The main type of “bunker” oil for ships is heavy fuel oil, derived as a residue from crude oil distillation. Crude oil contains sulphur which, following combustion in the engine, ends up in ship emissions. Sulphur oxides (SOx) are known to be harmful to human health, causing respiratory symptoms and lung disease. In the atmosphere, SOx can lead to acid rain, which can harm crops, forests and aquatic species, and contributes to the acidification of the oceans. Limiting SOx emissions from ships will improve air quality and protects the environment. IMO regulations to reduce sulphur oxides (SOx) emissions from ships first came into force in 2005, under Annex VI of the International Convention for the Prevention of Pollution from Ships (known as the MARPOL Convention). Since then, the limits on sulphur oxides have been progressively tightened. From 1 January 2020, the limit for sulphur in fuel oil used on board ships operating outside designated emission control areas will be reduced to 0.50% m/m (mass by mass). This will significantly reduce the amount of sulphur oxides emanating from ships and should have major health and environmental benefits for the world, particularly for populations living close to ports and coasts. Below you will find answers to some of the frequently asked questions about the sulphur limit. You can also download a more detailed set of FAQ here.
Limiting SOx emissions from ships will have a very positive impact on human health: how does that work?Simply put, limiting sulphur oxides emissions from ships reduces air pollution and results in a cleaner environment. Reducing SOxalso reduces particulate matter, tiny harmful particles which form when fuel is burnt. A study on the human health impacts of SOx emissions from ships, submitted to IMO’s Marine Environment Protection Committee (MEPC) in 2016 by Finland, estimated that by not reducing the SOx limit for ships from 2020, the air pollution from ships would contribute to more than 570,000 additional premature deaths worldwide between 2020-2025. So a reduction in the limit for sulphur in fuel oil used on board ships will have tangible health benefits, particularly for populations living close to ports and major shipping routes. IMO 2020 – A Breath of Fresh Air – download the infographic (PDF) by clicking on the image.
Why are ships already less harmful than other forms of transport?Ships do emit pollutants and other harmful emissions. But they also transport large quantities of vital goods across the world’s oceans – and seaborne trade continues to increase. In 2016, ships carried more than 10 billion tons of trade for the first time, according to UNCTAD. So ships have always been the most sustainable way to transport commodities and goods. And ships increasingly becoming even more energy efficient. IMO regulations on energy efficiency support the demand for ever greener and cleaner shipping. A ship which is more energy efficient burns less fuel so emits less air pollution. It has sometimes been quoted that just a few ships (all using fuel oil with maximum permitted sulphur content) emit as much harmful air pollutants as all the cars in the world (if the cars were all using the cleanest fuel available). Not only is this the very worst case scenario, but this does not take into account the amount of cargo that is being carried by those ships and the relative efficiency. It is important to consider the amount of cargo carried and the emissions per tonne of cargo carried, per kilometre travelled. Studies have shown that ships are by far the most energy-efficient form of transportation, compared with other modes such as aviation, road trucks and even railways. It is also relevant to remember that shipping responds to the demands of world trade. As world trade increases, more ship capacity will be needed.
How can ships carry so much cargo so efficiently?Ships are the largest machines on the planet and the world’s largest diesel engines can be found on cargo ships. These engines can be as tall as a four-storey house, and as wide as three London buses. The largest marine diesel engines have more than 100,000 horsepower (in comparison, a mid-sized car may have up to 300 horsepower). But the largest container ships can carry more than 20,000 containers and the biggest bulk carriers can carry more than 300,000 tons of commodities, like iron ore.So powerful engines are needed to propel a ship through the sea. And it is important to consider how much energy is used to carry each ton of cargo per kilometre. When you look at the relative energy efficiency of different modes of transport, ships are by far the most energy efficient.Ships can reduce air pollutants by being even more energy efficient, so they burn less fuel and therefore their emissions are lower.
What is the current regulation on SOx in ships emissions and by how much is that going to be improved?We are going to see a substantial cut: to 0.50% m/m (mass by mass) from 3.50% m/m. For ships operating outside designated emission control areas the current limit for sulphur content of ships’ fuel oil is 3.50% m/m. The new limit will be 0.50% m/m which will apply on and after 1 January 2020. There is an even stricter limit of 0.10% m/m already in effect in emission control areas (ECAS) which have been established by IMO. This 0.10% m/m limit applies in the four established ECAS: the Baltic Sea area; the North Sea area; the North American area (covering designated coastal areas off the United States and Canada); and the United States Caribbean Sea area (around Puerto Rico and the United States Virgin Islands). Fuel oil providers already supply fuel oil which meets the 0.10% m/m limit (such as marine distillate and ultra low sulphur fuel oil blends) to ships which require this fuel to trade in the ECAs.
What must ships do to meet the new IMO regulations?The IMO MARPOL regulations limit the sulphur content in fuel oil. So ships need to use fuel oil which is inherently low enough in sulphur, in order to meet IMO requirements. Refineries may blend fuel oil with a high (non-compliant) sulphur content with fuel oil with a sulphur content lower than the required sulphur content to achieve a compliant fuel oil. Additives may be added to enhance other properties, such as lubricity. Some ships limit the air pollutants by installing exhaust gas cleaning systems, also known as “scrubbers”. This is accepted by flag States as an alternative means to meet the sulphur limit requirement. These scrubbers are designed to remove sulphur oxides from the ship’s engine and boiler exhaust gases. So a ship fitted with a scrubber can use heavy fuel oil, since the sulphur oxides emissions will be reduced to a level equivalent to the required fuel oil sulphur limit. Ships can have engines which can use different fuels, which may contain low or zero sulphur. For example, liquefied natural gas, or biofuels.
Are low sulphur blend fuel oils safe? Can new low sulphur fuels cause problems for a ship’s engine?All fuel oil for combustion purposes on a ship must meet required fuel oil quality standards, as set out in IMO MARPOL Annex VI (regulation 18.3). For example, the fuel oil must not include any added substance or chemical waste that jeopardizes the safety of ships or adversely affects the performance of the machinery. IMO is currently discussing how to identify any potential safety issues related to new blends of fuel oil as it is recognized that if these fuels are not managed appropriately, there could be compatibility and stability issues. If needed, additional guidance for crew and ship operators could be developed. An International Standardization Organization (ISO) standard (ISO 8217) specifies the requirements for fuels for use in marine diesel engines and boilers.
How can ship operators and owners to plan ahead for the 0.50% sulphur 2020 limit?To assist ship operators and owners to plan ahead for the 0.50% sulphur 2020 limit, the MEPC has approved guidance on ship implementation planning. The guidance is part of a set of guidelines being developed by IMO for consistent implementation of the MARPOL regulation coming into effect from 1 January 2020. Download MEPC.1/Circ.878 here. The ship implementation planning guidance includes sections on:
- risk assessment and mitigation plan (impact of new fuels);
- fuel oil system modifications and tank cleaning (if needed);
- fuel oil capacity and segregation capability;
- procurement of compliant fuel;
- fuel oil changeover plan (conventional residual fuel oils to 0.50% sulphur compliant fuel oil); and
- documentation and reporting.