Researchers from the University of British Columbia have come up with an ingenious solution to the problem of overcast skies for solar cells. They have constructed bacteria-powered solar cells that work efficiently in both dim and bright light.
The field of solar cells made of living things, so-called biogenic cells, is an intriguing one. Researchers are trying to copy photosynthesis, the natural way to get something out of sunlight. Previous attempts focused on extracting light-sensitive dye from genetically modified bacteria, but the process is costly, complex, and extracting the dye using solvents can often damage it.
To avoid this, the Canadian team used a different approach. They used E. coli genetically engineered to produce an abundance of lycopene, the molecule that gives tomatoes their orange/red tint. Lycopene is an excellent natural dye and is great at harvesting sunlight. Their coloring is also well-suited for a broader range of weather conditions.
As reported in the scientific journal Small, the team coated the E.coli in a mineral that can be used as a semiconductor. They then applied the bacteria/mineral mixture to a glass surface. Like that, they constructed their biogenic solar cell. Tests showed a current density of 0.686 milliamps per square centimeter, almost double the previous record for these type of cells.
“We recorded the highest current density for a biogenic solar cell,” project leader Professor Vikramaditya Yadav said in a statement. “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.”
Yadav's team believes that this approach is not only more efficient but also cheaper. He estimates that biogenic solar cells constructed this way are about one-tenth the cost of previous approaches. While this technology holds a lot of promise, it still has several hurdles to jump through. One issue is that bacteria don’t survive the process. If researchers can find a way to keep them alive, the bacteria would happily produce the dye indefinitely. That would make the process a lot more economical.
Such technology could be employed in areas of Canada and Northern Europe that often have cloudy skies. Environments such as mines, the deep-sea, and other low-light environments could also be up for consideration. Bacteria is not the only way to get solar power when it is cloudy – there's also a type of solar cell that can work in the rain.
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