Another wind

According to the Energy Agreement, wind farms at sea will become the most important energy source in the Netherlands. Professor Simon Watson (faculty of Aerospace Engineering), the new director of the Delft research institute for wind energy, DUWIND, outlined the new research agenda in his inaugural address.

The wind blows in an entirely different direction for Watson than it did for his predecessor, Gijs van Kuik. Van Kuik embodied the optimism of the 1970s, but that did not change the fact that he had to fight his entire life to convince people of the importance of wind energy to our energy supply. Only after his retirement did the government issue a call for tenders for the first large wind farms at sea.

The National Energy Agreement now stipulates that in five years’ time there must be 4,450 MW of capacity in the North Sea. At the moment capacity is at 957 MW, less than a quarter of that amount. Offshore wind will therefore have to grow at an unprecedented rate over the next few years, and this expansion is likely to continue tenfold through 2040. The rapid growth of wind energy raises many research questions. 

  • With a larger role for wind energy comes an increase in the need for detailed wind forecasts. A detailed network of sensors linked to increasingly fine-tuned forecasting programmes, such as Professor Herman Russchenberg’s (CEG) Ruisdael Observatory is equipped with, can improve predictions on how many megawatt hours can be produced by wind energy.
  • Modern wind turbines are heavy-duty structures that are designed to withstand varying turbulence loads. Professor Jan Willem van Wingerden (3mE) is working on blades that can respond to variations in the wind. These active blades would experience 30% less load and could therefore be made lighter or longer.
  • Encroaching wind farms are bad news for porpoises and seals. Reports about the environmental effects state that the driving of ever-larger steel pipes could cause temporary or permanent hearing loss. Vibrating foundations seems to cause less disturbance, but it is unclear if those foundations retain their strength. Researchers in the group led by Professor Andrei Metrikine (CEG) are investigating this as part of the GROW consortium.
  • Replacing a gear box at 150 metres above sea level is a complicated process that can cause nightmares for service departments. Watson has found that electrical failures are the most common, but mechanical failures require more repair time. By embedding software that analyses the electrical output of generators, developing malfunctions can be detected earlier. 
  • Wind turbines in an offshore wind farm can influence other windmills. The wind speed behind a turbine is not only slower, but also more variable. This results in less revenue – a matter of a few per cent, according to Watson – and more stress on blades and structures. One of van Wingerden’s doctoral candidates is investigating how a wind turbine can reduce or adjust its wake so that downwind turbines experience fewer problems. 
  • If you generate hundreds or thousands of megawatts of electricity in the North Sea, you need a good plan to incorporate that power into the electricity networks of neighbouring countries. The international networks and energy markets of the future will regularly have to deal with energy surpluses such as those that have so far mainly occurred in Germany. During his inaugural address, Watson emphasised the importance of large-scale storage and mentioned the Battolyser, designed by Professor Fokke Mulder (Applied Sciences), which combines battery operation with hydrogen production. In addition, according to Watson, we will also not be able to avoid making demand flexible. In other words: we must use power when it is abundantly available. 

Some 30 doctoral candidates are currently working on this and other questions under the umbrella of the Dutch National Doctoral College in Offshore Renewable Energy and PhD@sea. They are located within five faculties: AE (15), CEG (3), EEMCS (5), 3mE (4) and TPM (2).  

Photo (c) Eneco
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