Carnival Corporation's
Advanced Air Quality Systems

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What is an Advanced Air Quality
System or “Scrubber”?

Scrubbers – A Clean Solution for Air and Water

Advanced Air Quality Systems (AAQS), commonly referred to as exhaust gas cleaning systems or “scrubbers,” are a significant technological innovation designed to improve air emissions, meet and exceed environmental regulatory standards and support sustainable operations in the global shipping industry.

Advanced Air Quality Systems are an important part of Carnival Corporation’s strategy to improve air quality in port and at sea, a strategy that also includes the use of liquefied natural gas (LNG), shore power and marine gasoil (MGO). By enabling ships to use heavy fuel oil (HFO) and treat it in a way that significantly improves air emissions, Advanced Air Quality Systems provide a safe and effective solution for compliance with International Maritime Organization (IMO) 2020 regulations, while meeting international air and water quality standards.

Carnival Corporation weighed many factors before choosing to pioneer the use of Advanced Air Quality Systems in the small confines of a cruise ship to comply with the upcoming IMO 2020 global sulfur regulations. Under these new regulations, as of January 2020, all ships must utilize fuel oil with a sulfur content of 0.50% mass by mass (m/m), except in Sulfur Emission Control Areas, or SECAs, where the limit is 0.1%, or use approved equivalent methods like Advanced Air Quality Systems to meet the sulfur oxide (SOx) emission requirements. As part of its overall environmental compliance strategy, Carnival Corporation chose to utilize Advanced Air Quality Systems as the most practical method for its existing fleet based on the ability to significantly improve air quality at least to the level of MGO – and in some ways outperform MGO – while continuing its commitment to meet and often exceed all applicable international environmental regulatory standards.

As of the second quarter 2019, Carnival Corporation has invested over $500 million in the development, testing and deployment of Advanced Air Quality Systems. To date, the company has installed over 220 Advanced Air Quality Systems on more than 75 of the more than 100 ships in its fleet, with a goal of installing nearly 400 scrubbers over time in these multi-engine ships. By 2020, the company expects 85% of its global fleet to be fitted with Advanced Air Quality Systems.

To learn more about Carnival Corporation’s Advanced Air Quality Systems, click here.

A Proven & Effective Solution
for Cleaner Emissions

Advanced Air Quality Systems have the proven capability to outperform low-sulfur fuel alternatives such as MGO, providing overall cleaner air emissions in a way that is safe for ocean environments. Results of extensive testing show that ships using Advanced Air Quality Systems produce emissions lower in sulfur and particulate matter (PM) than those running on low-sulfur MGO, a fuel consisting exclusively of distillates that is considered the benchmark for the IMO 2020 0.5% sulfur cap restriction.

In keeping with even the highest international standards, Advanced Air Quality Systems remove 99% of sulfur and 60-90% of PM from engine emissions, including black carbon, elemental and organic carbon. It also reduces nitrogen oxides by at least 5%. Research shows Advanced Air Quality Systems may be especially effective in capturing small-size PM (10 and 2.5 microns and ultrafine), while removing most of the soot from airborne distribution, including black carbon.

In late 2018, Carnival Corporation received the results of the latest rounds of extensive exhaust emissions tests of the company’s Advanced Air Quality Systems. The results are consistent with the major published research on this subject, such as a 2014 study by researchers in Sweden, Kent Salo and Erik Fridell, which concluded that scrubbers on ships using HFO can lower PM to a level below that of MGO.

HFO requires less refining than highly-refined MGO, which means less greenhouse gas created during production. HFO also has a lower combustion temperature than MGO, resulting in less nitrous oxides (NOx) produced by a ship’s engines.

Ships operating with Advanced Air Quality Systems are able to remove almost all the sulfur from engine exhaust – keeping it from being released into the air – and returns it in form of sulfate (SO4), the natural form in which it exists in abundance in the sea, which is the world’s natural reservoir for sulfur.

Since the global maritime bunker fuel sulfur limit will fall in January 2020 from 3.5% to 0.50 and 0.1%, depending on location, there is uncertainty in the market as to whether there will be sufficient compliant low-sulfur fuels (Marine Gas Oil, or MGO for 0.1% and Low Sulfur Fuel Oil, or LSFO for 0.5%) available for the world’s commercial fleets. A number of refinery modeling experts say it will be challenging even if refiners make a concerted effort to meet demand from the marine sector. Industry experts believe that implementing this global fuel specification change will create pressure on supply and upward pressure on cost, leading to increased costs of marine transport and logistics worldwide. If these forecasts are accurate, the use of Advanced Air Quality Systems will be an important component in the maritime industry’s ability to comply with IMO 2020 regulations.

To learn more about the environmental performance of Carnival Corporation’s Advanced Air Quality Systems, click here.

Performance Results

All Advanced Air Quality Systems comply with international regulations and are inspected by a classification society and certified by the ship’s flag administration. In addition, all systems utilize continuous monitoring equipment to automatically record all required parameters.

Advanced Air Quality Systems ensure that Carnival Corporation ships are in compliance with all relevant environmental regulations, including the upcoming IMO 2020 requirements.

The IMO, via strict guidelines from its Marine Environmental Protection Committee (MEPC), requires ships to monitor air and water emissions to safeguard against air and water environmental impacts:

  • To measure and record SO2 levels in the engine exhaust, a gas analyzer is installed above each Advanced Air Quality Systems tower to ensure 24/7 monitoring. Performance of the Advanced Air Quality Systems is constantly adjusted by automation to remain well within the regulatory SO2 limits.
  • IMO MEPC guidelines require that Advanced Air Quality Systems wash water be continuously measured and recorded for three parameters: pH, turbidity and polycyclic aromatic hydrocarbons (PAH). This data is collected in three locations – the inlet, after the AAQS tower and before discharge – and is required to be kept onboard for no less than 18 months.
  • IMO and, for ships operating in US waters, the U.S. EPA also require periodic monitoring in the form of annual sampling and laboratory analysis of wash water from Advanced Air Quality Systems to test for additional parameters, using measurement techniques that are more advanced than those possible to achieve during continuous monitoring.

Meeting Strict Water Quality Standards

An independently reviewed four-year scientific study of Advanced Air Quality Systems wash-water samples concluded that Carnival Corporation ships operating with Advanced Air Quality Systems consistently meet and, in some cases, outperform the industry benchmarks established by the IMO, European Union (EU) and the U.S. Environmental Protection Agency (EPA). The wash water from these systems is also well below the limits set by several major national and international water quality and land-based water discharge standards, even when compared to criteria like drinking water, including the WHO Drinking Water Guidelines.

Specific to the study regarding IMO wash-water requirements, DNV GL, one of the world’s leading classification societies and recognized advisor for the maritime industry, analyzed the laboratory test data and confirmed results from previous studies showing the quality of the water used in the Advanced Air Quality Systems process was always far below the IMO monitoring limits for polycyclic aromatic hydrocarbons (PAHs) and the annual limits for nitrates. In fact, when measured against IMO standards, the average wash-water test results in this study were over 90 PERCENT lower than maximum allowable levels. In many cases, the materials were completely undetectable in the laboratory testing process. To read the full study, click here.

To date, every significant and scientifically valid primary research known on the use of Advanced Air Quality Systems has come to the same conclusion – these innovative systems play an important role in compliance with upcoming IMO regulations and other standards for ship operations.

In fact, Japan’s Ministry of Land, Infrastructure, Transport and Tourism released a report in February 2019 strongly supporting scrubbers as a safe and effective option for IMO 2020 compliance. The report found that the ability of scrubber systems to remove airborne PAH and particulate matter (PM) makes them preferable to ships burning LSFO (or marine gas oil). Looking at 21 different PAHs and eight heavy metals, the study also found the impacts on water quality and marine life to be negligible. The report is available here.

To learn more about the environmental performance of Carnival Corporation’s Advanced Air Quality Systems, click here.

Carnival Corporation’s AAQS Adoption

Exhaust gas cleaning systems (EGCS) like Carnival Corporation’s Advanced Air Quality Systems have been used for decades on land in power plants as a proven and effective way to significantly reduce sulfur oxide (SOx) and particulate matter produced by an engine’s operation. Carnival Corporation is a forerunner in adapting this technology for maritime use within the confined space of a cruise ship, beginning to test, measure and modify Advanced Air Quality Systems prototypes beginning in 2006.

To further enhance its emissions profile, Carnival Corporation developed a catalytic filter for its engine exhaust to further reduce particulate matter before exhaust reaches the Advanced Air Quality Systems. Its standard Advanced Air Quality System then removes more than 98% of sulfur and between 60-90% of the particulate matter, including organic, elemental and black carbon. The combination of Advanced Air Quality Systems, catalytic filter and other systems all contribute to reduction of particulate matter, including the very fine PM 10- and 2.5-micron particles, with some reduction also of nitrogen oxides (NOx).

Given that a cruise ship operates on several engines, multiple scrubbers are installed on each ship. As of July 2019, Carnival Corporation has installed over 220 Advanced Air Quality Systems on 77 of the 100-plus ships in its fleet, with a goal of installing nearly 400 scrubbers over time – eventually covering 85 percent of the fleet.

In 2018, Carnival Corporation was a founding member of Clean Shipping Alliance 2020, a new industry association consisting of nearly 40 shipping and maritime leaders (as of June 2019), and providing education and information on the benefits of Advanced Air Quality Systems. Collectively, these companies represent over 3,000 ships across the sectors of commercial and passenger shipping.


As of July 2019
9Carnival Corporation Brands Utilizing AAQS
77Number of Carnival Corporation Ships Utilizing AAQS
220+Number of AAQS Systems Installed Across the Fleet

By 2020

Estimated by the end of 2020
9Carnival Corporation Brands Utilizing AAQS
85Percentage of Carnival Corporation Fleet Utilizing AAQS
330+Number of AAQS Systems Installed Across the Fleet

Fuel Solutions for Sustainability

Advanced Air Quality Systems are a key component of Carnival Corporation’s 2020 sustainability goals, first outlined in 2015 and updated in summer 2018. Coupled with other complementary technologies with ecological advantages, including launching the world’s first-ever cruise ships powered in port or at sea by liquefied natural gas (LNG), the world’s cleanest burning fossil fuel, and leading the industry in actively using and promoting the use of shore power, Advanced Air Quality Systems will help the company meet its aggressive carbon reduction and other sustainability goals, as well as all applicable regulations for the over 700 ports Carnival Corporation ships visit each year.

As an early mover and industry leader in the development and installation of Advanced Air Quality Systems, LNG and shore power operations, Carnival Corporation saw a complementary role for each solution in its strategic sustainability plan – with LNG seen as most appropriate for newbuilds due to major required design requirements, and Advanced Air Quality Systems the practical choice for retrofitting to the existing fleet.

Carnival Corporation currently has two dual-fueled ships in its fleet, which are capable of being powered by LNG while port. In December 2018, the company launched the first cruise ship in the world capable of carrying and running on LNG both in port and at sea. Ten more Carnival Corporation ships able to generate their power from LNG will be in operation by 2025, sailing for AIDA Cruises, Costa Cruises, Carnival Cruise Line, Princess Cruises and P&O Cruises (UK).

As an additional measure to improve the company’s air emissions, 43% of the Carnival Corporation fleet is equipped as of early 2019 with shorepower or “cold-ironing” capability, the ability to use available shoreside electric power when docked.

Carnival Corporation & Its Commitment to Sustainability

As the world’s largest leisure travel company and world’s largest cruise company, Carnival Corporation recognizes the importance of sustainability as a critical part of how the company and its nine global cruise line brands conduct business. With more than 120,000 employees from over 150 nations around the world – most of whom live and work at sea – Carnival Corporation has a deep commitment to protecting and maintaining clean air and healthy oceans and communities in the over 700 destinations its ships visit each year.

Carnival Corporation’s portfolio includes more than 100 ships sailing for nine of the world’s leading cruise lines: Carnival Cruise Line, Princess Cruises, Holland America Line, Seabourn, P&O Cruises (Australia), Costa Cruises, AIDA Cruises, P&O Cruises (UK) and Cunard.