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A Dirty Business
Dec. 17th, 2009 03:47 amA recent study by the Danish environmental agency has found that the largest container ships in the world each emit as much sulphur oxide pollution in a year as 50 million average cars.
No, that's not a typo: 50 million.
This huge disparity stems from three differences between cars and container ships. First, the average car is only used for a handful of hours each week while container ships operate 24 hours a day for roughly 280 days a year. Second, a car engine's output of about 150 horsepower is puny compared to the 109,000 horsepower monsters used on the biggest container ships. Finally, because of the lack of stringent emission controls, martime shipping tends to use the cheapest fuel that they can get their hands on, which contains about 2,000 times as much sulphur as the stuff we're allowed to put in our cars' tanks.
When you add (multiply, really) it all up the largest container ships in the world each generate about 5,200,000 kg of sulphur oxides a year compared to just 0.1 kg for the average car.
It's important to note here that that sulphur oxides are not greenhouse gases, so we won't be able to halt global warming by slapping exhaust scrubbers on the world's merchant fleet. But it could make a serious dent in the hundreds of thousands of deaths each year caused by sulphur oxide pollution.
Perhaps the most disturbing part of the article that I link to above is the statistical summary at its end. Despite the big numbers involved the shipping industry as a whole is only responsible for about 9% of the world's total sulphur oxide pollution. The biggest offenders are power generators, particularly those which burn oil or coal.
On a related note, here's one of the countless reasons why I love the Internet. While doing research for this post I was delighted to find that the primary method used to remove sulphur from flue gases is to react it with calcium oxide (lime) to form calcium sulphite. Further oxidation of calcium sulphite gives gypsum, the stuff used in drywall and plaster. It's also used as a coagulent in tofu, making it a major dietary source of calcium in many Asian countries. So reducing pollution from power plants saves lives, reduces the cost of housing, feeds people, and helps Asian children grow up tall and strong. Talk about your win-win-win-win situation!
No, that's not a typo: 50 million.
This huge disparity stems from three differences between cars and container ships. First, the average car is only used for a handful of hours each week while container ships operate 24 hours a day for roughly 280 days a year. Second, a car engine's output of about 150 horsepower is puny compared to the 109,000 horsepower monsters used on the biggest container ships. Finally, because of the lack of stringent emission controls, martime shipping tends to use the cheapest fuel that they can get their hands on, which contains about 2,000 times as much sulphur as the stuff we're allowed to put in our cars' tanks.
When you add (multiply, really) it all up the largest container ships in the world each generate about 5,200,000 kg of sulphur oxides a year compared to just 0.1 kg for the average car.
It's important to note here that that sulphur oxides are not greenhouse gases, so we won't be able to halt global warming by slapping exhaust scrubbers on the world's merchant fleet. But it could make a serious dent in the hundreds of thousands of deaths each year caused by sulphur oxide pollution.
Perhaps the most disturbing part of the article that I link to above is the statistical summary at its end. Despite the big numbers involved the shipping industry as a whole is only responsible for about 9% of the world's total sulphur oxide pollution. The biggest offenders are power generators, particularly those which burn oil or coal.
On a related note, here's one of the countless reasons why I love the Internet. While doing research for this post I was delighted to find that the primary method used to remove sulphur from flue gases is to react it with calcium oxide (lime) to form calcium sulphite. Further oxidation of calcium sulphite gives gypsum, the stuff used in drywall and plaster. It's also used as a coagulent in tofu, making it a major dietary source of calcium in many Asian countries. So reducing pollution from power plants saves lives, reduces the cost of housing, feeds people, and helps Asian children grow up tall and strong. Talk about your win-win-win-win situation!
