Bike riding is tough enough without the prospect of having hydrogen stored next to your nether regions. For a long time, that was one of the main reasons why electric bikes didn't all have fuel cells. One of many. Now the company SiGNa Chemistry has a way to make it safer and more feasible, using a special powder.
The range extending system that SiGNa developed uses a sandy metal powder called sodium silicide, which creates hydrogen gas as soon as water hits it. According to the company, sodium silicide is "a safe, air-stable reactive metal powder" that produces hydrogen at about half the pressure of a soda can. I'm not exactly clear on precisely how it's made, but it looks like the powder can be formed by absorbing sodium in porous silicon dioxide, or reacting sodium directly with elemental silicon.
After the powder in the cartridge creates hydrogen gas, the byproducts are sodium silicate, which is actually pretty useful stuff, and water vapor. Once all the powder is spent, the cartridge containing it can be reused. With SiGNa's fuel cell system, electric bikes should be able to go up to 60 miles without any pedaling, as opposed to the 20-mile limit for most existing e-bikes. A spent cartridge can be swapped out for a new one with no need for recharging.
Unlike lithium-ion battery energy density, which is around 65 Watt-hours per kilogram, the cartridge has an energy density of more than 1,000 watt-hours per kilogram, according to a press release published by Wired's Gadget Lab. The cartridge doesn't need special water, either — even urine will be enough to make it work. You know, in case something goes horribly wrong on that ride.
Recently the company worked with the electric bike manufacturer Pedego to demonstrate the range extender at the Interbike International Trade Expo in Las Vegas. SiGNa describes the 1.5-pound cartridges as "inexpensive," but didn't give a price. Currently the company is taking pre-orders for the fuel cells, so it will likely be a while yet before they make their way into any vehicle.
There are purists who don't approve of assisted bikes, but I'm in favor of ones that actually run clean if they can get more people out of gas-chugging vehicles. And I won't deny that there are times, while heading up a certain steep local hill, when I wish my trusty bike could run on magic powder.
© 2012 Discovery Channel