Chapter 9 - Offshore Wind

Abstract

The wind regime offshore is better for wind power generation than onshore and gaining authorization for offshore construction is often easier, but the cost of building offshore is much higher than onshore. Most offshore wind farms are in European waters. The technology for offshore wind turbines is the same as for large onshore wind turbines but sizes tend to be larger because it is easier to erect larger wind turbines offshore and because economics favor larger turbines. Foundations for offshore wind turbines are more complex than onshore. Some use gravity bases but the most common is the monopile foundation. In deeper water some tripod or multipile structures have been used. Meanwhile the development of floating wind turbine supports will eventually enable much deeper water sites to be utilized. Bringing power ashore from an offshore wind site is expensive. To reduce costs consideration is being given to the development of offshore grids that can collect power from a number of wind farms and bring it ashore at several key interconnections. For operation far offshore, a grid will have to be based on high voltage direct current technology to avoid reactive losses or high compensation costs.