...our kite-based system is made from just 10 per cent of the materials needed to build a ground-mounted wind turbine. This allows for reduced setup times and lower construction costs.
Swiss researchers have developed a high-tech kite to tap into the energy potential of wind currents 300m above the Earth’s surface…
Dr Rolf Luchsinger
Plans to generate clean electricity with the aid of high-flying, high-tech kites have received financial backing from the ‘venture kick’ jury.
‘TwingTec’, an Empa spin-off project, will use specially designed kites to harvest kinetic energy from winds blowing high above the Earth’s surface. Land-based turbines and generators will be used to transform this kinetic energy into green electricity.
Using only a kite, a reel and a console, researchers will harness wind power to generate clean electricity in a consistent manner. Whilst the masts of conventional wind turbines rarely sit higher than 100m in the air, the ‘Twing’ – short for ‘tethered wing’ – can reach heights of up to 300m where winds usually blow more consistently.
The system’s only airborne components are the kite and the tether. As the Twing rises, its tether turns a ground-based turbine that is connected to a generator. Once the Twing has reached its maximum altitude and its tether is fully extended, it is reeled back to a lower altitude so that it can rise again.
Reliable and cheap
Collaborating scientists from Empa, the University of Applied Sciences and Arts Northwestern Switzerland (FHNW), the Federal Institute of Technology in Zurich (ETH Zurich) and the Federal Institute of Technology in Lausanne (EPFL) are confident that their system will be more reliable and cheaper to produce than conventional, land-mounted wind turbines.
To learn more about TwingTec, I spoke to participating researcher Dr Rolf Luchsinger from Empa’s Center for Synergetic Structures.
"We wanted to use kites to harvest wind energy," he began. "This method of power generation has a number of advantages over conventional wind turbines. For example, a kite can reach higher altitudes than a wind turbine. Also, it requires fewer heavy and expensive components such as towers and foundations. Essentially, our kite-based system is made from just 10 per cent of the materials needed to build a ground-mounted wind turbine. This allows for reduced setup times and lower construction costs."
The Twing must be lightweight so that it can be carried upwards, yet strong so that it can deal with the stresses placed upon it by more vigorous, high-altitude winds.
"The kite needs to be very light because often, winds are not particularly strong at lower altitudes," Dr Luchsinger explained. "However, it must also be strong. To achieve this balance, we intend to utilise tensairity: a strong, lightweight, inflatable structure that incorporates struts and cables within its design. We are currently working to optimise the tensairity of the Twing."
Whilst conventional wind turbines are capable of generating greater quantities of electricity than this fledgling, kite-based technology, strong winds occur less consistently at lower altitudes. The researchers point out that such winds tend to be more consistent at higher altitudes. In order to further test their design, the TwingTec team aims to create a small-scale system within the next three years.
"Our first installation will be a 50kW system," said Dr Luchsinger. "We have decided to start with a small system so that we have the opportunity to optimise future designs. Today’s wind turbines can generate lots of electricity. It would take at least a decade for us to build a Twing system of comparable magnitude. We intend to begin, therefore, by building a scaled down version during a shorter timeframe.
"The 50kW system will have one ground station and one Twing; it will be a one-kite system," he concluded. "Eventually, it might be possible to have multiple systems operating in parallel with one another. Obviously, this approach will require more space, but it would be one way to scale up the power generated."
If you would like to find out more about Swiss kite power, visit the TwingTec website…