Ever scraped ice from your car windows until your hands were stiff, cold and raw red? Or missed an appointment because it took so long for your window defroster to thaw through your ice-entombed windshield? Or had your lights, cable TV or telephone black out—and stay out for days—because an ice storm downed power lines?
Good news: a group of researchers has developed technology designed to electronically zap ice off surfaces within in seconds. Unlike conventional windshield defrosters that rely on gradual warming to liquefy snow and ice, the IceController—created by Ice Engineering, LLC, in Lebanon, N.H.—delivers a swift (less than a second in some cases) jolt of high-power electricity that immediately melts ice at its interface with an object's surface. Once the bond between the ice and surface is broken, the ice slides away, says Victor Petrenko, Ice Engineering's chief technology officer and a professor of engineering at Dartmouth College's Thayer School of Engineering, where he invented the "electro-thermal pulse de-icing" technology behind the IceController.
The IceController can be connected to any device or structure that can be coated with ice and uses electrodes or a thin film of stainless steel, copper or aluminum foil placed on the surface to deliver a jolt of electricity whenever it senses ice buildup. The frequency, intensity and duration of the jolts depend upon what the IceController is trying to de-ice—a windshield, airplane wing or bridge cable.
"The objective is to heat an interface in-between the ice and the surface from [the] ambient temperature to ice['s] melting point quickly and with a lot of power," says Petrenko, a former research lab director at the Russian Academy of Science's Institute of Solid State Physics and a physics professor at the Moscow Institute of Physics and Technology. "It happens so quickly that, unlike other de-icing methods, heat is not wasted warming up the [object's] surface or the ice. Once the ice is dislodged, gravity or air-drag force [such as on an airplane wing) do the rest."
Ice Engineering's two biggest installations are on the Uddevalla cable bridge in Sweden (where the technology has been in place since 2005, see slide show) and on the 107,639-square-foot (10,000-square-meter) glass dome of a mall being built in Moscow City. The Swedish government–owned bridge has two pylons taller than 489 feet (149 meters) and 120 cables, each more than 655 feet (200 meters) long and 10 inches (25.4 centimeters) in diameter. Each steel cable is covered by a thin polymer tube (wrapped in stainless steel foil) to prevent rusting. "We apply [an] electric pulse to either end of the cable for about one second," Petrenko says, "and all ice attached to it falls down."
The company has also tested modified versions of its IceController to de-ice car windshields and airplane wings. A high-power windshield defroster heats the glass with up to 700 watts of power per meter, taking about eight minutes to bring the glass and ice interface to the melting point, Petrenko notes. Ice Engineering, he says, places an electrically conductive yet optically transparent film on the glass and then applies up to 20,000 kilowatts per meter to the film for up to four seconds, allowing the driver to clear the ice almost immediately.
Ice Engineering's technology could also be used to for in-flight de-icing of aircraft wings (glycol and other spray-on antifreeze chemicals are now used while the plane is on the ground), says Mark Hangen, the chief executive of ice machine manufacturer Simply Ice, LLC in Marquette, Mich., and a licensed pilot for 23 years. Today, commercial aircraft remove ice that accumulates on wings in-flight by redirecting hot air from the jet engines to the leading edge of the wings to keep them warm. "This consumes a lot of fuel," Hangen says. "They're looking for ways of getting rid of ice in-flight, without having to bleed air away from the engines, which causes them to use more fuel." Ice can also create maneuverability problems that could lead to crashes.
Hangen knows Ice Engineering's technology well—Simply Ice plans to use IceController to by 2010 upgrade its lineup of commercial ice-making machines, used by hotels and restaurants. Commercial ice machines generally do their thing by first pouring hot water into a mold and then using some form of heat (Simply Ice's units use hot gas) to loosen the ice so that it can be removed from the mold.
Hangen is counting on Ice Engineering's electro-pulse technology to more cost-effectively break up the cubes its ice makers create. "We've replaced that entire process with Dr. Petrenko's technology," he says. Whereas it can take several minutes for hot gas to get the ice out of the mold, a high-power electrical pulse takes about four seconds. A typical ice maker costs its owner $20,000 over 10 years for electricity and maintenance. The use of pulse power will conserve energy and require less maintenance, knocking that expenditure down by at least $5,000, he adds. Instead of needing 6.7 kilowatt-hours to produce 100 pounds of ice, the new machine will use 3.58 kilowatt-hours. (Hangen says he wants to drive energy consumption down to three kilowatt hours for 100 pounds, or 45 kilograms, of ice.)