FuelEU RFNBO Multiplier: 2x Reward & Sub-target

Why a multiplier rather than a mandate

FuelEU Maritime entered into force in October 2023 and applies from 1 January 2025 to ships of 5,000 GT and above calling at EU/EEA ports. Its central instrument is a well-to-wake GHG intensity limit on the energy used on board. The 2025 limit is 89.34 gCO2e/MJ, declining on a fixed trajectory to 85.69 gCO2e/MJ from 2030 and reaching 18.23 gCO2e/MJ by 2050, a reduction of 80 percent against the 2020 fossil-fuel baseline of 91.16 gCO2e/MJ. The full methodology is in Annex I and Annex II of the regulation and is explained in the FuelEU intensity formula breakdown.

The Commission’s design problem in 2022 was price. Pure RFNBO bunkers, specifically e-methanol and green ammonia, cost three to five times the equivalent VLSFO on an energy basis. A regulation that treated every megajoule identically would have produced a small intensity benefit per tonne of expensive fuel and no early-mover advantage. Biofuels, cheaper and already certified under RED II, would have absorbed the demand because they require no new production infrastructure. The EU did not want biofuels as the dominant decarbonization pathway, given land-use, food-versus-fuel, and indirect land-use change concerns.

The chosen response was to distort the compliance accounting in favor of e-fuels during a defined window. By doubling the credit per megajoule of RFNBO, the regulation effectively halves the cost disadvantage of those fuels on a compliance-value-per-tonne basis. The multiplier is explicitly time-limited because the Commission expects RFNBO production costs to fall as electrolyser capacity scales, and because a permanent multiplier would distort the market structure after 2033 when a hard sub-target is the preferred instrument.

Defining an RFNBO under RED II Article 2(36)

The legal anchor is the definition of renewable fuel of non-biological origin in Article 2(36) of Directive (EU) 2018/2001 (RED II), as updated by Directive (EU) 2023/2413 (RED III):

“renewable fuels of non-biological origin” means liquid and gaseous fuels the energy content of which is derived from renewable sources other than biomass.

Three elements determine eligibility:

Liquid or gaseous form. Solid fuels are excluded. Maritime candidates are hydrogen, ammonia, methanol, methane, dimethyl ether, and the synthetic hydrocarbon cuts produced via Fischer-Tropsch from green hydrogen and captured CO2.

Energy from non-biological renewables. The renewable input must be electricity, direct solar heat, or another non-biological renewable. Biomethane, hydrotreated vegetable oil, and FAME biodiesel are not RFNBOs even if fully renewable; they fall under the biofuels track.

Exclusion of biomass as energy source. The biomass exclusion is both a feedstock rule and a system-design rule. Hybrid pathways mixing biogenic and electrolytic carbon are treated separately; only the non-biological share may count as RFNBO.

The link from RED II to FuelEU is explicit. Article 3 of Regulation (EU) 2023/1805 adopts the RED II definition by cross-reference. A fuel that does not satisfy Article 2(36) of RED II cannot be an RFNBO for FuelEU purposes regardless of its GHG intensity.

The maritime RFNBO candidates through 2034:

The 70 percent GHG savings threshold

A fuel meeting the definitional test is not automatically an RFNBO. It must also clear the 70 percent life-cycle GHG savings threshold against the fossil fuel comparator of 94 gCO2e/MJ, as established in Delegated Regulation (EU) 2023/1185. Seventy percent below 94 gCO2e/MJ is 28.2 gCO2e/MJ. A fuel at 27 gCO2e/MJ delivers a 71.3 percent saving and qualifies; a fuel at 30 gCO2e/MJ delivers 68.1 percent and does not.

The GHG saving formula from Annex V Part B of the Delegated Regulation:

where $E_F = 94$ gCO2e/MJ is the fossil fuel comparator and $E_{\text{RFNBO}}$ is the actual well-to-wake intensity of the candidate fuel.

The threshold calculation includes:

Upstream electricity emissions. The grid emission factor of the electricity supplied to the electrolyser is the dominant variable. Pure renewable electricity counts as zero. EU average grid intensity in the early 2020s ran 230 to 280 gCO2/kWh. Without the additionality rules, an electrolyser running on grid-average power produces hydrogen above the threshold.

Carbon source for synthetic hydrocarbons. CO2 captured via direct air capture or from biogenic sources is treated as zero-emission. CO2 from fossil industrial point sources is treated as zero only during a transitional period where the source is covered by a carbon price; after that transitional period, fossil-CO2-derived e-fuels lose eligibility.

Process and conversion emissions. Electrolyser efficiency, methanation or ammonia synthesis losses, and any heat input from non-renewable sources.

Transport and distribution. Pipeline electricity, liquefaction energy, bunkering losses.

One frequent misconception: the 70 percent threshold is a gating test, not the intensity value used in FuelEU compliance. Once the fuel clears the threshold, its actual certified WtW intensity enters the intensity calculation. The multiplier then doubles the energy term, not the intensity term.

Additionality, temporal correlation, and geographical correlation

The three criteria of Delegated Regulation (EU) 2023/1184 prevent renewable electricity from being counted twice: once toward national renewable targets and again toward an RFNBO claim. They apply to electricity not supplied through a direct physical connection between a renewable installation and the electrolyser.

Additionality rule

The renewable installation supplying the electricity must be additional to existing capacity. Practically, this means the installation came into commercial operation no earlier than 36 months before the electrolyser, or has not received operating aid or investment aid incompatible with the additionality principle. A transitional regime until 1 January 2028 relaxes this for electrolysers commissioned before that date, recognising that large-scale rollout cannot wait for the full rule to stabilise.

The policy logic is straightforward: an RFNBO claim should drive new renewable construction, not simply re-label generation that would have been built anyway.

Temporal correlation rule

The renewable electricity must be produced in the same calendar month as the hydrogen production until 31 December 2029. From 1 January 2030, hourly matching is mandatory. Hourly matching closes a real arbitrage: an electrolyser that runs overnight on cheap fossil-heavy grid power while holding renewable certificates from a solar farm peaking at noon would fail the 2030 test. From 2030, every hour of electrolysis must match a contemporaneous hour of certified renewable generation under the relevant Power Purchase Agreement.

Geographical correlation rule

The renewable installation must be in the same bidding zone as the electrolyser, or in an interconnected bidding zone where the day-ahead price in that zone was equal to or higher than in the electrolyser’s zone. This prevents a Spanish electrolyser from claiming a Scottish wind farm purely by paper.

For shipping operators, these three rules sit upstream of the bunker supply chain. The certification scheme verifies them on behalf of the producer and issues a Proof of Sustainability (PoS) that travels through the supply chain to the bunker delivery note. The ship operator’s obligation is to hold the PoS, confirm it references the correct batch, and ensure the scheme is EU-recognised.

The 2x multiplier mechanics under Article 5(3)

Article 5(3) of Regulation (EU) 2023/1805 is concise:

Renewable fuels of non-biological origin shall be considered to have a multiplier of 2 in the calculation of the energy used by a ship until 31 December 2033.

The multiplier applies in the energy denominator of the compliance balance, not in the GHG intensity numerator. To see the effect, recall the FuelEU compliance balance from the formula breakdown:

For RFNBO fuel $r$, Article 5(3) substitutes $2 \cdot E_r$ for $E_r$ in $\sum_j E_j$ wherever it appears in the compliance balance calculation. The numerator $\sum_j E_j \cdot \text{WtW}_j$ uses the actual physical energy and actual intensity, because the multiplier’s purpose is to inflate compliance credit, not to misrepresent physical emissions. The compact form for this article’s companion formula:

In the two-fuel case (one RFNBO fuel $r$, one fossil fuel $f$):

The pattern is a denominator-only multiplier on the energy mass the regulation treats as consumed for accounting purposes. Physically the ship burned the actual quantity. The verifier reports actual quantities in the FuelEU report. The multiplier is applied at the moment the compliance balance is computed.

Worked illustration

A 14,000 TEU container vessel burns 10,000 t of VLSFO (WtW intensity 91.7 gCO2e/MJ, lower calorific value 41.0 MJ/kg) and 1,000 t of e-methanol (WtW intensity 5 gCO2e/MJ under certification, LCV 19.9 MJ/kg) in 2026.

Without the multiplier, the attained intensity:

With the 2x multiplier on the e-methanol energy term in the denominator:

Against the 2026 target of 89.34 gCO2e/MJ, the unmultiplied case produces a 1.65 gCO2e/MJ surplus; the multiplied case produces a 5.55 gCO2e/MJ surplus, more than three times the credit for the same physical burn. The FuelEU RFNBO multiplier calculator reproduces this arithmetic for arbitrary fuel mixes.

Denominator inflation versus intensity reduction

Operators reading the Article 5(3) language sometimes interpret the multiplier as a reduction in RFNBO’s intensity rather than a change in the energy term. The two formulations are not equivalent. Halving the RFNBO WtW intensity (from 5 to 2.5 gCO2e/MJ) would misrepresent the physical emission profile and produce a different compliance balance. The regulation’s instruction is to double the energy, not to alter the intensity. Some operator spreadsheets apply a 0.5 intensity factor instead of a 2x energy factor and arrive at the wrong compliance balance. The FuelEU RFNBO double-count calculator isolates the two effects.

Biofuels comparison: no multiplier, different reward structure

Biofuels and biogases are not RFNBOs and receive no multiplier. Relevant categories:

• Sustainable biofuels meeting the RED II Articles 29 to 31 sustainability criteria: bio-methanol from black liquor, FAME and HVO from used cooking oil, biomethane from anaerobic digestion using Annex IX-A feedstocks.
• Biogases of similar provenance.
• Recycled carbon fuels from non-renewable waste streams that clear the 70 percent GHG saving threshold.

For these fuels, FuelEU treats energy at face value: 1 MJ of certified bio-methanol counts as 1 MJ in both the numerator and denominator. The compensation is that certified bio-fuels carry their actual low WtW intensity, often in the 10 to 25 gCO2e/MJ range, which directly reduces the numerator.

The multiplier flips the competitive ranking at small RFNBO volumes. A ship covering 5 percent of its energy with HVO at 15 gCO2e/MJ achieves an intensity reduction of roughly 3.8 gCO2e/MJ. The same 5 percent covered by e-methanol at 5 gCO2e/MJ, without the multiplier, achieves about 4.3 gCO2e/MJ. With the multiplier, the effective energy share in the denominator becomes 9.5 percent (5% × 2 minus the 0.5% double-count) and the attained intensity drops by closer to 8.0 gCO2e/MJ. The multiplier is the policy mechanism that makes a small quantity of expensive e-fuel more valuable for compliance than a larger quantity of cheaper biofuel.

One practical restriction: crop-based biofuels are capped at effectively zero for FuelEU purposes from 2025 unless they meet strict sustainability criteria. Most operators rely on RED II Annex IX Part A advanced feedstocks. This matters for pool managers who blend biofuel-fuelled and RFNBO-fuelled ships into a single compliance entity.

Post-2034: the 2% RFNBO sub-target

The multiplier sunsets on 31 December 2033. From 1 January 2034, Article 5(4) of Regulation (EU) 2023/1805 replaces it with a conditional mechanism: an RFNBO sub-target of 2 percent of the total annual energy used by each in-scope ship.

The sub-target is conditional on one data point. The Commission monitors RFNBO uptake across the regulated fleet. If RFNBO penetration is below 1% of total fuel energy in the 2031 reporting period, the 2% sub-target activates from 1 January 2034. If RFNBO uptake has already exceeded 1% by 2031, the Commission may decide not to activate the sub-target or to set it at a different level based on market conditions at the time.

The architecture is deliberate. The multiplier acts as a demand pull from 2025 to 2033: it makes RFNBO economics competitive without mandating purchase. If the market responds and RFNBO exceeds 1% by 2031, no further intervention is needed. If the market stalls below 1%, the sub-target applies a supply push: a hard floor that forces every operator to bunker RFNBO regardless of price. The 1% trigger is calibrated so the mechanism never activates if the multiplier does its job.

If the sub-target activates, the compliance check from 2034 is:

where both terms are actual energy without multiplier. A ship missing the sub-target faces an additional penalty calculated under the same EUR 2,400 per VLSFO-equivalent tonne framework as the main intensity penalty, applied to the energy gap to the 2 percent floor. Critically, the sub-target operates in parallel with the intensity target. A ship meeting the GHG intensity limit via biofuels or LNG but bunkering no RFNBO will still be liable for the sub-target penalty if the Commission activates it.

For fleet planners, the implication is this: after 2034, RFNBO procurement may not be optional. The exact level depends on what the Commission observes in 2031, but a procurement contract written in the late 2020s must price two scenarios, a voluntary market where RFNBO competes on its intensity value alone, and a mandated market where every in-scope ship is a forced buyer of at least 2% RFNBO.

Verifier evidence and the Proof of Sustainability

A FuelEU report stands or falls on the evidence pack. Under Article 11 of Regulation (EU) 2023/1805, the verifier is an accredited body under Commission Implementing Regulation (EU) 2018/2067. For an RFNBO claim carrying the 2x multiplier, the verifier needs six elements:

Bunker Delivery Note. Must carry an explicit statement that the fuel is an RFNBO under RED II Article 2(36), identify the certification scheme, and reference the PoS batch number.

Proof of Sustainability. Issued by an EU-recognised voluntary scheme, the PoS travels with the batch from producer through each custody transfer. The schemes active in marine as of 2026 include ISCC EU, RSB EU RED, and 2BSvs. Each scheme issues its own template; the PoS must confirm the additionality, temporal, and geographical correlation attestations.

Mass balance documentation. Mass balance is the chain-of-custody method allowing physical co-mingling of certified and non-certified fuel, provided the energy content of certified inputs matches certified outputs over a defined period, typically a calendar quarter. It is not book-and-claim. The verifier checks that the scheme’s mass balance records support the claimed certified volume.

Life-cycle GHG calculation sheet. Shows the actual WtW intensity used in the FuelEU report. The methodology must be consistent with Annex V of RED II and Delegated Regulation 2023/1185.

Additionality and correlation evidence. Embedded in the PoS via attestations from the electrolyser operator. The ship-side verifier does not re-perform the upstream check but verifies the PoS is current and issued by a recognised scheme.

Monitoring plan documentation. If the ship is bunkering RFNBO for the first time in a reporting year, the monitoring plan must describe how RFNBO consumption is metered, how the BDN enters the data system, and how the verifier will sample records.

The verifier issues a Verification Report and a FuelEU Document of Compliance by 30 June following the reporting year. A material misstatement on RFNBO data constitutes a non-conformity under Article 23, which may trigger removal of the multiplier credit, a financial penalty, and in egregious cases an expulsion order from the administering authority.

A recurring operator error is late PoS arrival. If the certificate is dated after the verification deadline, the verifier cannot accept the multiplier claim for that batch. Procurement contracts for RFNBO bunkers should require PoS delivery within 60 days of bunkering, with liquidated damages for delay built into the standard clause.

Operational implications for newbuilds and procurement

The multiplier is the dominant term in the FuelEU economics for a newbuild decision in 2026. A 14,000 TEU container vessel running 50 percent of its annual energy on e-methanol earns a compliance balance surplus well into seven figures in euros each year while the multiplier applies. Four operational areas change as a result.

Newbuild fuel choice and engine selection

Owners choosing between LNG dual-fuel and methanol dual-fuel weigh not just CAPEX and OPEX but optionality on RFNBO bunkers. LNG dual-fuel can in principle run e-LNG, but e-LNG production is expensive and methane slip in low-pressure dual-fuel engines erodes WtW intensity substantially, often by 15 to 25 gCO2e/MJ depending on load profile. Methanol dual-fuel runs on grey, blue, bio-, and e-methanol with minimal hardware change. Ammonia dual-fuel offers the cleanest electrofuel pathway but the two-stroke ammonia engine was not in commercial volume service until 2024 to 2026, and class societies still issue conditional notations while engine duty cycles are validated.

The multiplier accelerates methanol and ammonia choices and decelerates the pure LNG choice, observable in the 2024 to 2026 orderbook. Orders for methanol-capable vessels rose above 200 in 2023 alone; ammonia-capable orders reached double digits by 2025. See methanol as marine fuel and ammonia as marine fuel for the technology and supply chain detail.

Bunker procurement contracts

RFNBO premiums of two to four times VLSFO on a per-tonne basis are common in early 2026 markets. The multiplier roughly halves the effective premium for FuelEU purposes, because each tonne earns double credit. Procurement teams now negotiate on a EUR per FuelEU MJ-equivalent basis rather than EUR per tonne. A long-form contract now typically includes:

• Fixed annual volume with seasonal tolerance.
• Price linked to a green hydrogen or e-methanol index, with a floor and cap.
• PoS delivery deadline with penalty for late delivery.
• Carbon intensity warranty: supplier guarantees a maximum WtW intensity, with a price reduction if exceeded.
• Sub-target option from 2034: right to convert volume rights into RFNBO sub-target compliance if the Commission activates the quota.

Pool design and the anchor-ship model

The classic FuelEU pool structure for 2025 to 2030 is one RFNBO-fuelled “anchor” newbuild paired with 5 to 10 conventional ships paying into the pool for their compliance deficit. The multiplier inflates the anchor ship’s surplus and lowers the cost-per-covered-ship. A pool of 8 conventional Panamax bulkers covered by one e-methanol-fuelled 14,000 TEU vessel is a realistic 2026 commercial structure.

The pooling arithmetic breaks down once the multiplier sunsets in 2034, because the anchor ship’s surplus drops by approximately half per MJ of RFNBO at that transition. Contracts should include a price-adjustment trigger at 2034 that reflects the loss of multiplier benefit. The FuelEU compliance balance calculator models the before-and-after arithmetic, and the pooling surplus transfer calculator sizes the cross-ship transfer.

Banking, borrowing, and the multiplier’s temporal value

FuelEU allows a ship to bank surplus from one year for use in the next, or to borrow against next year’s allowance at a penalty rate, within limits set in Article 20. The RFNBO multiplier has an important temporal interaction with banking: a surplus earned in 2026 when the target is 89.34 gCO2e/MJ is worth more in absolute gCO2e terms than the same physical RFNBO energy would earn in 2031 against a tighter 89.34 gCO2e/MJ target, because the 2026 intensity reduction per MJ of RFNBO is larger relative to a higher baseline. The early years of the multiplier window are the highest-value period per tonne of RFNBO bunkered.

Borrowing against future years has the opposite risk. A ship that borrows in 2032 to cover a shortfall and then finds the multiplier has expired in 2034 when the borrowed amount must be repaid faces repayment costs without the double-credit benefit. Fleet finance models should treat 2033 as the last year where RFNBO procurement materially deflates the cost of a borrowed balance.

Crew certification and class notation requirements

RFNBO-fuelled propulsion brings regulatory requirements beyond FuelEU compliance. Methanol-fuelled engines must comply with the IGF Code (International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels, adopted by IMO Resolution MSC.391(95)) and require a class-approved fuel-handling system covering ventilation, detection, and emergency shutdown. Ammonia-fuelled engines operate under a tighter toxicity regime, requiring gas-detection coverage to the thresholds in the IGF Code as extended for ammonia, crew training certificates specific to NH3 handling, and a class notation confirming the toxicity management plan.

Class societies including DNV, ABS, Lloyd’s Register, ClassNK, and Bureau Veritas issue provisional notations during the engine-maturity phase and require multi-year service agreements with the engine maker covering combustion tuning, slip mitigation, and post-delivery performance data. An owner that takes delivery of an RFNBO-capable newbuild in 2026 to 2028 but cannot confirm crew competency certificates and the class notation before first RFNBO bunkering risks losing the multiplier credit for non-compliant fuel-handling documentation, because the verifier checks operating compliance as part of the FuelEU evidence pack.

The cost of crew certification and class notations is recoverable across the multiplier window for a vessel trading actively on RFNBO. A typical e-methanol-fuelled container vessel running 40 percent of its annual energy on RFNBO earns a compliance surplus large enough to recover full crew training and class notation costs within the first operating year.

Voyage routing and bunkering port selection

Bunkering RFNBO at an EU port maximises the multiplier benefit because 100 percent of intra-EU energy and 50 percent of extra-EU voyage energy falls within FuelEU scope. An RFNBO bunker loaded at a non-EU port for a voyage between two non-EU ports earns no multiplier. Voyage planners now route RFNBO-eligible voyages through Rotterdam, Antwerp, or Singapore (on voyages with EU port calls) rather than non-scope routes, to capture the full 2x credit.

The scope-attribution rule matters for tankers and bulkers doing triangular routes. A ship bunkering e-methanol in the Middle East for a leg that terminates in Rotterdam has 50 percent of that leg’s energy in scope. Bunker plans that maximize the scope-eligible share of the RFNBO volume recover more compliance value from a fixed procurement budget.

Supply chain readiness and the multiplier uptake trajectory

The multiplier’s practical value depends on RFNBO actually being available in commercial bunker quantities at EU-scope ports. As of early 2026, the supply picture is still thin. Rotterdam has handled trial e-methanol deliveries for Maersk’s vessels; Gothenburg Port has completed initial e-methanol bunker operations. Green ammonia bunkering in commercial scale remains limited to the Middle East and Japan in pilot volumes.

The 2026 to 2029 period is the supply-ramp window. Several commercial-scale production projects are online or under construction: HyCC’s HY2GO project in the Netherlands (targeting 50,000 tonnes per year of green hydrogen from 2026), Yara’s Pilbara green ammonia expansion in Australia targeting 3.5 Mt/year from 2028, and Methanex-aligned e-methanol projects in Chile and Europe targeting commercial quantities from 2027 to 2028. None of these volumes were contractually committed to the maritime sector in full as of mid-2026, which creates a supply bottleneck even if demand grows rapidly due to the multiplier incentive.

The 1% fleet-wide RFNBO penetration threshold that triggers the 2034 sub-target requires roughly 3 to 5 Mt of RFNBO bunker equivalent across the regulated fleet per year by 2031. IMO fleet statistics and the FuelEU monitoring data covering the first full year (2025) will establish the baseline, but the gap between current volumes and the threshold is substantial, and the supply chain investment needed to close it is significant. The sub-target mechanism is credible precisely because the Commission and industry analysts both expect the 1% trigger to fire if no additional supply-side measures accompany the multiplier.

This supply risk is the argument for an RFNBO supply contract written in 2026 or 2027 rather than 2029 or 2030. Early offtake agreements at 2026 prices lock in a cost floor before the sub-target forces demand into existence. Producers pricing into the 2029 to 2031 mandatory-demand window will face a different supply-demand balance, likely at higher prices.

Strategic interaction with the IMO Net-Zero Framework

The IMO approved the Net-Zero Framework at MEPC 83 in April 2025. Formal adoption was adjourned at the October 2025 extraordinary MEPC session and deferred to a reconvened session, so the framework is approved but not yet adopted or in force. It introduces a global GHG Fuel Standard with a tiered compliance unit price and a “Net-Zero Fund” rebating revenue to zero or near-zero emission (ZNZ) ships. See the IMO Net-Zero Framework article and Marine GFS methodology for the full architecture.

The interaction with the FuelEU RFNBO multiplier is layered for EU-trading ships from 2027 to 2033:

• FuelEU multiplier inflates the EU-scope compliance benefit by 2x, reducing the effective attained intensity and generating a surplus that can be pooled or banked.
• IMO Net-Zero Fund rebate pays a per-GJ cash amount to vessels using ZNZ fuels globally, independent of FuelEU scope.
• EU ETS zero-rating applies to biogenic CO2 in e-methanol or e-LNG and to combustion-phase CO2 from green hydrogen derivatives, depending on ETS scope and the relevant emission factor.

An EU-trading ship running RFNBO in 2027 to 2033 can stack all three benefits simultaneously. The operator who locks in long-term RFNBO supply at 2026 prices captures all three streams. After 2034, the FuelEU sub-target replaces the multiplier, and IMO GFS stringency tightens. The strategic case for early RFNBO procurement holds across both regimes; the case for relying on cheaper biofuels weakens after 2030 as both regimes raise their intensity thresholds.

A point operators occasionally miss: the FuelEU 2x multiplier is a regulatory accounting device, not a real-world emission reduction. Corporate sustainability reporting under the Corporate Sustainability Reporting Directive (CSRD), voluntary carbon claims under the Green Claims Directive, and investor disclosure under the Sustainable Finance Disclosure Regulation all require actual life-cycle intensity, not multiplier-inflated values. The multiplier exists inside FuelEU compliance calculations only.

The GHG accounting boundary also differs between the two regimes. FuelEU is well-to-wake using EU-defined methodologies and emission factors from Annex II of Regulation (EU) 2023/1805. The IMO Net-Zero Framework uses a broadly similar well-to-wake approach but with default values negotiated at MEPC and a global rather than EU scope. For an RFNBO bunkered in Rotterdam and consumed on an Asia-EU rotation, the FuelEU multiplier applies to the EU-scope share and the IMO regime applies to the full voyage. Operators running parallel compliance systems for both regimes must ensure consistent bunker allocation between the two, because the same physical volume is allocated under different scope masks and verifiers from both regimes will reconcile the records.

Edge cases and common errors

Several calculation errors appear repeatedly in operator monitoring plans and verifier pre-screens:

Multiplying WtW intensity by 0.5 instead of doubling the energy term. This produces a different compliance balance and under-credits the RFNBO benefit. The regulation’s instruction in Article 5(3) is to double the energy in the denominator, not to alter the intensity in the numerator.

Applying the multiplier to a recycled carbon fuel. Recycled carbon fuels (waste-derived synthetic hydrocarbons) are not RFNBOs. They have their own separate treatment under FuelEU and do not qualify for the multiplier, even if they clear the 70 percent GHG savings threshold.

Counting RFNBO bunkered on a non-scope voyage. The multiplier follows scope. RFNBO energy consumed on a voyage segment outside FuelEU scope earns no multiplier.

Treating mass balance as book-and-claim. Mass balance allows physical co-mingling, but the certified energy flowing in must match certified energy flowing out within the scheme’s defined period and custody node. Pure book-and-claim, where physical and certified fuel are entirely decoupled by geography, is not accepted by FuelEU.

Forgetting the 2034 sub-target in fleet models. A scenario in which RFNBO use drops to zero after the multiplier expires in 2033 understates compliance cost after 2034 if the Commission activates the sub-target. Long-term planning models must carry both a sub-target-active and sub-target-inactive scenario weighted by the probability that 2031 RFNBO penetration stays below 1%.

Blended fuels and fractional RFNBO content. A fuel that is 30 percent RFNBO by energy, for example a 70/30 grey/green methanol blend, earns the multiplier only on the certified RFNBO share. The PoS must specifically certify the RFNBO fraction.

Boil-off and slip losses. RFNBO bunkered but lost to boil-off before reaching the engine, as with liquid hydrogen or LNG, is not eligible for the multiplier on the lost fraction. Methane slip from LNG dual-fuel engines and ammonia slip from NH3 engines are accounted in the WtW intensity numerator and reduce the net benefit independently of the multiplier.

Sunset transition from 2033 to 2034. RFNBO bunkered in late 2033 and consumed after 1 January 2034 should be recorded by date of consumption, per Article 15 of Regulation (EU) 2023/1805. Operators should not back-date late-December 2033 consumption records to capture the multiplier; verifiers check the BDN date against the voyage record and will reject the claim.

Limitations

This article describes the multiplier mechanics as specified in Regulation (EU) 2023/1805 and its directly applicable delegated acts as of June 2026. Several areas carry genuine uncertainty for planning purposes.

Delegated act evolution. The criteria in Delegated Regulation (EU) 2023/1184 for additionality and temporal correlation are subject to Commission review. The monthly-to-hourly transition at January 2030 is confirmed in the current regulation, but the additionality transitional period (to January 2028) may be extended or adjusted by further delegated acts. Additionally, the Commission has power under Article 9 of Regulation (EU) 2023/1805 to update the default emission factors in Annex II, which directly affects the certified WtW intensities of RFNBO fuels and therefore the compliance balance arithmetic shown in this article.

Sub-target trigger uncertainty. Whether the 2% RFNBO sub-target activates from 2034 depends entirely on the 2031 monitoring data and the Commission’s assessment at that time. No projection made in 2026 can reliably predict whether global RFNBO bunker supply and demand will have reached 1% of EU-regulated fleet energy by 2031. RFNBO supply in 2024 to 2026 is well below 1%, but the orderbook and supply project pipeline suggests rapid growth.

THETIS-MRV reporting gaps. The FuelEU monitoring data feeding the Commission’s sub-target trigger assessment flows through the THETIS-MRV platform managed by EMSA. As of 2025 and 2026, RFNBO data fields were newly added to the platform and verifier familiarity with RFNBO-specific fields is still developing. Reporting inconsistencies in early years could affect the quality of the 2031 penetration data used for the trigger decision.

Scope expansion. FuelEU currently applies to ships of 5,000 GT and above. The Commission review clause in Article 38 provides for scope expansion to smaller ships. Any scope change would alter the denominator of the fleet-wide RFNBO penetration monitored for the sub-target trigger.

IMO GFS interaction. The Net-Zero Framework’s ZNZ incentive structure and the FuelEU multiplier overlap in fuel categories but differ in accounting methodology. Regulatory interactions between the two regimes are still being worked through at flag-state level, particularly for ships carrying dual compliance documents.

Certification scheme recognition. The list of EU-recognised voluntary certification schemes may change. ISCC EU, RSB EU RED, and 2BSvs are recognised as of 2026. A scheme losing recognition would invalidate PoS certificates issued under it for FuelEU purposes, affecting the multiplier eligibility of batches already certified.

RFNBO intensity values. The certified WtW intensity of any specific RFNBO batch depends on upstream electricity provenance and process efficiency. Published default values serve as planning references, but actual values must come from certified supplier calculations. The well-to-wake hydrogen calculator, well-to-wake methanol calculator, and well-to-wake ammonia calculator provide sensitivity analysis across these variables. A batch of e-methanol produced from a wind farm under a direct power purchase agreement may certify at 3 to 7 gCO2e/MJ, while a batch from a grid-connected electrolyser in 2026 may certify at 15 to 22 gCO2e/MJ depending on the grid emission factor and additionality documentation. Both may qualify for the multiplier if they clear the 70 percent threshold, but the compliance balance benefit differs substantially, and the verifier will scrutinise the calculation sheet for the higher-intensity batch more carefully.

Article 5(4) wording and Commission discretion. Article 5(4) grants the Commission discretion to set the sub-target at a different level than 2% if market conditions justify a different approach. The 2% figure in the current regulation is a default, not a floor. A Commission decision in late 2031 or early 2032 could set the sub-target at 1%, 3%, or zero, depending on the monitoring data and the supply chain assessment at that time.

See also

• FuelEU Maritime explained
• FuelEU penalties, pooling, and multipliers
• FuelEU intensity formula breakdown
• FuelEU compliance balance and pooling
• RFNBO EU rules and certification
• Methanol as marine fuel
• Ammonia as marine fuel
• Marine GFS methodology
• IMO Net-Zero Framework
• EU ETS for shipping
• Well-to-wake intensity methodology
• RFNBO multiplier calculator
• RFNBO double-count breakdown calculator
• FuelEU compliance balance calculator
• FuelEU GHG intensity calculator
• FuelEU penalty calculator
• FuelEU pooling surplus transfer calculator
• Well-to-wake ammonia calculator
• Well-to-wake methanol calculator
• Well-to-wake hydrogen calculator
• RFNBO eligibility calculator