Facts: The technology of wind energy and offshore operations

The evolution of wind power

In the 1970s and 1980s, attempts to rapidly increase the size of wind farms led to failures (Growian).

In contrast, businesses that were mainly small and medium-sized, gradually pushing ahead the development of wind energy, were successful.
In 1990, the average capacity of a wind turbine was about 150kW. This capacity would increase to more than 1 MW per turbine by 2000. Good operating experience has already been gained with 2 - 2.5 MW turbines and 5 MW turbines are in development.

Reliability will be decisive for offshore wind farms

The year-round availability of offshore wind turbines will have a decisive effect on the economic viability of wind farms. Since maintenance and repairs at sea are heavily dependent on weather conditions, availability will play a much larger role offshore than it does onshore. Poor weather conditions and rough seas could otherwise lead to weeks of standstill.

Development needed

Offshore turbines will have to be much larger than their counterparts on land to compensate for the sizeable additional costs of laying foundations and the grid connection, and thus to enable economical operations. Most businesses planning to construct facilities in Germany's exclusive economic zone therefore intend to install 5 MW turbines. However, such turbines will not complete trial operations for several years. They must first be adapted to marine conditions and prove their reliability on land. Only then can they be used commercially.

Moreover, to develop the use of offshore wind energy, it will be necessary to combine wind technology with the classic offshore foundation technology used in offshore oil and natural gas extraction. But this process should also proceed carefully and gradually.

Caution is advisable

In the face of these new and severe demands, wind farm planners and turbine manufacturers will need to learn significantly. An overhasty expansion of offshore wind utilisation runs the danger of encountering considerable infrastructural, economic and technological setbacks. Planners and manufacturers alike will have to gather experience with proven wind turbines as well as with the grid connections and foundations. To facilitate this process, dena believes it is absolutely necessary to identify pilot areas that are in relatively shallow waters (not more than 30 meters deep) and relatively close to the coast (within 50 kilometres).