The reason you should care is this: Sulfur is present in coal and in most liquid fuels. When it is burned, it oxidized, much as the carbon is oxidized. Carbon becomes carbon dioxide; sulfur becomes sulfur dioxide. When sulfur dioxide enters the atmosphere, it becomes a strong acid: sulfuric acid, which is battery acid. This is one factor that contributes to acid rain, among other problems.
Regulations in the USA and elsewhere have resulted in a great reduction in domestic sulfur emissions. In part, this is because oil refineries limit the amount of sulfur that goes into gasoline and diesel fuel. But the sulfur, being an element, does not just go away. Have environmental regulations solved the problem? Hardly, explains Fred Pearce, environmental consultant to New Scientist magazine.
How 16 ships create as much pollution as all the cars in the world
By Fred Pearce
21st November 2009
...We've all noticed it. The filthy black smoke kicked out by funnels on cross-Channel ferries, cruise liners, container ships, oil tankers and even tugboats.
It looks foul, and leaves a brown haze across ports and shipping lanes. But what hasn't been clear until now is that it is also a major killer, probably causing thousands of deaths in Britain alone.
As ships get bigger, the pollution is getting worse. The most staggering statistic of all is that just 16 of the world's largest ships can produce as much lung-clogging sulphur pollution as all the world's cars...
Seems improbable, at first glance. But then, there are some really big ships out there. Pearce explains that the largest ships are a quarter-mile long. The biggest are the Emma Mærsk-class container ships. Their main engines weight over 2,300 tons, and produce 114,800 hp (84 megawatts). They also have five smaller engines that together produce another 40,000 hp.
Pearce explains how these things are powered:
Because of their colossal engines, each as heavy as a small ship, these super-vessels use as much fuel as small power stations.
But, unlike power stations or cars, they can burn the cheapest, filthiest, high-sulphur fuel: the thick residues left behind in refineries after the lighter liquids have been taken. The stuff nobody on land is allowed to use.
The consequences:
James Corbett, of the University of Delaware, is an authority on ship emissions. He calculates a worldwide death toll of about 64,000 a year, of which 27,000 are in Europe. Britain is one of the worst-hit countries, with about 2,000 deaths from funnel fumes. Corbett predicts the global figure will rise to 87,000 deaths a year by 2012.
The article does not describe the effects of the sulfur emissions upon the oceans. That is where the majority of the emissions occur. The International Maritime Organization "limits" the emission of each ship to 5,000 tons of sulfur per year. Someone else can do the math, but this would seem to be a factor that contributes to the acidification of the oceans. However, most of what I found on that subject attributes the acidification to carbon dioxide.
Pearce does make a questionable claim, however:
The recession has barely dented the trade. This Christmas, most of our presents will have come by super-ship from the Far East; ships such as the Emma Maersk and her seven sisters Evelyn, Eugen, Estelle, Ebba, Eleonora, Elly and Edith Maersk.
The recession has greatly impacted the shipping trade. The Financial Times reports:
London-based Drewry Shipping Consultants forecasts a year-on-year fall of 10.3 per cent in containers moved this year, compared with 4.6 per cent growth in 1982, the previous worst year since 1956, when container shipping started.
To be fair, the FT article was published after Pearce's article, so I don't fault him for this.
So, is the recession going to be good for the environment? Pearce addressed that question in a separate article:
Global recession is going to have two effects - pulling in opposite directions. The economic downturn will reduce fuel burning and so cause a slackening off in the recent inexorable rise in emissions of carbon dioxide. It happened in the 1930s; it will happen now.
That's the good news. The bad news is that, as the cost of fuel plunges (oil is back under $80 a barrel already), the incentives to use less and to switch to renewables will evaporate. Cheap coal will trump clean coal - let alone solar panels and wind turbines.
Conservation costs money. Money is increasingly hard to get. Nobody can predict how the two forces will play out. Will the decline in economic activity lead to lasting, overall reductions in pollution? Or will the need to cut costs result in a return to dirtier ways of doing business, offsetting the reductions?
Environment
