(introduction...)

Biomass is considered to be one of the key renewable energy resources of the future at both small- and large-scale levels (Johansson et al, 1992). It already supplies 14 per cent of the world's energy, and the many future projects being assessed, if implemented, could increase the role of biomass in the overall energy system. On average, biomass produces 38 per cent of the primary energy in developing countries (90 per cent in some countries), where it is the largest single energy source. Biomass energy is likely to remain an important global energy source in developing countries well into the next century. A number of developed countries also use biomass quite substantially, e.g., the United States of America which derives 4 per cent of its total energy from biomass (nearly as much as it derives from nuclear power), Sweden 14 per cent and Austria 10 per cent (Hall et al, 1992b).

Biomass is generally and wrongly regarded as a low-status fuel, and rarely finds its way into energy statistics. Nevertheless, biomass can lay claim to being considered as a renewable equivalent to fossil fuels. It offers considerable flexibility of fuel supply due to the range and diversity of fuels which can be produced (Jones, 1989). It can be converted into liquid and gaseous fuels and to electricity via gas turbines; it can also serve as a feedstock for direct combustion in modern devices, ranging from very-small-scale domestic boilers to multi-megawatt size power plants.

Biomass-energy systems can increase the energy available for economic development without contributing to the greenhouse effect since biomass is not a net emitter of CO₂ to the atmosphere when it is produced and used sustainably. It also has other benign environmental attributes such as lower sulphur and NO_X emissions and can help rehabilitate degraded lands. There is a growing recognition that the use of biomass energy in larger commercial systems based on sustainable, already accumulated resources and residues can help improve natural resource management (Hall and Rosillo-Calle, 1991).