Engineers from UNSW Sydney have converted a traditional silicon solar panel into a device that produces ammonia in a significantly more environmentally friendly way.
The traditional way of making ammonia creates large amounts of greenhouse gas emissions, since fossil fuels are 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 developed a way to generate ammonium ions from nitrate-containing wastewater using only a specially designed solar panel that works like an artificial leaf.
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 Parr (a DECRA Fellow) have built a 40cm2 artificial leaf system on the roof of Tyree Energy Technologies building at UNSW which 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.
Professor Amal said traditional ammonia production requires high temperatures – around 400 to 500 degrees Celsius – and high pressure, historically necessitating the use of fossil fuels.
She said 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,” Amal said.
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.
“It’s important to acknowledge that the wastewater we convert isn’t coming directly from municipal waste or runoff – it still needs to be processed first to filter out the organic matters and particulates,” Amal said.
“But we are hopeful that once we have generated ammonium from the nitrate wastewater, the treated water can then be put into irrigation.”
Amal is keen for further collaboration and involvement with potential industry partners to further develop the process into a fully viable commercial system.
“Industry partners would help us scale up this device, and we definitely would like to utilise a full-scale, traditionally sized solar panel for our application,” she said.