As the concept of wind power is still young, it is in the interest of the industry to explore new ways to improve efficiency. While experts are currently working on ways to optimise existing turbine designs to capture the most energy, various innovators and companies are focussing their brain power on entirely new ways of harnessing the wind.
At Risø National Laboratory near Roskilde in Denmark, News from Vattenfall meets Kenneth Thomsen, a section manager at the Department of Wind Energy of the Technical University of Denmark (DTU). The walls are decorated with photographs of turbines from past decades, demonstrating the journey wind power has taken since the 1970s. Immediately, Thomsen starts talking about the early turbines and how Denmark’s leading position in wind power is due to political backing, world-class research and an innovative industry.
“In Denmark, wind power has developed through evolution, rather than revolution. We took small steps and developed locally through organic growth to the present huge turbine manufacturers. The growth spurt came when the market was ready,” Thomsen says.
In cooperation with DTU , the wind turbine manufacturer Vestas has installed a concept demonstrator at Risø Test Centre to test the technical feasibility of operating and controlling a multi-rotor turbine. The turbine has four rotors instead of one, each with a diameter of 29 metres, and is mounted on two arms attached to the same tower. Each of the two arms can yaw independently in the wind.
“The concept is well known from old literature, but we’ve never seen a turbine like this in real life before, so there is still a lot for us to learn. For example, when four rotors operate so close to each other, it will influence both the overall performance and that of each rotor. Another problem is learning how to control four rotors. If one stops, should the opposite rotor then be shut down or kept running? The data will be valuable for both Vestas and also for us to use when developing future models,” Thomsen says.
The project is still rather new, with the turbine erected in April 2016. Many new load and control features need to be developed, tested and validated in order to assess the technical and commercial feasibility of the concept. Only after a successful demonstration will Vestas know more about the possible use of the technology. Ultimately, the goal is to assess whether it is possible to build an even more cost-efficient turbine by challenging the scaling rules.
“The concrete business case is not for us to decide on or judge. We don’t make products, we deliver knowledge for the industry to make a qualified decision,” Thomsen explains.
Beyond the three-bladed turbine
Looking at some of the more innovative future technologies being tested around the world, it is clear that there are many ways to generate wind power.
However, not all prototypes may be cost-effective or feasible. -Thomsen embraces innovation and welcomes the fact that some people are pondering new and different solutions. And at DTU, staff take their time to meet with inventors and provide feedback on innovative and different solutions.
“I see it as our responsibility to society, as there are not many places to go. We try to keep an open mind and not be too influenced by traditional industry, so we are also a hub for inventors. And yes, there are some inconceivable suggestions from time to time, but we are also confronted with interesting and achievable solutions that we assist and support as best we can. We forward some of these solutions to the industry to be implemented, which is satisfying,” Thomsen says.
“I think the future of sustainable energy production will be a combination of several sources, such as wind, water and solar. Energy storage will be the new black, but it needs further development before we can optimally exploit sustainable energy sources,” he continues.
“I don’t think we’re done optimising the current technology. There is still so much to explore, such as fine-tuning blades, sensors and instruments. I don’t think we’ve peaked with the current three-bladed turbine yet.”
Looking at prototypes of future options in the industry, it is clear that Thomsen is not the only one with an interest in novel and unconventional approaches. Other companies are researching technological alternatives to the traditional three-bladed turbine. From flying and floating turbines to minimalistic turbines that are essentially poles, many avenues are being explored in order to develop the most efficient and productive ways to harness wind power. Below you will find some innovations that are currently being tested.
Are these the technologies of the future?
This technology explores harnessing wind power from bladeless, oscillating poles. It is a lightweight cylinder without gears or bearings that need service or replacement. The whirlpool that arises when wind passes the poles makes it vibrate, and this vibration is used in a special generator to make electricity. Several tests have been carried out to demonstrate the feasibility of this technology, The company behind this is currently performing field tests with scaled models.
This technology, invested in by Google, is developing the use of wind turbines in kites. The theory is that more energy can be generated from higher altitudes where winds are stronger and more constant. The kite takes off using its small rotors as propellers and when the kite is airborne, it flies in a circle resembling the tip of an ordinary turbine blade. The rotors “collect” the wind power and an on-board generator converts it into electricity, which is then sent down to a ground station. The kite is connected to a ground station via conductive wires around a high strength core.
Altaeros creates a cost-effective innovation, combining an aerial lift platform with a modern flight control system. If successful, this will be the world’s first autonomous aerostat system able to deliver energy and telecommunication services from up to 600m above ground level. From such a height, strong and constant winds enable the turbines to generate much more energy in comparison with other similar competitors. Because the turbines are autonomous, the need for constant monitoring and control is also eliminated. This innovation could become useful in rural and isolated communities.
Although already on the market, the potential for further development of this technology is huge. The Hywind concept in Norway is the first full-scale floating wind turbine in the world. At Hywind, the floating structure features a steel cylinder that extends 100 metres beneath the surface of the sea, where it is anchored to the seabed by three lines. Norwegian oil and gas company Statoil, an investor in Hywind, is planning to build the first floating wind farm in 2017. The wind farm will boast five 6 MW turbines and will be positioned off the Scottish coast.
Another example of a floating turbine, this technology consists of a long vertical tube with a rotor at the top and a generator at the bottom. This turbine is also fixed to the seabed by a wire. However, the technology behind the simple structure is very complex, and much research is needed to overcome technical challenges such as the dynamics of the system. This vertical floating wind turbine enables wind power generation further out at sea, with more wind and more open space.