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Pollution from ships vs cars

Alasdair Anderson
In a recent article (E&T Feb - Hybrid Ships - https://eandt.theiet.org/content/articles/2019/01/hybrid-ships-take-to-the-high-seas/) it is stated that "According to figures originally published in the Guardian in 2009, one giant container ship can emit almost the same amount of cancer- and asthma-causing chemicals as 50 million cars, and around 50,000 premature deaths in Europe have been attributed to international shipping".  This seems a bit much to me, since there are only about 30 million cars in the whole of the UK. Can one container ship with say two diesel engines of 40,000 hp each produce the equivalent pollutants of the exhausts of 50 million cars with a combined engine power of perhaps around 2.5 billion hp? (Note that I am ignoring issues such as the 15,000-20,000 lorries kept off the road). As this information was originally published in the Guardian, does anyone know how the journalists gather and, more importantly, validate their statements?

Alasdair
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    Greetings from Southampton, a container port,  “the home of ocean cruising”, a city with an air pollution problem.

    I suspect the stats are to do with the fuel chemistry just as much as the raw arithmetic.

    Outside of territorial waters, ships can burn bunker fuel, it’s cheap and keeps the share holders happy.  I guess there is probably more to the exhaust than Co2, Nox and sulphur.
    At the last economic downturn, the conveyor belt of ships from China slowed down a couple of knots in order to keep the shipping capacity fully loaded. The reduced speed also saved about £250k per trip in fuel costs. Even cheap fuel is expensive.

    In uk regulated waters and when docked, ships must use “high quality” low sulphur fuel.  I’m guessing it’s probably not as clean as car diesel, i dont know ?

    “When docked” is part of the UK problem. Elsewhere, ships can plug into the quayside for eco power. In the UK they can’t and have to keep their engines running to generate the power.
    Probably not so bad for the container vessels, with a skeleton crew and all the hard work being done by the container terminal cranes but for the cruise ships, it’s a different story.
    The cruise ships generate enough power for a small town to provide facilities for passengers & crew [= 8000 people], kitchens, swimming pools, theatres etc......
    For perspective, here is the latest arrival...
    https://www.theguardian.com/travel/gallery/2016/may/17/harmony-of-the-seas-cruise-ship-southampton-in-pictures

    https://en.wikipedia.org/wiki/Harmony_of_the_Seas

    check out the flume tube !



     
    Installed power:



    • 2 × 19,200 kW (25,700 hp) Wärtsilä 16V46F[2]


    Propulsion:




    • 4 × 5.5 MW (7,400 hp) Wärtsilä CT3500

    •       bow thrusters[2]





  • 0

    Stuart Bradley:

    Ships emissions can be higher than expected if the crew use the wrong fuel; https://www.theguardian.com/world/2018/nov/26/cruise-ship-captain-fined-100000-for-using-dirty-fuel 

    Unlike cars where the fuel quality is tightly controlled. 

    And of course, ships have other emissions that cause environmental harm
    https://www.theguardian.com/environment/2016/dec/02/the-40m-magic-pipe-princess-cruises-given-record-fine-for-dumping-oil-at-sea
    https://www.theguardian.com/environment/2018/oct/22/po-cruise-ship-dumped-27000-litres-of-waste-on-great-barrier-reef-senate-hears


    Shipping needs to clean up, quickly




    The shipping stories here are ones where the ships contravened the tight regulations and so were fined. Ships are as tightly regulated as cars, even with low emission zones defined as has been done for cars in London, so ships can't come to the UK/North Sea/Baltic if unless they meet the low emission requirements.

    With regard to the comments from Clive and Nigel about Southampton, the engines on ships have much tighter emission requirements than the power stations providing the electricity they would plug into. However the critical factor is that the ships are berthing in the centre of a city while the power station is remote and so while the emissions from a power station are greater, they do not affect anything like the same number of people. Also remember that the installed power on a cruise ship may be high but the majority of that is for the electric propulsion and the load in port is only a few MW.

    The exhaust emissions on ships is monitored and recorded while they are in the ECAs (Emission Control Areas) so that they can demonstrate they are meeting the requirements. How many cars have their exhaust emissions measured more than once a year (at MOT test time)?

    With regard to Richard's comment that emissions is now a hot topic in Shipping, it has been a hot topic for the last decade. The biggest problem is that being an international trade with free movement in international waters you can't have the UK unilaterally saying ships passing through the channel must meet certain emission requirements - it needs to be agreed at an international forum, which is the International Maritime Organization, a branch of the UN (and has been agreed). This means that things take a bit longer as they have to be discussed. agreed and ratified. One country trying to go its own way would be like UK setting extreme emission requirements to be verified at manufacture and MOT, and then wondering what to do about the emissions from foreign cars arriving on ferries for holidays.....

    Alasdair

  • 0
    Thank you all for your comments and the links.


    I was aware that pollution from ships exhaust gasses had been a "hot" [ no pun intended] topic for a number of years and that the N sea, Baltic, Channel and other areas had strict limits.

    The point about floating towns and their loads  v a container ship, whilst alongside, is well made. As is the fact that power stations are needed to support the grid, if they pug in at a berth! At least we seem to be moving towards trying to limit the emissions 

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