Highflying wind power creates more energy

With the help of a helium balloon and a high altitude wind turbine, eight master’s students have tested a new concept for the harnessing of renewable energy.

“As far as we are aware, we are the first in Sweden to try out this concept”, says Tim Sirén, student and project leader.

It all began with a summer project carried out by some other master’s students last summer. They looked at trials held elsewhere in the world, building on the knowledge that the stronger the wind is, the more energy can be harnessed. At greater altitudes the wind blows more strongly and therefore trials are being held on ’High altitude wind power’, a concept that builds precisely on the fact that the amount of energy increases with altitude.

“The results of this summer project gave us a theoretical frame of reference to build upon. We analysed the various concepts and assessed which we wanted to take further,” Sirén explains.

Over the autumn the eight students worked hard to create a prototype to test the harnessing of energy at high altitude. The concept they decided to work on consisted of putting a wind turbine over 100 metres up in the air by means of a helium balloon, in order to use the strong winds to generate electrical energy to light a light bulb down on the ground. The work was time consuming and laborious – models were built, tested, rejected, rebuilt and tested again, explains Sirén.

“We learned a huge amount along the way. It’s one thing to produce a computer model; turning that into reality is a completely different thing. Simply choosing the balloon – what shape it should be, what material, how it would survive the cold. Safety was another important consideration. It wouldn't be good if the balloon burst one hundred metres up, since the turbine and everything weighs 10 kg. And it is important for the construction to face the wind so it doesn’t turn side on. It has to be facing the wind head on to harness the energy.

But the prototype was eventually finished, and during a freezing week in the middle of December the final test was carried out at Motala airport. The large balloon, 4.5 metres in diameter and attached to the ground with a 110 metre long cable, flew up into the air with its turbine.

“We tested all day long Friday. It was 15 degrees below zero C but it wasn’t very windy, so we were a bit unsure about how it would go. But the wind increased and the turbine began to spin and the lamp on the ground began to glow. We were overjoyed. It shows that it is possible to harness energy using the ’High altitude wind power’ concept.”

The students hope that their project will be a small piece of the puzzle in the development of new renewable energy.

“In the future it might be possible to imagine technology where helium balloons are used out at sea where there is more space. This would reduce the risk of negative aesthetic impact and would not affect air traffic, which flies over the sea at greater altitudes. Another advantage of being out at sea is that it might be possible to use hydrogen rather than helium. The advantage of hydrogen is that it is cheaper while the disadvantage is the risk of fire. But fire damage would not be so great if it was out at sea. A lot of engineer hours will be needed before this concept could become competitive,” Sirén cautions.

“This is a start and you have to start somewhere,” he says, adding that the eight members of the group of students come from different countries, with the working language being English. “We have four Swedes, two Frenchmen, one from Iran and one from Iraq.

It has been really fun and interesting. It hasn’t been always been easy but it has opened our eyes to different perspectives and it has been an enriching experience.”

Watch a film of the testing of the balloon at Motala Airport

Text: Eva Bergstedt
Photo: Corentin Van Praet