Analysis of energy comparison for crops in European agricultural systems

The energy input and output of three energy crop chains in Europe has been reviewed. The three chains are: bio-oil production from rape, soybean, or sunflower; ethanol production from cereal and sugar beet; and the use of herbaceous lignocellulosics as raw fiber biomass. The energy input measurements are taken from the literature in terms of the average, minimum, and maximum for current agricultural practice. The bio-oil and ethanol chains are well defined and use efficient and mature technology, while the herbaceous lignocellulosic chains is still under development. The yield of bioenergy is limited by land and it is not directly correlated with inputs level; for maximum gain the inputs must be minimized. There is considerable margin for improvement in many areas with low yields. While the study does not address social and economic issues, it is clear that many of the species considered are multifunctional, and the maximizing of the economic opportunity will depend also on the exploitation of co-and by-products. (C) 2003 Elsevier Ltd. All rights reserved.