Harnessing High Winds With Giant Kites
People are trying various sources to produce alternative energy. We have often witnessed children flying kites. But very few of us have given a thought to generate energy from kites. Scientists from Delft University of Technology in the Netherlands produced energy from the wind by flying a 10-sq metre kite that is attached to a generator. It generated 10 kilowatts of power. This energy was enough to meet the power needs of 10 family houses. Scientists are now aiming for a 50kW version of their invention. They have named it Laddermill. Their ultimate aim is to go for a version of multiple kites. They will be able to produce 100 megawatts of power that could meet up the energy requirements of 100,000 homes. In order to generate power the kite pulls a string attached to the generators on the ground. Upon reaching their maximum height, they are reeled back down to repeat the process.
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Wubbo Ockels, who is the professor of sustainable engineering and also a former astronaut, is leading the Laddermill project. “We need to use all the energy supplies that are offered to us by nature, we need diversity and kites are … intriguing and fascinating.” He explained that kites are a cheap way to reap the vast amount of energy available in the wind at a kilometer or more above the ground. It should be noted that winds carry hundreds of times more energy beyond one km or more above the ground than on the ground.
Google.org, which is the philanthropic wing of the California-based web-search company, agrees with Wubbo Ockels. Google.org spent $10m (about £5m) last year on a US kite company called Makani. Google.org has committed itself to invest and encourage the organization’s Renewable Energy Cheaper than Coal program.
Both of the above organizations are aspiring to avail the high-altitude wind. Tapping wind at considerable height is beneficial in many ways. First, it is the energy source that is more abundant than ground level wind. Wind at high altitude is dependable too. Speed of the wind at considerable height is more assured than ground-level wind which normal turbines depend on. Ken Caldeira, who is a climate scientist at Stanford University’s Carnegie Institution, has projected that the total energy contained in wind is 100 times the amount needed by everyone on the planet and most of it is available a higher altitude.
As we know, the blades of average windmills are situated about 80 meters from the ground. At that height normally the wind speed is five meters per second. But if we go higher say at 800 meters, wind speed is seven meters per second. More speed means more energy. Till now we don’t have a technique to place wind turbines at the height of 800 meters to generate more energy. But we can easily use kites at that height.
European countries such as UK, the Netherlands, Ireland and Denmark have another advantage too. They fall in the high stream jet area that is ideal for flying kites. Allister Furey of the University of Sussex is involved in developing computer control mechanisms that suggest ways to maximize the power generated from kites. Allister Furey said about the advantages of the kite energy, “Pretty much anywhere in the UK you could run a kite plant economically, but you couldn’t run a wind turbine economically.”
Furey’s computer models have established that flying kites in a figure 8 pattern means the air flowing over them travels even faster than the surrounding wind velocity. When a kite is reeled in, it falls out of the sky like a glider, without the need for much power. This way the kites can generate maximum power. He is considering applying the same prototype on multiple kites that behave like a yo-yo; when one kites comes down, another goes up. Ockels estimates that kites could generate power at less than 4p per kilowatt-hour, which is comparable to coal power and less than half the cost of electricity from wind turbines.
Furey explained further, “The first systems will be community scale that could power a large farm and sell some electricity back to the grid. Once the technical issues have been sorted out, you can scale them up to the level of a coal-fired plant. All you have to do is multiply the number of kites and you can have a farm as big as you want.”
Kitegen, an Italian company, has quite ambitious plan come regarding energy generated from flying kites. They are developing a theoretical paradigm for a system that could produce a gigawatt of energy. A normal coal-fired power plant produces that amount of energy. They think that flying 12 sets of lines with four 500-sq metre kites on each will be sufficient to achieve the target.
Nick Rau, an energy campaigner at Friends of the Earth, shared his views, “We could easily supply our electricity demand from offshore, even with other demands on sea such as shipping, fishing and defense radar. These new [kite] technologies allow us to go further offshore and avoid other problems. We have an abundance of renewable energy and there are a lot of visionary technologies coming along so that, in future, the sky’s the limit.”
