Herbaceous energy crop development: recent progress and future prospects.

Oil prices and government mandates have catalyzed rapid growth of nonfossil transportation fuels in recent years, with a large focus on ethanol from energy crops, but the food crops used as first-generation energy crops today are not optimized for this purpose. We show that the theoretical efficiency of conversion of whole spectrum solar energy into biomass is 4.6-6%, depending on plant type, and the best year-long efficiencies realized are about 3%. The average leaf is as effective as the best PV solar cells in transducing solar energy to charge separation (ca. 37%). In photosynthesis, most of the energy that is lost is dissipated as heat during synthesis of biomass. Unlike photovoltaic (PV) cells this energetic cost supports the construction, maintenance, and replacement of the system, which is achieved autonomously as the plant grows and re-grows. Advances in plant genomics are being applied to plant breeding, thereby enabling rapid development of next-generation energy crops that capitalize on theoretical efficiencies while maintaining environmental and economic integrity.

Safe and acceptable strategies for producing foreign molecules in plants.

The ability to express foreign genes using transgenic technologies has opened up options for producing large quantities of commercially important industrial or pharmaceutical products in plants. These technologies have made it possible to use well-developed systems of commercial agriculture that were developed principally to produce raw material for large-scale food, feed or processing applications for the production of foreign molecules. The possibility of the novel industrial or pharmaceutical molecules produced in such plants, or components derived from them, contaminating the environment and food chains has become especially controversial. This potential contamination has prompted detailed consideration of how such crops and the molecules that they produce can be effectively isolated and contained. First, the crop can be completely isolated physically from its food or feed counterpart during every aspect of its development and commercialization. Second, genetic isolation systems or genetic barriers that prevent normal reproduction can be used to reduce the likelihood of the industrial or pharmaceutical crop entering the food chain.