The Truth About Hydrogen - Popular Mechanics
When assessing the State of the Union in 2003, President Bush declared it was time to take a crucial step toward protecting our environment. He announced a $1.2 billion initiative to begin developing a national hydrogen infrastructure: a coast-to-coast network of facilities that would produce and distribute the hydrogen for powering hundreds of millions of fuel cell vehicles. Backed by a national commitment, he said, "our scientists and engineers will overcome obstacles to taking these cars from laboratory to showroom, so that the first car driven by a child born today could be powered by hydrogen, and pollution-free." With two years to go on the first, $720 million phase of the plan, PM asks that perennial question of every automotive journey: Are we almost there?
And the inevitable answer from the front seat: No.
At present, 95 percent of America's hydrogen is produced from natural gas. (...) And there's the rub: Using dirty energy to make clean energy doesn't solve the pollution problem-it just moves it around.
Chilled to near absolute zero, hydrogen gas turns into a liquid containing one-quarter the energy in an equivalent volume of gasoline. (...) The cooling process requires a lot of energy, though-roughly a third of the amount held in the hydrogen.
Some hydrogen-powered vehicles use tanks of room-temperature hydrogen compressed to an astounding 10,000 psi. The Sequel, which GM unveiled in January 2005, carries 8 kilograms of compressed hydrogen this way-enough to power the vehicle for 300 miles. Refueling with compressed hydrogen is relatively fast and simple. But even compressed, hydrogen requires large- volume tanks. They take up four to five times as much space as a gas tank with an equivalent mileage range.
Currently, most hydrogen is transported either in liquid form by tankers or as compressed gas in cylinders by trailers. Both methods are inefficient. Trucking compressed hydrogen 150 miles, for instance, burns diesel equivalent to 11 percent of the energy the hydrogen stores. It also requires a lot of round trips: A 44-ton vehicle that can carry enough gasoline to refuel 800 cars could only carry enough hydrogen to fuel 80 vehicles.