Storing Hydrogen

Hydrogen has a low energy density per unit volume. Because hydrogen is so light, it is hard to store a large amount of it in a small space. This is a challenge for auto engineers who want to match today’s 300-mile vehicle range.

Just to get an idea of what this means, it takes 2 cubic feet of space to store 15 gallons of gasoline on board a typical car. To store an amount of hydrogen with the same energy content at room temperature and atmospheric pressure, you would need 6,218 cubic feet. To store that much hydrogen, you would need about 9 rectangular tanks the size of a full-size pickup truck (18 feet long, 6 1/2 feet wide, and 6 feet tall).

Of course, hydrogen is a gas, and it can be stored more compactly in pressurized tanks like those used for compressed natural gas and propane. But a cubic foot of hydrogen compressed to 6,000 pounds per square inch still contains only 110,000 BTU, about the same as one gallon of gasoline.