Energy from agricultural residues and consequences for land requirements for food production

Using biomass as an energy source is often mentioned as an option to mitigate the enhancing greenhouse effect. Biomass for energy purposes can be obtained from dedicated energy crops and/or from agricultural residues. The available amount of residues is large and suggests a significant energy potential. However, most of these residues are currently used as livestock feed, which forms the basis for important proteins in the human diet. Use of residues for energy generation is likely to affect the supply of proteins in human diet, and therefore adaptations in the food system are required to compensate for this loss. The purpose of this paper is to indicate the adaptations required in the food system, if agricultural residues are used for energy generation instead of livestock feed. For this, three production systems that generate both protein and energy are compared. The difference consists in their production routes followed: (i) energy crops for energy and agricultural residues for feed, (ii) use of agricultural residues for energy and growing protein crops (e.g. beans and pulses) for a vegetarian human diet and (iii) use of agricultural residues for energy and growing feed crops (e.g. wheat) for livestock. The land requirements of the three systems are calculated. The system in which energy crops were used for energy generation and agricultural residues as feed required the smallest amount of land. From a land use perspective, therefore, it is better to produce energy from dedicated energy crops and use agricultural residues for livestock feed. (C) 2007 Elsevier Ltd. All rights reserved.