Basically, there are no real technical challenges to overcome for the vehicles. Technology exists for all components of hydrogen powered vehicles. The largest hurdle now is the lack of an infrastructure to produce, distribute, and deliver hydrogen to where people with hydrogen powered vehicles will need it - right down the street. Someone is going to have to go out on a limb and invest in this delivery system, gambling that it will become utilized to the point of profit. Another interesting application of hydrogen fuel cell energy is for home and commercial use. There are homes in upstate NY that are powered by fuel cells experimentally. Rather than revamping the power distribution grid of the country, stand-alone fuel cell power generators could be utilized, making obsolete much of the aging power grid. This would also provide a stable customer base for a company considering investing in hydrogen distribution and delivery.

Perhaps the biggest technical challenge remaining is how to store the hydrogen on the vehicle. Hydrogen just doesn't stay in typical tanks, the tiny molecules just leak through most tank materials so you can't keep a multiple-day supply in a light-weight tank. The most promising solution is currently a tank full of stuff that the hydrogen is more comfortable staying in - kinda like a hydrogen friendly sponge. I don't think they have a tank you can fill and use for days yet, and I don't think they can get nearly as many miles out of a tank of hydrogen as a tank of hydrocarbons - the volume/energy density is too low. Don't believe the comments about energy companies preventing new technologies. If it was possible to market hydrogen at a profit they would do it. If a car company could sell H powered cars at a profit, they would. As soon as the technology is viable there will be plenty of new and old energy companies anxious to serve the market. The other big hold-back is probably the cost of the fuel. The easiest way to get H is to separate water with electricity and it is likely more economical to use that electricity to run the cars directly.

I've been doing a lot of research on this subject, mostly inspired by the peak oil / nautral gas problem the world is beginning to face. The main problems with the hydrogen fuel cell solution are as follows: 1. Hydrogen is a carrier of energy, not a source. It holds the energy that is put into it, but does not generate its own energy. 2. In order to create hydrogen en masse, a great deal of energy is required to produce it from other finite energy sources like petroleum or nuclear power. Obviously it would be nice if we could someday use fuel cells in our vehicles, but we also need a way to generate energy from non-finite sources like fusion, solar, or wind/sea turbine technologies.

hydrogen explosions accidents infrastructure transportation of the hydrogen to station mileage issues repair issues recycling issues politic issues local issues society acceptance issues costs technology competing technology carbon footprint to name a few