of solar fuel production through artificial photosynthesis include: The solar energy can be immediately converted and stored. In photovoltaic cells, sunlight is converted into electricity and then converted again into chemical energy for storage, with some necessary losses of energy associated with the second conversion. The byproducts of these reactions are environmentally friendly. Artificially photosynthesized fuel would be a carbon-neutral source of energy, which could be used for transportation or homes. Disadvantages include: Materials used for artificial photosynthesis often corrode in water, so they may be less stable than photovoltaics over long periods of time. Most hydrogen catalysts are very sensitive to oxygen, being inactivated or degraded in its presence; also, photodamage may occur over time. The cost is not (yet) advantageous enough to compete with fossil fuels as a commercially viable source of energy. A concern usually addressed in catalyst design is efficiency, in particular how much of the incident light can be used in a system in practice. This is comparable with photosynthetic efficiency, where light-to-chemical-energy conversion is measured. Photosynthetic organisms are able to collect about 50% of incident solar radiation, however the theoretical limit of photosynthetic efficiency is 4.6 and 6.0% for C3 and C4 plants respectively. In reality, the efficiency of photosynthesis is much lower and is usually below 1%, with some exceptions such as sugarcane in tropical climate. In contrast, the highest reported efficiency for artificial photosynthesis lab prototypes is 22.4%. However, plants are efficient in using CO2 at atmospheric concentrations, something that artificial catalysts still cannot perform. See also Bacteriorhodopsin ATP synthase Photoelectrochemistry AlgaePARC Carbon footprint Fuel cell Hydrogen economy List of emerging technologies Metabolic engineering Photosensitizer References External links Engineering light-activated metalloproteins to split water at Australia National University Daniel Nocera describes new process for storing solar energy at Massachusetts Institute of Technology. Paul Alivisatos on Artificial Photosynthesis at Lawrence Berkeley National Laboratory Nanocapsules for artificial photosynthesis a Nanowerk News article MIT Solar Revolution Project Hydrogen production Photochemistry Renewable energy technology Fuel production Emerging technologies