Multi-megawatt wind turbines for offshore use: aspects of Life Cycle Assessment

Life Cycle Assessment (LCA) is an instrument to quantify environmental impacts of the entire energy supply chain. According to the LCA, an appropriate indicator system should comprise all steps of a system's life cycle: production, operational and disposal processes ("cradle-to-grave"). Cumulative Energy Demand (CED) might be seen as one part of LCA as far as the depletion of energy resources in the entire life cycle of any system is concerned. Since the methodology of finding CED is very close to that of LCA, it is suggested that CED can be used to indicate environmental impacts, especially in the case of power-producing systems. With regard to these aspects, two indicators are discussed in this paper: the CED and Energy Payback Time (EPT).Both terms, CED and EPT, have been calculated for a modern 5 MW wind energy converter (WEC) for offshore use. The CED of the WEC amounts to 85,000 GJ and the EPT is about 4 months.