Hydrogen's bid to become the fuel of future cars has hit a few roadblocks. First, in May, Toyota was forced to recall its fuel-cell hybrid vehicle in Japan when one of the cars leaked hydrogen from its tank. Then, a recent announcement revealed that supplies of natural gas—our main source of hydrogen—have reached their lowest levels in a quarter century.

Now, a study by a team of scientists from the California Institute of Technology (Caltech) is claiming that contrary to the hype, hydrogen—as a fuel for future fuel-cell vehicles (FCVs)—may not be environmentally friendly after all. Fuel cells generate electricity by chemically combining hydrogen and oxygen.

In a recent Science magazine report, the researchers say that the amount of hydrogen that will likely leak from FCVs (about 10-20%), coupled with comparable losses from the hydrogen production process, could harm the ozone layer, causing a 10% loss in atmospheric ozone. Nevertheless, the scientists concede that supplanting fossil fuels with hydrogen fuel cells would boost air quality in urban areas.

The Caltech team estimates that 132,000 lbs. to 265,000 lbs. of hydrogen would escape into the atmosphere annually from an expected 10-20% loss of hydrogen—four to eight times the amount of hydrogen currently leaking into the atmosphere due to human activities. This would produce additional water at high altitudes and augment the dampening of the stratosphere, the scientists say. As a result, the lower stratosphere would cool, and the ozone chemistry would be thrown off balance.

The magnitude of the damage to the stratospheric ozone levels would be determined in part by the amount of hydrogen released into the stratosphere by natural or human activities, the researchers say. They propose several scenarios in which the harm could be comparable to the damage chlorofluorocarbons wreaked on the ozone layer.

John Eiler, assistant professor of geochemistry, says that how hydrogen affects the environment will rest on whether the planet can consume excess amounts of hydrogen produced by human activities. Earth can either absorb the gas in soils or rely on other gases in the atmosphere to counteract it. "The balance of these two processes will be the key to the outcome," he explains.

If the hydrogen leakage does prove to be harmless, he says, then developers can concentrate on the most cost-effective systems and save billions of dollars in needless safety measures. Eiler says the industry has "a unique opportunity to study the anthropogenic implications of a new technology before it's even a problem."

Many scientists and industry insiders, however, think that the Caltech researchers have overestimated the amount of hydrogen that will likely leak into the atmosphere. For example, Larry Burns, vice president of research and development for General Motors Corp., says, "There's a lot to learn scientifically and we appreciate asking the question at this stage. That said, it's highly unlikely that we would put forth this much effort to help create the hydrogen economy and then accept a 10% to 20% waste rate being vented into the atmosphere." Burns points out that hydrogen is worth too much for that to be acceptable. "We certainly don't have a 10% to 20% (waste) rate with gasoline, even at $1.50 a gallon," he adds.

What's more, the two other roadblocks—low supplies of natural gas and defective gas tanks—hardly faze fuel-cell car developers who are confident they can develop alternative resources for hydrogen and repair leaky tanks.

They admit, however, that fuel-cell stacks, which combine hydrogen with oxygen, are still not sturdy and affordable enough for widespread use in cars. And hydrogen storage and distribution remains an obstacle. While oxygen can be extracted from the air, hydrogen is hard to store and distribute, requiring the development of an infrastructure of hydrogen refueling stations. "There is no infrastructure for getting hydrogen from the oil or gas company to the gas station safely, cost effectively and in a way that is environmentally beneficial," says Andrew Bocarsly, director of graduate studies for chemistry at Princeton University.

As a result, many predict that it will be improvements to the conventional gasoline engine—not advances in the fuel-cell stack—which will drive most of the gains in fuel economy in the near future. In fact, Bernd Bohn, a key executive at Robert Bosch, the German auto-components giant, recently estimated that internal combustion engines would still hold 95% of the market in 2015 and 85% in 2025, which means that FCVs may take decades to make inroads.

Sources:
Hydrogen Doesn't Come Squeaky Clean
Herb Shuldiner
Ward's Auto World, Aug. 1, 2003
www.wardsauto.com

Hydrogen Is No Gas, Yet
Mark Baard
Wired News, June 23, 2003
www.wired.com/news/technology/0,1282,59322,00.html

21st Century Cars Hit the Road
Thane Peterson
Business Week, Sept. 4, 2003
www.businessweek.com/technology/content/sep2003/tc2003094_5514_tc127.htm