[C Tech Now] "Ammonia Water Solubility and Economic Feasibility Are Challenges... Ultimately, It Will Lead to Liquefied Hydrogen," Professor Hwang Jihyeon of Kentec

"Han, Attention Needed on White Hydrogen Too"

Hwang Ji-hyun, Professor at Korea University of Energy and Technology

"Ammonia is a toxic substance that requires resolving community acceptance issues, and it is also difficult to guarantee economic feasibility when cracked into hydrogen. Ultimately, hydrogen carriers should move toward liquefied hydrogen."

On the 14th, Professor Hwang Ji-hyun of Korea Institute of Energy Technology (KENTECH) expressed strong confidence that the hydrogen carrier suitable for Korea’s reality is ultimately liquefied hydrogen. He also emphasized that Korea should pay attention to 'white hydrogen,' which is naturally stored in the environment.

Professor Hwang is a hydrogen energy expert with about 20 years of experience at leading domestic and international companies such as Hyundai Heavy Industries, Daewoo Shipbuilding & Marine Engineering, Samsung Heavy Industries, France’s Technip, the Netherlands’ SBM Offshore, and Germany’s Linde. He earned his bachelor's degree from Pukyong National University, a master's degree from Pusan National University, an MBA from Erasmus University in the Netherlands, and a Ph.D. in marine chemical engineering from Seoul National University in 2012. He was invited as a professor at KENTECH in 2021. He also serves as the director of FIP (Fraunhofer Innovation Platform), a research institute jointly established by Germany’s Fraunhofer and KENTECH on campus.

The Korean government has recognized ammonia as an important hydrogen carrier and has worked to build an ammonia ecosystem through policies such as the 'Clean Hydrogen Ecosystem Creation Plan,' the '10th Basic Plan for Electricity Supply and Demand,' and the 'National Carbon Neutral Green Growth Basic Plan.' The recognition of clean ammonia in the Clean Hydrogen Power Supply (CHPS) bidding market is also in this context. Several domestic companies are conducting projects to import clean ammonia from overseas.

Professor Hwang expressed skepticism about ammonia as a hydrogen carrier. First, ammonia is a toxic substance, and there is always a risk of leakage accidents during large-scale storage and transportation. Although ammonia’s distinctive smell makes leaks easy to detect and it is lighter than air, posing less risk in open spaces, local residents are unlikely to readily accept large ammonia storage facilities nearby.

Even if safety issues with ammonia are resolved, Professor Hwang believes it is difficult to secure economic feasibility. Storing and transporting hydrogen as ammonia requires enormous thermal energy twice?once during ammonia synthesis and again during cracking. He explained, "The Haber-Bosch process for ammonia synthesis has been established for over 100 years, but hydrogen cracking technology is still at the laboratory or pilot stage, and even then, it is difficult to obtain hydrogen with purity above 90%." Lower purity requires additional refining processes, which further increase costs.

Using ammonia directly for co-firing with coal or liquefied natural gas (LNG) is not without problems either. Professor Hwang pointed out, "Although ammonia is a clean fuel that does not emit carbon, it inevitably emits nitrogen oxides (NOx), another environmental pollutant." Catalysts are needed to remove NOx, which again raises economic feasibility issues. Similarly, liquid organic hydrogen carriers (LOHC) currently under R&D require dehydrogenation processes and face issues with disposing of organic compounds such as toluene.

Ultimately, Professor Hwang explained that hydrogen storage technology is most advantageous when liquefied hydrogen is stored and used directly at the point of demand. However, liquefied hydrogen technology is very challenging, and only a few companies worldwide?such as Germany’s Linde, France’s Air Liquide, and the United States’ Air Products?monopolize it. He emphasized that Korea must also accumulate experience in liquefied hydrogen technology and secure large-scale production and storage capabilities.

Professor Hwang also stated that white hydrogen, or gold hydrogen, could be a 'game changer' for the hydrogen industry. White hydrogen refers to hydrogen naturally stored in the environment. Numerous exploration projects are actively underway in the United States, Europe, Australia, and elsewhere. According to Professor Hwang, if white hydrogen is developed, hydrogen prices could be lowered to below $1 per kilogram, accelerating the hydrogen society. He said, "According to surveys conducted in the United States and France, the amount of white hydrogen stored worldwide reaches 5 trillion tons. Even extracting a portion of this would be sufficient for humanity’s needs."