Vehicles drive energy harvesting forward
07 September 2009
In 1834, Thomas Davenport demonstrated the first electric car in the UK. Dr. Peter Harrop, Chairman of IDTechEx, explains the importance of electric vehicles in the 21st century.
Pure electric mobility aids for the disabled (such as power chairs) sell at around the million unit level every year and most fork lift trucks across the world are electric so Davenport certainly achieved something.
All electric golf cars peaked at about 300,000 units yearly but unfortunately, pure electric on-road cars have yet to sell in more than tens of thousands yearly. It is mainly a problem of inadequate range from available batteries, lack of charging infrastructure, and lack of realistic fast charging. However, there are huge government incentives, some new in 2009, to break these logjams. Meanwhile, hybrid gasoline-electric cars will tide us over.
A big improvement is the availability of more and more plug-in hybrids with big enough batteries to go at least tens of miles on cheaper electricity alone.
In all forms of electric vehicle, power management is key and any form of energy harvesting is welcome. The modern car will increasingly use regenerative braking, solar panels outside, and maybe energy harvesting shock absorbers and other forms of energy harvesting too. Even those not interested in the automotive industry can learn from its eager adoption of types of energy harvesting that need volume to be used elsewhere. Regenerative braking is already commonplace in pure electric cars. From this year, the photovoltaic car roof will increasingly be the norm as well, initially only powering accessories but later, when transparent film solar is available and over the whole car, providing significant traction power as well.
This idea is not new, as evidenced by the 1982 solar powered "car" in Germany.
The world's largest car company, Toyota, already has a $5 billion electric vehicle business and IDTechEx projects in its new report, Hybrid and Pure Electric Cars 2009-2019, that Toyota's sales of hybrid cars will pass one million in 2014. The global sales of all forms of electric car from all suppliers will be 3.125 million at that time, forecasts IDTechEx. Such volume will be an excellent opportunity for numbers driven cost reduction of many forms of energy harvesting, benefiting the use of harvesting elsewhere.
The best selling Toyota hybrid is the Prius. Indeed, it is the best selling hybrid car in the world by a big margin. Toyota's third-generation Prius appeared this year with an optional solar panel on its roof that powers a ventilation system capable of cooling the car without help from the engine, claims Toyota.
In addition, Solar Electric Vehicles has been offering a solar roof conversion for existing Prius vehicles.
Because the Toyota cars are fully crash tested, and on-road vehicles currently used solar cells are heavy, the total weight precludes use of solar roofing to drive them along, although achieving an extra five to fifteen miles range is not unusual.
"Being able to power a car entirely with solar is a pretty far-reaching goal," said Tony Markel, a senior engineer at the federal government's National Renewable Energy Lab in Golden, Colorado.
In the new Prius, the photovoltaics provide energy for a ventilation fan that helps cool the parked car on hot days. The driver can start the fan remotely before stepping into the car. When the car is started, the air conditioning will not need as much energy from a battery to do the rest of the cooling. Although palm sized solar car coolers that fit in the window to cool the parked car have been available for some time, the Toyota roof unit does a far more robust job.
The next stage will be sufficient solar power to run the air conditioning at all times via battery storage. The best thing about using any form of harvesting in a car is that it saves on fuel.
Unfortunately, hybrids may put on weight as they become the plug-in versions desired by users. Plug-in hybrids permit the driver to travel useful distances on all electric power, saving a lot of cost over petrol. On the other hand, pure electric vehicles have no gasoline engine, but that weight can be offset by the extra size of the battery required. They will also benefit from new photovoltaics. Surely someone will use the new flexible copper indium gallium selenide (CIGS), di-sensitised solar cells (DSSC) or organic photovoltaics to make unfolding or unwinding panels that increase the area harvested during parking? There will be cross fertilisation from experience of energy harvesting in aerospace, something reflected in a forthcoming conference.
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