Overcast skies have posed problems for gathering solar energy in places like British Columbia that frequently have clouds on the radar, so researchers from the University of British Columbia took a stab at making a cheap and sustainable way to build solar cells using bacteria to convert light into energy.
These cells generated a current stronger than any previously recorded from such a device and worked just as efficiently in dim lighting. With further development, these solar cells—called “biogenic” because they are made of living organisms—could become as efficient as the synthetic cells used in conventional solar panels.
“Our solution to a uniquely B.C. problem is a significant step toward making solar energy more economical,” says Vikramaditya Yadav, a professor in UBC’s department of chemical and biological engineering who led the project.
Solar cells are the building blocks of solar panels. They do the work of converting light into electrical current. Previous efforts to build biogenic solar cells have focused on extracting the natural dye that bacteria use for photosynthesis. It’s a costly and complex process that involves toxic solvents and can cause the dye to degrade.
Yadav’s solution was to leave the dye in the bacteria. They genetically engineered E. coli to produce large amounts of lycopene—a dye that gives tomatoes their red-orange colour and is particularly effective at harvesting light for conversion to energy. The researchers coated the bacteria with a mineral that could act as a semiconductor, and applied the mixture to a glass surface.
With the coated glass acting as an anode at one end of their cell, they generated a current density of 0.686 milliamps per square centimetre—an improvement on the 0.362 achieved by others in the field.
“We recorded the highest current density for a biogenic solar cell,” says Yadav. “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.”
The expenditure and cost savings are difficult to estimate according to Yadav, but he predicts the process will reduce the cost of dye production to one-tenth compared to the usual.