VESSEL REVIEW | Al Shelila – ADNOC L&S acquires first ships in new dual-fuel LNG carrier series

UAE shipowner ADNOC Logistics and Services (ADNOC L&S) has taken delivery of four new LNG carriers in a series from China State Shipbuilding Corporation subsidiary Jiangnan Shipyard.

The series of six DNV-classed ships that include Al Shelila, Al Rahba, Al Reef, and Al Sadaf were designed and built by Jiangnan Shipyard. Their acquisition is part of ADNOC L&S’ strategic fleet expansion to meet the growing global demand for natural gas as a lower-carbon energy source.

Increased capacities coupled with enhanced boil-off mitigation systems

Each ship has an LOA of 298.5 metres (979.3 feet), a beam of 46 metres (150 feet), a design draught of 11.5 metres (37.7 feet), a depth of 26.5 metres (86.9 feet), and three GTT mark III membrane-type LNG cargo tanks with a total capacity of 175,000 cubic metres.

The ships’ capacities are greater than the 137,000-cubic-metre capacities of ADNOC L&S’ earlier LNG carriers.

The Bureau Veritas-certified membrane-type cargo containment system helps keep the gas evaporation rate to just under 0.085 per cent, thus ensuring reduced instances of cargo loss due to boil-off.

The thickness of the insulation and shielding layer in the cargo hold, which is responsible for isolating LNG from contact with the outside world, has been reduced from 530 mm to 400 mm, so that LNG carriers of the same size can load more cargo.

Versatile propulsion with optimisation features

The propulsion setup on each ship includes two WinGD 5X72DF-2.1 dual-fuel main engines that drive propellers via shaftlines.

ADNOC L&S said the engines themselves can also run on LNG, while an intelligent control by exhaust recycling (ICER) system enables the vessel to generate up to 50 per cent fewer methane emissions compared to older-generation technology.

The ICER system can help reduce methane slip (when the engines are operating in gas mode) as well as greenhouse gas emissions. By cooling and recirculating the exhaust gas, the ICER system allows some of the methane in the exhaust gas to be re-combusted, thus further reducing the ship's emissions.

An air lubrication system consisting of eight air compressors in the bow and 16 air release units on the hull bottom will form an air film between the hull and the water. The resulting film helps reduce wave resistance, allowing the ship to consume less fuel over the same sailing distances.

Jiangnan Shipyard also provided each of the LNG carriers with an intelligent ship system that can improve energy efficiency by monitoring and analysing operating status in real time to provide energy efficiency optimisation suggestions.

All six ships in the series are sailing under the flag of Liberia.