Power Plants: Solar Energy Harvested Directly for Sustainable Electricity

There's a whole new meaning to the term "power plant." Researchers are developing a new technology that allows them to harvest electricity directly from these green photosynthesizers. The technique could allow us to better harness solar energy for the use of sustainable electricity.

Plants are the champions of solar power. They can operate at nearly 100 percent quantum efficiency, which means that for every photon of sunlight a plant captures, it produces an equal number of electrons. Converting just a fraction of this energy into electricity would improve solar panels, which usually operate at efficiency levels between 12 and 17 percent.

In order to accomplish these astonishing feats of efficiency, plants undergo photosynthesis. At that time, the plant uses sunlight to split water atoms into hydrogen and oxygen which, in turn, produces electrons. These electrons then are used to create sugars that the plant uses for food. Now, researchers have developed a technique that utilizes this process that plants employ on a daily basis.

"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 Ramaraja Ramasamy, assistant professor in the UGA College of Engineering, in a news release. "This approach may one day transform our ability to generate cleaner power from sunlight using plant-based systems."

In order to actually interrupt photosynthesis and accomplish this feat, the researchers use a technique that separates out structures in the plant cell called thylakoids. These structures are responsible for capturing and storing energy from sunlight. By manipulating the proteins contained in the thylakoids, the researchers were able to interrupt the pathway along which electrons flow.

So what do they do with these modified thylakoids? The researchers then immobilized them on a specially designed backing of carbon nanotubes, which are cylindrical structures nearly 50,000 times finer than a human hair. These nanotubes acted as an electrical conductor and captured the electrons from the plant material.

Although the small-scale experiment resulted in electrical current levels that were two orders of magnitude larger than previously reported results in similar systems, the researchers caution that a lot more work needs to be done. The technique needs to be refined and scaled up before it can be used in commercial systems.

"In the near term, this technology might best be used for remote sensors or other portable electronic equipment that requires less power to run," said Ramasamy in a news release. "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 to traditional solar panels in the future."

The findings are published in the journal Energy & Environmental Science.