Home Cruise Safely Are Scrubbers the Answer to Cruise Ship Air Pollution?

Eagle-eyed financial reporters noticed legal disclosures in some cruise lines’ quarterly SEC that reported pending citations from Alaska’s Department of Environmental Conservation. When questioned, the DEC confirmed 48 violations since 2010 and stated “We have Carnival, Holland America, Princess, Royal Caribbean, Norwegian, Celebrity and one to Silver Seas.” Alaska has an air pollution law for ships that is different from EPA and SOLAS laws.

Alaska’s Marine Visible Emission Standard does not concern the content of ship’s exhaust but rather the density of their smoke. Visible emission readers (smoke readers) are trained and certified using a standardized national method referred to as EPA Method 9. The cruise industry has installed monitoring devices in the ship’s smoke stack to monitor and record emissions for internal purposes. In 2010, Royal Caribbean paid a fine to the DEC that was used to establish the current state monitoring system. The DEC would not give further details saying the violations are under negotiation. In the past, fines for violations averaged $37,000.

One of the terms mentioned in the violations is ‘scrubbers.’ A scrubber is a device whose purpose is to lower emission contents. Also called an advanced emission purification system (AEP), these are similar to systems used in coal fired power plants since the 1970s. Alaska sees the installation of scrubbers as a means to control pollution in the state’s cruise industry. All the major cruise lines and many international shipping corporations have ongoing programs of installing scrubbers aboard ships. The recent fire aboard the Freedom of the Seas is said to have been caused by the installation of an advanced emission purification system.

Why is Everyone Installing Scrubbers?

An EPA standard put into effect in 2012 drastically reduced the amount of sulfur allowed in the exhaust of ships within the 200 mile economic zone of America’s coast. The only way that the shipping industry could meet those standards was to switch to a very low sulfur content fuel which is much more expensive.

Alaska relies on shipping for most of its needs including food and the state estimated that the new requirements would raise food prices and other necessities by more than 25% and sued the EPA for an exception. Industry analysis at the time predicted that the inventory of the fuel needed to support the new standards did not exist. The EPA and concerned parties worked to establish mutually acceptable compliance plans which are still underway.

The start of 2015 saw the emission standard drop to 1% sulfur, down from the pre-2012 3.5% and the 2012’s 2.5% standard. The requirement drops further in 2017 (or 2020 based on an availability study next year) to 0.5%. There is a similar international standard, however, implementation dates are years away.

How Does a Scrubber work?

Royal Caribbean gives a good overview on how the system works when talking about their environmental initiative. In a nutshell, it’s freshman chemistry on a huge scale. The exhaust contains particles and ash of different chemicals released in the burning of the fuel with sulfur dioxide being one of the greatest concentration and concern. Jets of salt water are sprayed into the exhaust and the particles of sulfur dioxide react with the water to form sulfuric acid, which is then neutralized by the salt water.

The water also causes other debris to drop from the smoke. This water is then treated by filtering and centrifuge to remove the added chemicals. The process can be an open system, in which seawater is used and returned to the sea, or a closed system using a strong base solution instead of salt water. Currently all new builds are using some type of advanced emission purification system and most cruise lines are modifying their ships. While exact costs are not being released, the budget Carnival has reported and the number of ships it will upgrade places an average around $6 million dollars a ship.

Most environmentalists support these systems in combination with low sulfur fuels as an acceptable method to control air pollution.