Offshore Wind Farm Calculator
Estimates the total capital cost of an offshore wind farm based on turbine count, capacity, foundation type, water depth, and cable distance. Useful for early-stage feasibility and project finance screening.
About this calculator
Offshore wind farm costs break into four major components. Turbine cost = numberOfTurbines × turbineCapacity (kW) × $1,200/kW. Foundation cost = numberOfTurbines × unit foundation cost, where monopile foundations cost $2,000,000 each, jacket structures $3,000,000, and semi-submersible floaters $2,500,000. Export cable cost = distanceToShore (km) × $2,000,000/km. These three subtotals are summed and then multiplied by an installation complexity factor: installationMultiplier = 1 + (waterDepth / 50) + (distanceToShore / 100), which captures the higher marine logistics costs at greater depths and distances. The result is divided by 1,000,000 to express the total in millions of dollars. This model is suitable for order-of-magnitude budgeting; detailed engineering will refine each component.
How to use
Consider a farm with 20 turbines each rated at 8,000 kW, monopile foundations, 30 m water depth, and 50 km from shore. Turbine cost = 20 × 8,000 × 1,200 = $192,000,000. Foundation cost = 20 × $2,000,000 = $40,000,000. Cable cost = 50 × $2,000,000 = $100,000,000. Sum = $332,000,000. Installation multiplier = 1 + (30/50) + (50/100) = 1 + 0.6 + 0.5 = 2.1. Total = $332,000,000 × 2.1 / 1,000,000 = $697.2 million. This gives a ballpark capital expenditure for pre-feasibility planning.
Frequently asked questions
What foundation type is best for an offshore wind farm in shallow water?
Monopile foundations are the dominant choice for water depths of 0–40 metres because they are simple, well-understood, and relatively cheap to manufacture and install. Jacket (lattice) structures become competitive between 40–60 metres where monopiles would need to be excessively large. Beyond roughly 60 metres, floating semi-submersible or tension-leg platforms are typically required. Site-specific soil conditions, wave loading, and local fabrication capability also influence the final choice.
How does distance to shore affect offshore wind farm costs?
Distance to shore drives two major cost drivers: the length and cost of the subsea export cable, and the complexity of marine logistics for installation and maintenance. Cable costs scale roughly linearly with distance at around $1–3 million per kilometre for high-voltage DC links. Maintenance vessel transit times and fuel costs also rise with distance, increasing the operational expenditure over the project's life. Projects beyond 100 km from shore often require dedicated service operation vessels or offshore accommodation platforms.
What capacity factor can I expect from an offshore wind farm?
Offshore wind farms typically achieve capacity factors of 35–55%, compared with 25–40% for onshore sites, because offshore winds are stronger and steadier. Modern large-rotor turbines in prime North Sea locations have demonstrated capacity factors above 50%. Site-specific values depend on the Weibull wind speed distribution at hub height, turbine wake losses within the array, and availability. The capacity factor is essential for calculating annual energy production and the resulting levelised cost of energy (LCOE).