A fuel cell is a type of battery which converts chemical energy into electrical energy. Its invention goes back more than 150 years, yet its potential is just being realized in the space age.

Within a few weeks of Alessandro Volta's invention of his Voltaic pile in 1800, Englishmen William Nicholson (1753-1815) and Anthony Carlisle (1768-1840) used its electric current to decompose water into its two component parts, hydrogen and oxygen. This was the invention of electrolysis, and it paved the way for the fuel cell. Just as Michael Faraday discovered he could reverse Hans Christian Oersted's (1775-1851) discovery that electric current produces a magnetic field, William Grove (1811-1896) discovered in 1838 he could reverse electrolysis to produce an electric current, and the fuel cell was born. (Although thirty-six years earlier, Humphry Davy had described a fuel cell that used a carbon anode and aqueous nitric acid.)

As any...