The research team of Dr. Jung Unho in 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 require fossil fuels. The team’s breakthrough 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-powered vehicles, without the carbon dioxide emissions associated with the use of fossil fuels.
Ammonia, a compound of hydrogen and nitrogen, has a hydrogen storage density 1.7 times higher than liquefied hydrogen and is gaining traction as the most cost-effective method of transporting hydrogen. Especially since it has been used for over 100 years in various areas, such as fertilizer, it is equipped with infrastructure, handling and safety standards. It is considered the most practical solution to address the challenges of storing and transporting hydrogen.
Ammonia consists only of hydrogen and nitrogen, so no carbon is emitted when the hydrogen is separated. The decomposition process requires an input of thermal energy above 600℃, and currently fossil fuels are used, resulting in the emission of carbon dioxide. Therefore, to produce clean hydrogen, a carbon-free energy source must be used, including in the decomposition of ammonia.
By using the small amounts of hydrogen and ammonia left over from the decomposition reaction, researchers were able to produce hydrogen without the use of fossil fuels.
To produce pure hydrogen from ammonia, the decomposition of ammonia is carried out at a temperature above 600 ° C using a ruthenium (Ru) catalyst, followed by the purification of hydrogen by pressure swing adsorption (PSA).*) technology. Carrying out this process produces a residual gas mixture of nitrogen and hydrogen, which is used as a heating element for the ammonia decomposition reactor. Nevertheless, the residual gas alone does not provide sufficient heat of reaction, so additional heat must be supplied.
*Pressure Swing Adsorption (PSA): The most widely used hydrogen separation process. This is an adsorption-based process used to separate a specific gas from a mixed gas. This utilizes the adsorption equilibrium that gas molecules have on a specific adsorbent and separates gases by adjusting the process pressure.
With existing technology, the reaction heat is not supplemented with fossil fuels such as natural gas (LNG) or liquefied petroleum gas (LPG), so carbon dioxide is released during combustion. However, with the system developed this time, reaction heat can be supplied and carbon dioxide emissions can be blocked at the source by supplying ammonia instead of fossil fuels.
The developed system produces high-purity hydrogen of more than 99.97% at 5 Nm3 (approx. 0.45 kg) per hour, which can be delivered to fuel cells for hydrogen electric vehicles. In addition, the hydrogen produced has an impurity concentration of less than 300 ppm nitrogen and less than 0.1 ppm ammonia. It complies with ISO 14687*the international standard for hydrogen-powered electric vehicles.
*ISO 14687: International standard that specifies minimum quality characteristics for hydrogen fuel marketed for use in vehicles and stationary applications
The research team has reached a major milestone by demonstrating a 1 kW building fuel cell system that uses hydrogen derived from ammonia to generate electricity without emitting carbon dioxide. This demonstration, carried out in collaboration with Doosan Fuel Cell Power BU (Business Unit), is of great importance as it overcomes the problem of carbon dioxide emissions, which is considered a disadvantage of natural gas-based fuel cell (LNG) systems. It shows the potential for generating electricity using clean hydrogen fuel cells.
According to lead researcher Dr. The newly developed technology is of great importance to Jung Unho, as it enables carbon-free hydrogen production with ammonia, thus closing a previous gap in this area. There is an expectation that it will be practical in various areas where clean hydrogen is used. In his remarks, he further said: “The combination of ammonia and fuel cells represents a viable option for powering eco-ships.” And as we continue to scale, we can also have a significant impact in the area of clean hydrogen energy.”
Meanwhile, this research was carried out with the support of Korea Southern Power Co., Ltd. (KOSPO).