A study by a team of Caltech scientists questions the much-promoted environmental friendliness of hydrogen as a fuel for future fuel-cell vehicles (FCVs).
The researchers warn that an expected 10% to 20% leakage of hydrogen from FCVs, as well as similar losses from the hydrogen-production process, could cause a 10% decrease in atmospheric ozone. The scientists nonetheless admit the replacement of fossil fuels with hydrogen fuel cells would improve urban air quality.
The Caltech team reported its findings recently in Science, published by the American Assn. for the Advancement of Science. It estimates that 132,000 lbs. to 265,000 lbs. of hydrogen would be released into the atmosphere annually from a 10% to 20% leakage of hydrogen — four to eight times as much hydrogen as is now released into the atmosphere by human activities.
This would create additional water at high altitudes and increase the dampening of the stratosphere, the researchers say. The result would be a cooling of the lower stratosphere and disturbance of ozone chemistry. How much hydrogen escapes into the stratosphere from natural or human activities would have a bearing on how much damage would occur to the stratospheric ozone levels, the team adds.
The Caltech scientists suggest certain scenarios in which the impact could be similar to what chlorofluorocarbons inflicted on the ozone layer.
John Eiler, assistant professor of geochemistry, says hydrogen's impact on the environment depends on whether the Earth has the ability to consume excess hydrogen created by human activities. The hydrogen either will be absorbed in soils or react with other gasses in the atmosphere. “The balance of these two processes will be the key to the outcome,” he says.
The researcher adds that if hydrogen is shown to be benign in all respects, then developers could pursue the most cost-effective technologies and save billions in unnecessary safeguards. Eiler says this is “a unique opportunity to study the anthropogenic implications of a new technology before it's even a problem.”
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.” He says hydrogen is too valuable to let such waste occur. “We certainly don't have a 10% to 20% (waste) rate with gasoline, even at $1.50 a gallon.”
