Photovoltaic cells can generate electricity without adding greenhouse gases to the atmosphere, but solar power is significantly more expensive than the electricity produced by coal- and gas-fired plants. To boost the competitiveness of solar energy, researchers have striven to make solar cells convert sunlight into electricity more efficiently.
Inspiration may come from the most basic scientific research. Investigators are starting to delve into the intricacies of photosynthesis, which converts sunlight into chemical energy with almost 100 percent efficiency. A group led by Gregory S. Engel, formerly at the University of California, Berkeley, and now at the University of Chicago, cooled a green sulfur bacterium to 77 kelvins (−321 degrees Fahrenheit) and then zapped it with ultrashort pulses from a laser, enabling the tracking of the energy flow through the bacterium's photosynthetic apparatus.