Assessing the influence of lightweight generators on substructure cost and levelized cost of energy: a techno-economic model for large offshore wind turbines

Abstract

It is expected that lightweight drive train systems for large wind turbines can reduce overall levelized cost of energy (LCOE) compared to conventional designs, particularly through a less robust and therefore lower-cost turbine substructure. Representing a major share of drive train mass, the focus of mass reduction efforts concentrate on the generator. In order to assess the influence of specific lightweight generator designs on overall LCOE, a techno-economic software tool was created which feeds generator mass into the LCOE calculation through the design and capital expenditure (CAPEX) calculation of an appropriate wind turbine substructure. A case study was carried out, comparing a direct drive design featuring a permanent magnet generator with ring architecture and large diameter—resulting in significantly low mass and low CAPEX—to a reference turbine with conventional drive train design. The results show that a relevant LCOE reduction could be achieved, but generator mass reduction and substructure mass and consequently CAPEX reduction are highly disproportionate due to technical substructure design constraints. It is indicated that the assessed lightweight design has a high potential to economize on lightweight design decisions to reduce its CAPEX and in consequence overall LCOE even further.