I'm not sure if this website is credible, but here's what I found at

http://www.mb-soft.com/public2/hydrogen.html This website is clearly anti-hydrogen.

"Consider a mid-sized car, traveling at 60 mph down an Interstate Highway. It is well known (and easy to calculate) that roughly 40 actual horsepower is needed to maintain a constant speed. A horsepower is equal to 2544 Btu/hr, so we are talking about 102,000 Btu/hr of "actual" energy/work. For an hour's driving, we would therefore need 102,000 Btu of output energy, to ACTUALLY MOVE THE CAR THROUGH THE AIR AND WITH TIRE RESISTANCE. (A gasoline engine would use maybe 3 gallons of gasoline during that hour's driving [20 miles/gallon] which actually contained about 378,000 Btu of energy, but the engine/car efficiency is only roughly 25% to create the 102,000 Btu of output work.)

Consider now that a cubic foot of Hydrogen (not compressed) only contains 319 Btu per cubic foot. That hour of driving would therefore require (102,000 / 319) over 3,000 cubic feet of the Hydrogen! Notice that this does NOT refer at all to any engine or drive system, and is instead simply considering the Aerodynamic Drag of the vehicle pushing its way through the air at 60 mph and the Tire Resistance Drag due to the tire sidewalls flexing each time the tires rotate. The ACTUAL efficiency of existing vehicles being around 21% means that IF Hydrogen was burned as fuel in a vehicle, we would need to duplicate that actual 378,000 Btu of source chemical energy, and we would therefore need to use up (378,000 / 319) around 1200 cubic feet of Hydrogen for that hour trip.

We can say this same thing in terms of "gallons". A gallon of gasoline contains around 6 pounds, and has 126,000 Btus of energy in it. A "gallon" of hydrogen (gas) only contains around 40 Btus in it. Quite a difference! Instead of a two cubic foot gasoline tank (15 gallons) in your car, you would need a tank more than 3,000 times bigger, over 6,000 cubic feet, for the equivalent Hydrogen! That's a little more than TWO standard semi trailers (8'wide x 8'high x 45' long or 2900 cubic feet each). Pretty big gas tank!"

__________________