Strong incentives needed to drive shipowners to cut vessels’ overall methane emissions

Owners of vessels burning methane-based fuels such as LNG are not likely to pursue investments in methane emission reduction technologies without strong incentives or regulatory requirements, a study from Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping (MMMCZCS) says.

Illustration; Image credit: DSME

The study provides an overview of methane emission sources and levels onboard vessels and the technologies, solutions, and regulatory drivers that can help reduce them.

The center, with contributions from partners including ABS, Mitsui, MHI, MAN, Norden and BP, among others, studied two types of vessels, LNG carriers, and an LR2 tanker.

Methane emissions might occur throughout the value chain of the fuel pathways looked into, LNG, liquified electro-methane, and bio-methane, including production, transportation, and consumption onboard the vessel.

Considering the onboard section of the emissions, the most talked about portion is the so-called ‘methane slip,’ where a specific methane quantity evades combustion and is emitted via engine exhaust. However, there are other potential sources of methane emissions that are not related to the combustion process, namely fugitive emissions, operational releases, and emergency releases.

Overall, the study points out that when looking into methane emission reduction solutions, a vessel’s total methane emissions should be considered, focusing also on a ship’s operation, system dimensioning, machinery configurations and connected technologies.

The research has also shown that cost-efficient onboard vessel methane emission reduction is possible but limited for existing vessels.

For the vessels studied, onboard methane emissions can be cost-efficiently reduced by 40-80% for a newbuild and 20-50% for an existing vessel through the selection of baseline engine technologies and the use of after-treatment technologies and system solutions. These reductions translate to onboard methane emissions being reduced from 7- 14% of total tank-to-wake GHG emissions to 2-8% for a newbuild and 4-12% for an existing vessel,” the study findings show.

The center added that while it was technically feasible to further reduce onboard vessel methane emissions beyond these levels, utilizing low-emission fuels could be more cost-efficient if further GHG emission reductions are required.

Regulatory framework

Currently, there are no international regulations on methane emissions from vessels, but there are hints that they might appear soon taking into account the ongoing initiatives and regional guidelines, the study indicates.

From the Global Methane Pledge (COP26) to the US’ Inflation Reduction Act of 2022, growing worldwide concern is strongly pushing for GHG reductions to limit the increase in the global average temperature to well below 2°C above pre-industrial levels. It is expected that this social pressure will lead to definitive action by stakeholders across all industries,” the center points out.

While the International Maritime Organization (IMO) does not have specific regulations for methane slip, methane could be included in the IMO regulatory framework in a variety of ways, including:

  • Incorporating methane slip into marine fuels lifecycle GHG assessment guidelines (as agreed at the IMO’s 78th Marine Environment Protection Committee meeting (MEPC 78)).
  • Including methane slip in EEDI Phase 4 (ISWG-GHG 7/3 and MEPC 75/7/10).
  • Including methane slip measurement with the standardized methods (NOX technical file) during engine certification with methane determined as a CO2-eq.

At a regional level, the EU is implementing the Fit for 55 package that includes a set of methane-related measures, including:

  • By 31 December 2024, the Commission shall assess the impact on the global climate of greenhouse gas emissions other than CO2, including methane, nitrous oxide, and particles with a global warming potential, from ships arriving at, within, or departing from ports under the jurisdiction of a member state (EU ETS).
  • The FuelEU for Maritime regulation considers methane slip. This regulation (applicable from 2025) will limit CO2- eq emissions by ships on a well-to-wake basis. The effect of methane slip is introduced as a percentage of the mass of the fuel used by the engine (Cslip)
  • The Fit for 55 program predicts methane emission reductions in the energy sector.
  • Inclusion of CO2, nitrous oxide, and methane in Monitoring, Reporting, and Verification (MRV) Regulation.

Furthermore, Chinese regulations on marine engines include limits (GB15097- 2016 2nd stage: 1 g/kWh) and measurement methods for exhaust pollutants from marine engines (CHINA II). This regulation, which entered into force in 2018, applies to vessels with Chinese flags engaged in inland navigation.

Despite the slow progress to incentivize or require LNG-fueled vessels to limit their methane emissions, there is significant international social pressure to reduce emissions of GHGs, particularly methane.

Several industry-wide initiatives are looking into defining and measuring methane slips from the existing vessels, in order to evaluate the current amounts of methane released into the atmosphere and eventually entice owners to curb these emissions by adopting reduction solutions and technologies.

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The study released by MMMCZCS says that for the vessels studied, GHG emission levels are already compliant with the 2025 and 2030 FuelEU GHG intensity index limits without introducing any onboard vessel methane emission reduction measures.

This is due to LNG’s lower CO2 emission factor used within its 100-year GWP methodology. If a CO2-eq regulation with the proposed FuelEU limits is introduced, no emission reduction actions would be needed until 2035, MMMCZCS added.

Without strong incentives or regulatory requirements to reduce methane emissions, there is limited commitment from ship owners to adopt methane emission reduction technologies and solutions. There are ongoing discussions at the IMO to include methane into its LCA methodology, a CO2-eq approach like FuelEU. There is also the possibility that methane is regulated in a more direct way using a vessel’s Technical File like NOX emissions. This type of regulation could more directly target methane slip levels and the need to reduce them onboard the vessel either for newbuilds or existing vessels if retroactive,” the study concludes.