Wind power & commercialisation

A New Wind Blowing in the Wind Energy Industry

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Jon Wulff Petersen

Director, Technology Transfer

MSc Physics, PhD Semiconductor Physics, E-MBA

Just north of Bergen, Norway, a bunch of wind enthusiasts are on a path to revolutionise the wind energy industry with something as seemingly simple as kites. Norwegian start-up Kitemill is now planning to launch their first commercial kite power station.

Most children have felt the strong tug and pull of the wind when flying kites. Kite surfers use the same principle of wind
traction to tow their surf boards. This inspired the idea that became the foundation of Kitemill:

Why not use the kite principle to harness the traction force of the wind to create power?

Thomas Hårklau and Olav Aleksander Bu originally intended to use the kite principle to circumnavigate the world in record time. However, with the onset of the worldwide financial crisis sponsors were hard to come by and the project was abandoned.

But the two friends could not let go of the idea that there was an untapped potential in kite power. In 2008, they brought on board professional hang glider and investor Jon Gjerde, and Kitemill was formed.

How Kitemill’s Kite Power Works
Kitemill’s vision was originally inspired by kitesurfing as were their kites in the shape of light fabric membranes on pliable frames. However, Hårklau and his crew soon realized that the extreme force and traction of the wind at high altitudes would wear out the pliable kites in a matter of weeks. Instead, they developed a rigid kite shaped like a small airplane. (See fig. 1)

The design of the “kiteplane” is much like that of an airplane with flaps that can be released when the kite reaches the right altitude. The kite is fastened to a long wire attached to a generator at a power station on the ground. Small propellers bring the kite to the right altitude, the flaps are released to catch the wind and spin the kite in a long spiral with the help of the steering propellers, reeling out the wire with the traction force to create power.

Fig. 1 Kitemill’s kites are constructed in much the same way as modern aircrafts, with a surface and structure of composite materials.

The spiral pattern creates much more power than if the kite flew in a straight line – a principle that is also used in the rotation of traditional windmills.

When the kite reaches the end of its tether, it is reeled back in to the winch drum to be levitated once more. The entire return phase consumes less than 2 % of the power generated and requires less than 20 % of the total cycle time.

One kite generates approximately 35 kW which is enough to power 5 households. Kitemill expect to be able to enlarge the kites over time to create more energy from each kite, but for now, their goal is to generate more operational hours than any other kite power supplier.

Coasting in the Slipstream of Wind Power
While Airborne Wind Energy Systems (AWES), to give kite power its proper name, is still a budding technology, using wind as a sustainable source of energy is by no means a new idea. Large windmills can be seen on many a windswept hill, and offshore wind farms are dotted along the coasts of many countries.

The first power-producing windmills in Denmark were built in the 1970’s, often set up by small, private investor groups.

The first windmills had a power production capability very like that of Kitemill’s first power station.

It took the windmill industry more than 30 years to develop into the billion-dollar industry it is today, with hard and costly lessons along the way. The wind power industry paved the way for wind
energy in general, and the AWES industry can coast in their slipstream, learn from their mistakes and try to repeat their successes.

AWES has the potential to grow as an industry at a much faster pace because of this and because it relies on a patchwork of new technologies and technologies that already exist: The first
known kites were invented in China more than 2000 years ago, and the principle has been used by countless children and kite surfers alike.

In their kite design, Kitemill are utilising tried and tested technologies from airplanes in the kite’s aerodynamic shape and the flap functionality; from drones in the steering propellers; and from windmills in the spiralling flying pattern which creates more energy than a straight line.

The wire and winch are off-the-shelf technologies used in other industries as is the generator.

From the beginning, the founders of Kitemill were very conscious of the importance of protecting their new technology to attract investors.

This patchwork of new and existing technologies lowers development and production costs considerably, speeds up the growth process for the industry and improves the prospects of return on investment for investors.

Benefits of AWES Compared to Wind Power

  • Lower production costs
    The production of kites only uses 1/10 of the materials needed for windmills. Several of the components are off-the-shelf units, and logistics are easier as the components are relatively small and make for easy transportation.

  • Less windy locations
    Windmills only utilise a small percentage of the wind energy and need to be placed at very windy sites to be cost-effective. Kitemill’s kites can reach altitudes of up to 1500 meters, harnessing the stronger, more steady force of jet streams in the atmosphere which can be found in almost any location worldwide.

  • More full load hours per year
    When Kitemill’s kites reach their full potential, they are estimated to produce an average of 4200 full load hours per year. In comparison, windmills produced 2453 full load hours on average in 20121.

  • Less visible in the landscape
    To some, windmills are an eye-sore. Kites, on the other hand, are barely visible when they reach their spiralling altitude.

  • Safer in hurricane-prone areas
    Windmills cannot be placed in locations with a risk of hurricanes as the force of the wind might damage the propellers. Kites, however, can be reeled in quickly if the wind is too strong.

Drawbacks of AWES Compared to Wind Power

  • Dependent on investors willing to take risks
    Airborne Wind Energy Systems is still a budding industry relying heavily on investors willing to take risks.

  • Wider safety zones
    AWES hubs need a wider safety zone than windmills so the kites do not get tangled or endanger low-flying aircraft. In other words, they require more space per kite.

  • Unclear subsidy scheme
    Sustainable energy is a heavily subsidised industry, but AWES has yet to be officially defined and standardised as a sustainable energy technology. It is currently a work in progress.


Ironically, this is also the biggest challenge for Kitemill from an IPR perspective.

Patenting a Patchwork Technology
From the beginning, the founders of Kitemill were very conscious of the importance of protecting their new technology to attract investors and be seen as competitive in a heavily subsidised industry. However, the patchwork nature of the technology made it impossible to patent Kitemill’s airborne wind energy technology as a whole.

Instead, with the help of Plougmann Vingtoft and its techtrans and commercialisation team tto, Kitemill formed a long-term patenting strategy focusing on patenting smaller technological developments in an on-going process. Our experts continue to collaborate closely with Kitemill’s developers to safeguard Kitemill’s technology and help them become well-versed in the
jungle of sustainable technology patenting.

This sound, well-argued strategy has enabled Kitemill to attract several investors who might otherwise be wary of investing in a new technology where the patent protection will never be
entirely perfect.

tto’s profound knowledge of the wind power industry and vast experience in maturing and bringing sustainable energy technologies to market also helped shape Kitemill’s launch and investment strategy to the point where Kitemill are now ready to launch their first commercial power station hub.

The Potential of AWES
Kitemill are not the only ones developing kites to harness the power of the high-altitude winds. Competitors worldwide are working on various kinds of airborne wind energy systems, and while they are all racing to be the first to market a commercial version of their product, the widespread interest and competition in the field of this budding technology is largely a benefit to the players in the field rather than a drawback.

The competitors within the EU would do well to take a leaf out of the windmill industry’s book and work together to develop certifications and standardisation rules for the industry. They can use the same test sites and learn from each other, and the first competitor’s success will eventually pave the way for the other players in the field.

Despite the many benefits of AWES, the technology is not likely to replace wind power as the main wind energy technology anytime soon – if ever – but it is on its way to becoming a viable supplement in the sustainable energy grid and may even be used in conjunction with wind farms as kites harness the wind energy at much higher altitudes.


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