Floating Offshore Wind Foundation Selection Matrix (TLP vs. SPAR vs. Semi)

Floating offshore wind foundations must provide stable platform support for turbines in water depths beyond the economic reach of fixed-bottom structures (typically >60 m). The TLP relies on vertical taut tendons anchored to the seabed to minimize heave, pitch, and roll through high pretension; it offers excellent motion control but demands high-strength anchors and precise seabed conditions. The SPAR buoyancy-dominated design uses a deep-draft, slender cylindrical hull with ballast to achieve inherent stability via low center of gravity and high metacentric height; it excels in deepwater (>1,000 m) and low-wind-shear environments but requires large-draft transport and dry-dock integration. The Semi-submersible features multiple surface-piercing columns connected by submerged pontoons, deriving stability from waterplane area and column spacing; it offers modular construction, shallow draft for port handling, and adaptability to moderate depths (100–600 m), though it exhibits larger low-frequency motions requiring advanced control strategies. Selection hinges on multidimensional analysis: wave climate (significant wave height, period), current profiles, seabed soil properties (for anchor design), port infrastructure (crane capacity, draft), supply chain maturity, and lifecycle cost drivers—including fabrication, installation, maintenance, and decommissioning. Recent industry trends show Semi-submersibles dominating near-term deployments due to supply chain readiness, while SPARs gain traction in ultra-deepwater U.S. West Coast and Japanese projects, and TLPs are undergoing pilot validation for high-wind, low-wave sites with favorable geotechnical conditions.