Overplanting in offshore wind power plants in different regulatory regimes

Offshore wind power cost depends on many factors, of which some are controlled by the developer and some are determined by the regulatory authorities and others are outside control of both. A particular option is the overplanting of offshore wind farms with additional turbines relative to the tendered capacity.

There are two elements of savings related to this; the first is the increased use of connection capacity; the second can be an earlier support payment and higher availability. Both elements depend on the regulatory regime and this is analysed here by comparing UK and Danish conditions. Using a discounted cash flow model, regulatory regimes and geographic characteristics of offshore wind development areas are compared by their impact on the profitability of overplanting.

We find that UK conditions are favourable to the option of overplanting from the developer perspective, where the benefit of using the connection line more efficiently supports overplanting. In the Danish case the private incentive to overplant is absent due to the constraint of limiting subsidies for a given energy output.

When the cost of turbines decline relative to connection costs the overplanting tend to become more attractive and if the length of connections increases with for example far offshore projects in the North Sea the benefit of overplanting also rises. In a socioeconomic perspective the overplanting may also be an efficient strategy if the cost of the additional turbines is less than the value of the additional generation that can be served by the given cable.