BW LNG wants to reduce fuel consumption on its vessels (source: BW LNG)
Gas shipowner-operator BW LNG and its charterer oil major TotalEnergies are partnering with Nautilus Labs to improve vessel optimisation services
LNG transport poses a range of challenges: as a dynamic product, the temperature and pressure of the cargo changes over time, and the vessel’s engines are set to run on the boil-off of the -160°C cargo. The vessel’s master must ensure the cargo is in a specific condition when the ship arrives for discharge, and the challenges of cargo sloshing, the degree of boil-off gas and whether it is used as fuel or liquefied need to be considered.
The companies believe the contractual structures of the LNG segment lead to differing objectives for stakeholders. For instance, owners are not incentivised to share data or insights with their respective charterers.
“We knew we had to break down these siloes and barriers,” said Total head of LNG shipping Eric Lepesan.
Nautilus’s boil-off gas optimisation and voyage optimisation services specifically target the LNG segment, using integrated vessel data to build ship-specific machine learning-based performance models that power its voyage optimisation platform and enable owners like BW to share insights with their charterers.
Both charterer and owner evaluated the incentives and metrics within the industry. While gas consumed over a voyage has a direct impact on the environment, the companies said the CII and EEXI metrics potentially create different incentives as they are based on distance sailed.
‘Full steam ahead’ to keep tank pressure under control could result in the best CII rating, but conflict with the advice proposed by Nautilus’s data models.
Rather than leveraging a software vendor, BW and TotalEnergies sought to partner with Nautilus to determine optimal operations for improved long-term outcomes.
In late 2021 and 2022, Nautilus’ service was used over multiple voyages for BW Tulip, with the goal of getting the vessel to adhere to its estimated time of arrival (ETA) and ensure terminal requirements at the arrival port, while sailing with the lowest LNG consumption possible.
In this case, BW sought out a voyage model that helped cull overall consumption, thus maximising reliquefication and in some cases involved higher gas combustion unit (GCU) usage instead of using propulsion to obtain the best outcome for a voyage.
Nautilus first determined the optimal speed over ground based on the set ETA, calculated the corresponding shaft speed, and ultimately the total expected LNG consumption on BW Tulip’s leg. The Nautilus platform estimated the amount of gas that needed to be consumed against the reliquefied gas to meet the arrival requirements for temperature and pressure.
It was determined that BW Tulip could afford to travel at a much lower speed – even if this resulted in increased use of the GCU, while still meeting temperature and pressure requirements at the arrival terminal. The slower speed was expected to result in increased reliquefaction rates and ultimately lower total gas consumption and reduced emissions, according to Nautilus.
“We strongly believe in collaboration with the owners of our chartered-in fleet” said Mr Lepesan. “Taking a data-driven approach and leveraging machine learning-powered technology helps us reduce emissions today on our path toward decarbonisation to achieve TotalEnergies net-zero goals.”
