Ships being retrofitted with scrubbers?

[John&LaLa]

Sort of reminds me of whether you burned coal dug in western PA or coal dug in eastern PA. As long as it doesn't harm the sea life and keeps the air cleaner to breather is must be ok.

 

Love it when those who have real knowledge provide the answers to questions. A pleasure to read your replies.

I'm still waiting on a thorough explanation of the scrubber in the earlier replies. And from some one with extensive experience like Cheng.

 

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[John&LaLa]

Okay, as usual, the Capt has it right, but let me clarify some statements by others:

 

1. "all ships have them" is not correct. Not even is it correct that all ships must have them. The US ECA requires either a scrubber to allow burning higher sulfur fuel (cheaper), or the use of low sulfur diesel fuel within the ECA. Cruise ships are in the process of fitting scrubbers, but not all ships will eventually have them, and if the ship does not sail within one of the ECA's (North Sea, Baltic, or US), then they are not required.

 

2. There are two types of scrubbers, single engine and multi-engine. RCI has decided to go with the multi-engine type, which only requires two scrubbers per ship, but bigger ones than the single engine type, but that require more work and longer installation. Typically, it should take about a year for a multi-engine install, Freedom got set back by a fire up there during installation.

 

3. Scrubbers do not reduce NOX emissions. They do reduce SOX (sulfur oxides) emissions. The design of the engine, its intake and turbocharger determine NOX emissions. Scrubbers do not reduce ozone emissions, only burning less fuel can do that.

 

4. As the CAPT says, they essentially "scrub" the exhaust gas by spraying sea water into the exhaust (many power plants ashore do this in their big cooling towers). This precipitates out the particulates and the sulfur dioxide, which when it combines with water forms sulfuric acid. Now, sulfuric acid and steel are not a good mix, so an alkali is mixed with the sea water to neutralize the acid.

 

5. Some scrubbers are "closed loop" and others are "open loop" (kind of like PVSA cruises :p). Closed loop separates the pollutants from the water, and reuses the water. Open loop just returns the water from the scrubber to the sea. I'm no chemist or marine biologist, but it is felt that the sulfuric acid in the sea water is better than in the air.

 

6. The payback on scrubbers depends on how much time the ship spends in the US ECA, as they are free to bypass the scrubber and continue to burn the high sulfur fuel when outside the ECA. The NCL Pride of America, which spends 100% of her time in the ECA, has a payback period of 4-5 years. A scrubber costs $1-1.5 million per engine.

 

As one who has spent 40 years at sea, and seen the advances in pollution prevention, and who has to deal with maintaining the equipment, and keeping the records, I applaud the US ECA, even though it causes me problems every working day of my life, as my ship also spends 100% of its time in the ECA. It not only makes the cruise lines "feel good" it actually does reduce pollution.

 

And if they didn't burn the cheaper fuel, your cruise fares would go up, with the attendant whining.

All ships have them was a joke about having the staff 'scrubbing' the stacks. I missed it at first as well. 😉

 

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Edited November 18, 2016 by John&LaLa

[chengkp75]

I'm still waiting on a thorough explanation of the scrubber in the earlier replies. And from some one with extensive experience like Cheng.

 

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I will neither confirm nor deny any personal intimate knowledge of "scrubbers" that might or might not have been encountered in the many ports of call during my long career at sea. :o