Comparative analysis of environmental assessment methods: application to lead battery cases
Résumé
The objective of this study is to compare different methods of assessing environmental impacts in order to highlight their complementarities. Bouman et al. (1999) have used SFA (Substance Flow Analysis), LCA (Life Cycle Assessment) and Partial Equilibrium (which is an economic approach) methods by applying them on a highly simplified comparison of small all-lead batteries and hypothetical all-plastic ones. Following this idea, the objective of this study is to perform and compare SFA, LCA and an economic analysis on the more realistic cases of lead-acid batteries (PbA) and nickel-metal hydride batteries (Ni-MH) for electric vehicles. The SFA allowed us to identify low lead emissions into the environment at production and recycling stages of PbA batteries, whereas relatively large nickel emissions at the manufacturing step of Ni-MH batteries are observed. According to LCA, Ni-MH primary batteries (without recycled materials) have more impacts on the environment than primary PbA batteries, but this result is reversed when the batteries are made from recycled lead or nickel. The economic analysis showed that Ni-MH batteries are much more expensive than PbA batteries but if the decrease in price due to the scale effect is considered, the difference will decrease when the market will grow up. A multiobjective optimization finally proved that the best solution is to keep both battery technologies: it is therefore interesting to use not merely one method, but to compare several strategies.