Researchers in Washington state are working on a generator that might replace internal combustion engines in hybrid electric vehicles. It would give these vehicles a much greater driving range than solar powered cars while nearly eliminating hydrocarbon and carbon monoxide emissions. And because the device operates at relatively low temperatures, it's not expected to produce oxides of nitrogen (NOx).
Developed at Western Washington University's Vehicle Research Institute and X Crystals of Issaquah, Wash., the patented device is a ten-inch-long generator dubbed the Midnight Sun. A burner inside the the generator ignites a mixture of air and natural gas, heating a ceramic tube to more than 1,400C; in effect, the tube becomes a tiny sun. Super-efficient but expensive gallium antimonide solar cells are arrayed around the glowing core to convert thermal energy into electricity that could power a car and charge its batteries. Because the natural-gas generator burns fuel continuously, carbon monoxide and hydrocarbon emissions would be one-fiftieth those of vehicles with internal-combustion engines.
The researchers have already built a prototype of the Midnight Sun that is powerful enough to operate a small television. The next step is to construct an eight-burner generator that will be installed in the university's Viking 23 vehicle. While the car could operate strictly on natural gas, it's intended to run primarily on battery power. The Midnight Sun generator is a backup system designed primarily for recharging the batteries and for long trips.
The generator will produce 20 kilowatts, giving the car the horsepower of an early Volkswagen Beetle. Running on the generator alone, the vehicle could maintain a speed of 60 mph on level ground, but it would need help from the batteries in order to climb hills at that pace.
The primary obstacle to commercialization is the expense of the gallium antimonide solar cells: They currently cost about $300 apiece, and hundreds are required for each of the eight burners in the Viking 23 car. The generator could soon be cost-effective enough to be used in cabins, motor homes, and boats, however. In these applications, the Midnight Sun would serve as a co-generator, providing electricity as well as space heating.--Dawn Stover
Popular Science Feb. '95