Breaking Water

IMG_1041My book The Alchemy of Air traces the history of one of humanity’s greatest discoveries: How to make bread out of air. The Haber-Bosch process does that by turning air into fertilizer, using nitrogen and hydrogen. But it also creates a lot of air pollution, almost all of it from the process used to make pure hydrogen.

When Bosch designed the first plant to turn air into fertilizer around 1912, he made his hydrogen by electrolytically splitting apart water molecules, releasing pure hydrogen and oxygen. It was a pretty clean process. But it was also costly, because it took a lot of electricity to split the water.

So the industry moved to another source of hydrogen, which it still uses today: natural gas. Especially given today’s low prices for natural gas, it’s a lot cheaper to use than water. No wonder the entire nitrogen fertilizer industry is built around it. Problem is, purifying the hydrogen from natural gas releases a lot of CO2 along the way, making the industry a big polluter.

There might be an answer on the horizon. The trick will be making it easier to get H from H20, making it possible to get back to Bosch’s original vision of water-produced hydrogen. And a novel new approach to doing that has just been published.  It is part of a wider effort to find catalysts that can make it easier for water to break into its constituent atoms. But this one is interesting because it’s temperature sensitive, allowing the catalyst to do part of its work effectively at one level, then do another part when the temperature is changed.

It’s no more than a theory at this time, but it’s an interesting theory. And it could open the door to a much, much cleaner fertilizer industry.