Senior Research Fellow Park Jae-bum POSCO Research Institute

LNG: A Revolution in Cryogenic Materials That Made the Impossible Possible

■ The ‘Magic of Cryogenics’ and the Cleveland Tragedy

The idea of liquefying natural gas at -162°C and reducing its volume to one six-hundredth was once regarded in the early 20th century as nothing more than the theoretical ‘magic of cryogenics.’ At the time, engineers had succeeded in turning gas into liquid, but the development of cost-effective materials capable of safely containing that liquid remained a major challenge.

The roots of the LNG industry date back to 19th-century physicists’ experiments in gas compression and liquefaction. In 1941, the world’s first commercial LNG peak-shaving storage facility was built in Cleveland, Ohio. It introduced an innovative business model: storing gas in liquid form to prepare for winter heating demand surges, then regasifying it for supply when needed.

▲ The scene of the East Ohio Gas Company explosion in Cleveland in 1944 (Photo source: Cleveland Memory, http://www.clevelandmemory.org)

However, the early LNG industry soon faced a devastating disaster due to material limitations: the Cleveland tragedy of 1944. The cause can be traced back to wartime material shortages in 1941. Because stainless steel was unavailable, 3.5% nickel alloy steel was used instead in the storage tank construction. When the tank was filled with LNG at -162°C, the material lost its toughness—the ability to absorb impact—and underwent low-temperature embrittlement, becoming as brittle as glass.

Eventually, the tank seams ruptured, and the leaked gas triggered a massive explosion that killed 131 people and devastated the surrounding area. The blast was equivalent to 2.43 kilotons of TNT, roughly one-sixth the power of the Hiroshima atomic bomb. In the aftermath, LNG became synonymous with fear in the public mind, and the industry entered a deep two-decade dark age.

▲ A view of POSCO International’s Gwangyang No. 1 LNG Terminal

During this period, researchers relentlessly searched for materials that would not crack under cryogenic conditions. Their efforts led to the development of 9% nickel steel and 5083 aluminum alloy, both of which resist brittle fracture even at -196°C. In particular, 9% nickel steel has since become the global standard for the inner walls of onshore LNG storage tanks. This era also saw the establishment of modern safety management systems, including mandatory installation of dikes capable of containing more than 100% of tank capacity.

LNG Crosses the Sea: The Era of Marine Transportation and the Battle for Standards

Before the 1950s, natural gas produced from oil fields was routinely burned off on site through flaring because there was no practical means of transportation. To solve this problem, the Methane Pioneer, a converted cargo ship, made the world’s first attempt at seaborne LNG transport in 1959. Its insulation method was primitive—aluminum tanks wrapped in South American balsa wood—but its successful 27-day Atlantic crossing silenced skeptics who had claimed that transporting gas by sea was impossible, and marked the beginning of LNG’s global expansion.

■ Moss vs. Membrane: The Standards Battle and Korea’s Winning Move in Shipbuilding

As the LNG shipping market expanded, two containment systems competed to become the industry standard. One was Norway’s Moss-type system, which places giant spherical tanks on top of the hull. The other was the membrane-type system developed by France’s GTT*, which applies a thin special metallic membrane directly to the inner hull. *GTT (Gaztransport & Technigaz): A leading French engineering company holding the core source technology for LNG carrier membrane systems

The Moss-type system offered outstanding structural safety and was highly resistant to sloshing—the movement of liquid cargo—but suffered from poor space efficiency, causing shipbuilding costs to rise sharply as vessel size increased. The membrane-type system, by contrast, offered 10–15% better space utilization than Moss, allowing carriers to transport significantly larger volumes in a single voyage. However, it was more vulnerable to inner wall damage caused by sloshing.

▲ Mozah, the world’s first 266,000㎥ LNG carrier built by Samsung Heavy Industries in 2008 (Source: Samsung Heavy Industries Blog)

It was Korea that found a way through this challenge. Korean shipbuilders effectively overcame the membrane system’s critical weakness—sloshing—through advanced engineering design. Having focused on large-scale vessel technologies since the 1990s, they succeeded in the mid-to-late 2000s in building Q-Max LNG carriers with a capacity of 266,000㎥, realizing economies of scale. This dramatically lowered transportation costs per unit, and today more than 80% of LNG carriers worldwide use the membrane system led by Korea.

Beyond innovation in the vessels themselves, so-called ‘joker card’ technologies have recently made remarkable progress in overcoming energy security concerns and infrastructure constraints. One such example is the FSRU (Floating Storage and Regasification Unit), which stores LNG offshore, regasifies it, and then supplies it to land. Because FSRUs can be built faster and at lower cost than onshore terminals, they have emerged as critical assets for energy security. In fact, when pipeline gas (PNG) supplies were disrupted by the Russia-Ukraine war in 2022, the Netherlands and Germany deployed FSRUs in just six months, enabling them to overcome an unprecedented energy crisis.

Lessons from LNG History: The Key to the Hydrogen Era

The LNG industry’s history of challenge and resilience provides a critical milestone for those preparing for the coming hydrogen economy. Hydrogen is drawing attention as a future low-carbon energy source, but its successful adoption will require thorough preparation—taking LNG’s path as a lesson.

① Securing High-Value-Added Specialty Steel Technologies to Overcome Hydrogen Embrittlement

▲ Inside Tank No. 7 at Gwangyang LNG Terminal 2, built with POSCO’s independently developed high-manganese steel

Hydrogen presents a uniquely difficult challenge: not only is its liquefaction temperature far lower than LNG’s at -253°C, but its tiny atomic size allows it to penetrate metal lattices and cause cracking, a phenomenon known as hydrogen embrittlement. This is a major technical barrier for the steel industry, but also an opportunity to secure market leadership. R&D investment in hydrogen-dedicated specialty alloys such as high-manganese steel, as well as in high-pressure and embrittlement-resistant steel technologies, should not be viewed simply as a cost but as an essential investment for survival.

② Building a ‘Flexible Standardization Alliance’ Across Related Industries

Just as LNG standardization was made possible through close cooperation between shipbuilding and steelmaking, the hydrogen era cannot be unlocked through standalone technology development alone.

A standards alliance should be formed across the entire value chain—from the development of hydrogen-dedicated specialty steel to the construction of hydrogen carriers (for ammonia, liquefied hydrogen, LOHC*, etc.) and the operation of global hydrogen terminals—to secure leadership in the global market.

*LOHC (Liquid Organic Hydrogen Carriers): Liquid compounds suitable for storing and transporting hydrogen

③ Introducing an ‘FSRU Model’ and ‘Integrated Energy Management’ to Reduce Early Investment Risks

In the early stage of the hydrogen economy, large-scale infrastructure development carries significant stranded-asset risks. To minimize these risks, it will be necessary to actively adopt a ‘hydrogen FSRU model’ that either extracts hydrogen from ammonia onboard or directly supplies liquefied hydrogen at sea. In addition, just as LNG carriers reuse boil-off gas (BOG) generated during operations as fuel, hydrogen carriers should also improve operational efficiency by establishing an integrated energy management system that reliquefies evaporated hydrogen or uses it as feedstock for fuel cells.

Like LNG, which overcame the tragedy of 1944 to become one of humanity’s core energy sources, only by ensuring rigorous safety and establishing technology standards proactively can Korea and POSCO Group secure global leadership in the coming battle for the hydrogen economy.