ABSTRACT
Biomass energy in its traditional sense is vegetation (mostly woody plants but also sun-dried grasses) and, extrapolating further up the food chain, animal manure, combusted as a direct source of heat for cooking and heating. For commercial purposes, wood was also the major energy substrate before the rapid development of coal extraction in the late eighteenth and nineteenth centuries ushered in the Industrial Revolution. Even in the early twenty- rst century, traditional biomass still accounts for 7% of the total global energy demand, amounting to 765 million tonnes of oil equivalents (Mtoe) in 2002, and this is projected to increase to 907 Mtoe by 2030.1 Especially in Sub-Saharan Africa, much of this primary energy demand is unsustainable, as population growth outstrips the biological capacity of increasingly drought-and crisis-damaged ecosystems to replace continuous harvestings of rewood.
