Environmental impact efficiency in mussel cultivation

Recently, Iribarren et al. (in press) reported the results of a Life Cycle Assessment (LCA) for mussel cultivation in rafts in the northwest coast of Spain. A Life Cycle Inventory (LCI) and its corresponding Life Cycle Impact Assessment (LCIA) were carried out from the definition of a representative mussel culture vessel and an average raft. Since data were available on a whole sample of 83 mussel cultivation rafts, an LCI and an LCIA have been developed for each one separately and an efficiency analysis has been performed to identify those rafts that have the best practices and therefore can serve as benchmarks for the rest. A Slacks Based Measure (SBM) of environmental impact efficiency has been computed using Data Envelopment Analysis (DEA), taking into account the different inputs (as recorded in the LCI) as well as the characterization values for 10 environmental impact categories. An environmental impact efficiency score and reduction targets for both input consumption levels and environmental impacts have been computed. The estimated environmental impacts reduction potential for the whole sample ranges from 11% for terrestrial ecotoxicity to 67% for ozone layer depletion. This environmental performance assessment method is rather general and can be used in other LCA studies in order to identify operational inefficiencies and to reduce environmental impacts.