Engineers from UNSW Sydney have converted a traditional silicon solar panel into a device that produces ammonia in a more environmentally friendly way.
Ammonia is essential for producing fertilisers that support global agriculture and food production.
The traditional way of making it uses large amounts of fossil fuels required for the hydrogen production and the energy to power the high-temperature process.
UNSW Scientia Professor Rose Amal, collaborating with Professor Xiaojing Hao, and their teams have now developed a way to generate ammonium ions from nitrate-containing wastewater using only a specially designed solar panel that works like an artificial leaf.
Their research has recently been published in a paper in the Journal of Energy and Environmental Science.
The process is known as photoelectrocatalytics (PEC) and utilises a nano-structured thin layer of copper and cobalt hydroxide on the panel that acts as a catalyst to assist the chemical reaction needed to produce ammonium nitrate from the wastewater.
The research team, which includes lead author of the paper Chen Han, and Dr Jian Pan (a DECRA Fellow) have built a 40cm2 artificial leaf system on the roof of Tyree Energy Technologies building at UNSW.
This has been able to produce ammonium ions that can satisfy 1.49m2 of cropland.
The results encourage development of the size of the system in pursuit of creating ammonia without the associated greenhouse gas emissions.
“Traditional ammonia production requires high temperatures – around 400 to 500 degrees Celsius – and high pressure, historically necessitating the use of fossil fuels,” said Amal.
“This system works at ambient conditions and just uses sunlight to produce ammonium from nitrate-containing wastewater, which is an important chemical used in fertiliser.
“We think this new technology could be implemented on a relatively small scale in agricultural locations to produce ammonium onsite, which would decentralise the production process and further reduce CO2 emissions that are associated with the transportation process.”
In a real leaf, photosynthesis is the way that plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.
In this new photoelectrocatalytic process, the solar panel is acting like an artificial leaf to use sunlight, and nitrate-containing wastewater to create ammonium nitrate.
“We are combining photovoltaics’ expertise from UNSW’s School of Photovoltaics & Renewable Energy Engineering, and our expertise in chemical engineering, to take nitrate waste and turn it into an important commodity in the form of ammonia,” said lead author Chen Han.
“Our findings provide a clean, efficient and cost-effective solution for utilising solar energy and chemical wastes to produce ammonia and other value-added products.
The researchers hope that the generation of the ammonium from the wastewater will allow the processed water to be used to irrigate crops and further help them to grow.
Amal is keen for further collaboration and involvement with potential industry partners to further develop the process into a fully viable commercial system.