[News Terms] 10 Times More Transport Efficient Than Gas, Clean Energy 'Liquefied Hydrogen'

On the 17th, the first liquefied hydrogen refueling station in Korea opened in Incheon, officially marking the beginning of the liquefied hydrogen era.

On the morning of the 17th, a hydrogen bus is refueling at Incheon Gajwa Liquefied Hydrogen Charging Station, the first liquefied hydrogen charging station in Korea.
[Image source=Yonhap News]

Liquefied hydrogen is hydrogen gas, which normally exists at room temperature, cooled to minus 235 degrees Celsius to become a liquid. It is a colorless liquid at an ultra-low temperature with a boiling point of minus 252.7 degrees and a melting point of minus 259.2 degrees. When it comes into contact with liquid oxygen and a flame is applied, it combusts explosively and violently. This combustion is used as the propulsion power for large space rockets.

The first person to successfully produce liquefied hydrogen was the British chemist James Dewar. Dewar succeeded in liquefying hydrogen gas compressed to 25 atm (atmospheres) by cooling it to -190°C and then using a heat exchanger based on the Joule-Thomson effect. This method is still used by liquefied hydrogen manufacturers both domestically and internationally today.

The volume of liquefied hydrogen produced in this way is 1/800th that of hydrogen gas, allowing more than 800 times the amount to be stored in the same space. Transportation efficiency is also higher. While gaseous hydrogen can transport 300 kg at a time, liquefied hydrogen can transport more than 3 tons. In terms of safety, it is also considered superior to gaseous hydrogen. Gaseous hydrogen must be compressed to over 200 atmospheres to store large quantities, but liquefied hydrogen can be stored at low pressures below 10 atmospheres.

However, the production and storage of liquefied hydrogen are costly, which is considered a drawback. In particular, long-term storage is difficult. Without proper cooling and compression systems, it can evaporate back into gas.

Meanwhile, the Incheon Gajwa liquefied hydrogen vehicle refueling station was selected in 2022 by the Ministry of Environment’s hydrogen refueling station supply project. It is Korea’s first liquefied hydrogen refueling station with facilities capable of refueling 120 kg of hydrogen per hour. Equipped to refuel 120 hydrogen buses daily on average, the government plans to increase the number of hydrogen refueling stations from the current 290 to 660 by 2030. Among these, liquefied hydrogen refueling stations are expected to increase to 40 next year and over 280 by 2030.