- What is new
- Technical background — the developments below were reported on 22 September 2026, 31 March 2022 and 1 July 2025; they are not new announcements on 12 October 2026.
1. 200,000 m³ hybrid-electric LNG carrier concept — GTT, Shell and Lloyd’s Register described a joint development project combining a conceptual 200,000 m³ LNG carrier, hybrid-electric propulsion and GTT NEXT1 containment. This is a design study, not independently measured operational performance. Source: GTT, “GTT Energy unveils its latest innovations at Gastech 2026”, 22 September 2026, https://www.gtt.fr/news/gtt-energy-unveils-its-latest-innovations-gastech-2026
2. Mark III membrane LNG fuel tanks: 2 barg versus 1 barg — GTT announced ClassNK Approval in Principle (AiP) on 31 March 2022 for a Mark III membrane fuel-tank design rated up to 2 barg, specifically highlighting LNG-fuelled pure car and truck carriers (PCTCs) and cruise ships. This must not be described as an announced 2 barg container-ship installation or a 2 barg cargo-tank system for large LNG carriers. Separately, GTT announced on 1 July 2025 an order for six LNG-fuelled container ships, each with an 8,000 m³ Mark III Flex fuel tank designed for 1 barg, with deliveries scheduled for 2027–2028. Membrane fuel tanks can therefore be used on container ships; cylindrical Type C tanks are not the only option. Sources: GTT, “GTT obtains an Approval in Principle from ClassNK for a new design of LNG fuel tank with 2 bar gauge design pressure for Pure Car and Truck Carriers and Cruise Ships”, 31 March 2022, https://www.gtt.fr/news/gtt-obtains-approval-principle-classnk-new-design-lng-fuel-tank-2-bar-gauge-design-pressure ; GTT, “GTT receives an order from HD KSOE for the tank design of 6 LNG-fuelled container ships”, 1 July 2025, https://www.gtt.fr/news/gtt-receives-order-hd-ksoe-tank-design-6-lng-fuelled-container-ships
- How it works
- 1. 200,000 m³ hybrid-electric LNG carrier concept — The announced work integrates larger cargo capacity, a hybrid-electric propulsion concept and NEXT1 containment. The public announcement does not provide a verified vessel energy balance, battery sizing, operating duty cycle or sea-trial results.
2. Mark III fuel tanks and pressure holding — A membrane is not a self-supporting cylindrical pressure vessel: loads are transferred through the insulation/support arrangement into the surrounding ship structure. ClassNK and GTT examined maximum tank dimensions, structural reinforcement, in-service pressure and emergency conditions for the 2 barg concept. Here barg means gauge pressure above ambient; 2 barg is approximately 3 bar absolute at normal atmospheric pressure, not a required constant operating pressure. When engines stop consuming gas, heat ingress continues and tank pressure can rise. Higher allowable pressure can extend the interval before active gas management becomes necessary, but it does not stop boil-off gas generation. Holding time depends on initial pressure, liquid inventory and temperature, vapour-space volume, heat leak, pressure limits and gas consumption. The ratio 2/0.7 must not be used as a holding-time multiplier. The 1 barg Mark III Flex container-ship design is a separate, specifically announced application.
- Why it matters
- 1. 200,000 m³ hybrid-electric LNG carrier concept — A larger parcel could improve transport efficiency under favourable utilisation and terminal constraints, but there is no disclosed operational evidence supporting a fleet-wide fuel-saving percentage. Draught, berth compatibility, propulsion duty cycle and cargo handling remain decisive trade-offs.
2. Mark III fuel tanks and pressure holding — The engineering distinction is between LNG used as ship fuel and LNG transported as cargo. The ClassNK AiP covers a 2 barg fuel-tank concept particularly suited to PCTCs and cruise ships; it is not evidence that the same design is installed in large LNG-carrier cargo holds. GTT's separate 1 barg container-ship order demonstrates that membrane fuel tanks are also a real container-ship design choice. At 2 barg the pressure differential corresponds to roughly 200 kN per square metre before accounting for hydrostatic and other loads; the structural load path, safety devices and class approval therefore matter. AiP is an early design-review milestone, not proof of in-service holding time. The practical question is how many additional port hours are gained at realistic fill levels and heat ingress, after safety margins.
- LNG / shipping impact
- 1. 200,000 m³ hybrid-electric LNG carrier concept — Relevant to future large LNG-carrier newbuilding studies, subject to verified technical performance and port compatibility. It does not establish retrofit feasibility or commercial maturity.
2. Mark III fuel tanks and pressure holding — The 2 barg concept targets LNG-fuelled PCTCs and cruise ships; the separately ordered 1 barg Mark III Flex tanks target LNG-fuelled container ships. Reduced fuel-gas demand during shore-power operation can make pressure holding valuable, but it does not eliminate BOG or replace fuel-gas and pressure-protection systems. Neither fuel-tank development should be extrapolated to cargo tanks on large LNG carriers or to four-stroke DFDE operating results. Open engineering question: what additional holding time is demonstrated across realistic port-call profiles and tank filling levels? Source images have not been reproduced because reuse rights were not verified; consult the linked original GTT announcements for their official materials.