Abstract
This study employs a prospective life cycle assessment (pLCA) to evaluate the environmental impacts of two drivetrain configurations, direct drive (DD) and medium-speed (MS), at the wind farm level across the entire life cycle. The assessment considers how environmental impacts evolve in the future, reflecting projected changes in macroeconomic indicators and climate targets. The DD configuration shows higher impacts in the material extraction and production phase due to its reliance on critical metals and rare earth elements, which is also offset in the long term through recycling benefits at the end-of-life (EOL) stage. In contrast, the MS configuration has greater emissions during operations, requiring more drivetrain-related maintenance and component replacements, while the DD configuration benefits from lower maintenance demands. The total climate change impact for DD is 6.8 g CO2-eq/kWh, while for MS, it is slightly higher at 7.1 g CO2-eq/kWh. A comparison of static LCA and pLCA highlights key differences, particularly in the operational phase, where pLCA indicates lower emissions due to anticipated improvements in supply chains, such as greater use of renewable-powered refineries for vessel fuel. However, pLCA accounts for recycling benefits over time rather than immediately, leading to lower avoided burdens at EOL compared to static LCA. Beyond climate change, metal depletion is a key impact category, with DD showing a 12% higher impact due to its reliance on copper and rare earth elements, while MS exhibits higher emissions from fuel-intensive operations. This study demonstrates the prospective approach for conducting LCA, emphasizing the importance of integrating future technologies and processes in environmental impact assessments for offshore wind.