K-Water Electrolysis Technology Overcomes Renewable Energy Irregularity, Opening the Way for Mass Production of Green Hydrogen

As carbon neutrality and energy transition emerge as challenges of the era, global attention is focused on 'hydrogen,' a clean energy carrier that does not contain carbon. Hydrogen is called the 'ultimate clean energy' due to its characteristic of producing water instead of pollutants during combustion. According to a YTN Science video, hydrogen energy is forming a massive hydrogen economy ecosystem, from production to storage and transportation, centered on fuel cell technology that generates electricity through the chemical reaction of hydrogen and oxygen.

The 'Fuel Cell,' the Heart of Hydrogen Vehicles: Lightweighting and Efficiency are Key

Hydrogen vehicles (hydrogen fuel cell vehicles) are driven by electricity generated by reacting hydrogen with oxygen in the air instead of using gasoline internal combustion engines. Inside the fuel cell, the supplied hydrogen is ionized to release electrons, and these hydrogen ions move along the electrolyte to combine with oxygen and produce water. The principle involves creating an electric current using the potential difference generated in this process. The core component of a fuel cell is the 'MEA' (membrane electrode assembly), where catalysts are coated on both sides of a thin membrane; connecting hundreds of these in series forms the 'fuel cell stack' installed in vehicles.

South Korea has already been recognized globally for its technological prowess in the next-generation automotive market, having successfully mass-produced hydrogen vehicles for the first time in the world automotive industry in 2013. Domestic companies aim to produce 500,000 hydrogen vehicles annually by 2030. Researchers cite 'lightweighting' and 'high power output' as major challenges, especially for mobility applications. Fuel cells for mobility, such as hydrogen vehicles, must be supplied with high-purity hydrogen, and since output—the power that can be produced per unit weight—is extremely important, lightweighting of components is essential.

The video introduces the 'Dual-Exchange-Membrane Fuel Cell' technology developed by Dr. Kim Hyeong-jun's team. While conventional fuel cells required separate humidifiers to supply hydrogen and oxygen, this technology utilizes a 'self-humidification' principle by arranging two transfer membranes to reabsorb water generated at the oxygen electrode to humidify itself. This can simplify the system and reduce weight, which is expected to have high utility in the field of unmanned aerial vehicles, such as hydrogen drones, in the future.

'Green Hydrogen' Production Technology Overcoming Renewable Energy Irregularity

Hydrogen production methods are largely divided into three types: 'by-product hydrogen' obtained as a byproduct of petrochemical plants or steelmaking processes, 'reformed hydrogen' obtained by decomposing natural gas with high-temperature, high-pressure steam, and the 'water electrolysis' method that decomposes water using electricity. Reformed hydrogen is common, accounting for more than half of the world's hydrogen production, but it emits carbon dioxide during the production process. On the other hand, 'green hydrogen,' produced using renewable energy without carbon emissions, is considered the most eco-friendly ultimate goal, but renewable energy has the fatal disadvantage of irregular power supply. If power is suddenly cut or fluctuates heavily, it threatens the durability and safety of water electrolysis devices.

The efforts of the Korea Institute of Energy Research Hydrogen and Fuel Cell Research Group, which has been drawing the blueprint of the hydrogen economy since its establishment in 1987, are focused on overcoming these limitations. Dr. Kim Chang-hee's team has developed a 'Load-Following Water Electrolysis Stack' that can withstand the irregular power supply of renewable energy. Since the instability of power when directly utilizing renewable energy can have a fatal impact on water electrolysis devices, the key is to ensure safety by creating specialized materials themselves rather than using existing materials.

To increase the lifespan of the water electrolysis electrode, the researchers added materials with higher reactivity than existing catalysts, and they significantly strengthened the performance of the separator to prevent the risk of hydrogen and oxygen mixing and exploding. In particular, they applied technology to precisely control the density of the separator to prevent the phenomenon of hydrogen and oxygen mixing when regular renewable energy is supplied.

Domestic Separator Suppressing Gas Mixing by Three Times, the Key to Securing Economic Feasibility

The core of water electrolysis technology is controlling the density of the separator. If the holes in the separator are dense, it prevents gas mixing and increases safety, but ion conductivity decreases, leading to low efficiency; conversely, if the holes are large, efficiency improves, but the risk of gas mixing increases. The researchers have secured a new separator synthesis technology that simultaneously solves these two conflicting problems. According to the video, the newly developed separator is characterized by suppressing the gas mixing phenomenon by more than three times compared to existing products, while also increasing density so that ions can pass through easily to lower resistance. In other words, they simultaneously overcame the two conflicting effects of drastically lowering gas mixing while maintaining ion conductivity.

Until now, core materials such as separators and electrodes used in water electrolysis have relied heavily on imports from overseas, which led to high production costs. The successful localization of these separators and electrodes is highly significant in that it advances the possibility of mass-producing green hydrogen by securing the price competitiveness of core materials. The researchers are currently conducting demonstration research by simulating renewable energy power supply through a commercial-sized stack that combines several verified water electrolysis cells. If they secure megawatt (MW)-class stack design technology in the future, the full-scale competitiveness of green hydrogen is expected to be realized.