A comprehensive strategy for the reduction of air pollution from ships

Recent moves in the United States to launch unilateral legislation (*) which would limit the sulphur content of fuel for ships in U.S. ports to 0.1% by 2010 (well below and well ahead of industry plans but pretty much in line with the European Union (EU) Sulphur Directive) has focused minds in the international shipping industry and at the International Maritime Organization (IMO) on the necessity of coming up on time with a comprehensive, practical, efficient strategy to reduce air pollution from ships in the medium term as well as in the long term.


The environmental footprint of ships, which carry 90% of world trade covering over 30,000 billion tonne-miles a year, is extremely light compared to other forms of transport. And yet despite the industry’s tonne-mile efficiency, it has been left behind by other sectors which are already regulated and compelled to use clean, environmentally friendly fuels. This means that the shipping industry has become an easy-to-pick fruit, recently targeted by politicians eager to show that they are still doing something on the environmental front.


A switch from residual fuel to marine diesel oil (MDO) means a comprehensive and practical strategy for an efficient and long-term reduction of air pollution from ships. Should one expect ships to reduce air pollution while still burning residual fuels? These fuels have a significant content of sulphur, nitrogen (which contributes to nitrogen oxide (NOx) emissions and thereby to tropospheric ozone or greenhouse gas), hazardous components including heavy metals and polycyclic aromatic hydrocarbons (PAH) that combine to create a cocktail of particulate emissions and generated sludge.


The proposal that the shipping industry switches to distillate bunker fuel (MDO) according to a timescale that takes into account fuel availability, delivers immediate, real and global reductions in atmospheric pollution [SOx, NOx and particulate matter (PM)]. It deals with the cause of this pollution rather than the effect – i.e. rather than limiting the rulemaking development to cleaning up the pollution itself. These are among the reasons that this proposal has been gaining support from a number of IMO states – including Norway.


Looking at this course of action from a holistic point of view, it is environmentally sound, where CO2 emissions from refineries producing additional MDO are overtaken by CO2 reductions from overall ship operations, actually resulting in lower CO2 emissions overall.


Looking at the broader picture, switching to MDO aligns the shipping industry with other means of transportation and facilitates innovation to allow the industry to go further and faster in the future as emission regulations tighten still further.


Who will pay for cleaner air emissions from ships?

In addition to applying in-engine modifications, air pollution from ships can be reduced either by using cleaner fuels or through the use of exhaust gas treatment technology. The cost of all measures will be borne almost totally by ship owners. Either they will pay a higher price for cleaner fuel (cost often recoverable through freight rate adjustments). Or they will pay for the fitting, running, maintenance of fuel purification and emission abatement systems (cost not recoverable), as well as for the physical disposal of the liquid and solid wastes generated by these systems – and, not least, they will assume the liabilities linked to those disposals.


Who should do the cleaning?

Supplying cleaner fuels to ships places the burden of cleaning on the oil refiners - who pass the extra costs through to the ship owners in the cost of the fuel. The process of obtaining clean fuel is a current operation for the roughly 700 refineries around the world. The refiners would dispose of the waste at the end of the process – the ultimate bottom of the barrel is asphalt or coke. By doing this, economies of scale could be achieved rather than dispersing the problem to the individual ships.


Retaining residual fuels, and purifying the fuel and cleaning the emissions onboard ships, places on the ship owner the full burden of, and responsibility for, this cleaning process. Ships, numbering over 40,000 around the world, are not the most efficient vehicles to carry out such a task. These ships would be obliged to dispose of the waste – sludge from the purifying process and liquid (sulphuric/sulphurous acid) and solid (heavy metals etc.) waste from the emissions cleaning process – in a responsible manner at sea or ashore. If this waste should be disposed of at sea, such a decision rests with governments, not with ship owners. If such waste should be returned to shore, we might ask ourselves why such waste needs to be delivered to ships in residual fuels in the first place?


Will net CO2 emissions overall end up lower?

On the environmental ‘expense’ side, there would be an additional level of CO2 emissions from either the de-sulphurisation of residual fuels to produce low sulphur bunkers, or the production of additional low-sulphur MDO to replace residual fuels on ships (**), or the manufacture and operation of fuel cleaning equipment and 3-4 exhaust gas cleaning systems per ship on up to 40,000 ships


On the environmental ‘income’ side, the use of MDO is the only solution which gives a CO2 emission saving because it:

- reduces total fuel consumption for each ship by at least 4%;

- makes onboard fuel processing, including heating and treatment, redundant (MDO can be put straight into the engine);

- reduces to a minimum energy consumed for onboard waste treatment (200m tons of residual fuel leaves behind at least 1.4m tonnes of sludge, which needs to be incinerated).


This ‘income’ provides a significant reduction in CO2 emissions to offset against extra CO2 that would in theory be produced in the production of extra low-sulphur MDO. In theory? Yes, because, in a refining process, MDO is only one of many other product yields from the same distillation and refining processes. Refineries do not solely produce MDO; the same production capacity will be used to produce a multitude of other products for all the other transport industries. So the burden of extra CO2 from the refining process should not be laid solely at the shipping industry’s door.


In fact the greenhouse gas footprint of the shipping industry is already remarkably small. A 100,000 dwt vessel generates just over 3 grams per tonne/kilometre in CO2 emissions. A 747-400 cargo plane generates over 550 grams per tonne-kilometre in CO2 emissions.


But will the supply of MDO be sufficient?

According to International Energy Agency (IEA) figures, new refineries coming on stream by end 2011 will add 14% to refining capacity over end 2005, or 660m tpa. Out of this new capacity, one-third could produce yields of medium/heavy distillates (such as MDO) – or in this case 220m tpa. In addition, current refineries are being upgraded and they will have spare capacity for increased production. These two developments will create capacity that is more than enough to provide MDO for all ships.


(*) What does the U.S. Marine Vessels Emissions Reduction Act 2007 mean?

This Bill limits the sulphur content of the fuel for ships calling at U.S. ports to 0.1% by end 2010, and possibly to 0.2% by an earlier date, and will apply to new and existing, ocean-going ships of all flags. This compares to the current SECA (Sulphur Emission Control Area) limit of 1.5% and the current international limit of 4.5%. Europe has already adopted a 0.1% sulphur content rule at berth from 2010, through the latest amendments to the EU Sulphur Directive. Such low sulphur content will not be achievable by use of residual type fuel oils, thereby enforcing the use of a distillate marine fuel.


This unilateral regulatory move will put the pressure on the IMO to keep its revision of Annex VI on track for 2010 implementation. The world is looking to the IMO to introduce one single global standard, or as near to that as it can get, to counter the threat of regional legislation. The IMO Secretary General’s recently-announced Marine Environment Protection Committee (MEPC) study group is aimed at helping to clear up uncertainties and points of confusion, thereby assisting the process of introducing an effective international regulation.


(**) To strip the sulphur from its complex chemical links with the many elements existing in residual fuel requires a significantly more energy intensive process (and therefore more CO2) than stripping the sulphur from MDO, which to start with has a much lower sulphur content than most residual fuels. It also entails the destruction of the “stripping gas” containing the sulphur by adding refinery fuel gas, whose subsequent combustion creates even more CO2.


Contact: Bill Box