Future proofing Ultra Large liquefied Ethane Carrier Design : Leveraging LNG-Ready Advanced Membrane Technology
As the ethane market matures, industry stakeholders are increasingly focused on transporting larger volumes of ethane across the oceans. This trend has led GTT to develop designs for vessels with greater cargo capacities, particularly a 150,000-m³ Ultra Large Ethane Carrier (ULEC). This larger carrier enables a reduction of shipping cost per cubic meter while enhancing transported cargo volumes and improving petrochemical plant output. From an environmental perspective, large carriers also benefit from a reduced carbon footprint per cubic meter transported.
In response to the growing demand, GTT launched a study in 2020 to address limitations for ships calling at American terminals, Enterprise Morgan’s Point and Nederland. Interviews with pilot associations, export facilities and the US Coast Guard were conducted to identify channel restrictions and contextual factors that may influence ship design. Following the completion of the study, GTT began the development of ULECs, with shipyards and designers such as Samsung Heavy Industries, Hyundai Heavy Industries, Hudong-Zhonghua, Dalian Shipbuilding, Jiangnan, MARIC, and Deltamarin.
Operational and economic advantages of ultra-large-scale liquefied ethane transport
In the development of ULECs, a thorough understanding of industry requirements has been paramount. Through collaboration with the above mentioned industry stakeholders, key dimensions were established as the foundation of ULEC ship design. These include an overall length of 274.0 meters, a breadth of 42.0 meters, and a vessel draft of no more than 11.9 meters in seawater. This meticulous attention to dimensions ensures optimal manoeuvrability and cargo capacity, addressing the needs of both safety and efficiency in maritime transportation.
To further enhance operational performance, the proposed ULEC design is equipped with a main engine of relatively important maximum continuous rating, ensuring always-sufficient margin for long voyages. The reliquefication unit is sized with four trains, of 50% capacity each, allowing sufficient redundancy on the safety side, and enhancing liquefied ethane preservation to minimize losses during transit on the performance side. These enhancements deal with operational reliability and contribute to cost savings by maximizing cargo integrity.
In pursuit of enhanced volume efficiency, GTT has also validated two ULEC design variants: one with four cargo tanks, and one with only three cargo tanks. This innovative approach not only optimizes cargo capacity but also reduces shipbuilding costs, offering a compelling value proposition to ship owners and operators. Moreover, various Classification Societies have reviewed and granted approval in principle for the ULEC ship design, underscoring its compliance with international standards and regulations.
With options for either Mark III or Mark III Flex technology, the cargo containment system of ULECs offers flexibility. The latter, with its lower boil-off rate of 0.06% volume / day, and faster loading operations, presents a significant improvement in trade flexibility.
Bridging ethane and LNG: the versatility of the Mark III cargo containment system
In 2021, ABS unveiled at a joint event with GTT the first LNG Cargo Ready notation for ethane carriers. The notation confirms that an ethane carrier (whether a VLEC or a ULEC) outfitted with GTT Mark III technologies possesses the capability for future modification to facilitate the trade of LNG cargoes. GTT conducted a thorough evaluation of potential barriers and meticulously assessed the LNG capability of the carrier's equipment and systems. Subsequently, supplementary notations have been incorporated to validate the LNG readiness of systems, encompassing aspects such as piping, dual fuel systems, and other essential components.
Investing in ethane carriers equipped with Mark III technology allows owners to mitigate financial risks but also provides the flexibility to enter the LNG shipping market if required. This dual-cargo compatibility effectively addresses market uncertainties, offering a versatile solution to meet evolving market demands. The conversion process from an ethane carrier to an LNG carrier typically occurs at a specialized conversion yard. This involves primarily adapting the main engine, and possibly auxiliary engines, along with adjustments to the reliquefication unit.
Moreover, with the potential emergence of new trade routes, such as those from the Middle East to Northeast Asia, ULEC vessel design can be adapted to align with conventional 175,000 m³ LNG carriers, ensuring adaptability to evolving market dynamics. In addition, such ULEC could supply LNG cargoes to the existing FSRU and FSUs in service (more than 40 units), which look for cargo volumes between 140,000 and 160,000 cubic meters. Eventually the ULEC itself could also operate as an LNG FSRUs following reduced conversion work. All these possibilities significantly increase the residual value of such an asset.
These innovative ship designs have gained significant interest from stakeholders in the Natural Gas Liquids (NGL) and LNG shipping sectors. The synergy between the two industries, facilitated by larger ships and advanced technologies, leads to a substantial reduction in total supply chain costs, encompassing both capital expenditure and operational expenditure. This, in turn, lowers the break-even point for ethane feedstock competitiveness, thereby unlocking potential avenues for new projects and ventures.
