The researchers determined that when chlorophyll molecules in green plants take in more solar energy than they are able to immediately use, molecules of zeaxanthin, a member of the carotenoid family of pigment molecules, carry away the excess energy.
This study was led by Graham Fleming, director of Berkeley Lab's Physical Biosciences Division and a chemistry professor with UC Berkeley, and Kris Niyogi, who also holds joint appointments with Berkeley Lab and UC Berkeley. Its results are reported in the January 21, 2005 issue of the journal Science. Co-authoring the paper with Fleming and Niyogi were Nancy Holt, plus Donatas Zigmantas, Leonas Valkunas and Xiao-Ping Li.
Through photosynthesis, green plants are able to harvest energy from sunlight and convert it to chemical energy at an energy transfer efficiency rate of approximately 97 percent. If scientists can create artificial versions of photosynthesis, the dream of solar power as a clean, efficient and sustainable source of energy for humanity could be realized.
A potential pitfall for any sunlight-harvesting system is that if the system becomes overloaded with absorbed energy, it will likely suffer some form of damage. Plants solve this problem on a daily basis with a photo-protective mechanism called feedback de-excitation quenching. Excess energy, detected by changes in pH levels (the feedback mechanism), is safely dissipated from one molecular system to another, where it can then be routed down relatively harmless chemical reaction pathways.