Solving the ammonia dilemma

Fertiliser is crucial for Australia’s agriculture industries. But only a few places produce it. So when fighting broke out in the Gulf of Aden and the Black Sea (not to mention the COVID pandemic), the need for a home-grown industry was pressed home – hard.

“Ammonia-based fertilisers are in critically short supply due to international supply chain disruptions and geopolitical issues, which impact our food security and production costs,” says UNSW Sydney School of Chemical Engineering researcher Dr Ali Jalili.

“This, together with its potential for hydrogen energy storage and transportation, makes ammonia key to Australia’s renewable energy initiatives, positioning the country among the leaders in renewable energy exports and utilisation.”

Australia needs fertilisers for food. Its ancient soils simply need more nutrients than most to make the grade. However, the process behind feeding plants has made agriculture one of the nation’s biggest greenhouse gas emitters worldwide.

At the heart of the problem is ammonia. It’s the best means of delivering the most important of all crop nutrients – nitrogen – to the soil. It’s also a convenient way to store hydrogen.

But baking ammonia needs a pressure cooker hotter than 400⁰C while under the weight of 200 atmospheres. That’s why – as a whole – it consumes some 2% of all the energy produced on the planet. And emits 1.8% of the carbon dioxide.

So, finding a clean, lean means of manufacturing ammonia is very high on the scale of objectives for Australian researchers.

And making it economically viable enough to enable various production plants to be set up across the country would also address the sovereign risk issue.

UNSW Sydney Engineering thinks it may have an answer.

In a paper published in Applied Catalysis B: Environmental, Jalili and his team have detailed a new process that promises to produce ammonia at commercially viable scales while significantly improving its efficiency. His research team has been awarded an extra $842,000 to develop the technology – which uses renewable energy, air, water and captured C0₂ – for application in fertiliser production.

Study lead Jalili, who was recently named an Australian Research Council Future Fellow, says the enormous scale needed to make the existing Haber-Bosch ammonia production process worthwhile has limited its production to a relatively few sites, resulting in the need for long-distance bulk transport. This significantly adds to its carbon cost and also global supply chain risks.

That makes finding commercially viable ways of producing reduced emission ammonia imperative.

Earlier proof of concept work by this same research group is already being turned into commercial reality. PlasmaLeap Technologies has licensed the technology and is in the process of developing a prototype production facility.

The researchers say that ongoing refinements have produced greater efficiency and production outputs. And this improves the commercial profitability of the process.

“[It is] essential to establish a decentralised and energy-efficient production method that can effectively use surplus renewable electricity,” Jalili concludes.