HYDROGEN STORAGE ALLOYS
Gabriella Borzone
Dipartimento di Chimica e Chimica Industriale, Università di Genova, Italy
borzone@chimica.unige.it
At the start of the twenty-first century we face a significant energy challenge. Fossil fuels have
delivered energy for transport and for industry. However it is now clear that the unfettered use of
fossil fuels is causing the world’s climate to change.
Hydrogen is attracting substantial attention from governments, industry, academia as a potential
means to overcome these difficulties. Hydrogen is a clean fuel with no CO2 emissions and can be
produced and employed locally to generate electricity or used as a clean fuel for vehicles.
The lack of convenient and cost-effective hydrogen storage is a major hindrance to its widespread
use. Improvements in the energy densities of hydrogen storage systems, reductions in cost, and
increased compatibility with available and forecasted systems are required before viable hydrogen
energy use will be realized.
There are basically three different ways to store hydrogen, storage in pressure tanks, storage as a
liquid, storage via absorption.
Many elemental metals, solid solution alloys, intermetallic compounds and amorphous alloys
dissolve some hydrogen on interstitial sites in a solid solution phase and form a hydrogen-metal
alloy called a metal hydride.
Normally, to be useful as a hydrogen storage material in these applications, the material is tailored
to release hydrogen at moderate pressures and temperatures.
The hydrogen absorption behaviour will be considered in terms of pressure-composition isotherms.
Phase diagrams, thermodynamic properties, heats of formation and crystal structures of the
intermetallic hydrides will be discussed. Examples of hydriding metals and alloys, their properties
and gravimetric H-density will be presented.