High power energy harvesting becomes significant

Regenerative braking is now relatively common in trains, buses, trams and cars using generators and motors working backwards. Indeed, torque assist reversing alternators 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 soon be eliminated from sailing boats and even 50-150kW pure electric boats will use solar and electrodynamic harvesting.

On land, high power energy harvesting is increasing its percentage share of the $17bn market for remote power and microgrids, particularly in the form of small wind turbines and solar. IDTechEx predict that this will soon be followed by new airborne wind energy – mainly tethered multicopter kites. Water turbines in rivers and other options are also gaining traction, most of them being electrodynamic, the dominant form of HPEH from 10W to 100kW. In the future, the authors of the report will look at the Witt Energy electrodynamic harvesters of rotational and linear motion in 3D, as well as similar work by Caterpillar to harvest movement energy from their giant vehicles in 3D.

The report also covers other forms of energy harvesting, 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. 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 and expensive energy storage that has been holding the market back.

IDTechEx finds that many of the vehicle applications involve grabbing huge amounts of energy in only seconds, one increasingly popular form being the use of 60,000rpm lightweight flywheels during braking. The energy is returned electrodynamically, mechanically or via a combination of the two.

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 than the rest of the world put together, the power being typically 10 to 100kW. 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.”