Like a miniature fuel production plant, the leaf produces bio-ethanol and -propanol from light, water and CO2. Applied on a larger scale, this could be an interesting solution for the climate-neutral production of synthetic fuels - and thus represent a further step away from fossil fuels.
Last year, a group of researchers from the University of Cambridge presented a floating artificial leaf that can produce synthetic gas directly on water. Nature-like photosynthetic processes came into play to produce valuable fuel from sunlight, water and carbon dioxide. From the water splitting process it came to hydrogen and from carbon dioxide to the so-called "syngas". Now researchers have achieved new developments - a milestone for environmentally friendly fuel production.
The miniature power plant on the blade no longer produces only a mixture of hydrogen and carbon monoxide, but also more complex chemicals. The new prototype converts water and CO2 directly into e-fuels with the help of solar energy. In contrast to conventional production plants, the production of this liquid energy carrier is to take place without the use of fossil fuels, e.g. for the power supply for hydrogen production, and thus become climate-neutral.
As with the predecessor model of the synthetic sheet, which is only a few square centimetres in size, the combination of light-absorbing bismuth vanadate and perovskite produces synthesis gas. But now new catalysts made of copper and palladium are added, which lead to the production of "a mixture of ethanol and n-propanol" - explains project leader and chemist Erwin Reisner. Both alcohols can then be easily transported and used as sustainably produced fuels with high energy density.
However, the technology is still far from crossing the finish line, as some aspects still need to be perfected. For example, the carbon dioxide needed for the process currently still has to come from large CO2 emission sources such as industrial plants to ensure the carbon concentration needed. "However, we are already working on getting by with atmospheric CO2 concentrations," Reisner says in this regard, however.
Similarly, the research group needs much more resources and scope if such a technology is not to remain in the laboratory but gradually become established in the energy and fuel sectors. The Cambridge project could be an extremely important development for the carbon-neutral production of fuels that are completely free of fossil fuels - and considered more sustainable than the alternatives currently on the fuel market. The scientists will now work on scaling up the system to be able to produce larger quantities of fuel. Because only when e-fuels are available in larger quantities can they be included in the rules for environmental zones, the issuing of the various environmental badges in Europe and the ban on combustion cars from 2035.