47 offshore wind energy companies 1 47 offshore wind energy company 1 Allocative efficiency 1 Assessment of allocative efficiency Climate change 1 DEA models 1 Electricity-generation 1 Energy companies 1 Energy efficiency 1 European Countries 1 Fossil fuels 1 Gas emissions 1 Greenhouse gases 1 Input-oriented BCC DEA model 1 Nine european country 1 Off-shore wind energy 1 Offshore oil well production 1 Wind power 1 assessment of allocative efficiency 1 electricity generation 1 input-oriented BCC DEA model 1 nine European countries 1