KEY POINTS:
A lifetime of kite-flying has led Kiwi Pete Lynn to a California company at the forefront of research into converting wind into electricity.
Lynn works for Makani Power, a company of a couple of dozen engineers, designers and computer modelling experts who are trying to turn a popular pastime into a clean, cheap form of energy. Like Lynn, many happen to be kite enthusiasts.
They've received US$10 million from Google to test the feasibility of using giant kites - perhaps 1000sq m in size - flying at about 1000m to generate electricity.
The kites would be computer-controlled, following a figure-eight pattern, and be attached to a winch. Electricity would be generated as the kite took line out from the winch spool.
Some of the power would then be consumed as the winch wound line in to bring the depowered kite back from the furthest point of its flight path. But according to the physics of kite flight, 10 to 20 times more power should be generated than consumed.
It's almost inevitable that Lynn would make a career out of kites. By doing so, he is following in his father's footsteps.
Peter Lynn senior, of Ashburton, has been designing kites for 37 years and remains immersed in that world. He pioneered kite buggying and, these days, develops kites for yachts.
"Pete was our crash test dummy through the early years of kite development."
Lynn senior says his son, who is in his early 30s, has the perfect credentials for kite power research. He started designing kites himself aged about 10, was possibly the first kite surfer in the country and has an engineering degree.
A number of challenges face kite power projects, according to Lynn senior, including finding a suitable material for the kites, and convincing the communities over whose heads the kites are flying that they're safe.
The material that's most likely to be used is spectra, a tough polyethylene plastic. Kite surfers will be familiar with it because it is used for kite control lines. It's also the material heavy tow lines for shipping and soldiers' helmets are made of. Spectra is not only strong but also UV-resistant - which kevlar is not - so is a good bet for kites and the lines that tether them to the ground.
Everyone has seen how unpredictable kites can be, however, and people living near a kite energy site are probably going to worry less about a line breaking than a kite spinning out of control and landing on top of them.
Computers will keep power-generating kites in the air, tracking their position by GPS and using radio-controlled servo motors for trimming them in flight.
That's the theory, at least. But in fact, launching such massive kites, and autonomous flight remain to be mastered. If they can be, kites have compelling characteristics for power generation.
They have the advantage over wind turbines of being more scalable, Lynn senior says. Today's turbines can produce about 7MW of power and output of double that might eventually be possible. But beyond that, the stresses would be too great on turbine blades and towers.
"With kite systems, it's easily possible to envisage them producing 20MW and above, which is one of the reasons kite energy is considered a strong possibility."
Makani - the name is Hawaiian for wind - is just one of a number of kite power research efforts. Delft University in the Netherlands has come up with a "laddermill" design that would consist of several kites, one above the other, each with a surface area the size of two football pitches - about 13,000sq m - catching the strong winds above 5km.
They would be attached to a drum on the ground with 500m of line that would be spooled in and out as the kites flew about. A 2000-tonne weight would anchor the spool to the ground, giving an idea of the huge amounts of energy kites could tap. The laddermill researchers reckon their design could generate 100MW of power.
KiteGen, in Turin, is working on a design that theoretically will have several times the laddermill's output. Its scheme attaches numerous kites to a carousel whose spinning motion will be converted into electricity
"At the moment, all of them are attempting to prove technical feasibility and they have either done that or are close to it," Lynn senior says. "Within a year or two, I'd imagine they'll be planning pilot projects."
Lynn is thrilled that his son is involved with Makani, whose founders he knows from the world of kite design. But he won't speculate on the likelihood of the company being able to prove commercial feasibility.
"They've got the money and they've got the brains and I expect in the next five years it will become clear."
