Australian researchers may have unlocked the secrets to the production of zero emissions and environmentally friendly ammonia production, a key breakthrough that could massively expand the potential for green hydrogen exports.
In new research published in the journal Energy and Environmental Science, researchers from UNSW Sydney and the University of Sydney have developed new a method that allows for the production of hydrogen without the need for the production of high temperatures, high pressures and only requires air, water and renewable electricity as inputs.
Ammonia has long been a key input into agricultural production and when used as a fertiliser can significantly expand crop yields and more recently, ammonia has emerged as a potential candidate for the transport of hydrogen for use in the energy sector, acting as an ideal vehicle for safely storing and transporting hydrogen for export.
The researchers say that the innovative approach to the production of ammonia is more environmentally friendly than most methods currently used by industry, and could eliminate the use of fossil fuels in the process.
“The way that we did it does not rely on fossil fuel resources, nor emit CO2,” co-author the paper, Dr Emma Lovell, from UNSW’s School of Chemical Engineering said.
“And once it becomes available commercially, the technology could be used to produce ammonia directly on site and on demand – farmers could even do this on location using our technology to make fertiliser – which means we negate the need for storage and transport. And we saw tragically in Beirut recently how potentially dangerous storing ammonium nitrate can be.”
“So if we can make it locally to use locally, and make it as we need it, then there’s a huge benefit to society as well as the health of the planet,” Dr Lovell added.
Details of the new method, which has been successfully demonstrated in lab conditions, with the researchers stressing that more work is required before the method is ready for commercialisation, but added that it shows promise as a way to cut global greenhouse gas emissions.
“The current way we make ammonia via the Haber-Bosch method produces more CO2 than any other chemical-making reaction,” Dr Lovell said.
“In fact, making ammonia consumes about 2 per cent of the world’s energy and makes 1 per cent of its CO2 – which is a huge amount if you think of all the industrial processes that occur around the globe.”
Ammonia consists of three hydrogen atoms bonded to an atom of nitrogen (NH3), with each of these components readily found in water and air respectively. However, scientists have found it difficult to synthase ammonia without the need for producing very high temperatures and pressures, that require the use of fossil fuels.
However, the Australian researchers have successfully demonstrated a process for producing ammonia using a plasma, that can be created using renewable electricity. Using the plasma, the scientists were able to create intermediaries in the form of nitrous oxides (NOx), which could then be converted into ammonia through well understood methods.
“Working with our University of Sydney colleagues, we designed a range of scalable plasma reactors that could generate the NOx intermediary at a significant rate and high energy efficiency,” research co-author Dr Ali (Rouhollah) Jalili said.
“Once we generated that intermediary in water, designing a selective catalyst and scaling the system became significantly easier. The breakthrough of our technology was in the design of the high-performance plasma reactors coupled with electrochemistry.”
The research team said that the new process could unlock new ways of safely and efficiently exporting green hydrogen into a global market.
“Hydrogen is very light, so you need a lot of space to store it, otherwise you have to compress or liquify it,” co-director of ARC Training Centre for Global Hydrogen Economy, Scientia Professor Rose Amal, said.
“But liquid ammonia actually stores more hydrogen than liquid hydrogen itself. And so there has been increasing interest in the use of ammonia as a potential energy vector for a carbon-free economy.”
“We can use electrons from solar farms to make ammonia and then export our sunshine as ammonia rather than hydrogen. And when it gets to countries like Japan and Germany, they can either split the ammonia and convert it back into hydrogen and nitrogen, or they can use it as a fuel,” Amal added.
