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  • Over the past decade,

  • renewable energy has grown from a niche idea that many were skeptical of

  • to an energy source that delivers a significant part of our country's power needs.

  • Clean energy is now one of the world's fastest-growing industries.

  • Despite this continued growth, renewable energy generation in the United Kingdom fell by 1% in 2016,

  • not because of a decrease in renewable infrastructure

  • - in fact the UK's capacity to generate renewable energy grew by 13.7%.

  • It fell because 2016 had less wind and rain than 2015.

  • Drawing energy from such a highly variable energy source has its drawbacks,

  • forcing us to not over-rely on renewable energy and continue to use baseload power stations,

  • which typically are fossil-fuel powered.

  • But what if we could find consistent sources of renewable energy that were less variable?

  • What if we could build a giant solar farm in our deserts and transport the energy across the world,

  • without the worry of losing power through resistance in the cables?

  • Or if we could place some form of wind energy generation high into the atmosphere,

  • where winds are consistent and blow much faster?

  • As I explained in my video about the future airliner concept, the Aurora D-8,

  • when a solid body, like a plane, flies through a fluid,

  • the fluid near the surface of the body flows slowly due to friction.

  • This is called a boundary layer.

  • The exact same thing occurs on the surface of the planet. And so, as you go higher, wind speeds increase.

  • This means the vast majority of the wind's total available wind energy is located in the upper atmosphere.

  • Planes take advantage of this by flying in jet streams, where tail winds can reach 160 km/h.

  • For example, a flight from Dublin to New York takes nearly an hour longer

  • than a flight from New York to Dublin.

  • Wind turbines are typically placed on mountains to take advantage of the higher wind speeds.

  • But that obviously has its limits.

  • So how can we reach higher and harvest that valuable wind energy?

  • Some companies have designed and built small turbines that are suspended in the air with a large helium balloon,

  • but these produce very little power and are not easily scaled to a larger size.

  • Another solution is to use kites.

  • Last month, Shell invited me out to Make the Future Live, which is a festival of ideas and innovation in London,

  • to speak with the inventor of Kite Power Systems.

  • KPS is a U.K. company which recently received five million pounds of investment from E.ON, Schlumberger,

  • and Shell Technology Ventures,

  • which invests in companies to accelerate the development and deployment of technologies

  • to help meet future global energy needs.

  • The more I spoke with KPS, the more the technology made sense,

  • and I began to see where it could be used in places where wind turbines couldn't.

  • Let's first look at how it works.

  • The system consists of two kites that are tethered to a spool.

  • This spool unwinds as the kite soars through the air

  • at speeds of up to 160 km/h in a figure of 8 motion.

  • As the spool unwinds, it powers an electric generator, but also feeds a hydraulic accumulator.

  • The hydraulic accumulator stores potential energy in the form of pressure

  • that can be released to drive the generator to smoothen out variances in kite speed

  • - an essential quality to make the system's energy output compliant with the grid's needs.

  • Two kites are used, and that allows one kite to raise as the other is lowering,

  • with a small amount of energy from the kite raising being used to re-spool the tether of the descending kite.

  • This point confused me initially: I could not understand how this would not reach a point of equilibrium

  • where the lift on each kite would equal and the kites would get stuck.

  • But as the chief technology officer explained to me at Make the Future Live,

  • these are not drag bodies, they're lift bodies,

  • with control surfaces that are controlled by a small robotic pod.

  • This pod ensures the kites are flying at the optimal flight trajectories at all times.

  • By varying the lengths of the bridles from tip-to-tip, the kites roll is controlled,

  • and the pitch is controlled by varying the length between the front and back.

  • When the kite needs to be lowered, the pitch is changed, and the kite glides back to its start position.

  • So how much energy can these kites generate?

  • KPS is currently building a 500 kW version in the south-west of scotland.

  • This version uses two 16 m wide kites.

  • For comparison, an equivalent 500 kW wind turbine would have a diameter of around 54 m.

  • These wind turbines are not cheap, being constructed mostly from steel and composite materials.

  • To prevent damage to wind Turbines in strong winds, the turbines will be shut off.

  • The kite powered system, however, can operate in hurricane-force winds.

  • And in the event of a break, the relatively cheap tether will be the part that breaks,

  • and the kite will be able to fly itself to the ground,

  • as the controller pod is located on the upper end of the tether.

  • If this test location proves successful, KPS has plans to scale the kite,

  • with a 3MW version, that would consist of two 50m wide kites.

  • Where this system really saves money is reducing loading on the support structures.

  • Wind turbine blades need to be strong enough to resist both the rotational motion and bending motion of the wind.

  • The tower in turn need to be strong enough to hold the weight of the structure

  • and resist the bending load of the wind.

  • And all this needs to be supported by substantial foundations, both on land and sea.

  • In comparison, the kite powered system's main components that experience significant loading is the tether.

  • The ground station simply needs to be heavy enough to prevent the kites from lifting off the ground

  • This makes the system significantly cheaper.

  • A study published in 2016 by the International renewable energy agency

  • found that the cost per megawatt hour of energy generated by offshore wind cost about $170,

  • and that is expected to fall to about $95 by 2030.

  • A study conducted independently of KPS found that kite power could generate a megawatt hour

  • $62.5 by 2020, and $50 by 2030 -

  • significantly reducing the cost of offshore wind.

  • This is particularly useful for countries like Japan

  • that do not have a huge amount of shallow water surrounding them,

  • as the continental shelf dives to 50 to 200 meters,

  • too deep for traditional offshore wind Turbines.

  • KPS can deploy to these areas with a simple floating platform

  • that would be attached to the ocean floor with cables.

  • The on-shore version can even be delivered on a flat-bed that can be deployed in less than a day -

  • potentially being used for disaster relief situations, where energy has been cut off.

  • Without a doubt, this system has the potential to revolutionize wind power.

  • Bill gates has even been quoted saying that he believes kite power has a 10% chance

  • of being the world's magic solution to the energy crisis.

  • I'd like to thank Shell for inviting me out to Make the Future Live

  • and giving me the opportunity to speak directly with the inventors of the technology

  • that could help us address the world's energy challenges.

  • As the world's population grows, so does our energy demands,

  • and we're going to need increasing investments in solutions like KPS

  • to ensure we can keep producing more energy with less CO2

  • This year's regional Make the Future festivals were held in Singapore, Detroit, and London.

  • It's a great event that I highly recommend checking out when it visits your city.

  • I learned a lot about the future of energy while there.

Over the past decade,

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風力発電の未来?- カイトパワーシステムズ (The Future of Wind Power? - Kite Power Systems)

  • 60 9
    Sam Cheng に公開 2021 年 01 月 14 日
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