Using Bacteria to Convert Light to Energy

Researchers at the University of British Columbia have developed a solar cell that uses bacteria to convert light to energy even when the sun isn’t shining.

Solar cells are a good way to harvest alternative energy for electricity. But most conventional cells still have trouble converting solar energy when the skies are overcast. Researchers have of course been trying to overcome this problem. In a recent effort out of the University of British Columbia (UBC), for example, a team has used bacteria to convert light to energy to help cells generate electricity even when the sun isn’t shining. UBC’s Department of Chemical and Biological Engineering developed the cell, which is called a “biogenic” cell because it’s made from natural materials.

solar bacteria
Researchers at the University of British Columbia have found a cheap, sustainable way to build a solar cell using bacteria that converts light to energy. The cells they developed—called biogenic—can produce solar energy even when the sun isn’t shining. (Image source: Flickr/LillyAndersen)

Solar cells are the part of the solar panel that converts sunlight into an electrical current. Researchers have been experimenting with various materials to develop cells that are more eco-friendly and can work in places known for a lack of sunlight—something with which researchers in British Columbia are familiar, said Vikramaditya Yadav, a professor in UBC’s department of chemical and biological engineering, who led the project.

“Our solution to a uniquely B.C. problem is a significant step toward making solar energy more economical,” he said in a UBC news release. Previous efforts to build biogenic solar cells have focused on extracting the natural dye that bacteria use for photosynthesis, Yadav noted. However, this process is costly and complex, uses toxic solvents, and can cause the dye to degrade. To solve this problem, Yadav and his team devised a solution to leave the dye in the bacteria.

Specifically, they genetically engineered E. coli to produce large amounts of lycopene. Lycopene is found in fruits—namely, tomato and watermelon, giving them their color. It has been found to be effective at harvesting light for conversion to energy, researchers said.

The team coated the bacteria with a mineral that could act as a semiconductor and applied the mixture to a glass surface. In this system, the coated glass acts as an anode at one end of the cell, generating current density of 0.686 milliamps per square centimeter. This is an improvement on comparable solutions developed to date, which achieved 0.362 milliamps per square centimeter, Yadav said in the UBC release.

“We recorded the highest current density for a biogenic solar cell,” he said. “These hybrid materials that we are developing can be manufactured economically and sustainably and, with sufficient optimization, could perform at comparable efficiencies as conventional solar cells.” 

Moreover, the system worked as efficiently in dim light as in bright light, researchers said. The team published a paper about its work in the journal Small. The researchers see their innovation as a step forward toward broader adoption of solar panels in places where overcast skies are more common than sunny ones, such as British Columbia and northern Europe.

There are both advantages and challenges to the process developed by the team, Yadav acknowledged. One advantage is cost savings, making dye production about one-tenth of what it would be otherwise. A challenge, however, is to find a process that doesn’t kill the bacteria, Yadav said. If this could be done, the dye could be produced indefinitely.

In addition to solar panels, the process the team devised also could be used to develop biogenic materials for mining, deep-sea exploration, and other low-light environments.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.

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