Bioenergy: Potentials and limitations

In this lecture we explain 1) the biochemical basis for photosynthesis and plant production and 2) the future demands on biomass for human use. Summing all physiological processes, the efficiency of converting solar energy into biomass is < 1.6% in the tropics, and between 0.4 and 0.8% for the temperate regions. In view of the present and future high demand on biomass for food, bioeconomics, fiber, construction material, only a relatively small fraction of plant production will be available for bioenergy. We estimate this fraction to be between 3 and 8% of the global energy demand by 2050. The contribution of bioenergy is at the higher end in tropical regions and in the less industrialized parts of the world, but may even be < 3% in industrialized nations.