Once hydrogen is produced, the challenge becomes how to store it. Hydrogen is a bulky gas, making it much more difficult to store than gasoline, especially on board a vehicle. To be a viable and effective energy carrier, hydrogen will need to be stored at production sites, refueling stations, and stationary power sites. Storage issues also come into play in transporting hydrogen from its point of production to point of use.

Storage requirements for stationary applications are typically less stringent than those for storage on board a vehicle. For transportation, the key technical challenge is how to store enough hydrogen for a conventional driving range (> 300 miles) within the constraints of weight, volume, efficiency, safety, and cost.

One possible solution is to store hydrogen in hydride form. Hydrides act as sponges, reversibly absorbing hydrogen into the interstitial spaces of a crystal lattice. The two main classes of hydrides—metal and chemical—achieve hydrogen storage and release through different mechanisms, all of which require additional research before they are fully understood and incorporated into hydrogen systems.

Sandia researchers have developed a promising new class of hydrides called complex metal hydrides. These materials—known as alanates—operate at near-ambient temperatures and pressures and are theoretically able to store a greater percentage of hydrogen than other hydrides. Because of this, alanates are considered to be the most promising of the complex hydrides for onboard hydrogen storage applications and have been the focus of extensive research at Sandia, including complementary theoretical and basic science research looking at catalyst mechanisms.

DOE Metal Hydride Center of Excellence