Can zero CO2 emissions benefit from ammonia-based clean hydrogen production? Can we have a clean and healthy environment in this way? And get rid of polluted cities full of smoke?
The first carbon-free ammonia decomposition reactor. Credit: Korea Institute of Energy Research (KIER)
Dr. Jung Unho's research team at the Hydrogen Research Department of the Korea Institute of Energy Research (KIER) has developed Korea's first clean hydrogen production technology. This technology is based on ammonia decomposition and does not use fossil fuels.
The team's progress could pave the way for a more sustainable and environmentally friendly energy source. This enables the production of high-purity hydrogen that meets international standards for hydrogen vehicles without the emission of carbon dioxide produced using fossil fuels.
Ammonia, a combination of hydrogen and nitrogen, has a hydrogen storage density 1.7 times higher than liquid hydrogen and is considered the most cost-effective way to transport hydrogen. In particular, since it has been used for more than 100 years in various fields such as fertilizer, it has been equipped with infrastructure, transportation and safety standards. It is considered the most practical solution to address the challenges of hydrogen storage and transportation.
Ammonia is made up of only hydrogen and nitrogen, so when the hydrogen is removed, no carbon is released. The decomposition process requires the provision of thermal energy of more than 600 degrees Celsius, and fossil fuels are currently used, which results in the emission of carbon dioxide. Therefore, to produce clean hydrogen, a carbon-free energy source must be used even in the ammonia decomposition process.
Using small amounts of hydrogen and ammonia left over from the fission reaction, the researchers were able to produce hydrogen without using fossil fuels.
To produce pure hydrogen from ammonia, decomposition of ammonia is carried out at temperatures above 600 °C using a ruthenium (Ru) catalyst, followed by hydrogen purification through pressure swing absorption (PSA) technology.
Basic principles of ammonia-based carbon-free hydrogen production technology (above). Credit: Korea Institute of Energy Research (KIER)
During this process, a residual gas mixture of nitrogen and hydrogen is formed and used as a heating element for the ammonia decomposition reactor. However, the residual gas alone does not provide sufficient heat of reaction, so additional heat must be added.
In the case of existing technology, insufficient reaction heat is supplemented with fossil fuels such as natural gas (LNG) or liquefied petroleum gas (LPG), so carbon dioxide is released during combustion. However, using the developed system this time, by supplying ammonia instead of fossil fuels, it is possible to supply the heat of the reaction and block the emission of carbon dioxide at the source.
Using the developed system, hydrogen with a high purity of more than 99.97%, which can be supplied to the fuel cells of hydrogen electric vehicles, is produced at 5 Nm3 (approximately 0.45 kg) per hour. In addition, the hydrogen produced has an impurity concentration of less than 300 ppm for nitrogen and less than 0.1 ppm for ammonia. It met ISO 14687, the international standard for hydrogen-fueled electric vehicles.
A research team has achieved a major milestone by demonstrating a 1-kilowatt fuel cell system for buildings that uses hydrogen extracted from ammonia to generate electricity without emitting carbon dioxide.
The demonstration, carried out in collaboration with Doosan Fuel Cell Power BU (business unit), is of great importance because it overcomes the issue of carbon dioxide emissions, which is considered a weakness of fuel cell systems based on natural gas (LNG). Is considered. It shows the potential of power generation using clean hydrogen fuel cells.
According to senior researcher Dr. Jung Unho, the newly developed technology is of great importance because it enables the production of carbon-free hydrogen using ammonia, bridging a previous gap in this field.
It is expected to be practical in various areas that use clean hydrogen. He continued in his words: "The combination of ammonia and fuel cell is a suitable option for providing energy for environmental ships. And by increasing the scale, we can have a significant impact in the clean hydrogen energy sector."
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