Grove Gas Battery

Every cell before this one carried its own fuel. Volta's pile ate its zinc discs; Daniell's cell ate a zinc rod and a copper sulfate solution. When the metal was gone the cell was gone, and the only way to get more energy was to build a bigger cell. In 1839 William Robert Grove, a barrister who did physics in his spare time, reported something else in the Philosophical Magazine. He half-immersed two platinum strips in dilute sulfuric acid and sealed the upper half of one in hydrogen and the other in oxygen. The cell produced about a volt with no consumable metal in it at all - the platinum was untouched, and what was consumed was the gas. He stacked fifty of them into what he called a gas voltaic battery and used it to electrolyse water, running the reaction backwards with itself. That is the whole idea of a fuel cell, and it arrived a hundred and twenty years before anyone could use it. The reason is in the third step: the reaction can only happen along the line where gas, liquid and catalyst all meet, and on a smooth platinum wire that line is vanishingly short. Grove's cells gave a good voltage and almost no current. Everything since - platinum black, Mond and Langer's porous plates, Bacon's pressurised nickel electrodes, the modern membrane stack - is an attack on that one geometric problem. Grove never patented it. He published it, in a letter, and moved on to arguing about the conservation of energy.