Sleeve oil and its substitutes post MEPC 72

Up to now, owners have been a bit wary about putting their ships’ fuel consumptions in the public domain. For one thing, charterers might compare notes. I can recall three Freedom Twos, employed on the same trade, one of which seemed to need about 20% more fuel than the other two did, until the charterers gently let it be known that they had not been born yesterday. This sort of thing, along with ingenious plumbing arrangements, used to be considered all part of the fun.

But now we have a problem. Since there is no practical way of measuring the carbon dioxide, solid carbon particles, sulphur dioxide, carbon monoxide, nitrous oxide and so on that leaves the funnel of a ship at sea, if we want to calculate what has gone out of the funnel we must determine what has gone into the engine(s). This, too, has been all part of the fun, and the running battle between owners and time charterers has been mirrored in the running battle between bunker suppliers and owners. Beside the owners and the charterers, chief engineers have, at least since the invention of the oil burning steamship and motor ship, made a point of having some fuel aboard that only they know about, cunningly hidden in plain sight, and known, by analogy with cylinder oil, as sleeve oil.

There used to be a type of infernal combustion engine, beloved of the late, great, Sir Harry Ricardo, (the engineer – the economist was an ancestor) called the sleeve valve engine, hence the pun. The potential for confusion is vast, and the ‘simple’ seaman may not know where to turn, rather like the chief engineer of a gas carrier whom I remember. His ship was on time charter to a very large firm of traders, who had been persuaded, by the awfully famous owners of the ship, to ‘go halves’ on the cost of new super duper antifouling, on the grounds that it would save them money. So far so good, but the ship screwed up a bunker ullage figure at a Middle Eastern port which shall remain nameless, to the undoubted, but private, delight of the barge crew, whose Eids came early that year, and the ship’s crew decided that the best way to cover up their mistake was to over-state the consumptions, which was fine until the trader’s people asked why the new super duper antifouling that they had paid for had made the consumptions so much worse..

All of this is going to come under the eyes of other people, including governments, who will want to know how much carbon dioxide the ship has added to the atmosphere, and who may very well want to levy a tax on that number. Many owners are already reporting these numbers, or rather, guesses at them, on a ‘trial’ basis, so the system can be debugged before it happens for real. The EU, for instance, likes to know how much fuel you used on the passage from your last non-European port to your first port in Europe (Suez doesn’t count, unless you worked cargo there) and whilst this number can vary hugely (“Singapore? Anyone for Jeddah?”) the database will be constructed and it will eventually provide a standard against which obvious nonsense will stand out clearly enough for an algorithm to spot it.

The ‘Freedom of the Seas’ is going to take another knock…

Now, let’s do another thought experiment. Let us assume that world trade by sea, measured in ton miles, which quadrupled between 1968 and 2008, and which has been growing at around 4.2% since then, (if we exclude the 9% ‘bounce back’ in 2009) so that world trade by sea will have doubled again by 2025, does indeed continue on the trend line.

Let us further assume that we set out to ‘decarbonise’merchant shipping completely by 2035, as the OECD International Transport Forum suggests.

Let’s answer the easy question –how?

First, let’s be clear that, as an engineering and as a commercial objective, when compared with similar tasks in the past, this one is not that hard. We could perhaps compare it with the ‘carbonising’ of shipping in the last quarter of the century before last – that was actually a much bigger enterprise, requiring huge investments in much more expensive steel ships, in coaling ports, in the development and the laying of submarine telegraph cables, and in the development of reliable high pressure steam boilers and compound expansion engines, with associated developments in metallurgy and let us not forget, in the financial engineering required to get this all done. But it was done, in a few short years.

At this point, we should keep in mind the wise words of the man who started that revolution – Alfred Holt – in 1877:

“It is found that anything that can go wrong at sea generally does go wrong, sooner or later, so it is not to be wondered at that owners generally prefer the safe to the scientific…. Sufficient stress can hardly be laid on the advantages of simplicity. The human factor cannot be safely neglected in planning machinery. If attention is to be obtained, the engine must be such that the engineer is disposed to attend to it.”

How can we propel a ship without putting carbon dioxide, carbon particulates, carbon monoxide, sulpur dioxide, methane, etc , in the atmosphere?

Let’s put the sailing ship on one side for now – F. Laeitz in Hamburg were the last people to seriously try to improve the sailing ship, before World War One, and whilst they were highly successful at that time, they must be tired of people telephoning them and asking if they have any new ideas.

We could start with methods that are well proven – nuclear power is the obvious candidate. The financing rather than the engineering is the issue, here. A civil, as opposed to a military, reactor, will require refuelling, because the ‘sealed for life’ package reactors used in modern submarines use highly enriched nuclear fuel and we don’t want the wrong people getting hold of that stuff.

Refuelling a reactor is not something that is done in a few hours, so rather longer off hire periods have to be built in, and from the financing point of view you have bought several years’ fuel supply ‘up front’, so from the perspective of the time value of money, we need rather low interest rates. We also have a power plant which we can expect to last 50 years, because experience tells us that they do last that long, so we can expect a ship’s propulsion system to last twice as long as the ship. That need not be a problem – we can build a new ship round the old power plant, but we won’t be running the old lady up a beach and gas axe-ing her in place.

With those provisos, nuclear is not necessarily a silly answer for large ships on long hauls, be they ore carriers, tankers or container ships, and the ‘financial profile’ of such a ship suggests that she might as well be a very high powered ship, operating at the upper end of the practical speed range, so we welcome back the thirty knot containership, along with the twenty five knot bulk carrier and tanker.

The next candidate, for low emissions rather than no emissions, is of course methane. The more carbon atoms in your hydrocarbon, the more carbon dioxide you emit as you burn it…

Methane is CH4, so.. 2 CH4 + 3 O2 = 2CO2 +4H2O…

Ethane is C2 H6, Propane is C3H8, Butane is C4H10, so..

2C4H10 +13O2 = 8Co2 + 10H2O

The proportion of carbon dioxide to water in the combustion products of methane is 1:2, but in the case of butane (still a gas and still a pretty simple hydrocarbon) it is 4:5, so you get much less greenhouse gas from burning methane.

For practical purposes, we take petrol/gasoline as octane, C8H16, so…

2C8H16+25 O2 = 16 CO2 + 18 H2O ( even more CO2 in relation to water).

Diesel is a mixture of stuff from C10H20 to C15H28, and up, but for convenience we can call it C12H24.

Looking at the financial engineering as well as the mechanical engineering, methane is easier than nuclear power and works for smaller ships.

Now coming on to the technology that is just around the corner, so to speak, whilst port equipment can easily be ‘all electric’, battery powered ships are not going to ‘add up’. We need to use shore generated carbon free electric power to produce a fuel that we can burn at sea without generating greenhouse gases. Ideally we want to generate nothing but pure water, so hydrogen is the ‘ideal fuel’, but it is not at all ideal from the cost or the engineering points of view, because it is horribly difficult to store. Being the smallest atom and the smallest molecule, hydrogen liquefies at a temperature just above absolute zero, which is a whole different ball game to methane. Park that idea in the ‘too difficult’ file.

How about carrying our hydrogen in another form? There is a rather promising contender – ammonia – NH3. Ammonia at sea was once familiar enough – it was the refrigerant used on the earlier generations of refrigerated cargo ships. It is fairly unpleasant stuff, but so are all the other contenders, including heavy fuel oil. It is simple and easy to make using electricity – this has been done for a century and more – and ammonia can be carried in liquid form when refrigerated to not such a very low temperature, or under fairly modest pressure. It’s an everyday chemical. It is not at all easy to burn in an infernal combustion engine – although this has been done – but it is fairly easy to turn it back into nitrogen and hydrogen by passing it over a catalyst. So we put the nitrogen back in the atmosphere where it started from and we use the hydrogen – either in an engine, which is dead easy, or, better, in a proton exchange fuel cell, to generate electric power, which we know how to use. This isn’t very exotic technology, either in engineering or in financial terms. It could be done by 2035, if, as an industry, we were given enough in the way of sticks and carrots to get on with it.

Andrew Craig-Bennett

Andrew Craig-Bennett works for a well known Asian shipowner. Previous employers include Wallem, China Navigation, Charles Taylor Consulting and Swire Pacific Offshore. Andrew was also a columnist for Lloyd's List for a decade.


  1. Great Read – look forward to what the industry will do and who will be the leader

    Somehow sense there is a lack of competence to take this in (not that I’m that smart – got lost on the chemistry part). But if wrong actors take the lead – many will just follow and we will not see much improvements, other than endless discussions and delays.

    IMO does not seem to have sufficient mandate, technical competence or will to dictate the drive – simply if all had to follow strict guidelines the cost would be dispersed.

    Now it is open for “Sleeve oil” but in a different form – somehow if the ingenuity used to come around rules etc. was used to make things better, we would have solved this long ago

    1. Thank you, Peter.

      My little quote from Alfred Holt comes from an award winning paper that he presented to the Institution of Civil Engineers in 1877 – they spent four sessions discussing it. Not only was he a qualified engineer (originally in railways) but he found time apart from building up his own fleet and his own business and setting new standards in ship operations ( he self insured, and did not think Mr Samuel Plimsoll’s ideas, or those of the Board of Trade, were anything like good enough!) but he acted as a consultant and a designer for others.

      He would have agreed with you.

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