A revolving tag-team of student researchers at Middle Tennessee State University has developed a plug-in hybrid retrofit kit for cars that bolts inside the rear-wheel hubs without requiring any changes in the brakes, suspension, or any other mechanical systems. Kits like this might not gain much of a foothold in the individual market until gas prices spike again, but they could provide vehicle fleet managers with an economical way to increase their zero-emission, electric vehicle profile and reduce their dependency on liquid fuels.
Electric Vehicles vs. Liquid Fuels
The days of “easy oil” are quickly fading, and petroleum is not the only liquid vehicle fuel on shaky ground. This year’s heat wave and drought has exposed a key vulnerability of conventional biofuels, which will persist until the next generation of biofuel crops emerges into commercial scale. (That new generation includes biofuel from algae as well as biofuel from waste materials or woody, drought-tolerant plants.)
In the meantime, fleet managers will have to deal with price spikes and supply issues whether they use biofuel or petroleum fuel. That makes electric vehicle conversion more attractive, particularly for fleets that travel short distances at low speeds.
The MTSU In-Wheel Hybrid Retrofit
The student team at MTSU has been working with lead researcher Dr. Charles Perry since 2008, using a 1994 Honda station wagon as their platform.
The MTSU retrofit consists of an electric motor bolted into each rear wheel, in the space between the hub and the brake. The motors are powered with a lithium-ion battery.
The high price of li-ion batteries is one significant obstacle to a cost-effective retrofit, so the idea was to cut costs by reducing the installation time and avoiding the need to tinker with other mechanical systems in the car.
You can find examples of that kind of approach among other hybrid retrofit innovators, such as an electric motor that can be bolted onto the differential developed by the company XL Hybrids.
Hybrid Retrofits and Gas Dependency
So far, the MTSU team has demonstrated that its kit can increase the gas mileage of an 18-year-old car by an impressive 50 to 100 percent!
That would seem to indicate that the best candidates for retrofits are older fleets with lousy mileage, but with the market uncertainty of both biofuel and petroleum fuel in mind, retrofits could make sense even for newer fleets with relatively good mileage.
Image: Courtesy of MTSU
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Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.