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Mediterranean SECA 2025: MARPOL Annex VI emission control area

The Mediterranean Sea Emission Control Area is the fourth Sulphur Emission Control Area (SECA) designated under MARPOL Annex VI and the largest by sea-surface area, covering the entire Mediterranean basin from Gibraltar in the west to the Sea of Marmara in the east. The SECA was adopted by Resolution MEPC.361(79) on 16 December 2022 at MEPC 79 and entered into force on 1 May 2025 with the full 0.10% m/m sulphur limit applicable from day one, with no graduated phase-in of the kind used for the Baltic SECA + NECA or the North Sea SECA + NECA. The proposal was co-sponsored by 21 Mediterranean coastal states acting through the Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea (REMPEC) under the umbrella of the 1976 Barcelona Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean. The geographic scope spans the Adriatic, Tyrrhenian, Ionian, Aegean, Levantine and Alboran sub-basins plus the Sea of Marmara to a defined boundary at the Bosphorus, with coordinates listed in the annex to MEPC.361(79). The SECA designation is distinct from the PSSA Western European Waters regime that covers the French, Spanish and Portuguese Atlantic coasts, and from the North American ECA and US Caribbean ECA. Compliance is achieved through ULSFO ≤ 0.10%, VLSFO/MGO blends, LNG dual-fuel, methanol or certified scrubbers. The Mediterranean regime layers on top of the IMO 2020 sulphur cap, the EU ETS and FuelEU Maritime, and exists under the umbrella of the MARPOL Convention. Companion calculators include the Reg 14 sulphur and ECA fuel-cost premium tools at the calculator catalogue.

Contents

Background: Annex VI Reg 14 framework

MARPOL Annex VI is the air-pollution annex of the MARPOL Convention and entered into force on 19 May 2005 after the 1997 Protocol gathered the requisite ratifications. The annex regulates ship-source emissions of sulphur oxides (SOx), nitrogen oxides (NOx), particulate matter (PM), volatile organic compounds (VOC), ozone-depleting substances and, since the 2011 amendments, greenhouse gases through the energy-efficiency framework. The legal basis for the Mediterranean SECA is Regulation 14 of Annex VI.

Regulation 14 caps the sulphur content of any fuel oil used on board. The global limit fell to 0.50% m/m on 1 January 2020 under the IMO 2020 sulphur cap. Inside a Sulphur Emission Control Area (SECA) the limit is one fifth of that figure, namely 0.10% m/m. Compliance can be achieved either by burning fuel that meets the cap on a sulphur-content basis, or by operating an equivalent arrangement, typically an exhaust gas cleaning system (a scrubber), that produces an SO2/CO2 ratio in the stack equivalent to compliant fuel. Particulate matter is controlled in parallel because PM emissions correlate strongly with fuel sulphur content.

The designation procedure for any SECA is set out in Appendix III to Annex VI. A coastal state, or a group of states acting jointly, submits a proposal documenting the air-quality case, the population exposed, the shipping density and the proposed boundary. The proposal is examined by MEPC’s Sub-Committee on Pollution Prevention and Response (PPR) and adopted as an MEPC resolution amending Regulation 14. Entry into force follows the standard MARPOL article-on-amendments rule of twelve months after deemed acceptance by parties, with an additional grace period of typically twelve months built into the resolution itself before the SOx limit becomes operative.

The pre-2025 SECA inventory comprised four areas: Baltic Sea (2006), North Sea (2007), North American ECA (2012) and US Caribbean ECA (2014).

Mediterranean SECA: 2022 designation, 2025 entry

The Mediterranean SECA proposal was submitted to MEPC 78 in June 2022 by 21 Mediterranean coastal states acting through REMPEC. The proposal package, document MEPC 78/INF.10 and a substantive paper at MEPC 78/10/3, ran to several hundred pages of air-quality modelling, emission inventories, health-impact assessment and shipping-density mapping. The technical work was led by EU Member States (France, Italy, Spain, Greece, Cyprus, Malta, Slovenia, Croatia) with a core analytical role for EMSA and the Joint Research Centre (JRC) of the European Commission, supplemented by national contributions from non-EU states (Türkiye, Israel, Egypt, Morocco, Tunisia, Algeria) and by REMPEC’s own regional modelling.

MEPC 78 in June 2022 approved the proposal in principle and instructed PPR to finalise the resolution text. PPR 9 in December 2022 reviewed the boundary coordinates and the entry-into-force timetable. MEPC 79 adopted Resolution MEPC.361(79) on 16 December 2022 by consensus, with no objections from any party. The resolution amended Regulation 14.3 of Annex VI to add the Mediterranean Sea as the fifth SECA.

The entry-into-force date was set as 1 May 2025, approximately twenty-eight months after adoption. The lead time was negotiated to give the regional refining industry, the bunker market and the fleet trading in the Mediterranean enough runway to provision ULSFO supply, install scrubbers, sign LNG bunkering contracts and adapt commercial fixtures. Critically the resolution applies the full 0.10% m/m sulphur limit from 1 May 2025 with no graduated phase-in. This contrasts with the Baltic and North Sea SECAs, which entered with a 1.50% limit and stepped down to 0.10% over nine years. The single-step approach reflects the post-2020 maturity of the global ULSFO market: the supply, distribution and bunker-handling infrastructure for 0.10% fuel was already in place by 2025 across the Mediterranean, so a phase-in was unnecessary.

The legal text of MEPC.361(79) is concise. The operative paragraph adds the Mediterranean Sea as defined in the Annex to the resolution to the list of SECAs in Regulation 14.3.1 of Annex VI; it sets the entry into force at 1 May 2025; and it confirms that the existing Regulation 14.4 sulphur limit of 0.10% m/m and the existing fuel-oil sampling, BDN and certification provisions of Regulations 14.6 to 14.10 apply without modification.

Geographic scope: Mediterranean + Sea of Marmara to Bosphorus

The geographic scope of the Mediterranean SECA is set out in the Annex to MEPC.361(79) and covers the entire Mediterranean Sea plus the Sea of Marmara to a defined boundary at the Bosphorus. The included sub-basins are:

  • The Western Mediterranean: Alboran Sea, Balearic Sea, Ligurian Sea, Tyrrhenian Sea.
  • The Central Mediterranean: Adriatic Sea, Ionian Sea, Sicilian Channel, Strait of Messina.
  • The Eastern Mediterranean: Aegean Sea, Levantine Sea, Cilician Sea.
  • The Sea of Marmara, included in full from the Dardanelles entrance up to the southern entrance of the Bosphorus.

The western boundary of the SECA is the meridian of longitude 5°36’W drawn through the eastern entrance of the Strait of Gibraltar, namely between Punta Marroquí (Spain) and Punta Cires (Morocco). Ships transiting Gibraltar from west to east enter the SECA when they cross 5°36’W.

The eastern boundary lies at the southern entrance of the Bosphorus, with the SECA covering the entire Sea of Marmara up to a line drawn at the Bosphorus southern entrance between Ahirkapı Feneri (the Ahirkapi lighthouse on the European side of Istanbul) and the Kadıköy İnciburnu light on the Asian side. The Bosphorus itself, the Black Sea, and the Sea of Azov are outside the SECA. Ships transiting from the Mediterranean to the Black Sea exit the SECA at the southern entrance of the Bosphorus.

The northern boundary follows the coastlines of Spain, France, Monaco, Italy, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Albania, Greece and Türkiye. The southern boundary follows the coastlines of Morocco, Algeria, Tunisia, Libya, Egypt, Israel, Lebanon, Syria, Cyprus and Türkiye (the southern Anatolian coast). All islands are inside the SECA, including Sicily, Sardinia, Corsica, the Balearics, Malta, Crete, the Cyclades, the Dodecanese, Cyprus and the smaller archipelagos.

The SECA does not extend into the Strait of Gibraltar west of 5°36’W, the Black Sea, the Suez Canal or the Red Sea. A ship sailing from Genoa to Singapore exits the SECA at the southern end of the Suez Canal at the latitude of Port Suez (the Suez Canal itself is not formally part of the SECA but is enclosed by it on the Mediterranean side; the Red Sea is unregulated under Annex VI for sulphur).

The total sea-surface area covered is approximately 2.5 million square kilometres, making the Mediterranean SECA the largest SECA by area. By comparison the Baltic SECA + NECA covers roughly 0.42 million square kilometres and the North Sea ECA roughly 0.75 million square kilometres.

21 co-sponsoring coastal states

The Mediterranean SECA was co-sponsored by 21 IMO Member States bordering the Mediterranean. The list mirrors the membership of the Barcelona Convention with a single exception (Palestine is a Barcelona Convention party but not an IMO Member State and therefore did not co-sponsor). The 21 co-sponsors at MEPC 78 were:

  • Albania (Adriatic coast).
  • Algeria (western Mediterranean coast).
  • Bosnia and Herzegovina (short Adriatic coast at Neum).
  • Croatia (extensive Adriatic coast).
  • Cyprus (Levantine sub-basin).
  • Egypt (Levantine and Suez approaches).
  • France (western Mediterranean and Corsica).
  • Greece (Aegean, Ionian, Cretan).
  • Israel (Levantine).
  • Italy (Tyrrhenian, Adriatic, Ionian, Sicilian).
  • Lebanon (Levantine).
  • Libya (central Mediterranean coast).
  • Malta (central Mediterranean island).
  • Monaco (Ligurian).
  • Montenegro (Adriatic).
  • Morocco (Alboran).
  • Slovenia (Adriatic).
  • Spain (Alboran, Balearic, Ligurian).
  • Syria (Levantine).
  • Tunisia (central Mediterranean coast).
  • Türkiye (Aegean, Marmara, Levantine).

Unanimous co-sponsorship by all 21 IMO-member coastal states is politically significant. No SECA before the Mediterranean had been proposed by such a large group, and the proposal crossed major regional fault lines (EU and non-EU states, states with disputed maritime boundaries). Co-sponsorship was negotiated through REMPEC over approximately five years from the 2018 ministerial declaration to the 2022 submission. No IMO Member State objected at MEPC 78 or MEPC 79, and several non-Mediterranean states (Norway, the United Kingdom, Australia) submitted statements of support.

REMPEC and the Barcelona Convention coordination

The proposal was coordinated by the Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea (REMPEC), an inter-governmental body established in 1976 under the Barcelona Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean. REMPEC is administered jointly by the IMO and the United Nations Environment Programme Mediterranean Action Plan (UNEP MAP) and is headquartered in Floriana, Malta.

The Barcelona Convention is the legal umbrella for environmental cooperation in the Mediterranean. Adopted on 16 February 1976 and amended on 10 June 1995, it covers seven protocols on dumping, emergency response, land-based pollution, specially protected areas, offshore activities, hazardous waste and integrated coastal-zone management. The Convention operates on a Contracting Parties model with biennial Meetings of the Parties (COP) and a permanent Secretariat in Athens. Parties include the same 21 coastal states plus the European Union itself (the EU is a party to the Barcelona Convention in its own right, alongside its Member States).

REMPEC’s role in the SECA proposal was three-fold:

  1. Political coordination. REMPEC convened the Mediterranean Action Plan Focal Points and the inter-ministerial meetings at which the SECA concept was negotiated. Key milestones were the 2016 Marrakech ministerial meeting, the 2018 Tirana ministerial declaration on shipping emissions, the 2019 Naples agreement to begin the technical work, and the 2021 Antalya endorsement of the proposal package.
  2. Technical support. REMPEC’s secretariat subcontracted the air-quality modelling to a consortium led by the JRC of the European Commission, with peer review by IMO’s MEPC PPR sub-committee. The modelling produced a regional inventory of SO2, PM10 and PM2.5 emissions with attribution to ship-source, and a chemical-transport model of population exposure.
  3. Submission to IMO. REMPEC drafted the unified text and coordinated co-sponsorship; individual coastal states submitted the proposal under their own flag.

The SECA does not displace any Barcelona Convention obligation, including the Specially Protected Areas of Mediterranean Importance (SPAMI) network or the Pelagos Sanctuary for cetaceans.

Bunker fuel impact: ULSFO switching, refinery reconfiguration

The Mediterranean is the second-largest bunker market in the world after the Singapore Strait/Indian Ocean cluster. Approximately 50 million tonnes of bunker fuel are sold annually across Mediterranean ports, with the bulk concentrated at Algeciras, Gibraltar, Ceuta, Malta, Piraeus, Istanbul, Augusta, Genoa, Marseille, Las Palmas (technically Atlantic but often grouped with the Mediterranean cluster) and Barcelona. Of this volume approximately 5 million tonnes are HFO/VLSFO grades that did not meet the 0.10% SECA limit at the time of designation and that have switched to ULSFO since 1 May 2025.

The ULSFO supply has been delivered through a combination of refinery reconfiguration and import:

  • Cepsa (Spain): La Rabida and San Roque refineries reconfigured hydrodesulphurisers and added a new ULSFO blending unit at San Roque in 2024; dominant supplier at Algeciras and Ceuta.
  • ENI (Italy): Sannazzaro and Taranto refineries upgraded vacuum-distillation and gas-oil hydrotreatment 2023 to 2024. ENI operates bunker barges at Augusta, Naples and Genoa.
  • TotalEnergies (France): shifted ULSFO supply to imports from Donges and from the Ras Lanuf network. Marseille is the principal Mediterranean French bunker port, served by TotalEnergies and Bunker One.
  • Petrom (Romania): supplies ULSFO into Constanta and onwards into the Marmara through coastal trading; Petrobrazi refinery upgraded 2023 to 2024.
  • Hellenic Petroleum (Greece): Aspropyrgos and Elefsina refineries are major ULSFO suppliers at Piraeus and into the Aegean and Levantine market.
  • Tüpraş (Türkiye): İzmit and Aliağa refineries dominate ULSFO supply in the Marmara and Aegean.

The ULSFO premium over VLSFO at Mediterranean ports averaged USD 50 to 150 per tonne in 2024 to 2025, widening to USD 200 to 250 per tonne in March and April 2025 as the fleet stocked up, and contracting to USD 80 to 120 by July 2025.

The bunker market response was orderly. There was no repeat of the December-2014 Baltic price spike when Baltic bunker prices rose USD 250 to 350 per tonne; the Mediterranean transition was smoother because ULSFO infrastructure had matured globally since the IMO 2020 cap and because the twenty-eight-month lead time gave refiners ample notice.

The fuel-oil sampling and BDN provisions of Regulations 14.6 to 14.10 apply unchanged. Every BDN must be retained on board for three years, and a sealed representative sample of the fuel as delivered must be retained on board for 12 months in a one-litre container. Port-state inspectors lift these samples at random; sniffer drone deployments along the French Riviera, the Italian coast, the Adriatic and the Aegean became routine in 2025.

Cruise-traffic impact: 10+ million Mediterranean pax annually

The Mediterranean is the world’s second-largest cruise market after the Caribbean. Approximately 10 million cruise passengers embark or transit Mediterranean ports each year (CLIA 2024 figures), with the western Mediterranean (Spain, France, Italy) accounting for roughly 70% of the volume and the eastern Mediterranean (Greece, Türkiye, Croatia) for the remainder. The fleet comprises approximately 130 cruise ships of more than 5000 GT operating Mediterranean itineraries seasonally, with peak deployment May to October.

Cruise ships have historically been heavy users of HFO with scrubber retrofit. The Mediterranean SECA forces a step change:

  • Pre-2025: cruise ships could operate on HFO at 3.5% sulphur with an open-loop scrubber at sea, switching to 0.10% MGO only at berth (under EU Sulphur Directive 2005/33/EC) and inside the Strait of Gibraltar tunnel zone.
  • From 1 May 2025: cruise ships must comply with 0.10% across the entire Mediterranean basin, either by burning ULSFO/MGO continuously or by operating a scrubber that delivers 0.10%-equivalent SO2/CO2 ratio.

Several jurisdictions have layered additional restrictions on top:

  • France: open-loop scrubber discharge prohibited in the territorial sea since January 2022; closed-loop residual discharge restricted at port.
  • Italy: Venice and the Lagoon are off-limits to cruise ships above 25,000 GT since 2021 (separate Venice ruling); open-loop scrubber discharge prohibited in territorial waters from 2024.
  • Spain: Balearic Islands open-loop scrubber discharge prohibited in territorial waters from 2024; Barcelona port has imposed cruise-ship caps on number of simultaneous calls.
  • Greece: open-loop discharge restricted in the Saronic Gulf and the Cyclades from 2024.
  • Croatia, Montenegro, Slovenia: Adriatic-wide phase-out under negotiation through the Adriatic and Ionian Initiative.

The combined effect is that cruise lines (Carnival/Costa, MSC, Royal Caribbean, Norwegian, TUI, Disney, Virgin) have largely converted Mediterranean itineraries to ULSFO operation since 2024 and reserve scrubber use for the deep-sea repositioning legs across the Atlantic. Several lines (MSC, Costa, Royal Caribbean, AIDA) have placed LNG-fuelled newbuildings on Mediterranean routes since 2022.

Major Mediterranean ports: Barcelona, Civitavecchia, Marseille, Genoa, Naples, Palma, Venice

The principal Mediterranean cruise and cargo ports affected by the SECA include:

  • Barcelona, Spain. Largest Mediterranean cruise port by passenger throughput (3.0 to 3.5 million pax per year). Onshore power supply (OPS / cold-ironing) phased in 2024 to 2030 across all six terminals. ULSFO bunkering by Cepsa and Repsol; LNG bunkering operational from 2022 via Enagás.
  • Civitavecchia, Italy (port of Rome). Second-largest cruise port in the Mediterranean (2.5 to 3.0 million pax). Cruise terminal renovation 2023 to 2025 includes OPS readiness on three berths. ULSFO bunkered by ENI subsidiaries.
  • Marseille and Marseille-Fos, France. Major cruise (1.6 million pax) and container port. LNG bunkering operational since 2017 (TotalEnergies); methanol bunkering pilot in 2024 with Maersk and CMA CGM. OPS deployed at five terminals.
  • Genoa and the Ligurian ports (La Spezia, Savona), Italy. Combined cruise throughput of 1.5 million pax. Genoa is the major Italian container and ferry hub; Savona is a Costa cruise hub. ULSFO supplied by ENI and Iplom.
  • Naples, Italy. Major cruise (1.3 million pax) and ferry port. Connected to Sicilian and Sardinian ferry network. ULSFO supplied by ENI and Q8.
  • Palma de Mallorca, Spain (Balearic Islands). 2.0 million cruise pax; largest yacht-and-superyacht port in the Mediterranean. ULSFO bunkering by Cepsa and Repsol.
  • Venice and the Adriatic cluster (Trieste, Ravenna, Ancona, Bari, Brindisi), Italy. Cruise traffic shifted from Venice proper to Trieste and Ravenna after the 2021 ban on large ships in the Lagoon; combined cruise pax 1.2 to 1.5 million.
  • Piraeus, Greece. Largest cruise port in Greece (1.0 million pax) and major Aegean ferry hub. ULSFO supplied by Hellenic Petroleum.
  • Valletta, Malta. Mid-sized cruise port (0.7 million pax) and major bunkering anchorage offshore.
  • Algeciras, Spain. Largest container and bunker port in the western Mediterranean (4.5 million TEU, 5+ million tonnes bunker).
  • Gibraltar (UK). Major bunker anchorage; outside the SECA west of 5°36’W, but ships departing eastbound enter the SECA at the Strait.

OPS rollout is driven simultaneously by the SECA, the EU AFIR Regulation and FuelEU Maritime, which mandates OPS use at major EU ports from 2030. Major Mediterranean ports have committed to OPS at all main berths by 2030 (TEN-T core) and 2035 (TEN-T comprehensive).

Relationship to Atlantic European waters (not in Med SECA)

The Mediterranean SECA does not extend into the Atlantic. The boundary at 5°36’W in the Strait of Gibraltar marks the western extent. Ports on the Spanish, Portuguese and French Atlantic coasts are outside the Mediterranean SECA:

  • French Atlantic and Channel ports: Le Havre, Saint-Nazaire, Bordeaux, Brest. All outside the SECA. The Channel is in the North Sea ECA from approximately 51°N northwards but the southern Channel and the Bay of Biscay are not in any SECA.
  • Spanish Atlantic ports: Bilbao, Santander, Vigo, La Coruña, Cadiz (just outside the Strait). All outside the SECA.
  • Portuguese ports: Lisbon, Sines, Porto, Leixões. All outside the SECA.

These Atlantic waters are partially regulated under the PSSA Western European Waters, designated by Resolution MEPC.121(52) in October 2004 alongside the Baltic SECA. The PSSA regime introduces routeing measures (mandatory ship-reporting, pilotage, separation schemes) but does not impose a 0.10% sulphur cap. Ships sailing from Portugal or western France to a Mediterranean port therefore cross from a non-SECA into the SECA at the Strait of Gibraltar and must change over to ULSFO before the 5°36’W boundary.

Several proposals to extend the SECA westward into the Atlantic have been discussed informally at MEPC since 2023, but no formal proposal has been submitted and the political constituency is not yet built. Spain and Portugal have hesitated to add their Atlantic coasts; France has not pursued an Atlantic SECA proposal in parallel with the Mediterranean.

The result is a dual-zone reality for Iberian-Atlantic shipping. A ferry running Algeciras to Tangier crosses 5°36’W several times per day and switches between SECA and non-SECA fuel, or burns ULSFO permanently and absorbs the cost. A container line running Casablanca to Genoa stays inside the SECA from the Gibraltar entry; a container line running Casablanca to Lisbon stays outside.

Relationship to Mediterranean Annex IV special area for sewage

Annex IV of MARPOL regulates sewage discharge from ships. The Mediterranean is not yet a Special Area under Annex IV, although a proposal has been under review at MEPC since 2019. The proposal would prohibit untreated sewage discharge from ships within twelve nautical miles of land in the Mediterranean and would require sewage-treatment plant approval to a higher standard than the global default.

The Annex IV proposal is technically separate from the Annex VI SECA but has been advanced through the same REMPEC and Barcelona Convention coordination mechanism. The political linkage is real: the ministerial declarations at Tirana (2018) and Naples (2019) endorsed both an Annex VI SECA and an Annex IV Special Area as a paired regional package, although the Annex IV component has moved more slowly because of the cost of upgrading port reception facilities and onboard sewage-treatment systems.

The current status (2026) is that the Annex IV Mediterranean Special Area proposal has been examined by PPR but has not been adopted by MEPC. Adoption would be expected at MEPC 81 or MEPC 82 with an entry-into-force date no earlier than 2028. The impact on cruise ships and ferries would be considerable, since many older ships rely on direct discharge of macerated and disinfected sewage outside three nautical miles, which would no longer be permitted.

EU FuelEU + EU ETS layered compliance

The Mediterranean SECA does not exist in isolation. The Mediterranean is dominated by EU and Schengen-area waters (Spain, France, Italy, Slovenia, Croatia, Greece, Cyprus, Malta), and the EU has layered three separate regimes on top of the IMO regulation:

  • EU ETS (Emissions Trading System) for shipping. From 1 January 2024 the EU ETS has been phased into shipping (40% of CO2 emissions in 2024, 70% in 2025, 100% in 2026 onwards). Voyages between two EU ports count at 100%; voyages from an EU port to a non-EU port count at 50% (and vice versa). A Genoa-Algeria voyage therefore triggers 50% of EU ETS exposure; a Genoa-Marseille voyage triggers 100%.
  • FuelEU Maritime. From 1 January 2025 FuelEU Maritime has imposed a well-to-wake greenhouse-gas intensity limit on every voyage to or from an EU port. The limit starts at 2% below the 91.16 gCO2eq/MJ baseline in 2025 and tightens to 6% in 2030, 14.5% in 2035, 31% in 2040, 62% in 2045 and 80% in 2050. Compliance is per-ship and per-year, with pooling and banking provisions.
  • Sustainable Aviation Fuel adjacent regulation (RefuelEU Aviation). Not directly applicable to shipping but creates competitive pressure on biofuel feedstocks (HVO, used cooking oil, lignocellulosic biomass) that overlaps with shipping demand.

A ship calling at Mediterranean EU ports therefore faces four cost layers simultaneously:

  • MARPOL Annex VI Reg 14 (SECA): ULSFO premium of USD 50 to 150 per tonne above VLSFO.
  • EU ETS: EUA cost of approximately EUR 70 to 100 per tonne CO2, equivalent to USD 220 to 320 per tonne fuel oil at 100% phase-in. The 50% rule for non-EU port pairs roughly halves this for a Mediterranean-North-African voyage.
  • FuelEU Maritime: GHG-intensity penalty of EUR 2400 per tonne of VLSFO-equivalent gap, applied to the well-to-wake intensity excess. For a fully fossil-fuelled ship the 2025 penalty is approximately USD 8 to 15 per tonne fuel.
  • Port-state air-quality fees: variable port-by-port (Marseille Low-Emission Zone, Barcelona AQ surcharge, Venice Lagoon access fee).

For a 25,000 tonnes-per-year Mediterranean ferry the combined annual cost layering is approximately:

  • USD 1.25 to 3.75 million per year SECA premium.
  • USD 5.5 to 8.0 million per year EU ETS at 100% phase-in (assuming 100% intra-EU operation).
  • USD 0.2 to 1.5 million per year FuelEU compliance balance.
  • USD 0.1 to 0.5 million per year port-state surcharges.

Substitution toward LNG, biomethane, biomethanol, bioammonia and renewable HVO satisfies all four regimes simultaneously and is the strategic direction of Mediterranean ferry, cruise and short-sea operators.

Scrubber retrofit decisions 2024-2025

The twenty-eight-month lead time between MEPC 79 adoption (December 2022) and entry into force (May 2025) gave shipowners a clear window for scrubber retrofit decisions. The economic logic differs from the 2014-2015 Baltic and 2018-2019 IMO 2020 retrofit waves because by 2024 the ULSFO/VLSFO spread had compressed to USD 50 to 150 per tonne and the payback on a USD 4 to 8 million scrubber retrofit was longer than the typical 5 to 7 year horizon used in Mediterranean fleet analysis.

Three categories of decision emerged in 2024:

  1. No retrofit; switch to ULSFO. The dominant choice for Mediterranean trading vessels with low or moderate fuel consumption (ferries, ro-ro, passenger ships, smaller container feeders, tankers). ULSFO is fully compatible with conventional bunker handling and the marginal cost is modest at the prevailing spread. Approximately 70 to 75% of Mediterranean-trading ships chose this path.
  2. Scrubber retrofit at Mediterranean yards. Yards in Genoa (Fincantieri, T. Mariotti), Naples (Castellammare di Stabia), Marseille (Chantiers de la Ciotat), Piraeus (Elefsis, Neorion) and Tuzla (Türkiye) absorbed approximately 60 to 80 retrofits in 2024 to early 2025. Retrofit cost typically USD 4 to 6 million plus 3 to 5 weeks yard time for a closed-loop or hybrid scrubber. Closed-loop and hybrid configurations were favoured because of the patchwork of national open-loop bans across the Mediterranean basin (France, Italy, Spain, Greece).
  3. Newbuild dual-fuel orders. Major operators (MSC, CMA CGM, Grimaldi, Costa, Tirrenia, Brittany Ferries) accelerated newbuild orders for LNG dual-fuel and methanol dual-fuel ships specifically to handle Mediterranean operation post-2025. Approximately 40 dual-fuel ships were delivered into Mediterranean service between mid-2023 and mid-2025.

Open-loop scrubbers became increasingly problematic over the 2024 season as France, Italy, Spain and Greece all extended territorial-sea bans. By the May 2025 entry-into-force date a Mediterranean transit on a pure open-loop scrubber was operationally unworkable: most of the basin lay inside one or another national open-loop ban. Hybrid and closed-loop installations dominated the retrofit market.

A small number of operators chose to switch from VLSFO+scrubber to MGO operation in the Mediterranean only, retaining HFO+scrubber on deep-sea legs outside the SECA.

Mediterranean NECA proposal under review

A Mediterranean NECA (Nitrogen Emission Control Area) was proposed in parallel with the SECA but was not adopted at MEPC 79. The NECA proposal is under review at MEPC 80 and subsequent sessions. If adopted, the NECA would mirror the SECA geographic scope and would trigger the Tier III NOx limit (3.4 g/kWh at low rated speeds, with the scaling rule 9⋅n−0.29 \cdot n^{-0.2} for higher rpm) on engines installed on ships with a keel-laying date on or after the NECA effective date, as in the Baltic and North Sea NECAs.

The NECA proposal has run into greater resistance than the SECA. The technical case is more complex (Mediterranean dust loadings and ozone formation are non-trivial; the NOx-PM trade-off depends on EGR/SCR pathway choice), and the cost of Tier III retrofit (USD 1.5 to 4 million per main engine) is significantly higher than the cost of ULSFO switching. Several shipowner associations have argued the NECA should not be adopted before the SECA has been operating for at least three to five years.

The current trajectory (2026) is that a Mediterranean NECA proposal could be adopted at MEPC 84 or MEPC 85 with an entry-into-force date in the early 2030s. The proposal would likely follow the Baltic and North Sea precedent: full Tier III for new keels only, no retrofit obligation on the existing fleet.

The geographic scope of a Mediterranean NECA, if adopted, would mirror the SECA boundary at 5°36’W and the Bosphorus southern entrance. The relationship to the North American ECA (which already combines SECA and NECA in a single 200-nautical-mile zone) would remain operationally separate; ships transiting from a North American ECA newbuild keel into a future Mediterranean NECA would need Tier III certification covering both regimes.

LNG/methanol bunkering: Marseille, Algeciras, Barcelona

LNG bunkering in the Mediterranean is operational at several major ports and expanding rapidly:

  • Marseille-Fos, France. TotalEnergies and Elengy operate LNG bunker barges from the Fos LNG terminal since 2017. Annual LNG bunkering volume approximately 200,000 tonnes by 2025. Methanol bunkering pilot with Maersk and CMA CGM since 2024.
  • Algeciras, Spain. Cepsa, Enagás and Vopak operate LNG bunker truck-to-ship and ship-to-ship since 2020. Annual LNG bunkering approximately 150,000 tonnes by 2025.
  • Barcelona, Spain. Enagás operates LNG bunkering from the Barcelona LNG terminal since 2018. Methanol bunkering pilot from 2025 with MSC.
  • Sines, Portugal (Atlantic but adjacent to the Mediterranean). REN operates LNG bunkering from the Sines LNG terminal since 2022. Major hub for Atlantic-Mediterranean LNG-fuelled deep-sea shipping.
  • Piraeus, Greece. DESFA-affiliated bunker barge operations from Revithoussa LNG terminal since 2022.
  • Augusta, Italy. ENI LNG bunkering operations from 2023.
  • Malta. Bunkering anchorage with planned LNG bunker barge operations from 2026.
  • Limassol, Cyprus. Vassiliko LNG terminal under construction; bunker capability planned from 2027.

Methanol bunkering is at an earlier stage but progressing rapidly. The first ship-to-ship methanol bunker operations in the Mediterranean were carried out at Algeciras (Cepsa) in 2024 for a Maersk methanol-fuelled container ship, followed by Marseille (TotalEnergies). Technical barriers are lower than LNG (no cryogenics) but volumetric energy density is half.

Ammonia and hydrogen bunkering in the Mediterranean remains experimental in 2026 with no commercial bunker operations yet.

Eastern Mediterranean trade and pipeline-shipping mix

The eastern Mediterranean trade flows have a particular sensitivity to the SECA because of the dense mix of pipeline-and-ship logistics and the absence of refining capacity on the Levantine coast in some countries.

The major eastern Mediterranean trade flows are:

  • Türkiye-Israel-Egypt triangle. Container, ro-ro and bulk trades among Mersin, Ashdod, Haifa, Damietta and Alexandria. ULSFO supply for this trade is bunkered at Mersin and Aliağa (Tüpraş), Damietta (EGPC) and Haifa (Bazan). The Bazan refinery upgraded ULSFO output 2023 to 2024.
  • Eastern Mediterranean gas pipeline-and-LNG mix. The EastMed gas field complex (Israeli Tamar and Leviathan, Egyptian Zohr, Cypriot Aphrodite) feeds both pipeline (to Egypt and Jordan) and the Egyptian LNG export terminals at Idku and Damietta. Supporting tanker traffic now operates under the SECA.
  • Suez Canal feeder traffic. The eastern Mediterranean is a major staging area for Suez Canal feeder operations. The SECA covers Port Said staging and the Levantine basin; the canal itself and the Red Sea are outside.
  • Black Sea outbound traffic. Ships exiting the Bosphorus from Black Sea ports (Constanta, Novorossiysk, Trabzon) enter the SECA at the southern Bosphorus entrance. The Marmara passage to the Aegean is approximately 24 hours of steaming under ULSFO.

Russian-flag ships are subject to the SECA regardless of EU sanctions (Annex VI is a flag-neutral regime). Compliance with the 0.10% limit is verified at port-state inspection on the bunker-delivery-note and sample basis.

The SECA is widely expected to be followed by a Mediterranean NECA in the early 2030s and by an Annex IV sewage Special Area before then.

Formula, assumptions, and limits

Formula

The core SECA constraint is a single sulphur-content limit:

cS,Med SECA≤0.10% m/m since 1 May 2025 c_{S,\text{Med SECA}} \leq 0.10\% \text{ m/m since 1 May 2025}

The fuel-cost premium for ULSFO compliance relative to the global VLSFO grade is approximated by:

ΔpremiumULSFO vs VLSFO≈50 to 150 USD/tonne (typical 2024-2025) \Delta \text{premium}_{\text{ULSFO vs VLSFO}} \approx 50 \text{ to } 150 \text{ USD/tonne (typical 2024-2025)}

The annual fuel-cost layering for a Mediterranean-trading ship with annual fuel consumption m˙fuel\dot{m}_{\text{fuel}} tonnes per year is:

CSECA premium=m˙fuel⋅ΔPULSFO-VLSFO C_{\text{SECA premium}} = \dot{m}_{\text{fuel}} \cdot \Delta P_{\text{ULSFO-VLSFO}}

where ΔPULSFO-VLSFO\Delta P_{\text{ULSFO-VLSFO}} is the per-tonne ULSFO/VLSFO spread. For a 25,000 t/year ferry at a USD 100/tonne spread the SECA premium is USD 2.5 million per year.

The scrubber-equivalence test under Regulation 14 uses the SO2/CO2 ratio:

SO2(ppm v/v)CO2(% v/v)≤4.3 for a 0.10% sulphur fuel equivalence \frac{\text{SO}_2 \text{(ppm v/v)}}{\text{CO}_2 \text{(\% v/v)}} \leq 4.3 \text{ for a 0.10\% sulphur fuel equivalence}

Derivation

The 0.10% m/m sulphur limit derives from the SECA-default Annex VI text adopted in MEPC.176(58) of 2008. Annex VI Regulation 14.4 sets the SECA limit at one fifth of the global cap; the 2020 reduction of the global cap to 0.50% m/m therefore made the SECA cap 0.10%. The Mediterranean SECA inherits this number directly, with no graduated step-down.

The ULSFO/VLSFO spread of USD 50 to 150 per tonne reflects the marginal cost of additional hydrodesulphurisation between 0.50% and 0.10% sulphur. The cost depends on refinery configuration: refineries with dedicated hydrocracking capacity (Cepsa San Roque, ENI Sannazzaro, Tüpraş İzmit) produce ULSFO at the lower end of the spread; refineries reliant on resid blending pay closer to the upper end.

The scrubber SO2/CO2 ratio of 4.3 is set out in Resolution MEPC.184(59) (the 2009 EGCS guidelines, updated by MEPC.259(68) and MEPC.340(77)). The ratio is derived from stoichiometric combustion of a 0.10% sulphur fuel and the typical CO2 yield of marine fuel oil at full combustion.

Assumptions

  • The bunker fuel sulphur content is verified by bunker delivery note (BDN) and confirmed by retained sample analysis. Discrepancies between BDN and sample are resolved under MEPC.182(59) sampling and analysis guidelines.
  • Compliance is measured per bunker delivery; commingling of compliant and non-compliant fuel on board after 1 May 2025 is prohibited under Annex VI Regulation 14.1.
  • Scrubber compliance assumes the SO2/CO2 ratio is continuously monitored and logged under the EGCS Approval Scheme A or B. Monitor failure for more than four hours triggers a non-compliance event.
  • ULSFO and VLSFO prices reflect spot market quotations at major Mediterranean bunker hubs (Algeciras, Genoa, Piraeus, İzmit). Long-term contract prices may differ.
  • The 50 million tonne annual Mediterranean bunker market figure aggregates ports inside the SECA boundary plus Gibraltar (which is technically outside the SECA but commercially integrated with Algeciras).

Worked example

A 50,000 GT ro-ro ferry operating Genoa to Tunis weekly burns 8,000 tonnes of fuel per year. Pre-1 May 2025 the ferry burned 0.50% VLSFO at USD 600 per tonne. Post-entry it switches to 0.10% ULSFO at USD 700 per tonne (USD 100/tonne premium).

Annual SECA premium:

C=8000×100=800,000 USD/year C = 8000 \times 100 = 800{,}000 \text{ USD/year}

For a fleet of 6 ferries on the same Tyrrhenian-Tunisian rotation, the annual SECA cost to the operator is approximately USD 4.8 million. Layered with the EU ETS at 50% phase-in for 2025 (the Tunisian leg is non-EU; the Genoa leg is intra-EU), the EU ETS exposure adds approximately USD 1.5 million per ship per year, totalling approximately USD 9 million per year for the rotation.

Substitution to LNG dual-fuel reduces both the SECA premium (LNG is sulphur-free) and the EU ETS exposure (LNG combustion CO2 is approximately 25% lower per MJ than VLSFO, and biomethane qualifies for FuelEU near-zero treatment). Newbuild LNG dual-fuel ferries on the route had been ordered by Grimaldi and CMA CGM by 2024.

Edge cases and limits

  • Strait of Gibraltar transit. Ships passing through Gibraltar at 5°36’W must be on compliant fuel from the moment of crossing. Bunkering at Gibraltar (which is outside the SECA on the Atlantic side) is permitted, but the fuel taken on must be 0.10% if the ship is bound east into the SECA. Bunkers may be lifted at Algeciras (inside the SECA) instead.
  • Bosphorus transit. Ships exiting the SECA at the southern entrance of the Bosphorus may switch to non-compliant fuel only when fully clear of the SECA boundary. Fuel changeover during the Bosphorus transit itself is not permitted because the transit is inside the Sea of Marmara and therefore inside the SECA.
  • Suez Canal southbound. The SECA boundary at the southern Mediterranean coastline (Port Said) is the relevant boundary; ships entering the Suez Canal proper may switch to non-compliant fuel only after clearing Port Tewfik on the Red Sea side.
  • Fuel-availability exception (Reg 18.2). If compliant fuel is unavailable at a particular port the ship may submit a Fuel Oil Non-Availability Report (FONAR) to the next port-state. FONARs are accepted but scrutinised; routine FONAR submissions for Mediterranean SECA voyages are not anticipated given the mature ULSFO supply network.
  • Pre-2025 fuel onboard exception. Fuel taken on before 1 May 2025 that does not meet the 0.10% limit may be consumed in the SECA only until exhaustion, with notification to flag-state. The exception applied for the first six months of the regime.
  • Naval and government-owned ships. Annex VI applies to all ships under Reg 3, with limited exceptions for sovereign immunity. Naval ships are typically exempt under flag-state policy but most coastal-state navies operate ULSFO voluntarily.
  • Domestic short-sea ferries. Ferries operating wholly inside one coastal-state’s territorial sea are subject to the SECA on the same basis as international ferries; there is no domestic-trade exception.

Regulatory basis

The legal basis is Annex VI Regulation 14.3.1 as amended by Resolution MEPC.361(79) (16 December 2022). Entry into force: 1 May 2025. The SECA limit is set by Regulation 14.4 at 0.10% m/m. Sampling and BDN provisions are at Regulations 14.6 to 14.10 and MEPC.182(59). Scrubber equivalence is at Regulation 4 and EGCS guidelines MEPC.340(77).

EU implementing measures comprise Directive 2005/33/EC (port-emission limit, parallel 0.10%), the EU MRV Regulation 2015/757, the EU ETS extension to maritime under Directive 2023/959/EU and the FuelEU Maritime Regulation 2023/1805. National measures include the French open-loop scrubber discharge ban (Décret 2022-78), the Italian Lagoon-of-Venice protections (Decreto-Legge 121/2021) and the Spanish Balearic-Islands open-loop ban (Real Decreto 87/2024).

Common errors

  • Confusing the SECA boundary with the EU ETS scope. The SECA covers the Mediterranean basin from 5°36’W to the Bosphorus, while EU ETS scope depends on EU port calls regardless of basin. A ship calling Algeciras-Casablanca is in the SECA throughout but only 50% in the EU ETS.
  • Treating Gibraltar as inside the SECA. Gibraltar is outside the SECA west of 5°36’W. Bunkers lifted at Gibraltar must be 0.10% if the ship is sailing east into the Mediterranean.
  • Assuming the Black Sea is in the SECA. The Black Sea is outside. The SECA terminates at the southern Bosphorus entrance.
  • Confusing the 0.10% SECA limit with the EU port-emission limit. Both are 0.10% but legal bases differ: SECA is Annex VI, the EU port limit is Directive 2005/33/EC. The SECA applies at sea; the EU port limit applies at berth in EU ports.
  • Interpreting open-loop scrubber bans as SECA non-compliance. Open-loop scrubbers are SECA-compliant under the Annex VI equivalence rule provided they meet the SO2/CO2 ratio; the open-loop discharge bans are coastal-state environmental measures separate from Annex VI.
  • Mistaking the pre-2025 fuel-onboard exception for an indefinite carve-out. The exception applied only to fuel taken on before 1 May 2025 and required notification; it expired in practice within six months as the affected stock was exhausted.

See also

References

  1. IMO. Resolution MEPC.361(79): Designation of the Mediterranean Sea as an Emission Control Area for SOx and Particulate Matter. London: International Maritime Organization, 16 December 2022.
  2. IMO. MARPOL Annex VI Regulation 14: Sulphur Oxides and Particulate Matter. London: IMO, 2008 as amended.
  3. IMO. Resolution MEPC.176(58): Revised MARPOL Annex VI. London: IMO, October 2008.
  4. REMPEC. Mediterranean Action Plan: Roadmap for the Designation of the Mediterranean Sea as an Emission Control Area for Sulphur Oxides. Floriana, Malta: REMPEC, 2021.
  5. UNEP MAP. Barcelona Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean (1976, amended 1995). Athens: UNEP MAP Secretariat.
  6. European Commission. Directive 2005/33/EC on Sulphur Content of Marine Fuels. Brussels: EC, 6 July 2005.
  7. European Commission. Regulation (EU) 2023/1805 on the Use of Renewable and Low-Carbon Fuels in Maritime Transport (FuelEU Maritime). Brussels: EC, 13 September 2023.
  8. European Commission. Directive (EU) 2023/959 amending Directive 2003/87/EC concerning the EU ETS in Maritime Transport. Brussels: EC, 10 May 2023.
  9. EMSA. European Maritime Safety Agency Annual Reports on Air Pollution from Shipping in the Mediterranean. Lisbon: EMSA, 2023, 2024, 2025.
  10. CLIA. Cruise Lines International Association Mediterranean Statistics 2024-2025. Brussels: CLIA Europe, 2025.
  11. DNV. ECA Fuel and Machinery Options: Mediterranean SECA Briefing. Høvik, Norway: DNV Maritime, 2024.
  12. JRC (European Commission Joint Research Centre). Air Quality Modelling for the Mediterranean Sea SECA Proposal. Ispra: JRC Technical Report, 2021.

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