Also see: Fuel Cell: Hydrogen's Dirty Secret
WASHINGTON—While hydrogen is touted as a clean fuel waiting to replace fossil energy sources, a new study concludes its widespread use could increase damage to the ozone layer that protects Earth from ultraviolet radiation.
The report in Friday's editions of Science magazine says such trade-offs shouldn't prevent development of hydrogen fuel cells, but they should be taken into account when considering what measures might be needed to limit any environmental downside of a hydrogen-fuel economy.
Ever since President George W. Bush earlier this year singled out hydrogen development as a top energy priority, the fuel has been the buzzword in energy debates.
Congress plans to pump billions of dollars into hydrogen research as part of its energy agenda and the Bush administration is talking about an international push to develop the fuel.
Unlike fossil fuels—coal, oil or natural gas—which produce an array of chemicals that pollute the air as well as the greenhouse gas carbon dioxide, a hydrogen fuel cell when making energy releases only water as a byproduct.
But in the Science article, researchers at the California Institute of Technology raised the possibility that a hydrogen economy will not necessarily be a totally environmental friendly one.
Their study says that if hydrogen fuel replaced fossil fuels entirely it could be expected that 10 percent to 20 percent of the hydrogen would leak from pipelines, storage facilities, processing plants and fuel cells in cars and at power plants.
Leaks could cool stratosphere
Because hydrogen readily travels skyward, the researchers estimated that its increased use could lead to as much as a tripling of hydrogen molecules—both manmade and from natural sources—going into the stratosphere, where it would oxidize and form water.
"This would result in cooling of the lower stratosphere and the disturbance of ozone chemistry," the researchers wrote, resulting in bigger and longer-lasting ozone "holes" in both the Arctic and Antarctic regions, where drops in ozone levels have been recorded over the past 20 years. They estimated that ozone depletion could be as much as 8 percent.
The loss of some of the Earth's ozone layer is of concern because ozone blocks much of the sun's ultraviolet light, which over time can lead to skin cancer, cataracts and other problems in humans.
Ozone depletion has been contained with the banning and phaseout by international treaty of ozone-killing chlorofluorocarbons, or CFCs.
But the Cal Tech researchers said huge increases in the concentration of hydrogen in the stratosphere "could substantially delay the recovery of the ozone layer" as a result of CFC controls, even if a hydrogen economy is still decades away.
John Eiler, an assistant professor of geochemistry at Caltech and one of the article's authors, acknowledged there remains much that is not fully understood about the hydrogen cycle. For example, much of the leaking hydrogen might become absorbed in the soil, instead of drifting into the sky.
"If soils dominate, a hydrogen economy might have little effect on the environment. But if the atmosphere is the big player, the stratospheric cooling and destruction of the ozone ... are more likely to occur," said Eiler.
Risks called exaggerated
Caltech scientist Tracey Tromp, another of the authors, said that with advanced warnings of a problem, a hydrogen energy infrastructure could be fashioned to allow more control of leaks and reduce the adverse environmental impact.
"In the past ... we always found out that there a were problems long after (chemicals or fuels) were long in use," says Eiler, citing the case of CFCs and ozone depletion, and carbon dioxide that long was viewed as not a problem when released from burning fossil fuels, but now is the principal "greenhouse" gas linked to potential climate change.
Nejat Veziroglu, president the International Association for Hydrogen Energy and director of the Clean Energy Research Institute at the University of Miami, expressed skepticism about the Caltech findings.
"Leakage will be much less than what they are considering," he said.
Jeremy Rifkin, a leading advocate for developing a hydrogen economy, said "when you move into a new energy source you have to assume there's going to be some environmental impact" but that hydrogen, as a replacement for fossil fuels, still "is our hope for the future."
"We know we can't continue to burn fossil fuels because the planet is warming up. And we know hydrogen is where we have to head," said Rifkin in an interview.
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