Cargo ships mainly run on VLSFO (very low-sulphur fuel oil) since the IMO’s 2020 sulphur cap took effect. Older heavy fuel oil (HFO) is still used on ships fitted with exhaust scrubbers, and a small but fast-growing fleet burns LNG or methanol instead. This article compares the fuels cargo ships actually carry and the rules that decide which one they burn.
What Types of Fuel Do Cargo Ships Use?
Cargo ships mainly run on one of three fuels: VLSFO, heavy fuel oil (HFO) on scrubber-fitted ships, or MGO/MDO in emission-controlled waters. A small but growing fleet burns LNG or methanol instead of conventional oil-based fuel.
- VLSFO (Very Low-Sulphur Fuel Oil) — the default main-engine fuel for most cargo ships since 2020
- HFO (Heavy Fuel Oil) — cheaper, high-sulphur residual fuel, legal only with an exhaust scrubber fitted
- MGO / MDO (Marine Gas Oil / Marine Diesel Oil) — cleaner distillates used in ECAs and for engine start-up
- LNG (Liquefied Natural Gas) — an established dual-fuel alternative with lower sulphur and CO2 output
- Methanol — the fastest-growing alternative fuel, burned by a small but expanding container-ship fleet
- Biofuel blends — renewable diesel or biodiesel blended into conventional fuel as a drop-in option
- Ammonia and hydrogen — zero-carbon fuels still in pilot and early-adoption stages
| Fuel | Sulphur Limit | Typical Use | Key Regulation |
|---|---|---|---|
| HFO | up to 3.50% (scrubber required for compliance) | Cheapest option, scrubber-fitted ships only | MARPOL Annex VI Reg 14, scrubber exemption |
| VLSFO | ≤0.50% | Default main-engine fuel outside ECAs | MARPOL Annex VI Reg 14 |
| MGO / MDO | ≤0.10% (ECA-grade) | ECAs, engine start-up, maneuvering | MARPOL Annex VI Reg 14.4 |
| LNG | Negligible | Dual-fuel newbuilds, LNG carriers | IGC Code, MARPOL Annex VI |
| Methanol | Negligible | Dual-fuel newbuilds, fast-growing fleet | IGF Code (interim guidelines) |
| Ammonia / Hydrogen | Zero | Pilot projects | IMO interim guidelines in development |
VLSFO became the default fuel almost overnight when the IMO’s global sulphur cap took effect in January 2020. HFO is still legal only on ships fitted with an exhaust gas scrubber, which cleans sulphur oxides from the exhaust before it reaches the funnel. Without a scrubber, burning HFO outside a controlled trial is a compliance violation.
MGO and MDO are lighter distillate fuels, cleaner-burning than either VLSFO or HFO. Ships switch to one of them before entering Emission Control Areas, and keep a supply on board for engine start-up and maneuvering. MGO and MDO marine fuels covers the ISO 8217 grades and the differences between the two in full.
Why Don’t Cargo Ships Just Use Regular Diesel Fuel?
Cargo ships could run on automotive diesel, but marine-grade MGO and MDO already fill that role at sea. Land diesel is refined to a tighter cetane and additive specification for road engines, while marine distillates follow the ISO 8217 marine standard instead. Slow-speed marine diesel engines also tolerate more sulphur and impurities than a truck engine ever could.
LNG is natural gas cooled to about -162°C, which shrinks it to roughly 1/600th of its gaseous volume for storage. It burns with far less sulphur and particulate matter than oil-based fuels, and modestly lower CO2.
LNG has been a proven marine fuel for over a decade. It runs mainly on newbuild container ships and on LNG carriers burning their own cargo as fuel.
Methanol is the fastest-growing alternative marine fuel, burned as a liquid at normal temperature rather than requiring cryogenic storage like LNG. Maersk operates more than a dozen methanol dual-fuel container ships as of 2025, with more on order. Dual-fuel engines explains how a single engine switches between methanol and conventional fuel.
Biofuel blends are the simplest low-carbon option, since biodiesel or renewable diesel can be blended into conventional fuel without engine modification. Ammonia and hydrogen burn with no carbon emissions at all, but both remain in pilot projects rather than mainstream use. Storage, toxicity, and a lack of bunkering infrastructure are the main barriers holding them back.
Why Do Sulphur Regulations Decide Which Fuel a Ship Uses?
MARPOL Annex VI Regulation 14 caps fuel sulphur content at 0.50% globally and 0.10% inside Emission Control Areas. That single rule is why VLSFO replaced HFO as the default fuel almost overnight in January 2020.
Before 2020, most cargo ships burned cheap HFO with sulphur content as high as 3.5%. The new cap cut allowable sulphur by around 85% overnight, and the IMO estimates it reduced sulphur oxide emissions from shipping by roughly 77%. Shipowners had three compliance paths: switch to VLSFO or MGO, install a scrubber and keep burning HFO, or switch to an alternative fuel like LNG.
Where Do Cargo Ships Have to Use Cleaner Fuel?
Ships must burn 0.10%-sulphur fuel inside designated Emission Control Areas (ECAs), instead of the 0.50% global limit. Current ECAs cover the Baltic Sea, North Sea, North American coastal waters, the Caribbean, and the Mediterranean Sea.
The Canadian Arctic and Norwegian Sea joined the ECA list in March 2026, tightening sulphur and NOx limits in northern waters. The North-East Atlantic Ocean ECA follows in September 2027. A ship crossing into or out of an ECA must complete its fuel changeover before crossing the boundary, not after.
Can Cargo Ships Legally Use Heavy Fuel Oil?
Yes, but only with an exhaust gas scrubber fitted. A scrubber washes sulphur oxides out of the exhaust before it leaves the funnel. That lets the ship meet the 0.50% limit without switching fuel.
Scrubbers cost several million dollars to retrofit, but they let a ship keep burning cheaper HFO instead of paying the VLSFO premium. Open-loop, closed-loop, and hybrid designs handle the wash water differently, and that difference matters in port. Around the world, a growing number of ports and some entire countries ban open-loop scrubber discharge in their waters.
What Fuel Do Cruise Ships Use?
Cruise ships burn the same VLSFO and MGO that cargo ships do, not a different fuel. The difference is scale and priority: cruise ships run large auxiliary generators around the clock for hotel power, alongside propulsion.
Most large cruise lines now use VLSFO as the default fuel, switching to MGO inside ECAs just like cargo ships. A small but growing number of new cruise ships run on LNG instead, including some of the largest vessels built since 2022. Scrubber-fitted older ships can still burn HFO on the open ocean.
Fuel choice on a cruise ship follows the same MARPOL Annex VI sulphur rules as a cargo ship. There’s no separate passenger-ship fuel standard. The real difference is hotel load — power for cabins, galleys, and pools that a cargo ship never carries.
What Fuel Will Cargo Ships Use in the Future?
The IMO’s 2023 GHG strategy targets a 20–30% emissions cut by 2030 and 70–80% by 2040, against a 2008 baseline. The ultimate goal is net-zero emissions by or around 2050. Methanol and LNG lead that transition, with ammonia expected next.
Reaching those targets means most of the current fleet will need engines that can burn something other than oil-based fuel by the 2030s and 2040s. Maersk’s methanol fleet and a growing number of LNG-fuelled newbuilds are early evidence of that shift. Fuel choice is now as much a compliance decision as an operating-cost one.
Fuel choice also feeds directly into a ship’s Carbon Intensity Indicator (CII) rating, which grades vessels annually on efficiency. A poor rating can affect chartering and resale value, giving owners a commercial reason to adopt cleaner fuel beyond the regulatory minimum.
Fuel type does not change how much a ship burns or carries — those depend on size, speed, and engine power. Fuel consumption by ship type covers daily burn rates, and fuel tank capacity by ship class covers how much a vessel can carry.
What is the most common fuel used by cargo ships?
Most cargo ships run on VLSFO (very low-sulphur fuel oil), the default fuel since the IMO’s 2020 global sulphur cap took effect. Ships fitted with scrubbers can still burn cheaper heavy fuel oil (HFO) instead.
What is VLSFO?
VLSFO stands for very low-sulphur fuel oil, a blended fuel with sulphur content capped at 0.50%. It became the default marine fuel worldwide when MARPOL Annex VI Regulation 14 took effect in January 2020.
Can cargo ships still use heavy fuel oil?
Yes, but only on ships fitted with an exhaust gas scrubber that removes sulphur oxides before they reach the funnel. Without a scrubber, burning HFO outside emission limits is a compliance violation.
What fuel will cargo ships use in the future?
Methanol and LNG are leading the shift away from oil-based fuel, with ammonia expected to follow. The IMO’s 2023 GHG strategy targets a 70–80% emissions cut by 2040 and net-zero by or around 2050.
Is LNG a clean fuel for ships?
LNG burns with far less sulphur and particulate matter than HFO or VLSFO, and modestly lower CO2. It is not zero-carbon, since methane slip during combustion offsets some of that benefit.
What is the difference between MGO and MDO?
MGO (marine gas oil) and MDO (marine diesel oil) are both lighter distillates than VLSFO or HFO, used mainly in Emission Control Areas. MDO can contain a small amount of heavier residual blend, while MGO is a pure distillate.
What fuel do cruise ships use?
Cruise ships burn the same VLSFO and MGO as cargo ships, not a separate fuel type. A growing number of new cruise ships run on LNG instead, and older scrubber-fitted ships can still burn HFO.
Is ship fuel diesel or petrol/gasoline?
Ship fuel is a form of diesel, not petrol or gasoline — marine engines don’t run on gasoline at all. Most ships burn VLSFO or HFO, both heavier than automotive diesel, with MGO/MDO as the closest equivalent to a true diesel fuel.
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