Lifetime extension and Repowering of Offshore Wind Farm – Financial viability, GHG reduction, and Monopile reinforcement.

Abstract

Offshore wind is the fastest-growing sustainable energy source gradually replacing fossil fuels. Aside from addressing arising challenges like logistic, infrastructure, and recycling, there is the challenge of making the right end-of-life (EoL) decision. The discussion is whether these offshore wind turbines can last longer than their 20 to 25-year design life. At the end of the technical lifetime or economic lifecycle, their lifetime has to be extended, repowered or decommissioned. The decision to extend the lifetime or repower an offshore wind farm depends on several factors such as site conditions, regulations, technology, and profitability. The core of this thesis is to compare several EoL options in terms of energy production costs and GHG reduction. The thesis includes a case study on Horns Rev 1 OWF, in which four distinct EoL scenarios are compared in terms of energy production cost and GHG reduction using technical and financial performance. RETScreen Expert software was used to analyse the feasibility of all scenarios. The result of the case study shows that lifetime extension is more financially viable and has the highest gross annual GHG reduction. Next in line was partial repowering. The optimised design shows theoretically that an installed monopile can be reinforced to carry a bigger turbine load by distributing the load to additional piles.