It has long been a source of surprise to me that the airline industry consistently comes in for so much criticism over carbon dioxide emissions, destruction of the ozone layer and various other environmental sins but we almost never hear a word said against the shipping industry. It could be because sea freight is seen as essential but travel by air is seen as a largely unnecessary luxury but the reality is both industries account for about the same level of carbon dioxide emissions 3% – yet shipping has only recently come under any real pressure to reduce them. As a result, it is may be not too much of a surprise that the shipping industry has only reduced cut emissions per metric ton of freight shipped by 25% since 1970. The industry holds this up as a major achievement but when one considers the increase in vessel size, the improvements in hull design and new engine technology, it isn’t much of an achievement.
Maersk lines started introducing a series of eight E-class container ships from 2006, the monstrous vessels carry 13,500 twenty foot containers (TEU’s) and measure over 1,300 feet in length. These vessels have twice the capacity of vessels only a decade ago and although their 14 cylinder diesel engines consume 16 metric tons of fuel oil an hour they are said to be some of the most efficient container ships afloat. As vessels increase in size, the engines increase at a lesser rate, for example if the vessel is tripled in terms of carrying capacity the engines increase by only 50%. Under such a metric, a 25% increase in fuel efficiency per ton is almost a given without any other improvements.
Quoted in a FT article Bo Cerup-Simonsen, head of Maersk maritime technology, says that improvements have been on many levels, hulls are of better design so they slip through the water with less drag the bulbous nose on container and bulk cargo freighters being a prominent example. Anti fouling paints keep the hull barnacle free, reducing drag. Barnacle growth alone can push up fuel consumption by 20%. Engine technology has improved efficiencies by re-using exhaust gasses and new steels have reduced vessel weight while improving hull strength.
But it could be that diesel engine technology is reaching the limits as far as reducing carbon dioxide emissions and if carbon emissions become taxable the cost may drive designers towards fuel cells or even nuclear power. It is not inconceivable that standardized fuel cells or nuclear power plants could become viable in an operating regime where oil cost much more and carbon emissions were punitive. Then the industry’s emissions reductions may be something to shout about.