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In the evolving landscape of ethane transportation, GTT has pushed the boundaries with the largest Very Large Ethane Carriers (VLECs) and has also developed and promoted Ultra Large Ethane Carriers (ULECs).

2024 marks the beginning of a new era in ship types with the ULEC, a 150,000 m2 liquefied ethane carrier. The chemical giant "Zhejiang Satellite" has decided to charter eight ULECs (with an option for two additional vessels), with EPS as the ship-owner and Jiangnan shipyard (JN) and Hyundai Heavy Industries (HHI) as the ship-builders. These eight carriers will be delivered in 2027.

In early 2025, Thailand's Siem Cement Group and PTT decided to move ahead for their half dozen VLEC shipping programmes, with SHI and HHI as the shipyards, utilising the world's largest VLEC size of 100,000 cbm and equipped with GTT Mark III technology.

This growing preference for GTT technologies is driven by several key advantages that enhance operational efficiency, reduce costs, and improve overall vessel performance.

Key Advantages of GTT Technology

GTT technologies offer unparalleled cargo flexibility. Unlike self-supporting IMO tanks, which are restricted to ethane, ethylene, and LPG cargoes, membrane tanks can accommodate a broader spectrum of liquefied gases, including ethane, ethylene, propane, propylene, butane, LNG, and ammonia (with loading limitations due to its 25% higher density).

This multi-cargo capability enables ship-owners to diversify operations, adapt to market fluctuations, and maximise fleet profitability. One of the most significant benefits of GTT's technologies is its lower Boil-Off Gas (BOG) rate. Advanced insulation reduces BOG generation, minimising the need for reliquefication plants. Unlike LNG carriers, where BOG is burned in the engines for propulsion, ethane carriers run on liquid fuel, requiring full reliquefication of the BOG. GTT's thermal insulation performance not only lowers operating costs (OPEX) but also enhances energy efficiency. Additionally, its increased design pressure (compared to the conventional 250 mbarg) further reduces reliance on reliquefication units, providing greater operational flexibility and enhanced energy savings.

The GTT technology systems also provide a significant lightship advantage. Weighing approximately 1,650 tons, the membrane technology is considerably lighter than self-supporting IMO tanks, which can reach up to 5,000 tons in their nickel alloy version. This weight reduction results in lower fuel consumption or faster service speeds, and easier compliance with CII regulations.

Regarding operational efficiency, GTT's VLEC and ULEC designs are capable of loading cargo more quickly. At major terminals, self-supporting IMO tank VLECs experience a 25% longer loading time for ethane cargo due to higher BOG generation as well as thermal inertia, which together conflicts with the reliquefication unit capacity. In contrast, GTT's superior insulation prevents excessive BOG, enabling quicker loading times and increased efficiency.

Given its construction philosophy and compliance with International Gas Codes requirements, GTT cargo containment systems come with easier inspection and maintenance plans compared to self-supporting IMO tanks, which often require welding repairs and scaffolding installation. Continuous monitoring of GTT cargo containment system tanks ensure higher reliability, enhanced safety for the crew, and lower maintenance costs throughout the vessellifetime.

Recent Design Breakthroughs

In recent months, GTT and its partners have introduced a series of ship design optimisations. Korean shipyard partners, SHI and HHI, have both refined their latest designs developed in 2025, increasing cargo tank capacity from 98,000 cbm to 100,000 m2. Additionally, GTT has collaborated with its Chinese partner CMHI-JS and ship designer Delta Marin to develop a three-tank GTT Mark III VLEC, enabling a cargo capacity of 103,000 m2. This layout further reduces construction costs (CAPEX), enhances hull integration, and optimises cargo space utilisation. Lastly, GTT and ship designer MARIC have developed a 155,000 cbm ULEC design, which was granted Approval in Principle by Bureau Veritas in late March 2025.

GTT’s Membrane Technology Featured in MARIC’s ULEC Design

A recent AiP has been awarded by Bureau Veritas to MARIC for its 155,000 m2 ULEC design, underscoring the suitability of GTT’s Mark III membrane technology for large ethane carriers. With optimised cargo capacity and reduced boil-off, this design enables ethane to be transported even more efficiently.


GTT is also developing a new portfolio of dedicated cargo containment systems, with both Mark III and NO96 technologies, for LPG and LEG cargoes that are warmer than LNG. Not only will the cost be lower, but the cargo volume will be increased thanks to a thinner insulation system.

GTT technologies offer superior operational efficiency, cargo flexibility, increased cargo volume, and reduced maintenance costs compared to self-supporting IMO tanks. These advantages make GTT an optimal choice for both ULECs and VLECs, supporting the industry's shift toward sustainability, adaptability, and cost-effectiveness.

 

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