Developing Offshore Wind Farms in Aotearoa New Zealand: An Analysis of Life Cycle Carbon Emissions, Materials and Energy Implications

Abstract

The technologies for offshore wind projects have evolved to larger wind turbines, which provide enhanced efficiency and power generation. Permanent magnet synchronous generators with a direct drive design have enabled these advancements. In recognition of deeper insights into their implications, this paper addresses the need for updated life cycle assessments (LCAs) for offshore wind systems adopting large wind turbines. An LCA for an offshore wind project in Aotearoa New Zealand employing 15-MW turbines, with a total capacity of 1 GW, was undertaken. Different approaches to model the operation of the offshore wind farm were compared. The results indicate a carbon footprint of between 18.4 and 25.2 gCO2eq/kWh, a greenhouse gas payback time ranging from 2.8 to 3.9 years for avoided combined cycle gas turbines and an energy payback time of up to a year. The outcomes underscore the environmental efficiency of the system and position it as an option ideal for facilitating the energy transition. Notably, the manufacturing of components is the primary contributor to the carbon footprint, highlighting a critical area for targeted environmental mitigation strategies in the life cycles of offshore wind energy systems.