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08 July 2010

Michael Blunk: "These are the challenges to be faced by the wind power of the future"

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Michael Blunk works on the wind power of the future. He talks about the competitiveness of wind power, challenges and possible solutions 

Engineer and project manager Michael Blunk, Fraunhofer Institute for Wind Energy and Energy System Technology IWES, is one of the experts in the European project UpWind. The aim is to develop a new type of turbine. This turbine will be much larger than the ones on the market to significantly contribute wind power to the world’s grids.

What are you focusing on right now in your research?
Within the UpWind project we are working on how to simulate and predict the behaviour of offshore wind turbine support structure accurately. For example, it is important to consider realistic joint flexibilities.

What are the biggest challenges when designing very large wind turbines (8-10MW)?
On the one hand, we want to have increased reliability of the turbines, making them more robust. On the other hand we want to make them cheaper. Wind turbines are still a low budget technology. The price pressure is very strong compared to any other industry. For example, if you design an airplane, the money doesn’t matter as much as in the wind turbine area. It is a relatively new technology. The procedures of designing turbines will change and the knowledge will increase. There is still a lot to find out.

When will wind power be competitive with other energy sources?
It already is. If you take all cost into account, the long term of CO2 emissions, insurance costs and probable failure of nuclear power plants, it is cheaper today. We usually ask, what’s the cost of not doing it? If we continue to produce CO2 the cost is immense. The development of nuclear power plants has extensively received federal support. Also, if the operators would be forced to have realistic insurances and to contribute to the final storage, nuclear power would be more expensive. However, you don’t have one price for wind power anyway, the price goes down near the shore in Germany and up in the middle of the country, where it is less windy.

What are the disadvantages of wind power?
Wind power generation is more difficult to predict compared to fossil fuels and coal. The power produced is not stable. In addition, you see the turbines, but you don’t see CO2. However, intelligent grid operation including the consumer and storage systems as well as a growing energy sense of the consumer will overcome these disadvantages.

What impacts the competitiveness of wind power?
By normal improvements wind power will become very competitive. The price of wind power will decrease, while the price for fossil fuels will increase. In order to keep at eye level with international competitors, innovation is the driving force. New turbine concepts for the offshore market emerge and influence also the development of innovative turbines. This is driven by the demand for turbines that are reliable, light and show high performance. One very big problem is the grids, but the grids need political solutions rather than technical solutions. The grids are designed for big nuclear power plants and not for decentralised wind turbines. The grids need to be adapted.

What is being developed in the wind turbines area at the moment?
Offshore turbines are really in the infant stage. In Germany we have exactly 12. We go offshore because there is a more constant wind at a higher mean speed available and we don’t have problems with people who live near the wind turbines. However, it is more cost-efficient to build the turbines onshore where they are easier to maintain. Ways to reduce the costs of offshore turbines are to develop lighter and simpler drive trains as well as to reduce the loads that wind and waves induce on the turbine. Another promising way is to make them float. When we go offshore the water gets deeper, 10 to 20 meters to the bottom is not a problem. But when the depth becomes more than 100 meters, floating structures could be the answer.
Steal constructions with lengths of more than 100 meters are too expensive. It is difficult to construct such turbines because the entire system is very dynamic. At the moment, there is no software available that considers the entire aero- and wave dynamics. But we have already made progress by using a Finite Element beam approach to model the support structure of offshore wind energy turbines. Modelling with any branched support structures became possible without simplifications such as modal reduction of components. The acting wind loads can be generated from 3-dimensional turbulent wind fields. The aero-elastic simulation considers deterministic or stochastic hydrodynamic loads as well as any non-linear soil/seabed characteristics. Together with our partners from the industry we are facing the next steps to come closer to simulation of realistic loads.
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