Petrol burning personal cars, about 50 million of them produced peryear, account for some 20% of the 8000 million tons of CO2 that weinfuse into the atmosphere annually. The world is therefore looking atelectric cars as an important step towards limiting this emission. Every major car maker around the world is introducing new electric vehicleseach year and concerned people are beginning to buy EVs despite the high price tag.
One of the principal concern for an EV user is the battery capacity. A typical petrol engine car has a tank capacity that gives some 500 km of driving range before it requires re-fueling. Current EVs have a battery capacity that can at best give some 120-150 km before it needs arecharge . Such a battery already weighs around 150 kg, so fitting alarger battery is not a solution. Therefore, it must await theavailability of improved batteries with far better power to weightratios than is currently possible.
In addition, battery recharging is a slow process that typicallycould take a minimum of 2 hours and even up to 12 hours. This is insharp contrast to petrol refilling that takes just few minutes. The gasstations for refueling, in over 100 years of petrol usage are nevermore than few kilometers from any road whereas EV recharge stations arestill being installed. These issues have led to the users buying ahybrid vehicle that incorporates a petrol engine into an EV.
Even when the EV is used in a city environment, where rechargestations will eventually be plentiful, plugging in a charging cord isstill not the best solution. Though, many of the early concerns withsafety from electric shock have been overcome by the improved designs of the current outlets and the charging cord, many drivers still find theprocess unfamiliar and difficult. In addition , there have been issueswith people forgetting to unplug before driving the car away and so on.
The need for change
There would be much easier acceptance of EVs if there was an easierway to recharge batteries than the present method of plugging in a cordinto a power outlet. Also if the re-charging can be accomplished without the need of any special effort by the driver.
The concept of wireless recharging of the EV battery isgaining traction with many of the leading car manufacturers teaming with technology companies to test pilot models. The technology is not newand it has been used with electric toothbrushes for over 10 years andthere are devices to recharge mobile phones using inductive chargers. The challenge is to apply it to the much greater power needed for an EV.
1. Toyota Teams Up With WiTricity for Wireless Car Charging
Toyota has teamed up with WiTricity of Massachussets, a start-up working with MITtechnology, to launch the Power Source Resonator. In this, a pad, thesize of a pizza box, containing a high frequency coil and powerelectronics components is embedded in the floor of a car garage or in aparking lot. The underside of the car is fitted with a matching powercapture plate . The power source resonator is connected to the utility240 volt power source and produces a high frequency ( 20kHz or higher )electromagnetic field. This field induces an electric current in thecoil contained in the power capture plate fitted to the car and thatalternating current is rectified to DC and charges the battery.
WiTricity affirms that its unit can deliver 3.3KW of power at about90% efficiency ( i.e to deliver 3.3kW it will take in some 3.7kW ofpower). The concept is certainly very attractive, the driver of the EVjust parks the car in the garage or a parking lot and activates therecharge process while he/she is at home or at work or even, shopping .
The Toyota EV is expected to have a battery of 22 kWh which meansthat a near – drained battery would take over 6 hours to charge. Theassumptions Toyota and WiTricity make is perhaps that the battery wouldusually need only “top-up” charging and that could be easilyaccomplished in the 30 to 60 minutes while the car would be in ashopping mall lot . Cars parked at home or at work would have more timeand accomplish full recharge.
2. Volvo focuses on wireless charging to electric cars
Volvo in partnership with a Belgian technology company has suggestedinductive charging not just when the car is parked, but when it is being driven. They suggest that select lanes of a highway, designated forEVs, could be embedded with a charging conductor that continuallygenerate inductive fields that the receptor in the car picks up torecharge its battery.
While this could overcome the issue of long recharge time for thebatteries, it appears unlikely to be economical until the population ofEVs begin to be more significant than they are now. Even in London,which aims to be the EV capital of Europe, the total number of electricand hybrid cars in use is only some 17000 compared with the total carpopulation of over 3 million.
3. HaloIPT launches world’s first market-ready wireless charging system for EVs
HaloIPT, a New Zealand based technology company, inpartnership with Arup the engineering company, has debuted its ownversion of the Inductive Wireless charging station. The London city council already offers a number ofincentives to the use of EVs in the inner city area including the freerecharging for an annual membership fee from power outlets being set upall around .This new technology could help accelerate the process ofadoption of EVs.
HaloIPT has also suggested electrification of Motorways to providecontinuous re-charging that could improve acceptance of EVs forpassenger commuting needs.
4. Evatran unveils wireless charging solution for electric vehicles.
Evatran of Virginia, a spinoff from a transformer manufacturer, has demonstrated its inductive charging station named “Plugless Power”. One major fillip for thiscompany is that Google Inc. has installed one of Evatran’s rechargestations at it Mountainview office building as a measure to encourageemployees to consider shifting to EVs. Google’s example of corporatecitizenship could trigger adoption by other corporates which could helppersuade employees to change to EVs.
Though inductive wireless charging appears to be the comingtechnology, the car makers, so far, have not got on-board which requires the EV user to retrofit this device, at around $ 5000. That couldchange soon as Nissan has announced that its new EV models will haveinductive charging as a built-in feature. The Society of AutomotiveEngineers ( SAE ) also appears to have determined this to be the comingtechnology in forming a task force to write the first industry standardfor inductive charging of EV batteries.
With several major car companies endorsing the inductive chargingtechnology, we should expect this to become the industry standard andwith user education and wider deployment. Wireless recharging ofbatteries in electric cars should find wide acceptance.
The Solar Electric Vehicle Bus Charger by Gavin Harvey