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PLANTS DO IT, SO WHY DON’T WE?
PLANTS CONVERT SUNLIGHT into food. So why not use photosynthesis to transform sunlight into a useful fuel? Indeed, as described by BBC News, August 22, 2022, “Cambridge University Scientists Create Fuel From ‘Artificial Leaves.’ ”
This exciting finding came to me through a recent Nice News, a daily online review of heartening happenings around the world.
Photosynthesis. Merriam-Webster writes, “The Greek roots of photosynthesis combine to produce the basic meaning ‘to put together with the help of light.’ Photosynthesis is what first produced oxygen in the atmosphere billions of years ago, and it’s still what keeps it there.”
M-W continues, “Sunlight splits the water molecules (made of hydrogen and oxygen) held in a plant’s leaves and releases the oxygen in them into the air. The leftover hydrogen combines with carbon dioxide to produce carbohydrates, which the plant uses as food—as do any animals or humans who might eat the plant.”
Cambridge Research. Professor Erwin Reisner leads a research group at England’s University of Cambridge in a quest for replacing the global shipping industry’s reliance on fossil fuels. And for good reason: “80 percent of global trade relies on cargo vessels powered by fossil fuels, representing about three percent of total emissions,” reports the university.
The university says that in 2019 the researchers “developed an artificial leaf, which makes syngas – a key intermediate in the production of many chemicals and pharmaceuticals – from sunlight, carbon dioxide and water. The earlier prototype generated fuel by combining two light absorbers with suitable catalysts. However, it incorporated thick glass substrates and moisture-protective coatings, which made the device bulky.”
A New Generation of Artificial Leaves. “For the new version of the artificial leaf,” the university writes, “the researchers took their inspiration from the electronics industry, where miniaturisation techniques have led to the creation of smartphones and flexible displays, revolutionising the field.”
The report continues, “Tests of the new artificial leaves showed that they can split water into hydrogen and oxygen, or reduce CO2 to syngas. While additional improvements will need to be made before they are ready for commercial applications, the researchers say this development opens whole new avenues in their work.”
Perovsites. Key to their design are synthetic perovskites, photovoltaic compounds modeled after the naturally occurring perovskite, a calcium/titanium/oxygen mineral. Details are given in “Floating Perovskite-BiVO4 Devices for Scalable Solar Fuel Production,” by Virgil Andrei et al., Nature, August 17, 2022. From the Abstract: “Their potential for scalability is demonstrated by 100 cm2 stand-alone artificial leaves, which sustained a comparable performance and stability (of approximately 24 h) to their 1.7 cm2 counterparts. Bubbles formed under operation further enabled 30–100 mg cm−2 devices to float, while lightweight reactors facilitated gas collection during outdoor testing on a river.”
“This leaf-like PEC device,” the researchers continue, “bridges the gulf in weight between traditional solar fuel approaches, showcasing activities per gram comparable to those of photocatalytic suspensions and plant leaves. The presented lightweight, floating systems may enable open-water applications, thus avoiding competition with land use.”
“Solar farms have become popular for electricity production; we envision similar farms for fuel synthesis,” said researcher Andrei. “These could supply coastal settlements, remote islands, cover industrial ponds, or avoid water evaporation from irrigation canals.” ds
© Dennis Simanaitis, SimanaitisSays.com, 2023
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