With Maersk’s recent change of heart in its decarbonization strategy, diversifying its fuel portfolio including previously criticized liquified natural gas (LNG), the fuel takes center stage demanding a closer look at its role under FuelEU Maritime regulation. The fuel brings the critical challenge of managing boil-off gas (BOG) within the regulation’s framework.
What is Boil-Off Gas and how is it accounted for under FuelEU?
Boil-off gas is the vaporized LNG that naturally occurs as the liquid fuel warms up during storage in a ship's cryogenic tanks. This gas needs to be managed carefully to prevent pressure buildup within the tanks.
The different ways of managing boil-off gas ultimately define how it is accounted for in calculating the GHG intensity under FuelEU:
BOG as Fuel: If the BOG is utilized as fuel in the ship’s engines, the resulting emissions are included in the GHG intensity calculation as part of the energy consumed. This is a straightforward scenario where BOG contributes to the total GHG emissions. The use of BOG as fuel is common, especially in LNG carriers.
BOG Reliquefaction: If the BOG is reliquefied, the energy consumed in this process contributes to the overall energy use and indirectly affects the GHG intensity. The emissions associated with the energy used for reliquefaction are factored into the GHG intensity calculation, albeit as an indirect contribution.
BOG Venting: Venting BOG is the most concerning scenario. When BOG is released into the atmosphere without being burned, it contributes directly to methane emissions. Under the FuelEU Maritime regulation, the ‘lost fuel’ is used with the default emission factor and corresponding methane slip percentage to calculate the related emissions but the direct emission of unburnt methane is not at all accounted for.
The Challenge of Boil-Off Gas and Onshore Power Supply
The occurrence of boil-off gas presents a significant operational challenge—especially when ships are connected to onshore power supply (OPS). With engines shut down, the typical use of BOG as fuel is interrupted, forcing companies to consider either reliquefication (using OPS) or venting. The latter results in significant methane emissions that are not accounted forunder FuelEU.
The reliance on OPS, mandated by FuelEU Maritime for container and passenger ships by 2030, adds another layer of complexity. The integration of OPS is intended to reduce emissions in port areas by shifting the energy burden to the local electricity grid. However, without a clear strategy for managing BOG during these periods, the very environmental benefits that OPS is designed to achieve are undermined.
A Controversial Trade-Off: Are We Truly Reducing Emissions?
This scenario presents a controversial trade-off. On one hand, OPS represents a step forward in reducing emissions at berth, particularly in densely populated port cities. On the other hand, the potential increase in emissions from improperly managed BOG during these periods could offset these gains while not even quantified.
Will the shift to LNG, combined with OPS requirements, truly result in lower overall emissions? Or are we simply shifting the burden, trading one environmental challenge for another? This debate is far from settled!
Stay tuned for more insights on navigating these complex challenges in our upcoming newsletters. If you have any questions or want to learn more about how BetterSea’s solutions can help you stay ahead in this evolving landscape, feel free to reach out!
Best regards,
The BetterSea Team
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