5. Offshore Wind

5.1.1. History and Development (Level 2)

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From 1970 to 1990, mainly onshore wind turbines were being installed due to economic factors. The capacity was lower and the costs for offshore wind farms were high compared to onshore.  However, with the increase in size and efficiency of the wind turbines, in combination with advantages in offshore wind power, have reduced the costs of contracting and operating an offshore wind farm. One of the first wind farms to be constructed was Irene Vorrink, Netherlands in 1996, with 28 wind turbines of 16.8MW capacity. By 2002, the Horns Reef wind farm on the West Coast of Denmark had a total capacity of 160MW from 80 wind turbines.

Most wind turbine manufacturers are manufacturing wind turbines specially designed for offshore wind farms. In the past, manufacturers were designing wind turbines mainly for onshore deployment. Now most manufacturers design wind turbines purely for use in offshore wind farms.

One of the factors that influenced the development of offshore wind was the development in design which led to the introduction of new materials (e.g. carbon fibre, glass fibre) which enabled engineers to tackle issues such as the corrosive marine environment, or larger, stronger and lighter rotor blades.
Wind turbine manufacturers are testing larger wind turbines with high tip speeds in order to increase efficiency and produce more power. Multi-MW machines may be the future of offshore wind since the main barrier for offshore wind was the capital cost of the wind farm. By producing larger machines it is possible to reduce the capital cost as well as operation and maintenance cost per kWh.

Manufacturers are now developing direct drive generators. This removes the gearbox from the nacelle. This improves the efficiency of the wind turbines and their reliability, due to the absence the gearbox.

Inverters or other means of transforming power are now being used in order to allow the turbines to operate at variable speeds, harnessing more wind power and increasing runtime.

Improvements to foundation structures are subject to research in order to make deployment in deeper waters and difficult seabed conditions feasible.  Floating support is the main foundation structure under investigation.

llp logoThis project has been funded with support from the European Commission (EU Lifelong Learning Programme Agreement no LLP/LdV/TOI/2009/IRL – 515). This publication reflects the views only of the author, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

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