True, the sales of small off-grid wind turbines is a tiny fraction of the $100bn market for wind turbines overall but this is just one of the electrodynamic ways of generating electricity where it is needed using ambient energy. Think of regenerative braking of trains, buses, trams, cars and so on using generators and motors working backwards. Indeed Torque Assist Reversing Alternators (TARA) are being prepared in the UK for use in conventional cars. The humble bicycle dynamo has been followed by regenerative soaring of Electraflyer aircraft and regenerative sailing of Beneteau, Milper, Rensea and other sea-going boats with thrust propellers that work backwards to generate electricity. Diesel will be eliminated from sailing boats and even 50-150 kW pure electric boats will use solar and electrodynamic harvesting.
On land, the market for remote power and microgrids is $17bn and high power energy harvesting is an increasing percentage of that. It is particularly in the form of small wind turbines with solar to be followed by the new airborne wind energy – mainly tethered multicopter kites. Water turbines in rivers and other options are gaining traction, most of them being electrodynamic, the dominant form of HPEH from 10W to 100kW. For the future, the Witt Energy electrodynamic harvesters of rotational and linear motion in three dimensions also excites the authors of the report as does similar work by Caterpillar to harvest movement of their giant vehicles in 3D.
The report fully covers the other forms, finding that photovoltaics is next most important now and in the future with stretchable, conformal, transparent, fabric and other new formats likely to greatly increase the variety of off-grid applications. Analysts IDTechEx advise that multi-mode energy harvesting will increase greatly in land vehicles, boats, ships and aircraft and in static off-grid applications on land, where harvesting typically employs hours of sunshine, wind or heat. In combination, the supply of electricity will sometimes be continuous leading to elimination of most of the troublesome expensive energy storage that has been holding things back.
IDTechEx finds that many of the vehicle applications involve grabbing huge amounts of energy in only seconds, one increasingly popular form being use of 60,000 rpm lightweight flywheels during braking. The energy is returned electrodynamically, mechanically or both.
Dr Peter Harrop, team leader of the research project reveals, “We were interested to find that Europe is in the lead in flywheel adoption and research, with 500 London buses trialling GKN/ Williams ones for example. The technology derives from the $9bn British motor racing industry which is rapidly moving to pure electric and hybrid racers. Europe has more organisations developing airborne wind energy (AWE) than the rest of the world put together, the power being typically 10kW to 100kW –that is also electrodynamic harvesting. The Europeans took a large boat around the world on nothing but sunshine and now they are repeating the trick with an aircraft. Faraday would be proud.”
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