24 December 2004
Hydrogen and Stupidity, Together at Last
In the quest for alternatives to fossil fuels and ways to slow global warming, many have latched on to hydrogen fuel cells. At first glance, they seem wonderful: the only immediate byproduct is water vapor, the fuel source (hydrogen) is the most abundant element in the universe, they're even quiet. But, as the San Francisco Chronicle reports, the devil is in the details:
Auto-industry ads depict hydrogen cars as the vehicular route to clean, blue skies.That should be a clue right there that something is fishy.
President Bush and Gov. Arnold Schwarzenegger are among their biggest champions.
The politicians' enthusiasm for the technology -- a leading proposal to solve global warming -- is shared by many scientists.It could also worsen ozone layer depletion. Bob Park observes that "hydrogen leakage could gobble up ozone faster than CFCs." (more below)
But reality could prove more complex, some critics say. Among the problems detailed at the American Geophysical Union conference in San Francisco last week:
-- Hydrogen is a very "leaky" gas that could escape from cars and hydrogen plants into the atmosphere. This could set off chemical transformations that generate greenhouse gases that contribute to atmospheric warming.
-- The extraction of hydrogen for cars from methane, which is currently the richest available source of hydrogen, will generate carbon dioxide, a major greenhouse gas.Actually, if anything, that's quite an understatement. As Bob Park notes, "95% of the hydrogen currently produced in the United States comes from steam methane reforming, which belches CO2 and does nothing to promote energy independence." And just who would profit from this? Why, "oil companies are gearing up to generate [hydrogen] from methane."
-- Hydrogen can also be extracted from ordinary water via a process called electrolysis. However, using current technology, mass electrolysis of water would require intense sources of energy. If those energy sources burn fossil fuels, they, too, would generate greenhouse gases.There's also the tricky little issue of thermodynamics. If the hydrogen is made through electrolysis, it's generated by separating water into oxygen and hydrogen (2H2O + energy -> 2H2 + O2). Then to generate power in a fuel cell, the hydrogen binds with available oxygen (2H2 + O2 -> 2H2O + energy). Anyone who claims this 'produces' energy, rather than acting as a kind of chemical battery, is selling you a perpetual motion machine. In fact, some Congressional energy bills rejected the First Law (probably) and Second Law (definitely) of thermodynamics. It's really quite simple if you always remember Ginsberg's theorem:
- You can't win
- You can't break even
- You can't get out of the game
"I'm supportive of research and development, but we are at least two decades away from (deploying) the vehicles on a mass level," said MIT-educated physicist Joseph J. Romm, a former U.S. Department of Energy official, in an interview. Romm's book, "The Hype About Hydrogen: Fact and Fiction in the Race to Save the Climate," was published earlier this year by Island Press.Aside from the greenhouse gases produced in steam methane reforming or whatever power generation (coal, natural gas, garbage, etc.) is used, however, it appears to be mostly safe. I use so many caveats because molecular hydrogen isn't quite as inert as it is often portrayed (note: by "inert" I mean 'chemically nonreactive' not 'nonflammable'):
"Americans are very much believers in technology and optimism, and yet when you look at the compelling details" about hydrogen cars, Romm said, "it doesn't make bloody much sense."
Economically, hydrogen devices remain highly unattractive: "Fuel cells are very expensive," Romm said. "The demonstration vehicles all cost hundreds of thousands of dollars."
Atmospheric scientists, meanwhile, are trying to figure out how Earth's atmosphere would be affected by leaked hydrogen from cars, hydrogen gas stations, delivery trucks and hydrogen production plants. Unfortunately, the politicians aren't necessarily getting the best scientific advice on the atmospheric issue, said Professor Michael J. Prather of UC Irvine at the geophysics conference on the atmospheric impact of hydrogen cars.There's also some discussion of hydrogen production by electrolysis used in conjunction with alternative energy sources, such as wind power. I think this is a reasonable long-term idea, as long as we don't delude ourselves into thinking the hydrogen is an energy source - barring the discovery of a hydrogen well, it's a storage method. The potential environmental problems of hydrogen itself are also worth addressing, but (a) we have a couple decades before widespread use is even feasible during which we can study the potential effects; and (b) we already know the effects from fossil fuels are very negative and ongoing. So hydrogen power isn't something to be afraid of or to avoid, but it's often hopelessly oversold to the detriment of genuine progress on energy independence and environmental protection.
A 2004 National Academy of Sciences report on "The Hydrogen Economy" was prepared by "economists and engineers, remarkably lacking any atmospheric scientist or biogeochemists who understand the natural (atmospheric) cycle of H2," said Prather, a professor of Earth system science and former editor-in- chief of Geophysical Research Letters. "It is surprising that all of these groups examining a hydrogen economy are secure in the belief that H2 is a pure fuel, safe and harmless to the environment," although studies suggest otherwise.
One problem is that hydrogen leaked into the atmosphere binds with oxygen molecules, forming water vapor and clouds. A change in cloud abundance in some regions might alter the local temperature and climate -- for example, the climate might warm if the clouds trap heat like blankets, or the climate might cool if they reflect sunlight back into space.
"The widespread use of hydrogen fuel cells ... would cause stratospheric cooling, enhancement of the heterogeneous chemistry that destroys ozone, an increase in noctilucent clouds, and changes in tropospheric (lower-atmosphere) chemistry and atmosphere-biosphere interactions," scientists from Caltech and Jet Propulsion Laboratory in Pasadena proposed in the journal Science in 2003. Noctilucent clouds are eerie high-altitude clouds whose abundance, some scientists suspect, is influenced by climate change.