RT Journal Article SR Electronic T1 Comparing Photosynthetic and Photovoltaic Efficiencies and Recognizing the Potential for Improvement JF Science JO Science FD American Association for the Advancement of Science SP 805 OP 809 DO 10.1126/science.1200165 VO 332 IS 6031 A1 Blankenship, Robert E. A1 Tiede, David M. A1 Barber, James A1 Brudvig, Gary W. A1 Fleming, Graham A1 Ghirardi, Maria A1 Gunner, M. R. A1 Junge, Wolfgang A1 Kramer, David M. A1 Melis, Anastasios A1 Moore, Thomas A. A1 Moser, Christopher C. A1 Nocera, Daniel G. A1 Nozik, Arthur J. A1 Ort, Donald R. A1 Parson, William W. A1 Prince, Roger C. A1 Sayre, Richard T. YR 2011 UL http://science.sciencemag.org/content/332/6031/805.abstract AB Comparing photosynthetic and photovoltaic efficiencies is not a simple issue. Although both processes harvest the energy in sunlight, they operate in distinctly different ways and produce different types of products: biomass or chemical fuels in the case of natural photosynthesis and nonstored electrical current in the case of photovoltaics. In order to find common ground for evaluating energy-conversion efficiency, we compare natural photosynthesis with present technologies for photovoltaic-driven electrolysis of water to produce hydrogen. Photovoltaic-driven electrolysis is the more efficient process when measured on an annual basis, yet short-term yields for photosynthetic conversion under optimal conditions come within a factor of 2 or 3 of the photovoltaic benchmark. We consider opportunities in which the frontiers of synthetic biology might be used to enhance natural photosynthesis for improved solar energy conversion efficiency.