Hydrogen is the holy grail of green technology, but it also comes with what may be insurmountable problems.

For starters, hydrogen is highly flammable. In 1937, the German dirigible Hindenburg, filled with about seven million cubic feet of hydrogen, exploded when landing in New Jersey. Thirty-six people died.

The fuel cell’s potential is tantalizing and simple. Hydrogen and oxygen are separated by a catalyst. The catalyst allows the hydrogen and oxygen to react at room temperature, releasing energy that’s harnessed as electricity. The byproducts are heat and water - making the fuel cell a potential savior to smoggy cities everywhere.

Hydrogen isn’t a source of energy. It stores energy and delivers it in a usable form, but hydrogen must be derived from compounds that contain it because the pure gas doesn’t occur in nature in commercially viable amounts.

The drawbacks: hydrogen contains less energy by volume than conventional vehicle fuels such as gasoline or diesel. This drives up the cost of transporting and storing hydrogen. It’s also unclear how hydrogen could be produced in sufficient quantities to keep the nation’s cars and trucks rolling.

Lacking a perpetual motion machine, the energy required to produce hydrogen would come from traditional sources - and burning oil, natural gas or coal produces greenhouse gases. Solar or wind power would solve that problem, but neither has the capacity to produce hydrogen in the needed volume. Nuclear power would be a good bet, except for the radioactive waste and the regulatory nightmare created by environmentalists who routinely make it difficult to build new plants.

“Given current technology, switching from gasoline to hydrogen-powered fuel cells would greatly increase energy consumption even if the hydrogen were extracted from water rather than from fossil fuels,” Donald Anthrop says in a report for the Cato Institute, a Libertarian think tank in Washington, D.C. “That’s because it takes a tremendous amount of electricity to harvest hydrogen and to deliver it to consumers. Moreover, a transition from gasoline to hydrogen would nearly double net greenhouse gas emissions attributable to passenger vehicles, given the current fuel mix in the electricity sector.”

Even if Team Genius solves these problems, the initial cost of fuel cells and the distribution system needed to supply hydrogen to the nation’s drivers are prohibitive.

Some peg the cost of a 200-horsepower fuel cell at about $75,000 - and that’s before it’s loaded into a sleek car filled with arctic air conditioning, a super-powered stereo, a global positioning system along with other gizmos.

There are no commercial hydrogen filling stations. Some estimate the stations would cost about $1 million each to build and at least 12,000 would be needed across the nation. Total cost: $12 billion.

Drivers are accustomed to driving about 300 miles on a tank of gas, but that number would be difficult to match with existing hydrogen technology. Hydrogen would have to be compressed -- perhaps to as much as 10,000 pounds per square inch -- and that would require bulky storage tanks guaranteed to give car designers fits.

The added weight would also reduce fuel efficiency while increasing tire and road wear. Hydrogen could be stored in liquid form, but that would require refrigeration, adding another system to the car and further increasing cost.

Hydrogen can be bonded to a metal, forming metal hydride. This reduces the storage space needed, but greatly increases the weight.

Despite hydrogen’s potential, its development as an auto fuel faces a Catch-22: Who will invest in the development of fuel cells for cars if there’s no reasonably priced hydrogen distribution system in the offing - and who will invest in hydrogen production and distribution until there are millions of fuel cell-powered vehicles on the road to assure a hefty return? This makes betting on Internet startups with no earnings and little more than a business plan in the 1990s look like a slam-dunk.

Main Street has generally shied away from direct investment in hydrogen-powered vehicles, but major automakers are working on fuel cells, including Honda (HMC), Toyota (TM), Ford (F) and General Motors (GM).

Maybe someday you can pack the kids into your hydrogen-powered car and drive to grandmother’s house, but don’t dump your ExxonMobil (XOM), Chevron (CVX) or Conoco (COP) stock just yet. In the meantime, keep the lesson of the Hindenburg in mind when dreaming about a hydrogen-powered future under smog-free skies.