This year marks an historic bicentenary anniversary – in 1819 the Savannah became the first steamship to cross the Atlantic albeit with assistance from her sails. The US-built and owned Savannah was equipped with side paddle wheels as well as sails. Savannah was by no means the first steam-powered water craft as there had been many more going back several decades operating on rivers and inshore waters.
Like most paddle steamers of the time that were engaged in seagoing trades, she could run under steam alone, under sail alone or with both combined. When running under sail alone, the paddle wheels were moved into the hull so as not to act as a drag.
Almost certainly at the time nobody would have been concerned over Savannah’s use of fossil fuels, in fact it was probable that it was seen as being the future. Although sail would continue to play a role in shipping for more than a century, the advantages of powered navigation were such that seven years after Savannah’s historic voyage, concerned sailing ship owners were petitioning parliament in the UK to do something about the growing competition from steamers.
For most of the two hundred years since, the concern of shipowners has been to improve upon the performance, reliability and efficiency of first steam and then diesel engines. When competing against sail, the attraction of mechanical propulsion was the ability to operate almost regardless of wind speed and direction. The idea that the exhaust gases from burning coal or oil was anything to be concerned about other than for safety reasons was not a factor that figured in shipowners’ decisions.
And that is a position that prevailed almost until today. Until the MARPOL convention was adopted, there was no thought of controlling normal operating emissions from ships including those from the engine. Annex VI of MARPOL is where regulation on engine emissions are found and this was only adopted in 1997. Although shipping’s CO2 emissions came on the IMOs agenda in 1997, until Annex VI it was amended with the addition of a new Chapter four in 2011, no control on CO2 emissions had been formulated.
With the revised Annex VI came the EEDI rules and a mandatory reduction in CO2 emissions for new ships beginning in 2015. By the time all of the initial laid down EEDI reductions are in force which is presently set as 2025, new ships will on average be at least 30% more efficient than the ships built prior to 2011.
That is where we are but what of the future?
At MEPC 72 when the IMO launched its new decarbonisation plan, there was no commitment to any defined reductions beyond the Phase 3 of EEDI which occurs in 2025 although a new Phase 4 of EEDI is in the offing for 2030 which could mean a 40% reduction of CO2 for newbuildings over the 2012 baseline figures for EEDI. There is then a future target of 50%-70% for CO2 reduction by 2050 and movement thereafter towards an eventual phase out of all greenhouse gases from shipping.
The decarbonisation of shipping may be the IMO’s next target but as things stand the technology choices to achieve that are just not available. Slow steaming can dramatically reduce an individual ship’s annual emissions but it also restricts that ships earning and carrying potential.
The capacity issue may be less of a problem in over-tonnaged sectors where freight rates can be jacked up by ships sitting idle or running slow but its is not a viable strategy when demand for shipping space matches or exceeds the supply. Slow steaming is also not popular with cargo owners because unavoidable delays near the end of the voyage cannot be made up and late delivery is the result. Shipping is not an industry that can dictate to its customers and slow steaming has seemingly made schedule reliability in the liner sector worse rather than better.
Going further, exactly how the reductions are to be realised has so far been left open and not even the IMO is exactly sure how it might be achieved. In a statement issued immediately after MEPC 72 the IMO noted that ‘technological innovation and the global introduction of alternative fuels and/or energy sources for international shipping will be integral to achieve the overall ambition.
Alternative fuels such as LNG could perhaps aid towards the lower reduction targets but despite some advances in the number of gas-fuelled vessels, they still represent only a very minor percentage of new vessels. More to the point LNG, methanol and ethane all contain carbon and will produce CO2 when combusted either in an internal combustion engine or if burned to produce steam to power a turbine.
CO2 emissions from LNG are between 25% and 30% lower than from oil fuels depending upon the methane number of the LNG fuel. None of the other alternative hydrocarbon fuels can match this reduction in CO2 although LPG and methanol come close. Even so, the reduction in CO2 from using LNG may not be as great as the chemistry of combustion suggests because unburnt methane that escapes through methane slip is also a potent GHG.
One study done on a ferry in 2012 actually concluded that the dual-fuelled ship actually emitted more GHG when running on LNG than on MDO. On the other hand, a more recent study by the Norwegian research organisation Sintef suggests that the problem is being contained. The IMO has already recognised the problem of methane slip as impacting negatively on shipping’s GHG emissions.
Anything beyond the current EEDI regulations is really only possible with new technology especially if a growing global demand for shipping is met, not as some by additional newer and slower vessels but by existing vessels increasing speed. Batteries have become a consideration for many different types of ships and can provide a possible solution for ferries, tugs and other vessels that operate in a restricted area, but for deep sea vessels they are impractical because they cannot store the energy needed for ships to make voyages across oceans.
Another disadvantage of batteries is that if the energy they store is produced ashore by anything other than completely clean means such as hydro, wind, solar or nuclear; then the problem of emissions has merely been moved from sea to shore. There are also valid arguments against many of these so-called ‘clean’ power sources which may in fact be more carbon intensive than burning fossil fuels. Norway, where most battery fitted ships are based, is fortunate in having more than sufficient clean hydro power but most countries around the globe do not.
To meet the IMO targets, most hope is being pinned on fuel cells and it may well be that at some point in time this technology advances to the point where it is both technically and economically viable. A fuel cell requires either a source of stored hydrogen or a reform system that can extract the hydrogen from another product such as methane. In most cases where fuels are reformed, CO2 is a waste product of the process so these would not help the decarbonisation target.
Only liquid hydrogen meets the requirements but it is expensive to produce and difficult to store. MAN Energy Solutions has developed a cryogenic storage system announced in December and this and similar projects may aid the move towards fuel cells although no shipowner has yet even announced firm plans for such a vessel.
One option that was previously discussed quite recently is for shipping to consider the possibility of nuclear power. Selling this alternative to the world at large is an almost impossible task and although it would allow for decarbonisation to occur quite rapidly it is almost certainly not really an option.
What is noticeable in many of the various studies that have been commissioned on reducing GHG from shipping is that they appear to take little account of the structure of the shipping industry. Calls for co-operation and transparency and working for a common goal ignore the fact that shipping is by and large financed by private capital and is highly competitive. Forcing shipowners into bankruptcy by obliging them to fit new equipment, convert propulsion systems or even to scrap ships and replace them with newbuildings will not solve matter of shipping’s GHG emissions.
If existing ships were to be made obsolete the effect on world trade – even allowing for the overcapacity that exists – could be catastrophic with insufficient tonnage available to carry essential goods and commodities. It is highly doubtful that many governments would consider turning back two centuries of shipping improvements and sacrifice their nations’ prosperity and the outcome could be the very opposite of what is being aimed for.