Limitations and prospects of natural photosynthesis for bioenergy production.

Solar energy is clearly a major future source of energy for humans. While solar photovoltaic and thermal harvesting are attractive there will be a need for biofuels to replace fossil fuels. Natural photosynthesis offers a means to do this, but photosynthesis is inherently inefficient. Terrestrial plants have already been used as a source of biofuels and this use will increase in the future, despite a number of attendant problems. Microalgae as a source of biofuels have to be technically proven and artificial photosynthesis/biohydrogen production lies further into the future. Consideration of these approaches must be weighed against (i) crop production in a hungry, as well as a fuel-hungry, world and (ii) the need to sustain biodiversity.