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Electricity from heaven!

Installed close to the ground, wind turbines often struggle due to a lack of wind - but a few hundred metres higher up, it is never calm. ZHAW scientists therefore intend to generate electricity at lofty heights with the help of a new wind energy concept. The project is funded by the Swiss National Science Foundation, Innosuisse and Stadtwerk Winterthur.

Modell der ultraleichten Windturbine Zarawind
The “lighter-than-air” turbine, as Yasser Safa has named his patented system, is a key component of the Zarawind power station.

Integrating expertise from three institutes, the ZHAW School of Engineering is developing a new wind power station, which will operate several hundred metres off the ground. Their aim is to design a system that is compact, cost-efficient and environmentally friendly - which would make it perfectly suited for regions without access to power grids. Project manager Yasser Safa of the Institute of Computational Physics (ICP) has already founded ZHAW’s spin-off Zarawind, thus creating a basis for the commercial exploitation of this novel concept. The power station will turn wind into electricity at a height of approximately 400m above the ground. «At these heights, wind speeds are approximately twice as high as close to the ground, and wind power is even eight times stronger,» explains Yasser Safa.

Zarawind will be more robust and more efficient than any previous system.

Yasser Safa, project manager of Zarawind

More efficient than any previous concept

The idea for the Zarawind project came to Yasser Safa while he was high in the sky himself. The ZHAW scientist, who was born in Lebanon, was once again travelling by plane when it occurred to him that the wind power at higher altitudes could be very attractive for electricity generation. «Sitting in a plane, you can sometimes feel yourself how powerful the winds outside are», says Mr. Safa. Of course, this idea is not entirely new. There are already wind power stations that generate electricity up in the sky. However, none of these systems has been really convincing so far. It is therefore Yasser Safa's intention to improve the concept. He says: «The existing systems cannot guarantee stable operation in the sky. Zarawind will be more robust and more efficient than any system before.»


It is true that Zarawind, just like other concepts, relies upon a balloon to keep the turbine up in the sky. Being one of the crucial cost factors, the Zarawind balloon, however, will be kept as small as possible, thanks to an ultralight wind turbine. This «lighter-than-air» turbine, as Yasser Safa has named his patented system, is a key component of the Zarawind power station. Within the framework of a project funded by the Swiss Federal Office of Energy (SFOE), the scientist has already been able to deliver proof of concept, as well as a first prototype. Thanks to further funding by the Swiss National Science Foundation (SNSF), Innosuisse and the local utility company Stadtwerk Winterthur, Yasser Safa is now working on an improved prototype. «The propeller of the wind turbine itself will help the turbine to stay up in the sky», says the scientist, thus explaining his next goal. «Furthermore, we want to improve its mechanical sturdiness, so that the system can withstand the strong winds».

Institutes working together

With the help of numerical simulations, material tests and wind tunnel experiments, Yasser Safa wants to further develop the new propeller and prove its efficiency. “We are investigating the geometric influences on propeller output. This helps us to construct and arrange the rotor blades in a way that enhances power generation,” says the ZHAW researcher. While Yasser Safa himself is developing the mechanical design and the computer simulations at the ICP, the aerodynamic tests are carried out in the wind tunnel of the Centre for Aviation (ZAV). At the same time, the Institute of Materials and Process Engineering (IMPE) ) (in German) is developing and testing suitable lightweight materials. It is planned that the Zarawind prototype will rise into the sky in about one year for the first time.