Electric cars still have room for efficiency

If you are currently thinking about taking your parents’ electric car on your spring break road trip (yes, it’s never too early to think about spring break), a word of advice: Don’t. At least not this year.

Since every electric vehicle under $35,000 on the market has a range of no more than 100 miles on a full charge, road trips with most electric cars require impeccable planning of when and where to charge up. Add the fact that the efficiency of electric cars decreases when traveling at highway speeds, and a charge may only last 45 minutes to an hour. The two most reasonable approaches for providing electric cars with longer range are to increase the size of the battery, which adds weight and cost, or to figure out a way to charge electric cars as they drive.

Researchers at Clemson University have been exploring the second option, as the University’s Industrial Center for Automotive Research is in the progress of developing and testing a charging system that could be embedded in roads to charge cars as they drive.

The idea is not completely new, however; the United Kingdom declared its intent to develop an in-road charging system in August, and Volvo was already looking into the idea back in 2013. Evatran and Bosch have also recently released plugless charging stations for the Chevrolet Volt and Nissan Leaf.

What makes the Clemson technology groundbreaking, then, is its potential for greater amounts of energy transfer from charger to car battery. The maximum possible power transfer for the Clemson system is 250 kW, and one test yielded a transfer rate of 6.9 kW with greater than 85 percent efficiency. While this power transfer is nowhere close to the ideal maximum, it marks a significant improvement over technology that the U.K. is looking into from North Carolina State University, which most recently reached 0.5 kW at peak efficiency. With further refinement, the Clemson technology will likely become more promising yet.

Long-range wireless charging may sound like some sort of dark electrical engineering wizardry, but a brief dissection of the Clemson system reveals a relatively simple idea behind the design. The primary actors behind the charging are copper coils in the ground and in the car, and these create a magnetic field to pass electricity wirelessly. For the transfer to occur, the charging station and the car must be in wireless communication with each other.

Here also the Clemson model differs from previous wireless charging attempts: by using the Dedicated Short Range Communication (DSRC) protocol a much faster technology than, say, Wi-Fi communications between charging station and vehicle can be established quickly at reasonable distances and more energy can be transferred efficiently. The DSRC technology, with its fast 5.9 GHz rate, already has its frequency band protected by the U.S. government and is used in vehicle-to-vehicle communications for crash avoidance as well as vehicle-to-toll booth communications to electronically collect fees.

An efficient wireless charging technology based off the Clemson design could be used to create special freeway lanes, where electric cars would be able to charge by simply driving over magnetic charging coils embedded in the road. As Clemson professor Joachim Taiber told ComputerWorld, “How much power [the vehicle] can absorb depends on the speed of the car,” with slower speeds resulting in greater power absorption.

For years, concerns about the viability of electric cars have inhibited their adoption by consumers. The top concerns: not enough environmental benefit to make electric cars worth the investment and not enough range for them to be practical. A massive infrastructure overhaul, then, implementing wireless charging lanes with a technology such as Clemson’s, may quell fears and be an effective way to stimulate the electric car market and promote a more sustainable future.