Researchers have developed two unique energy -efficient and inexpensive systems that use urea in urine and wastewater to create hydrogen.
The unique systems show new ways to the economic production of “green” hydrogen, a sustainable and renewable energy source and the potential for the renovation of nitrogen -containing waste in aquatic environments.
Typically, hydrogen is generated by using electrolysis to split water in oxygen and hydrogen. It is a promising technology to tackle the global energy crisis, but the process is energy -intensive, which makes you cost -intensive compared to extracting hydrogen from fossil fuels (gray hydrogen), even an undesirable process due to the carbon emissions it generated.
In contrast to water, an electrolysis system that generates hydrogen consumes significantly less energy.
Despite this advantage, existing urine -based systems are exposed to several restrictions, such as:
Researchers from the Australian Research Council Center of Excellence for Carbon Science and Innovation (Coe-CSI) and the University of Adelaide have developed two urea-based electrolysis systems that can overcome these problems and produce green hydrogen at a calculated costs that is comparable or cheaper than the costs of generating gray hydrogen.
Research for each system was published in separate work, one in the magazine Applied Chemistry International EditionPresent the other in natural communication. The doctoral student Xintong Gao was the first author of the paper. Chemistry International Edition and comes from the university team under the direction of the Coe CSI chief researcher, Professor Shizhang Qiao, deputy director and chief investigator from Coe-CSI, which comes to the School of Chemical Engineering.
It is not new to make hydrogen made of pure urea, but the team has found an accessible and cheaper process that uses urine as an alternative source for pure urea.
“While we have not solved all problems, these systems should be scaled, but our systems produce harmless nitrogen gas instead of the toxic nitrites and nitrites, and a system will use between 20 and 27 percent less electricity than water gap systems,” says Professor Zheng.
“We have to reduce the costs for the production of hydrogen, but in a carbon neutral way. The system used in our first paper a unique membrane-free system and a new-type copper-based catalyst that has used pure urea that is generated by the Haber-Bosch -ammonia-synthesis process, which is energy-intensive and releases a lot of CO2.
“We solved this by using a green urine source – human urine – which is the basis for the system examined in our second paper.”
Urine or urea can also be obtained from waste water and other waste water with high nitrogen -containing waste. However, the urine in an electrocatalytic system shows another problem. Chloride ions in the urine trigger a reaction that creates chlorine that causes irreversible corrosion of the system's anode occurring in oxidation and loss of electron.
“In the first system, we have developed an innovative and highly efficient membrane-free urea electrolysis system for the production of inexpensive hydrogen. In this second system we have developed a new chlorine-mediated oxidation mechanism that uses carbon catalysts to generate hydrogen from urine,” says Professor Qiao.
Platin is an expensive, precious and finite metal, and its increasing demand as a catalytic material is not sustainable. It is a central mission of the ARC competence center for carbon science and innovation to enable transformative CO2 catalyst technologies for traditional energy and chemical industry.
The team of the University of Adelaide will build on this fundamental research by developing with carbon, non-specific metal catalyst for the construction of membrane-free urine-water systems and at the same time reduces the restoration of green hydrogen and at the same time eliminates the sewage environment.