From an engine standpoint, the path from here to hydrogen nirvana looks fairly clear: Start burning it in internal combustion engines now, and bring fuel cells on line sometime in the coming decade. But the engine is just half the puzzle. The other half involves figuring out how to make enough cheap hydrogen and build a network of fueling stations. And not everyone is convinced that this is either possible or desirable. The Cato Institute, a highly respected libertarian think tank, dismisses the idea of a hydrogen economy as a fantasy, while others call it a smokescreen to avoid raising fuel efficiency in the here and now. Their argument is multifaceted, but it can be cooked down to the claim that at every stage of the process, hydrogen is simply too expensive, both economically and environmentally. Building out a whole parallel infrastructure of hydrogen production facilities and gas stations would cost hundreds of billions of dollars, and it would have to be done up front, before consumers will switch en masse to hydrogen cars. As it's now produced, hydrogen costs far more than gasoline and won't get cheaper when demand for it surges. And since the main way of making it involves burning natural gas, which produces CO2, hydrogen does nothing to address global warming. One study concluded that converting to a hydrogen-based economy would double both net energy consumption and net greenhouse gas emissions. Better, say the skeptics, to skip the intermediate step of making hydrogen and just redesign cars to burn domestically produced natural gas.

The response of hydrogen's fans is just as multifaceted, but it can also be cooked down to a couple of basic arguments: The infrastructure will cost a fraction of the pessimistic estimates, and progress on all technological fronts will bring costs and environmental impact into acceptable territory within a decade. Since each piece is crucial, let's consider them in turn:

Cheap Hydrogen

Hydrogen is already being produced on a commercial scale by industrial gas makers like Air Products, Praxair, and BOC, which operate dozens of plants around the world where they mix natural gas and steam to "reform" about 60 million tons of hydrogen each year. Take a map of the United States and draw a 50-mile circle around every place where hydrogen is made, and you'd cover most of the population. Hydrogen produced this way and delivered by truck costs about $4 per kilo, which is the energy equivalent of a gallon of gas. So the problem isn't hydrogen's availability but its price. On that front, there's plenty of activity and a certain amount of guarded optimism. Scaling up existing plants and building more of them would probably generate economies of scale in production and transportation that might, all else being equal, knock a dollar or so off the gallon-equivalent price. But it would still leave the industry vulnerable to gyrations in the price of natural gas and charges that it contributes to rather than fixes global warming. The last point is a deal breaker, so the search is on for new hydrogen sources.

Electrolysis is one possibility. Run an electric current through water and it separates into hydrogen and oxygen. Neat, huh? Unfortunately, hydrogen produced this way is more expensive than that derived from steam reformation, though it does become more attractive if the electricity source is cheap and/or environmentally benign. So as wind turbines and solar cells gain efficiency, setting up electrolysis plants to store excess peak power in the form of hydrogen has a certain green symmetry. Another interesting possibility is hydrogen "gas stations" where cheap rooftop solar panels would run on-site electrolysis facilities. Eliminating the need to transport hydrogen from distant plants would lower the cost a bit. Meanwhile, lots of new ideas for improving the economics of electrolysis are being pursued, many, of course, with "nano" prefixes. California start-up QuantumSphere, for instance, claims to have developed "highly reactive catalytic nanoparticle coatings" that increase the effective surface area of electrodes and raise the efficiency of the electrolysis process. The company estimates that its breakthrough will lower the price of hydrogen to competitive levels.

And now that people are looking, it turns out that hydrogen can be made in lots of other, less obvious ways.  ....read more