Material and carbon intensity of offshore wind foundations for sustainable infrastructure

Offshore wind is central to global decarbonisation, yet the lifecycle impacts of turbine foundations remain insufficiently quantified. This study develops a systematic comparative framework to assess seven foundation types (i.e., monopile, jacket, tripod, gravity-based, semi-submersible, tension-leg platform, and spar) using data from 62 projects. We integrate material intensity, regional carbon factors, operational lifespans, and capacity factors to estimate embodied carbon emissions per unit of installed capacity and per unit of electricity generated. The life cycle inventory is compiled across key upstream and project stages, including material production (steel and cement) and end-of-life management. The analysis highlights a core design duality: steel-dominant foundations are typically more recyclable and support higher end-of-life recovery, while concrete-intensive foundations can be harder to recycle yet may offer longer technical lifetimes, creating trade-offs in lifecycle carbon intensity. Fixed-bottom foundations exhibit the lowest carbon intensities, averaging 2.2–2.5 gCO₂/kWh over a 25-year lifespan, with gravity-based foundations achieving 1.2 gCO₂/kWh when operating for 50 years. Floating designs show higher values, ranging from 4.7–6.4 gCO₂/kWh over 25 years, though longer lifespans can reduce it to 2.4–3.2 gCO₂/kWh. Adoption of sustainable manufacturing practices, including low-carbon steel and green cement, could cut foundation-related carbon emissions by 66 % to 76 %. At the terawatt scale of planned offshore deployment by 2050, foundation design, material choices, and end-of-life strategies will be decisive in ensuring offshore wind aligns with global net-zero targets.