2024-01-29 18:00:00
It looks quite inconspicuous: about ten by ten centimeters in size, green, with a gray square in the middle, the whole thing shrink-wrapped in foil. But what is floating in the River Cam against the backdrop of the famous Bridge of Sighs in Cambridge is a spectacular invention. An artificial leaf that can produce green fuel from water and carbon dioxide (CO2) using the power of the sun.
It’s still small, but the inventors are already thinking big: Virgil Andrei, who is involved in the project, is talking about large floating farms for synthetic fuel. “They could supply coastal towns or remote islands.” A key advantage: “Many renewable energy technologies such as solar fields require large areas. If production is moved to water, there will no longer be competition between clean energy and land use,” says Erwin Reisner. The chemist is driving the artificial leaf forward significantly.
The first version of the art sheet was still too difficult
Since 2012, the Austrian-born artist has been working at the University of Cambridge in eastern England to, in a certain way, recreate nature. Plants use solar energy to convert CO2 into sugar and release oxygen in the process. The artificial leaf that Reisner and a team of 25 scientists are currently developing at the university’s Faculty of Chemistry uses a similar principle.
The first version of the art sheet was ready in 2019. It used solar energy to convert water and CO2 from the air into synthesis gas – a mix of hydrogen and carbon monoxide. This gas is an intermediate product that can be used to produce kerosene, for example. The chemical industry also uses it as a raw material for plastics, fertilizers and cosmetics. To date, synthesis gas has primarily been obtained from fossil sources such as natural gas. However, the first artificial leaf was still very heavy, partly because glass was used. It couldn’t swim.
Market opportunities are likely to be huge
As a result, the researchers made the leaf lighter and used other materials. It swam for the first time in 2022, but still needed clean water, more like laboratory conditions. Elements in dirty water poisoned the catalyst, the core of the leaf, or delivered undesirable chemical effects. There is now a new version that can be used everywhere: in the harbor, on rivers, lakes and even in the sea. The artificial leaf still produces synthesis gas or hydrogen – and now clean drinking water as a byproduct. And it doesn’t need direct sunlight. The blade also works in cloudy skies or even rainy weather.
The market opportunities are likely to be huge. According to the WHO, around two billion people do not have access to clean drinking water. It often affects remote regions or areas in developing countries. As a rule, green energy is also missing there. A device that uses dirty water solves two problems at once, says Ariffin Mohamad Annuar, who is conducting research with Reisner. “It can break down water to produce clean fuel while also providing clean drinking water.”
Still a long way from an industrial application
In very simple terms, the artificial leaf consists of two layers, even if it doesn’t look like that to the naked eye. Sunlight heats a very fine carbon network, many times thinner than a human hair, where the water evaporates and rises. In the leaf’s catalyst, hydrogen is then converted from the clean water vapor using sunlight, or synthesis gas is converted from the air using CO2. In addition, some of it condenses back into a container to form water that is of drinking water quality. “The hydrogen or the synthesis gas collects in the sealed shell,” says Reisner. “In the longer term, we aim to convert the gases into liquid energy sources – for example alcohol or kerosene,” said the expert. “It can then be transported relatively easily, in this case as green fuel.”
Currently, the artificial leaf is still far from industrial application and a large floating biofuel factory. The hydrogen drinking water leaf lasts about six and a half days. The leaves cannot yet be used commercially, says Reisner. These are the first prototypes. “But we are committed to using the technologies in the long term.” He hopes that they will be ready for the market in five to ten years. An important factor: money. So far, the European Research Council has supported Reisner’s work, among others, and financial help has also come from the EU program “Horizon 2020” and from the study programs of the Cambridge Trust and a foundation of the Malaysian state oil company Petronas.
Efficiency must be significantly improved
Reisner and his team are currently working on improving the efficiency of the artificial leaves. The efficiency is still manageable. It is currently given as 0.14 percent for hydrogen production. In 2019, Reisner and his colleagues believed that five to ten percent were necessary if it was to be profitable on a large scale.
More efficiency is also necessary, otherwise huge areas of water will have to be covered with the artificial leaves. This in turn would darken lakes, for example – with potentially serious consequences for life there. However, the artificial leaves could also cover industrial ponds or irrigation ditches in hot regions. Then the energy suppliers prevented too much water from evaporating and not making it to the fields.
And the artificial leaves have another advantage: “Theoretically, you can roll them up and lay them out almost anywhere in almost any country,” says Reisner. “This also helps with energy security.”
#Solve #problems #power #sun