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Shortly after Michael Lefenfeld graduated from Washington University in St. Louis in 2002, his grandfather asked him to solve a problem. "He wanted something that he could take to the bathroom with him and drop in the toilet ... an air freshener of sorts," says Lefenfeld, who majored in chemical engineering. "I started thinking about how to volatilize a fragrant oil off the surface of toilet bowl water."
Lefenfeld hired James Dye, a chemist at Michigan State University, to help with the project. In 2004 the pair patented the world's first process for producing air-stable alkali metals. These compounds are normally highly reactive; they combust when exposed to most liquids and vapors. Lefenfeld and Dye found a way to keep them from burning in air, a feat they quickly realized had plenty of non-bathroom uses. That year they founded the Manhattan company SiGNa Chemistry.
Most of SiGNa's business is in selling alkalis to chemical companies that use them in oil refining, drug development, and more. For the past three years Lefenfeld, now 30, has focused on adapting them for fuel cells. SiGNa makes a sodium silicide powder that, when mixed with water, releases hydrogen gas that many fuel cells use to create an electrical charge. SiGNa's powder is nontoxic and can be triggered by almost any water—salt or fresh—or even urine. Lefenfeld says it can efficiently power anything that uses three kilowatts or less, from laptops to lawn mowers.
This summer the California company Pedego will start selling an electric bicycle that includes a refillable SiGNa fuel cartridge to extend the range of its lithium battery from 20 to 100 miles. In October, the Swedish fuel cell company myFC plans to begin selling a brick-size cell phone charger that will run on SiGNa "PowerPukks." Each aluminum puck, about the size of its hockey namesake, is enough to provide 10 hours of juice for a typical smartphone. The charger will cost around $200, and each puck will run about $2.50. SiGNa supplies the fuel and builds custom canisters for both Pedego and myFC.
John Kopasz, a chemist at Argonne National Laboratory, says the advantage of SiGNa's fuel is that "you don't have to supply heat," and "the starting materials are relatively cheap." The downside is that its powder is not regenerable, so it's not a contender in the race to power hydrogen-fueled cars.
Still, Lefenfeld says there are plenty of uses beyond bikes and smartphones. SiGNa currently is using a U.S. Agency for International Development grant to produce mobile power units for disaster relief areas. And the invention solved his grandfather's problem: The "plop and drop" tablet "made the bathroom smell really, really nice," says Lefenfeld.
His grandfather asked for a toilet-activated air freshener
Air-stable alkali metals with a variety of industrial uses
Could be used to power laptops and lawn mowers