Hydrogen economy's effects on stratospheric ozone disputed.

In July, scientists from NASA, Georgia Tech, the University of Wisconsin, and Hampton University in Virginia announced a notable slowing in the rate of destruction of the ozone layer. While not a reversal of the thinning, the detected change is viewed as a significant turning point in the effort to heal the ozone layer, due to curbs on chlorofluorocarbon (CFC) emissions.

These findings heightened the significance of a study recently released in Science, which found evidence that the leakage of hydrogen gas during production, storage, and distribution could moisten and thus cool Earth's stratosphere, making the ozone hole larger, deeper, and more persistent. The study, conducted by scientists at the California Institute of Technology (CalTech) and the Jet Propulsion Laboratory (JPL), suggested that recovery of the ozone layer could be delayed considerably, depending on how soon a hydrogen economy develops. It also revealed additional potential impacts of increased hydrogen emissions, including their potential to affect lifetimes of various gases in the stratosphere, including some greenhouse gases. If such findings were to prove true, the development of a hydrogen-based economy, purported to be the answer to a host of concerns ranging from energy security to global warming, could in itself pose a serious threat to some of Earth's natural systems.

However, the Science paper is not without critics. Physicist Amory Lovins, an energy analyst and CEO of the Rocky Mountain Institute, contends that the article "should not have passed peer review," and that the whole argument is invalid because it is based on faulty assumptions. The CalTechJPL study projects that human-caused hydrogen emissions would rise to four to eight times current levels if all technologies now running on oil or gas were replaced by hydrogen fuel cells. But Lovins argues that the study authors grossly overstate current hydrogen leakage rates (hydrogen is used today in several industries, with some leakage during commercial transport) by misreading existing literature. Lovins also says that a hydrogen economy based on renewable energy would reduce or eliminate most of the present causes of hydrogen emissions (from fossil fuel and biomass usage) and that hydrogen is more efficient than conventional fuels (less is needed to provide the same energy services). As a result, a hydrogen economy could actually reduce current hydrogen emissions by as much as one to two orders of magnitude.