Who would have thought that the humble kite could rise so far? Not only is kitesurfing an exhilarating sport, but energy production using kites to deliver power at ground mounted power generators is making serious headway. The IETs Engineering & Technology October 2016 Magazine reports that a ‘first of its kind’ kite power station is currently being built in Scotland and expected to be operational by March 2017. The kite, it seems, has come a long way from its humble origins thought to date back to China in the fifth century BC.
There is nothing new in kites being used for scientific purposes. In 1750 Benjamin Franklin proposed an experiment to fly a kite in a storm to prove that lightning was caused by electricity and kites have been used in meteorology, aeronautics, human flight, wireless communications and numerous other applications. However, the global drive for renewable energy has seen an increase in kite based power solutions.
Power generation using different types of kite design has been proposed and patented. Earlier concepts in airborne kites suggested windmills and generators mounted within kites which were to be flown at high altitude. Designs based on this concept are still being proposed – Google Inc’s US patent application, US2016/0273519 dating from 2014, proposes an airborne rigid kite of this type for ship propulsion.
Other kite based power generation relies on repeated, cyclical deployment and retrieval of a kite to deliver net power at a ground based combined reeling, generator / motor mechanism. Different wing designs for the kite have also been discussed with a first relying on a lightweight parachute shaped kite to exploit air thermals to ascend and which may be partially collapsed to minimise wind resistance for its descent. A second design of kite has controllable surfaces to steer the kite perpendicular to the wind during deployment and reposition the kite along a path of minimum wind resistance when the kite is reeled back down. Both these kite types would rely on repeated cyclical deployment and retrieval to the ground to deliver power at the ground through the power generation/reeling mechanism which is also an area of research and development.
The kite power station being built in Scotland by Kite Power Solutions is to use two, 70 square metre, asymmetric parachute type kites tethered to either side of a turbine. In a generator phase, one kite will fly in a defined path to turn the turbine and generate power. The two kite configuration allows the other kite to be retracted whilst the first kite is in the generation phase. Underwater kites are also being developed for water flow based renewable power.
The Green Channel for UK patent applications allows applicants to accelerate the patent application process if the invention is deemed environmentally friendly. Approved Green Channel applications take around 11 months from filing to grant. Kite based power generation would certainly qualify but there appear to have been few made so far. Although the Green Channel patent application list to date includes many applications in wave, solar and wind turbine based power applications, there are only one or two for kite based power generation systems, suggesting this is still a niche research and development area at least in the UK.
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