Given these requirements, the Utah State researchers opted for DURAGRID® pultruded GFRP bar gratings from Strongwell Corporation, headquartered in Bristol, Va. The gratings, which won one of the Awards for Composites Excellence (ACE) at CAMX 2015, feature a polyester resin reinforced with longitudinal glass roving and multidirectional glass mat. The grating is heat cured, with bearing bars and cross-rods first pultruded and then assembled into the final shape. A standard rectangular shape wouldn’t work because the grating had to cover an oval track. The bearing bars and cross-rods were custom fabricated to fit the contour.
“Additionally, it’s not your standard grating that you or I might walk on,” says Barry Myers, marketing manager for Strongwell. The application uses DURAGRID HD-4000, a heavy duty version of the grating. “It’s a much heavier and thicker bearing bar that’s actually 2½ inches thick to be able to support vehicle traffic without a problem,” Myers says. He adds that the composite grating doesn’t interfere with cellular and radio frequencies, which is important not only in wireless recharging, but also in wireless communication.
In the testing program at the Utah State facility, half of the track will provide wireless recharging. As vehicles travel around the track, researchers will evaluate how well a given recharging approach works. The eventual goal is to deploy a system that pumps in a tiny bit of electricity each time a car passes over a recharging zone. The dwell time over each recharger might only be fractions of a second, and it’s likely that the energy imparted might only be just a bit more than what is consumed moving between one recharger and the next. Over time and hundreds of miles, though, an electrified road could completely top off a battery, Zane says.
As for the future, one thought is to develop recharger modules that can be buried when new roads are poured. This option would be akin to putting in piping and wiring that currently goes in with new road construction. Composites might be used in the structure to hold coils and other parts of the recharging system in the right position while providing protection against asphalt or concrete and offering the necessary electromagnetic transparency, Zane says.
In other situations, the current setup on the Utah State test track might be replicated. Real estate in a city’s downtown is expensive and shutting down traffic costly, so tearing up the road to bury an inexpensive module might not be the most cost-effective approach. A better option would be an installation method that minimizes disruption. “In those areas it might make sense to have something like this GFRP grate that gives you easy access,” Zane says.
It likely will be years before demonstration projects are put into place, he says. Possible initial locations include shipping ports and airports, where vehicle fleets and roadways are closely controlled. This project is just one step on the road to an expansive use of electric vehicles.
