Fuelling the future: solid phase hydrogen storage

Fuel cell-powered cars have been hailed as the answer not only to eliminating our reliance on diminishing fuel supplies but also to reducing CO₂ emissions from vehicles. The portable and safe storage of hydrogen will be fundamental to the exploitation of fuel cells for transport.

Fuel cells are not new. They were invented in the late 1830s by British scientist William Robert Grove.¹  They operate by converting a fuel - either hydrogen, or natural gas or untreated coal gas - into electrical power via a catalysed chemical reaction. There are several different types of fuel cell, depending on the electrolyte used. For example, alkaline fuel cells (AFC) use potassium hydroxide solution as the electrolyte, and proton exchange membrane (PEM) fuel cells use a proton conductive polymer as the electrolyte.  

PEM fuel cells are of particular interest to car manufacturers, who have been trying to exploit this technology as a source of motive power since the early 1990s. These fuel cells have the advantage of a simple design and produce a high electrical potential (1.23V at 25^o C) via the chemical reaction:¹

2H₂ + O₂→ 2H₂ O