Feeding billions of people around the globe takes a lot of energy. Much of the carbon cost of this effort comes down to making ammonia, the key ingredient in many fertilisers. To do this, we rely on the Haber-Bosch process, invented a century ago by German chemists Fritz Haber and Carl Bosch. No one has yet come up with anything that can compete with it on massive scales without breaking the bank.
Until now. and his colleagues at the University of Central Florida in Orlando, created a process that can take water, nitrogen from the air, electricity and a very special catalyst to help turn the ingredients into ammonia, the key ingredient of ammonium nitrate fertiliser. It works at room temperature, with no need for high pressure.
This is a far cry from the current Haber-Bosch process, which crams nitrogen and hydrogen together to make ammonia at temperatures of around 550掳C and 350 times atmospheric pressure. It gobbles up around 2 per cent of all global energy and generates more than 1 per cent of carbon dioxide emissions contributing to global warming.
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The new process needs so little power that it could be driven by solar or wind energy. 鈥淣o energy is needed for heating and compressing,鈥� says Feng.
Locally-sourced ammonia
The secret is a palladium catalyst. Feng coats nanoparticles of palladium onto a carbon electrode, then dunks it into a water electrolyte solution. When he passes electricity and nitrogen gas through the system, the palladium particles sponge up hydrogen atoms from the water and transfers them to nitrogen molecules, which then break apart to form ammonia molecules.
Like some other attempts to simplify ammonia production, the process only works at the lab scale. But Feng is hopeful it can one day become practical.
If it can be scaled up, it would enable cheap ammonia production locally in any town, village or farm, says , head of crop performance at the ADAS research agency in Boxworth, UK.
鈥淚t has the potential to greatly reduce energy costs and greenhouse gas emissions associated with fertiliser production,鈥� says of the Environmental Defense Fund in Washington DC. But if it makes ammonia too cheap, she worries farmers may use it indiscriminately. 鈥淔armers will have less incentive to use fertiliser carefully, leading to possible over-use which generates nitrogen pollution,鈥� she says.
Nature Communications
Read more: Bad news: Carbon emissions have suddenly started rising again
