IMO 2020 looked like a global regulation story. The better reading is more practical: marine fuel rules work when the bunkering system can absorb them. That matters now because shipping is heading into a much harder fuel transition.
From 1 January 2020, ships had to use fuel oil with sulphur content no higher than 0.50%, down from 3.50%. That was an 86% cut in the allowed sulphur level. IMO later said the rule cut total sulphur oxide emissions from shipping by about 70%, and that the first year of implementation was smooth. Only 55 cases of compliant fuel being unavailable were reported through IMO’s system in 2020, against a trading fleet of more than 60,000 ships.
Those numbers make IMO 2020 look easy in hindsight. It wasn’t. The sulphur cap worked because shipowners had usable compliance options: very low sulphur fuel oil, marine gasoil, scrubbers, LNG and, in limited cases, low sulphur biofuels. Refiners adjusted. Bunker suppliers blended. Ports inspected. Classification societies, flag states and fuel labs gave the rule enough machinery to function.
A fuel rule has to land in tanks, contracts, sampling bottles, certificates and port-state inspections. Otherwise it stays in London, Geneva or Brussels, looking clean on paper and useless at the quay. Singapore is a good example, but it shouldn’t be treated as the whole story. In Q1 2020, the Maritime and Port Authority of Singapore said about 96% of ships arriving at the port were using compliant fuel. It carried out 326 port-state and flag-state inspections, found 12 ships with marginal sulphur exceedances, and detained 2 foreign-registered ships until they switched to compliant fuel.
Rotterdam, Fujairah, Antwerp-Bruges, Houston, Zhoushan and other major fuel hubs play the same structural role. They sit between IMO ambition and shipowner behaviour. If these hubs can supply, test, document and police a fuel, it becomes commercially usable. If they can’t, shipowners will wait, hedge or buy the least risky option.
The 2023 IMO GHG strategy aims for net-zero GHG emissions from international shipping by or around 2050. It also sets a target for zero or near-zero GHG fuels to reach at least 5% of shipping energy use by 2030, with an effort to reach 10%. Total GHG emissions are meant to fall by at least 20% by 2030, with a 30% stretch target, then by at least 70% by 2040, with an 80% stretch target.
That is much more complex task than sulphur control.
IMO 2020 was mainly a fuel-quality switch inside the petroleum system. The next phase asks shipping to change the carbon profile of the energy system itself. Ammonia, methanol, bio-LNG, biofuels and synthetic fuels all come with different infrastructure, safety, certification and cost problems.
Biofuels can move first because they fit more easily into the liquid-fuel system. That does not make them unlimited. Waste oils and residues are capped, and certification gets ugly fast once multiple sectors chase the same feedstocks. Aviation wants them. Road fuels still want them. Shipping is now joining the queue.
Methanol is more advanced on the vessel side than the fuel side. Ships are being ordered, but low-carbon methanol supply is still thin and expensive. LNG has infrastructure and commercial familiarity, which explains why shipowners keep buying it. More than two-thirds of the 515 alternative-fuel ship orders in 2024 were LNG-powered vessels, while methanol accounted for less than one-third, according to DNV figures cited by the Financial Times.
Shipowners buy what they think they can bunker. A port that can handle ammonia safely will shape ammonia adoption. A port that can offer certified biofuel blends with credible chain-of-custody will shape biofuel adoption. A port that can bunker methanol repeatedly, at scale, with clean documentation and trained operators, will do more for methanol than another target buried in a policy paper. Green corridors, liner routes and large bunker hubs will carry the early volumes. Singapore is already supplying these new fuels. That fits how shipping actually works. This favours hubs with scale, regulation and balance-sheet depth.
The risk is that policymakers confuse targets with demand. The IMO 2020 experience is useful because it shows the plumbing. The sulphur transition benefited from years of preparation, existing refinery and bunker infrastructure, enforceable fuel specifications and a compliance route that did not require the shipping industry to rebuild its energy system from scratch. The system became boring enough to work.
Low Carbon will be less forgiving. Future fuel regulation will need a much thicker layer of implementation: port standards, fuel certification, safety codes, offtake confidence and enforcement that is predictable rather than symbolic. The first serious winners will be the fuels that major bunker hubs can make routine.
