ECN publication
Large-scale offshore wind energy: cost analysis and integration in the Dutch electricity market
Published by: Publication date:
ECN Policy Studies 1-2-1999
ECN report number: Document type:
ECN-I--99-003 ECN publication
Number of pages: Full text:
71 Download PDF  

The results of analysis of the construction and integration costs oflarge-scale offshore wind energy (OWE) farms in 2010 are presented. The integration of these farms (1 and 5 GW) in the Dutch electricity distribution system have been regarded against the background of a liberalised electricity market. A first step is taken for the determination of costs involved in solving integration problems. Three different types of foundations are examined: the mono-pile, the jacket and a new type of foundation: the concrete caisson pile: all single-turbine-single-support structures. For real offshore applications (>10 km offshore, at sea-depths >20 m, the concrete caisson pile is regarded as the most suitable. The price/power ratios of wind turbines are analysed. It is assumed that in 2010 turbines in the power range of 3-5 MW are available. The main calculations have been conducted for a 3 MW turbine. The main choice in electrical infrastructure is for AC or DC. Calculations show that at distances of 30 km offshore and more, the use of HVDC will result in higher initial costs but lower operating costs. The share of operating and maintenance (O&M) costs in the kWh cost price is approximately 3.3%. To be able to compare the two farms, a base case is derived with a construction time of 10 years for both. The energy yield is calculated for a wind regime offshore of 9.0 m/s annual mean wind speed. Per 3 MW turbine this results in an annual energy production of approximately 12 GWh. The total farm efficiency amounts to 82%, resulting in a total farm capacity factor of 38%. With a required internal rate of return of 15%, the kWh cost price amounts to 0.24 DFl and 0.21 DFl for the 1 GW and 5 GW farms respectively in the base case. The required internal rate of return has a large effect on the kWh cost price, followed by costs of subsystems. O&M costs have little effect on the cost price. Parameter studies show that a small cost reduction of 5% is possible when the total construction time is reduced to 7 years. Different financing options are regarded: a required internal rate of return of 10% or even 5% reduces the kWh cost price with 27% up to 50%. The effect of including the lifetimes of components in the price calculations is analysed, as well as the effect of considering the electrical grid as part of the public grid. With a maximum public effort the kWh cost price could be reduced to 8 ct. Integration of large-scale offshore wind energy in the distribution system can cause several technical and economic effects. These effects are caused by the variable wind supply, and can vary from insufficient grid connection capacity to the potential danger of a black out in the distribution system and large price fluctuations on the electricity market. To solve these problems, the application of backup power is introduced. Three types are regarded: an old coal plant, a new STEG plant, and hydroelectric power from Norway. Calculations show a moderate effect on the wind energy price due to backup power: this price increases with 6% up to 13%. In the backup power calculations an assumed market price is used, which makes it possible to predict a provisional value of an OWE green certificate. Finally, a comparison is made between the effect of possible technology improvements, public incentive effects and the effect of using backup power. This results in the conclusion that the feasibility of large-scale offshore wind energy depends more on public policy than on technology. 22 refs.

Back to List