Biomass and Bioenergy into the 21st Century

Bioenergy, the world's fourth most important energy resource, contributes about 50-55 exajoules (EJ) of primary energy (after petroleum, 119 EJ; coal, 86 EJ; and natural gas, 67 EJ). Industrial countries use biomass indirectly in industry, agriculture, forestry, and power generation at reasonable process efficiency. Conversely, two billion (2 X 10 9) people in developing countries use biomassdirectly, as solid fuel for their daily needs such as cooking and do so at low efficiency and often to the detriment of the environment. As incomes rise in developing countries, the trend is away from biomass towards purchased fuels that are efficient, clean, and convenient. However, such a trend replaces a renewable, carbon-neutral energy source by fossil fuels that have the potential to raiseglobal greenhouse-gas emissions by 10%. The challenge, therefore, is to find technologies that fit a social model of development that will facilitate the high-efficiency use of biomass as Bioenergy while reducing the environmental risks of biomass use and avoiding growth in fossil-fuel use. The future Bioenergy system must be predicated on sustainable biomass feedstocks supplied by agricultureand forestry, coupled with the management of biomass-derived material flows in society. The biomass must then undergo efficient transformation into clean secondary energy forms that are compatible with the much larger equipment and facilities base now provided by commercial fossil fuels. Significant components of future ststems are already developed or are being demonstrated. In most developingcountries agricultural yields are rising, thus providing both more foodstuffs and more crop residues that may be used for Bioenergy purposes. In parallel, the scale of food-processing mills and livestock operations is increasing, all of which increase the economic potential of converting biomass into compatible and efficient secondary energy forms such as methane, low- and medium-calorific-valuegases, and elictricity. Efficient technology to do this is being developed and applied worldwide.