ABSTRACT
As hydrogen nds increasing use in emerging applications, the need for improved storage methods is becoming more important. Hydrogen has a normal boiling temperature of about 20 K and a critical temperature of approximately 33 K, above which a liquid cannot be formed through the application of pressure. It is therefore a gas at essentially all normal use and storage temperatures. Hydrogen is the lightest of all elements, and since it behaves as an ideal gas close to ambient temperatures (∼300 K) and pressure conditions, it has a very low normal density of 0.09 g/L (or 11 L/g) at 288 K and 0.1 MPa. To put this density in perspective, with a lower heating value of about 120 kJ/g, the normal energy density of hydrogen is 10 kJ/L. While gasoline has a specic energy of only about 42 kJ/g, its energy density is 32,000 kJ/L [1] and thus has an energy density about 3,200 times greater than normal hydrogen gas.
