|Grab ammonia out of thin air for fuel of the future|
|Tuesday, 06 August 2013 14:15|
AS VITAL chemicals go, it's hard to beat ammonia. Industrial production began in the early 20th century, and it played a key role in the second world war and in two Nobel prizes. It brought about a global revolution in agriculture – today, crops grown using ammonia-based fertilisers feed no less than 48 per cent of the planet. Could ammonia also be the clean fuel of the future?
When burned, it produces nothing more than water vapour and nitrogen, which makes up 78 per cent of Earth's atmosphere. Earlier this year Italian tyre-maker Marangoni built an ammonia-gasoline hybrid automobile, the Marangoni Toyota GT 86-R Eco-Explorer (see picture). The car can go for 178 kilometres on just one tank of ammonia. So can ammonia itself be made in a clean way?
Most ammonia is produced by heating natural gas or coal as a source of hydrogen, then forcing it to react with atmospheric nitrogen. It's highly energy-intensive, accounting for between 2 and 3 per cent of the world's energy budget and emitting over a billion tonnes of carbon each year in the process.
Now engineer John Holbrook has developed a technique he hopes will make the process cleaner. Instead of heating a fossil fuel, his technique, called solid state ammonia synthesis, works by drawing hydrogen out of water vapour through a charged membrane, and then reacting it with nitrogen.