says Galán-Mascarós. “We cannot just focus on the science, if we want to make the transition to a fossil-free economy.”

Decarbonised future

Having demonstrated the feasibility of the technology, the next step is to bring in more industrial partners and scale the process up. “We have shown that this technology works, without relying on expensive, critical raw materials,” says Galán-Mascarós. The question now is not whether efficiencies can be improved by 10 or 15 %, but whether production can be scaled up from, say, 50 mg of fuel an hour to 50 kg an hour. “We need to produce quantities that are of interest to industry,” he adds. The project has also pioneered some new scientific techniques and computational tools. These could help scientists to investigate the performance of materials under strict conditions, down to nanometric resolution. Galán-Mascarós stresses however that the key impact will be the project’s contribution to the renewable fuel transition. “A new generation of researchers and technologists have been trained in solar fuels,” he remarks. “Our most relevant contribution has been to increase knowledge and awareness of the importance and the potential of this field. We hope A-LEAF has played a role, even if modest, on the road towards a decarbonised future.”

Keywords

A-LEAF, solar, photosynthesis, energy, electricity, fuels, decarbonised, renewable

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Climate Change and Environment

2 April 2014