(Sydney) – Engineers from Australia's University of New South Wales (UNSW) and the University of Sydney have found a way to "produce green ammonia from air, water and renewable electricity." According to the researchers, this works without the high temperatures, high pressure and infrastructure currently required to produce this compound.
According to the scientists, ammonia synthesis is “one of the decisive achievements of the 20th century.” By using fertilizers that quadrupled food yields, agriculture was able to support an ever-growing world population.
Ammonia production is energy intensive
However, industrial production using fossil fuels is energy-intensive: it requires temperatures of more than 400 degrees Celsius and pressures of more than 200 bar. Emma Lovell, co-author of the study at UNSW's School of Chemical Engineering, says the traditional way of producing ammonia (NH3) using the Haber-Bosch process requires around two per cent of global energy production and one per cent of CO2 emissions responsible – more than any other reaction to produce chemicals.
Plucked out of thin air
Lovell and colleagues investigated how ammonia could be produced cost-effectively on a smaller scale and using renewable energy. The process now presented neither relies on fossil fuels nor does it emit CO2.
Co-author Ali Jalili and his colleagues developed proof-of-concept laboratory experiments that used plasma to convert air into the intermediate NOx, either NO2- (nitrite) or NO3- (nitrate). The nitrogen (N2) in these compounds is more reactive than N2 in the air. The researchers developed scalable plasma reactors “that can produce the NOx intermediate at a significant rate and high energy efficiency,” says Ali Jalili: “Once we created this intermediate in water, developing a catalyst and scaling the system became much easier. The breakthrough of our technology lay in the construction of high-performance plasma reactors in conjunction with electrochemistry.”
Storage and transport solution
Rose Amal, co-director of the Training Center for Global Hydrogen Economy at the Australian Research Council, says the green method of ammonia production could solve the problem of storing and transporting hydrogen. To store hydrogen, you need a lot of volume or you have to compress or liquefy the gas. Ammonia could “potentially be produced in large quantities for export” using renewable energies. The receiver can then either split the ammonia and convert it back into hydrogen and nitrogen, or use it as fuel. “Therefore, there is increasing interest in using ammonia as a potential energy vector for a carbon-free economy.”
Spin-off for commercialization
The new production method has the potential to play a role in the global transition to a hydrogen economy, in which ammonia is increasingly seen as a solution to the problem of storing and transporting energy. In the next step, the research team wants to turn to commercializing its laboratory results and is aiming for a spin-off. Once the method is commercially available, the technology can be used to produce ammonia directly on site and on demand.” Farmers could even do this on site, eliminating the need for storage and transport.
deep link
https://newsroom.unsw.edu.au/news/science-tech/new-eco-friendly-way-make-ammonia-could-be-boon-agriculture-hydrogen-economy
Energy & Environmental Science: “A hybrid plasma electrocatalytic process for sustainable ammonia production”
https://pubs.rsc.org/en/Content/ArticleLanding/2021/EE/D0EE03769A#!divAbstract
Photos
University of New South Wales / © UNSW
