GLOBAL CHALLENGES

Quicker Recharges for Hybrid Owners?

Dave Greenfield | Date: 05-27-10 | Comments

A major problem with electric cars is that their short-distance ranges on single charges make them impractical for long trips. Researchers from the U.S. Department of Energy�s Oak Ridge National Laboratory have developed a prototype that they hope will combat this problem.

One of President Obama�s initiatives is to get more than 1 million electric cars on the road in the next five years. While a problem keeping many would-be plug-in hybrid electric vehicle (PHEV) drivers from hitting the road is �range anxiety,� studies have shown that most drivers are perfectly satisfied with the 100-mile average range on a single charge and that they are, for the most part, able to avoid recharging in public for their everyday driving needs.

But what about more extensive trips? When home plug-in is not possible and you need to refuel before continuing on your drive, a charge can take up to 8 hours. Researchers from the U.S. Department of Energy's Oak Ridge National Laboratory (ORNL) have developed a prototype that they hope will combat this problem.

The prototype developed by the ORNL would cut recharge time from 8 hours to only 45 minutes, a remarkable reduction that is far more conducive to longer trips. Currently, PHEV drivers recharge via a 110-volt outlet, which is standard in homes. The new system utilizes 220- or 240-volt outlets, which allow batteries to recharge at 20 kilowatts, as opposed to 2 kilowatts with standard outlets. A potential downside is that homeowners would have to install 220- or 240-volt outlets if they don�t already have them. Public facilities would also have to be equipped with the outlets (which are already widely used for heavier appliances, like washers and driers).

According to Gui-Jia Su, senior research engineer at ORNL�s Power Electronics and Electric Machinery Research Center, the prototype system uses two inverters to charge the battery from the power outlet. A separate charger is unnecessary, and the car is able to recharge more quickly and efficiently. The system could also be used to hold an electrical charge when there is surplus energy on the grip (such as during off-peak hours). And it could take energy from the car to power a house or transfer it back to the grid.

While offering undeniable benefits, there are issues with the implementation of ORNL�s prototype. One issue is that major car manufacturers are likely just to develop their own recharging technologies for use with electric cars with backup combustion engines. Another stumbling block of fast charging, according to University of California-Davis Mechanical and Aeronautical Engineering Professor Andrew Frank, �is that the more power you use to recharge the battery, the less efficient the charging system is, and a lot of power is wasted. For this reason, you really want to use a trickle-charge system for a PHEV; otherwise you�re throwing away electricity, not to mention money.�

ORNL hopes that its technology will be valuable for new, exclusively electric cars, like the Nissan Leaf and Ford Focus RV. These don�t have backup combustion engines, so batteries need quicker recharges in order to be a viable mode of transportation.