Economic benefits of hydraulic-electric hybrid wind turbines

Abstract

As wind turbines increase to multi-megawatt power ratings and move offshore, the costs associated with maintenance, support structure and infrastructure will escalate. The proposed hydraulic-electric hybrid turbine design with compressed air energy storage (CAES) can meet these concerns. This study considers the cost implications of this design, both with and without CAES. The model uses the National Renewable Energy Laboratory 5 MW offshore reference turbine as a baseline and is validated with existing correlations and industry data. The results show that a hybrid system without CAES eliminates the gearbox and reduces tower mass by 36%, leading to capital expenditure (CAPEX) reduction of 6%. Adding CAES substantially reduces generator size by 65% and electrical infrastructure by 55%, yielding a total CAPEX reduction of 17%, but also reducing total energy output by about 10%. Additional cost reductions are expected but need to be quantified with a full lifecycle cost assessment.