FuelEU Maritime

International shipping is one of the largest emitters of greenhouse gases in the EU. In 2022, it accounted for 4.0% of all greenhouse gas emissions. While this makes it a smaller sector compared to the transport sector with 20.5%, there is a projected higher increase in emissions in this sector due to the increase in global trade. For this reason, efforts are being made in the EU to reduce greenhouse gas emissions in this sector in the long term.

FuelEU Maritime is the EU’s cornerstone for decarbonizing shipping, establishing binding life cycle GHG-intensity limits on the energy used on board vessels and incentivizing the uptake of renewable fuels. In Article 1, the Regulation “lays down uniform rules imposing […] a limit on the greenhouse gas (GHG) intensity of energy used on board by a ship arriving at, staying within or departing from ports under the jurisdiction of a Member State” and “an obligation to use on-shore power supply (OPS) or zero-emission technology in ports under the jurisdiction of a Member State”.

Beginning 1 January 2025, every large ship must ensure that its yearly average GHG intensity does not exceed a progressively tightening threshold. Article 4(2) specifies that this limit is derived by reducing the 2020 reference value of 91.16 g CO₂ eq/MJ by 2 % from 2025, 6 % from 2030, up to 80 % by 2050. By defining both the reference and the reduction steps in law, the EU gives shipowners a clear multi-decade roadmap toward near-zero emissions.

Bio-LNG: A Drop-In Renewable Solution

Against this backdrop, biomethane bunkered as Bio-LNG offers an immediate “drop-in” pathway. The Regulation’s Annex II explicitly recognises “Liquefied Bio-methane as transport fuel” alongside conventional LNG in its default emission-factor table , ensuring that operators can apply the same monitoring, reporting and verification framework used for fossil LNG.

Bio-LNG thus marries compatibility with existing dual-fuel engines and bunkering infrastructure to the potential for maximal life-cycle GHG reductions—even achieving negative Well-to-Tank credits for waste-based biomethane pathways. However, before a bunkering invoice can translate into climate credits, the fuel must first clear FuelEU Maritime’s precise legal definitions and certification hurdles.

Defining Biomethane (Article 3)

FuelEU Maritime borrows its key glossary from Directive 2018/2001 (RED II) via Article 3 (2). By delegating the definitions fully, the Regulation guarantees that any biomethane qualifying as “biogas” or “biofuel” under RED II automatically qualifies under FuelEU Maritime. This alignment removes ambiguity and creates a seamless legal bridge between land-based renewable-energy mandates and maritime compliance.

Certification Requirements (Article 10 & Article 4(3))

Once a biomethane cargo meets the definitions, it must then satisfy sustainability and reporting rules under Article 10:

“Where biofuels, biogas, RFNBO and recycled carbon fuels, as defined in Directive (EU) 2018/2001, are to be taken into account for the purposes referred to in Article 4(1) of this Regulation, the following rules apply:”

Specifically:

• Article 10(1)(a) mandates that “biofuels and biogas that do not comply with the sustainability and GHG emissions saving criteria set out in Article 29 of Directive (EU) 2018/2001 … shall be considered to have the same emission factors as the least favourable fossil fuel pathway for that type of fuel;”
• Article 10(1)(b) extends the same worst-case default to RFNBO and recycled carbon fuels failing to meet RED II thresholds.

Finally, Article 4(3) ties together definitions and certification by requiring that:

“On the basis of the fuel bunker delivery notes complemented in accordance with Annex I to this Regulation, companies shall provide accurate, complete and reliable data on the GHG emission intensity and the sustainability characteristics of fuels … that have been certified under a scheme that is recognised by the Commission in accordance with Article 30(5) and (6) of Directive (EU) 2018/2001…”

In practice, this means that a RED II certification (e.g., REDcert-EU, ISCC-EU) is necessary but not sufficient. Operators must still calculate and report the full Well-to-Wake intensity of Bio-LNG per Annex I’s methodology before any GHG credits can be claimed.

With Articles 3 and 10, and the reporting mandate in Article 4(3), the Regulation lays out a clear, legally robust path: biomethane that meets RED II’s definitions and sustainability criteria can be bunkered and credited under FuelEU Maritime—provided its life-cycle emissions are fully documented. In the next sections, we will apply Annex I’s equations to quantify Bio-LNG’s Well-to-Wake profile and explore how shipowners can leverage compliance flexibilities such as pooling, banking and borrowing to meet each five-year reduction milestone.

Calculating GHG Intensity (Well-to-Wake)

Even though the FuelEU Maritime Directive refers to the Renewable Energy Directive, there are differences in the calculation of GHG emissions. While it is sufficient to calculate well-to-tank emissions for biofuels within the scope of the Renewable Energy Directive, well-to-wake emissions must also be included in the FuelEU Maritime Directive. This means that not only the emissions for the production of the biofuel are calculated, but also those for its combustion. As the average emissions may not exceed 89.34 gCO2eq/MJ in 2025 and 18.23 gCO2eq/MJ in 20250, the following calculation is carried out for biomethane to determine whether it is suitable as a fuel to meet the GHG requirements in the long term:

Overall Well-to-Wake

The Well to Wake emissions are calculated by adding the Well to Tank and Tank to Wake emissions. These added emissions can be reduced, for example, by using a sail (fwind). In this example, however, this is not calculated for the sake of simplicity.

Well-to-Tank (WtT)

Well-to-tank emissions are calculated by multiplying the absolute amount of energy used by the emission factor in gCO2eq/MJ. In this case, 1000 MJ and a GHG value of -100 gCO2eq/MJ are assumed. -100gCO2eq/MJ is a realistically achievable value for biomethane produced from manure. If CO2 capture also takes place during biomethane production in order to replace fossil CO2 (CCR) or store it geologically (CCS), values lower than -120 gCO2eq/MJ can also be achieved. There are several projects in Europe that are already producing and marketing these qualities.

CO2-Combustion (TtWcomb)

Tank-to-Wake combustion emissions quantify the CO₂ released when Bio-LNG is burned on board. These emissions are calculated by multiplying the ship’s total energy use by the fuel’s CO₂-per-energy emission intensity, EF₍comb₎, which is itself derived from the fuel’s carbon content and calorific value:

Determine EF₍comb₎

Divide the CO₂ emission factor of methane (Cf₍CO₂₎ = 2.750 g CO₂/gFuel) by Bio-LNG’s lower calorific value (LCV = 0.0491 MJ/gFuel):

Compute TtW₍comb₎

Multiply EF₍comb₎ by the ship’s energy demand (Q = 1 000 MJ):

This term typically dominates the ship’s onboard emissions profile and, together with methane-slip (TtW₍slip₎), completes the Tank-to-Wake leg of the life-cycle calculation.

CH4-Slip (TtW slip)

Not all methane burns cleanly in a dual-fuel engine—some fraction bypasses combustion as unburned CH₄. Because methane has a 100-year global-warming potential (GWP) 28 times that of CO₂, even small slip rates can add disproportionately to a ship’s GHG burden. FuelEU Maritime factors this in via Annex I, Eq. 2, which defines the methane-slip emission factor, EF₍slip₎:

Calculate EF₍slip₎

Multiply the slip fraction (C₍slip₎ = 3.1 % = 0.031 gCH₄/gFuel) by the methane emission factor (C₍f,CH₄₎ = 0.00011 gCH₄/gFuel) and the GWP₍CH₄₎ = 28, then divide by the lower calorific value (LCV = 0.0491 MJ/gFuel):

Compute TtW₍slip₎

Multiply EF₍slip₎ by the ship’s energy demand (Q = 1 000 MJ):

Total Well-to-Wake Emissions (WTW₍total₎)

This equation aggregates all life-cycle contributions—upstream credits (WtT), CO₂ combustion (TtW₍comb₎), and methane slip (TtW₍slip₎)—and applies the wind-reward factor (f₍wind₎):

Well-to-Wake Intensity (EF₍WTW₎)

Finally, the ship-level intensity metric normalizes total Well-to-Wake emissions by the reference energy demand:

In this example, a GHG value of -43.97 gCO2eq/MJ well to wake would be achieved with biomethane that was procured with -100 gCO2eq/MJ well to tank for the bunkering of the ship. All requirements regarding the GHG value would therefore be permanently fulfilled here. Other fuels with a higher GHG value could even be added in the long term.

Compliance Flexibilities & Advantages

Having achieved a Well-to-Wake intensity of –43.97 g CO₂ eq/MJ, a vessel burning Bio-LNG can more than meet each FuelEU Maritime target on its own. Allowing system participants to make use of the regulations options for fleet-wide and multi-year mechanisms to leverage those significant savings. By pooling compliance balances, a ship with Biomethane made from manure can offset higher-emitting vessels in the same pooling group, ensuring the group hits its average GHG targets even if some units continue to burn conventional fuels. Likewise, banking allows that WTW-emission-saving surplus to be carried forward to smooth out peaks and troughs in renewable fuel availability.

Under Article 21, “the compliance balances for GHG intensity … of two or more ships … may be pooled for the purposes of complying with the requirements set out in Article 4” EUR-Lex. In practice, this means a ship recording –43.97 g CO₂ eq/MJ can generate a compliance surplus, which is then allocated across the pooled vessels—under the condition, that compliant vessels stay compliant, deficiant vessels benefit from the pooling and that the total pool remains compliant. This flexibility transforms a lone Biomethane fueled vessel into a fleet enabler, allowing operators to stagger investments in alternative fuels and still ensure collective compliance.

Meanwhile, Article 20 empowers companies to bank genuine compliance surpluses into future reporting periods or borrow a limited advance against next year’s allowance. “Where the ship has … a compliance surplus … the company may bank it to the same ship’s compliance balance for the following reporting period,” and if a deficit arises, the operator “may borrow an advance compliance surplus …”, the fulfillment of which however will require 1.1-times the GHG-savings to be added in the coming year EUR-Lex. Banking preserves the negative-WTW credits that Bio-LNG delivers today, smoothing compliance over leaner years; borrowing lets an operator front-load up to 2 % of their allowed emissions to avoid short-term penalties.

Together, pooling and banking/borrowing make it possible not only to meet the straight-line targets set by FuelEU Maritime, but to optimize the use of Biomethane’s exceptional carbon profile—turning one ship’s negative emissions into a strategic asset for the entire fleet, both now and in the years to come.