In many ways, plants are the ultimate solar energy technology. Through photosynthesis, plants operate at nearly 100 percent quantum efficiency, meaning that for almost every photon of sunlight that's absorbed, they produce an equal number of electrons, so it's no surprise that for years scientists have been trying to either mimic that process through creating artificial leaves or have found ways to tap plants themselves as energy sources.
We've seen technologies where the electrons in the soil near plants' roots was are used to power a fuel cell and concepts for moss-powered lamps, but this discovery from University of Georgia researchers taps photosynthesis directly for producing electricity.
During photosynthesis, plants use sunlight to split water molecules into hydrogen and oxygen, which produces electrons. Those electrons help create sugars that plants use to fuel growth and reproduction.
"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.
The university explains the device:
Ramasamy's 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 immobilized on a specially designed backing of carbon nanotubes, cylindrical structures that are nearly 50,000 times finer than a human hair. The nanotubes act as an electrical conductor, capturing the electrons from the plant material and sending them along a wire.
In their experiments, the researchers found that the device delivers electrical current levels that are two orders of magnitude larger than those reported in similar systems. The team is currently working to stabilize and increase the power output of the device before commercialization can be considered, but they already see it as an energy source for low-power gadgets.
"In the near term, this technology might best be used for remote sensors or other portable electronic equipment that requires less power to run," Ramasamy 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 to traditional solar panels in the future."