Researchers at the University of Georgia have been looking at ways to artificially imitate the efficiency of green plants in creating electricity directly from solar energy, and they are now in the early stages of developing a new technology that makes it possible to use plants for generation.
"Clean energy is the need of the century," said Ramaraja Ramasamy, assistant professor in the UGA College of Engineering and the author of a paper describing the process in the Journal of Energy and Environmental Science. "This approach may one day transform our ability to generate cleaner power from sunlight using plant-based systems."
After billions of years of evolution, plants operate at nearly 100 percent conversin efficiency, meaning that every photon of sunlight a plant captures produces an electron. Converting even a fraction of this into electricity would improve upon the efficiency seen with solar panels, which generally operate at efficiency levels between 12 and 17 percent.
During photosynthesis, plants use sunlight to split water atoms into hydrogen and oxygen, which produces electrons. These electrons help create sugars for cell growth.
"We have developed a way to interrupt photosynthesis so that we can capture the electrons before the plant uses them to make these sugars," said Mr Ramasamy. The technology involves separating out structures in the plant cell called thylakoids, which are responsible for capturing and storing energy from sunlight. Researchers manipulate the proteins contained in the thylakoids, interrupting the pathway along which electrons flow.
These modified thylakoids are then immobilised on a specially designed backing of carbon nanotubes that are nearly 50 000 times finer than a human hair. The nanotubes conduct electrons away from the plant material. In small-scale experiments, this approach has resulted in electrical current levels that are two orders of magnitude larger than those previously reported in similar systems.
Ramasamy cautions that much more work must be done before this technology reaches commercialisation, but he and his collaborators are already working to improve the stability and output of their device.
"In the near term, this technology might best be used for remote sensors or other portable electronic equipment that requires less power to run," he said. "If we are able to leverage technologies like genetic engineering to enhance stability of the plant photosynthetic machineries, I'm very hopeful that this technology will be competitive with traditional solar panels in the future."
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