“In the best case scenario, the transition to a hydrogen economy would take many decades, and any reductions in oil imports and carbon dioxide emissions are likely to be minor during the next 25 years,” the National Academy of Sciences says in a report.
The fuel cell’s crisp simplicity is stunning: It consists of hydrogen and oxygen separated by a catalyst. The catalyst allows the hydrogen and oxygen to react at room temperature and the energy that’s released is harnessed as electricity. The only byproducts are heat and water.
Hydrogen is an energy carrier – not a source of energy. It stores and delivers energy in useable form, but must be derived from compounds that contain it. Hydrogen doesn’t occur free in nature in useful amounts.
Hydrogen contains less energy by volume than conventional fuels such as gasoline or natural gas, making its transportation and storage costly. Fuel cells require a constant supply of hydrogen – the biggest bump on the road to a non-polluting energy source because no one is yet sure how hydrogen can be efficiently produced in sufficient quantities, transported and stored at a competitive price to fuel the nation’s vehicles.
Burning oil or coal to produce the energy needed to create hydrogen produces emissions. The long-term goal is to develop hydrogen with renewable, non-polluting energy such as solar or wind power. But such sources don’t have the capacity to produce hydrogen in the needed volume, and probably won’t in the future. Ethanol could be used, but there isn’t enough production capacity from corn to replace gasoline or diesel. Nuclear power could be used to extract hydrogen molecules from water, but the environmental lobby has made it difficult to build new plants. Then comes the problem where to store the nuclear waste.
Even if the supply problem can be solved, the initial cost of fuel cells as well as storage and distribution of hydrogen are prohibitive.
The current cost of a 200-horsepower fuel cell system is about $75,000, Plunkett says.
There are no commercial hydrogen filling stations. Some estimate that each station would cost about $1 million to build and that 12,000 stations in cities across the nation would be needed to put the new fuel within two miles of about 70% of the population. That’s $12 billion for the stations alone.
Hydrogen is a highly flammable gas. It reacts instantly with oxygen if exposed to a spark – the 1937 explosion of the German dirigible Hindenburg, filled with about seven million cubic feet of hydrogen, is the best known example.
“It’s also difficult to store enough hydrogen in a vehicle to take it the 300-plus miles that drivers are used to getting on a tank of gasoline,” Plunkett says. “To do so, hydrogen must be compressed to 10,000 pounds per square inch and stored on board in bulky pressure tanks.”
Such tanks would drive designers nuts and the added weight would reduce the car’s fuel efficiency. Hydrogen could be stored in liquid form, but that would require constant refrigeration, adding another mechanical system and more weight to the car.
It's possible to chemically bond hydrogen to a metal, forming a metal hydride, which significantly reduces the amount of storage space required. However, the storage system weighs about 700 pounds.
Despite the problems, major automakers are working on fuel cells, including General Motors, Ford, DaimlerChrysler, Toyota and Honda.
In his 2006 State of the Union address, President Bush outlined a $1.2 billion hydrogen fuel initiative. Combined with the current programs at the U.S. Department of Energy, the program seeks to develop hydrogen-powered vehicles by 2020.
It’s a lofty plan that someday might ease the nation’s dependence on oil from unstable regions of the world – just don’t plan any cross-country trips in your spiffy hydrogen-powered car any time soon.