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On the Road to Hydrogen

It’s the most abundant element in the universe. It is also one of the most difficult to work with, and that’s one of the obstacles in the effort to create a so-called “hydrogen economy.”

A new approach to storing hydrogen in solid form could overcome one of the most difficult challenges to using hydrogen as a clean alternative to gasoline.

“We’re going to make hydrogen a practical fuel,” asserts Bob Stempel.

If the name is familiar, that’s because he briefly served as CEO of General Motors Corp. in the early 1990s. These days, Stempel is still deeply immersed in the auto industry, but now as chairman of a quirky Detroit company known as Energy Conversion Devices. Over the last few decades, ECD has patented a number of innovative technologies in a wide range of fields, from copiers to solar cells to batteries – it developed the high-power nickel metal-hydride cell, among other things. Now ECD engineers believe they can solve the thorny problem of hydrogen storage.

The lightest element in the universe, hydrogen is being touted these days as a sort of wonder drug of fuels. Most of the major automakers are racing to develop commercially viable fuel cell powertrains. A few others, such as BMW, are focusing on hydrogen powered internal combustion engines. Either way, when you use it, all you get out the tailpipe is water vapor.

Even if such technologies prove feasible and affordable, there’s the issue of producing enough hydrogen for the nation’s fleet of nearly 200 million automobiles, delivering the gas to your local service station, and then storing it onboard your car.

Bringing it all together

“If you’re going to have a hydrogen economy,” cautions ECD founder Stan Ovshinsky, “you’re going to have to have the entire system.”

The storage problem might seem simple to solve and, indeed, there are a number of alternatives. You can compress the gas, but even at the crushing pressure of 10,000 pounds per square inch, you need so many tanks, range is limited to little more than 150 miles on a fill-up. You can cool it to liquid form, but that requires a temperature as low as you’d find in deep space, near absolute zero. Getting there requires a lot of energy and over time, liquid hydrogen will boil off from a parked car.

The approach unveiled by ECD is to store hydrogen in solid form. Ironically, the material that does this is quite similar to the compound in a nickel metal-hydride battery. Hydrides are so named because they tend to bond with loose hydrogen. But apply heat and the hydrogen breaks free, and can be fed into a fuel cell or IC engine.

Hydride storage is under development by a number of companies, it must be noted, but ECD is the first to put it into serious field testing. The firm last week unveiled a modified 2002 Toyota Prius hybrid-electric vehicle. Much of the HEV was left as you’d find it at the local showroom. But instead of running on gasoline, the Prius’s engine was converted to use hydrogen instead of gasoline.

Open the trunk and you’ll find a prototype hydride tank developed by Texaco Ovonic Hydrogen Systems, a joint venture between ECD and Chevron-Texaco. The tank can hold about 3 kilograms of hydrogen, each kg equal to roughly a gallon of gasoline. It might not sound like much, but in the current configuration, that’ll give you about 150 miles range. And the plan is to double the volume of hydrogen, so the Prius could match the range of a conventional automobile.

That’s one of the promises, anyway, and there are others still requiring a small leap of faith. According to ECD officials, it currently takes about 10 minutes to get a 90 percent fill-up, with the goal to cut that time in half.

Fill 'er up -- quickly

Of course, that would require you to find a filling station that not only offered hydrogen, but which used the special, three-piece nozzle currently required by the ECD tank.

ECD Hydride Storage TankThe entire storage assembly weighs over 400 pounds, a hefty penalty compared with a conventional gas tank. And even though it’s a potentially significant improvement compared with compressed or liquid hydrogen storage, the hydride tank is still relatively inefficient. When full, hydrogen accounts for only about 1.6 percent of the system’s total weight.

There are more efficient hydride compounds, explains Ovshinsky, but to get them to release their hydrogen would require temperatures of as much as 300 degree Celsius. And that would require a lot of energy. The system shown last week draws upon waste heat generated by the Prius’s internal combustion engine that would normally be shed through the radiator. And at just 90 degrees C, the system could rely on waste heat from a cooler-running fuel cell, as well.

As to the price tag? “Our goal is to compete with any hydrogen storage system,” contends Rosa Young, the vice president of technology for Texaco-Ovonics. Eventually, experts say, that will mean not a lot more than a conventional gasoline fueling system, though getting there will be a challenge.

Indeed, despite all the enthusiasm over hydrogen, the reality of getting the fuel into widespread use remains daunting. Few expect to see the fuel cell in widespread use before the latter part of the next decade. But it might never happen if the storage issue isn’t solved.

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