Issues to consider, existing tools and constraints in biofuels sustainability assessments

Biofuels world production has increased sharply in recent years. Oil reserves depletion, the oil high price and the confidence in biofuels carbon neutrality are the main causes of this phenomenon. However, claims related to the negative consequences of biofuel programs are frequent; mainly those related to the biofuels/food competition and sustainability. This paper aims to contribute for the development of a framework for sustainability indicators as a tool for performance assessment. The most used indicators to measure the biofuels sustainability are: Life Cycle Energy Balance (LCEB), quantity of fossil energy substituted per hectare, co-product energy allocation, life cycle carbon balance and changes in soil utilization. On the other hand, existing assessment tools, such as Life Cycle Assessment (LCA) and Integrated Environmental Assessment (IEA), are compared emphasizing their advantages and disadvantages. Main constraints related to the studied frontiers, as well as the lack of reliable data and their effects are also discussed. Discussions are held on the basis of real life cycle studies carried out by the authors about palm oil biodiesel and different alternatives for the stillage treatment and disposal. Finally, suggestions and recommendations are made to improve existing methodologies for biofuels sustainability evaluation, all this from a south perspective. (C) 2010 Elsevier Ltd. All rights reserved.