Sustainable harvest: Bioenergy potential from agroforestry and nitrogen-fixing wood crops in Africa

As the world’s population grows, the demand for food and fuel also keeps rising. Agroforestry systems, in which naturally fertilising nitrogen-fixing wood crops are planted alongside food crops, offer opportunities to boost fuel and food supplies simultaneously.

This study aims to estimate the potential for sustainable bioenergy production in Africa through such systems, based on the evaluation of yields for 15 short-rotation woody crops.

While location-specific information on those crops is largely unavailable in agricultural databases, yields can be estimated from soil and climate data.

• First, the constraint-free potential for biomass production for a given region, country or area is calculated by analysing biophysical processes such as photosynthesis and respiration, taking account of temperature, precipitation and solar irradiation data.
• The resulting biomass yield is then reduced to reflect climate and soil constraints to arrive at the net theoretical yield potential.
• Finally, the technical yield potential is calculated by excluding unsuitable land areas, such as cities, roads, industrial infrastructure, as well as undisturbed forest and environmentally protected areas.