Energy use indicators in energy and life cycle assessments of biofuels: review and recommendations
Journal article, 2012
In this study we investigate how indicators for energy use are applied in a set of life cycle assessment
(LCA) and energy analysis case studies of biofuels. We found five inherently different types of indicators
to describe energy use: (1) fossil energy, (2) secondary energy, (3) cumulative energy demand, (4) net
energy balance, and (5) total extracted energy. It was also found that the examined reports and articles,
the choice of energy use indicator was seldom motivated or discussed in relation to other energy use
indicators. In order to investigate the differences between these indicators, they were applied to a case.
The life cycle energy use of palm oil methyl ester was calculated and reported using these five different
indicators for energy use, giving considerably different output results. This is in itself not unexpected, but
indicates the importance of clearly identifying, describing and motivating the choice of energy use
indicator. The indicators can all be useful in specific situations, depending on the goal and scope of the
individual study, but the choice of indicators need to be better reported and motivated than what is
generally done today.
palm oil methyl ester