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FAQs about Cruise Ship Emissions

For more than 20 years, the Port of Seattle has prioritized protecting the environment while growing cruise to deliver $900 million in annual business revenue to the region during typical operations.

The Port is also committed to working with our shipping and cruise partners to make Seattle the cleanest, greenest, most energy efficient port in North America.

Here’s more information on how the Port and its cruise partners are doing that.

How have emissions changed over time?

31% Down - GHG from Ocean-going VesselsGreenhouse Gas emissions from all types of seaport-related oceangoing vessels in the Seattle harbor, including cruise and grain ships that call at the Port of Seattle and marine cargo ships that call at Northwest Seaport Alliance terminals, decreased 31 percent between 2005 and 2016.   


Diesel particulate matter emissions have decreased 88 percent over the same period.  

Down 88% DPM from Ocean-Going VesselsThe decrease in emissions results from a combination of factors. Port activity declined from 2005 to 2016, with 28 percent fewer vessel movements. The decline in diesel particulate matter emissions is largely the result of new regulation. The North American Emissions Control Area, introduced in 2015, requires vessels to use cleaner diesel fuel or equivalent technology. Increasing numbers of shore-power equipped ships and increasing use of shore power while at berth where connections are available has also helped reduce emissions, and its use continues to avoid greenhouse gas and diesel emissions today.   

The Port does not have cruise ship-specific emissions data for the 2005 baseline year, so cannot speak to a cruise-specific trend. 

The Port of Seattle is acutely aware of the far-reaching impacts that climate change is having on the region today and is planning for the future. As part of its ambitious Century Agenda, the Port set a long-range commitment to reduce greenhouse gas emissions 

  • by 50 percent by 2030
  • Net zero or better by 2040 for port-controlled or indirect emissions
  • and to be carbon neutral or better by 2050 for port-influences emissions

From investing in renewable natural gas at Seattle-Tacoma International Airport (SEA) to using shore power to reduce emissions from cruise ships at berth, the Port is working to fulfill its responsibility to address climate change. 

How are cruise ships regulated? And what do large ships do to abide by regulations while berthed at port?

Cruise ships are typically registered under flags of various foreign countries but must comply with many requirements to be able to take on passengers at United States ports. Cruise ships must comply with the International Convention for the Safety of Life at Sea and other international regulations, including environmental protection. The U.S. Coast Guard is responsible for cruise ship safety and conducts routine inspection to ensure compliance.  

Most regulations for large ships, which includes cruise ships along with marine cargo ships and other oceangoing vessels, are made at the international level through the International Maritime Organization (IMO). The Maritime Environmental Protection Committee (MEPC) within the IMO addresses environmental issues related to shipping, including air and water pollution, garbage, underwater noise, and greenhouse gas emissions.  

Air quality regulations 

One key regulation to protect local air quality is the North American Emissions Control Area, which requires all ships to meet rigorous emission standards and limit the sulfur content in their exhaust. Some cruise lines choose to comply with the law by using low sulfur fuels, like marine gas oil, whereas other ships choose to use exhaust gas cleaning systems. Exhaust gas cleaning systems are a relatively new technology that some ships use to reduce the amount of sulfur oxide and particulate matter emitted in the ship’s exhaust to comply with the legal emissions limits.   

Water quality regulations  

The Port of Seattle, the Washington Department of Ecology, and the Cruise Lines International Association Northwest and Canada have signed a voluntary memorandum of understanding (MOU) to prevent wastewater discharges from cruise ships into Washington state waters. The MOU was first signed in 2004. The agreement also allows Department of Ecology to inspect wastewater treatment systems on each vessel and requires that cruise lines sample and monitor wastewater discharges from their ships. In recent years there have been no requests to discharge treated wastewater.        

In 2018, Washington passed a law making Puget Sound a ‘No Discharge Zone, a law that applies to commercial and recreational vessels and prohibits the release of sewage, whether treated or not.  

How much do cruise ships contribute to air and greenhouse gas emissions in Seattle?

Cruise ships represent 18 percent of all maritime-related greenhouse gas (GHG) emissions in Seattle, according to the most recent Puget Sound Maritime Air Emissions Inventory (2016). Marine cargo ships represent 35 percent of maritime-related GHG emissions, grain ships represent only 2 percent, and other maritime activities including drayage and provisioning trucks, equipment that handles marine and cruise cargo, rail locomotives, and tug and assist, commercial fishing, and recreational vessels represent the remaining 45 percent.  


Data source: 2016 Puget Sound Maritime Air Emissions Inventory  

These estimates are limited to:  

  • emissions associated with the energy to power the ship during a cruise ship’s journey through the Puget Sound airshed, which extends north to the Canadian border, west and to mouth of the Straits of Juan de Fuca and east to the Cascade mountain range 

  • emissions associated with powering onboard operations like cleaning, loading, and provisioning while the ship is at berth at Port of Seattle cruise terminals  

What is the Port doing to reduce the environmental impact of cruise ships?

Shore power 

Shore power is one of the most effective techniques to reduce port-related maritime air emissions here in the Northwest. Providing shore power connections to cruise ships allows them to “plug-in” and turn off engines while at berth, significantly reducing air pollution. Because Seattle City Light is a leader in low carbon electricity (the first carbon neutral utility in the nation), there is a significant reduction in greenhouse gas emissions.  

The Holland America Group, including Princess Cruises and Holland America Line, was instrumental in establishing shore power for cruise ships in Seattle in 2004 at the former Terminal 30 cruise facility. In partnership with the Holland America Group, The Port of Seattle was the first cruise home port in the world to offer two shore power-enabled cruise berths (at Terminal 91) and it’s widely used. All three of the Port’s cruise berths will be shore power capable in 2023 with the completion of a shore power connection at Pier 66.  

Water quality  

In 2020, the Port of Seattle banned all discharges of exhaust gas cleaning system wash water from cruise ships at berth. And in 2021, the Port worked with its home port cruise lines to pause all discharges of exhaust gas cleaning system wash water throughout Puget Sound until findings from a third-party research study can show that wash water discharges do not impact Puget Sound water quality.    

Clean air strategies 

For more than a decade, the Port of Seattle has partnered with the Port of Tacoma, the Vancouver Fraser Port Authority, and the Northwest Seaport Alliance to take voluntary action to reduce air and greenhouse emissions through the Northwest Ports Clean Air Strategy. This regional, multi-port agreement has achieved significant results that exceed its targets for reducing emissions. in 2021, the Northwest Ports adopted an updated strategy that establishes a new vision to phase out emissions from seaport-related activities by 2050, supporting cleaner air for our local communities and fulfilling our responsibility to help limit global temperature rise to 1.5 degrees Celsius. Charting the Course to Zero: Port of Seattle’s Maritime Climate and Air Action Plan identifies strategies and actions Port of Seattle will take through 2030 reduce emissions toward that vision.  

The Port also established new a partnership between the Port of Seattle, the Northwest Seaport Alliance, and the local electric utility Seattle City Light to develop the Seattle Waterfront Clean Energy Strategy that will help create a holistic plan for decarbonizing the maritime industry in Seattle. 

Learn more about the Waterfront Clean Energy Strategy 

Habitat restoration 

The Port currently has an ambitious goal to restore, create, or enhance 40 acres of habitat across Port properties that builds upon previous work including over 100 acres of fish and wildlife habitat. Additionally, the Port has improved the marine environment by removing or remediating more than 10,000 creosote-treated derelict pilings and over 100 acres of contaminated soils and sediment at numerous sites.  

The Port is also advancing several pilot projects to enhance the Puget Sound ecosystem, including kelp conservation. At our Smith Cove Cruise Terminal site, we are testing the efficacy of kelp, eelgrass, and native oyster restoration techniques and measuring their ability to enhance resilience of our shorelines to the effects of ocean acidification.  

How does the Port measure and track emissions from cruise ships?

Emissions MapAir and greenhouse gas emissions from cruise ships and other maritime activity sources that the Port has influence but not direct control over are inventoried every five years through the Puget Sound Maritime Air Emissions Inventory (PSEI). Data is available for 2005, 2011, and 2016. The next update to the PSEI is underway now.  

The PSEI quantifies emissions for cruise ships and other types of oceangoing vessels for the portion of the vessel’s journey through the Puget Sound airshed, which extends from a vessel’s berth in Seattle to the Canadian border and the mouth of the Strait of Juan de Fuca (see gray-shaded area in map). This focus on emissions within the airshed is consistent with port emissions inventory guidance developed by the U.S. Environmental Protection Agency.   

The PSEI does not include all emissions associated with the cruise industry, such as passenger travel to and from the ship, supplies for each ship, or shoreside waste disposal; and it does not cover the full round-trip journey from Seattle to Alaska. Additionally, other maritime-related emissions sources are limited to port authority activities, and do not include emissions from all marine transportation sources, such as Washington State Ferries, the U.S. Coast Guard, private companies, and others.   

Maritime-related emissions by the numbers:  
Maritime Source 2016 Greenhouse Gas Emissions (Metric Tons CO2 equivalent) 2016 Diesel Particulate Matter Emissions
(Metric Tons DPM)
Marine cargo ships  106,042  33
Trucks 79,642 21
Cruise ships 53,625  19 
Rail locomotives 23,097  9
Cargo-handling equipment 14,446  5
Harbor vessels 11,229  6
Recreational vessels 6,700  0.3
Grain ships 4,912  1
Light-duty vehicle fleet 420 .01
Total 300,113 94

Data source: 2016 Puget Sound Maritime Air Emissions Inventory (totals include Port of Seattle and the Northwest Seaport Alliance marine cargo operations in Seattle and are converted from short tons to metric tons) 

For comparison, the GHG emissions generated by the City of Seattle are 5,766,042 tonnes annually, according to the 2018 GHG Inventory (includes GHG emissions from building energy use, transportation energy use (air, marine, passenger cars, trucks), and waste). 

What is shore power?

Each time a cruise ship docks in Seattle, it takes an average of 10 hours to offload guests, load provisions, welcome new guests on board, and prepare for its next departure. While the ships are at berth, they still need energy to run lights, chill food, operate equipment, and power myriad other onboard services. A shore power connection allows cruise ships to plug into cleaner, landside electrical power and turn off fossil fuel- powered engines while at berth. As a result, each ship that plugs in can reduce diesel emissions by 80 percent and CO2 emissions at berth by 66 percent on average.  

Learn more about how shore power works in this short video.  

How many ships have shore power? How many connect at Port of Seattle facilities?

The number of cruise ships that call at the Port of Seattle that are equipped with shore power and connections to shore power infrastructure have increased in recent seasons. 

Column bar chart showing connection rates for cruise ships that are equipped with shore power connecting at Terminal 91 where each berth has an operable shore power system. Connection rates have increased compared to 2017 and 2018, but 2022 connections rates were lower than 2019 and 2021.

More detail on the number of cruise calls and shore power-capable calls from 2018, 2019, 2021, and 2022 is included in the table below. 

  Pier 66 (P66) Terminal 91 (T91)
Year  P66 Total Calls P66 SP-Equipped Calls * T91 Total Calls T91 SP-Equipped Calls T91 Connected Calls
2018 62 22 154 65 40
2019 63 45 148 95 85
2021 29 12 53 31 30
2022 105 58 190 83 69

*There is not currently a shore power connection at Pier 66. Shore power installation is planned in the future.


Are cruise ships required to use shore power?

Cruise ships that are shore power-capable connect to the Port’s shore power infrastructure when a connection is available. Existing agreements between the Port and cruise lines require these connections. 

  • The Smith Cove Cruise Terminal at Terminal 91 has two shore power-capable cruise berths, and shore power connections by cruise ships have been increasing in recent seasons.  
  • A project is underway to install shore power at Pier 66 and is expected to be completed in 2023.   
Where does the energy for the shore power come from?

When cruise ships connect to shore power, the energy comes from electricity provided by Seattle City Light. Seattle City Light is committed to using clean power to help improve air quality and lessen greenhouse gas emissions. About 94 percent of the power generated by City Light comes from clean and carbon-free resources. The remainder is purchased on the energy market and the utility pays credits to offset emissions so that the utility’s entire electricity portfolio is carbon neutral. 

Why will it take several years to install shore power at Pier 66?

The Pier 66 Shore Power Project is a complex project and involves more than installing a new plug and cable. A cruise ship requires a lot of energy to power — more than the site has available now. Constrained access to electrical infrastructure on the downtown waterfront delayed progress for years until the Port team reached the innovative solution of installing a submarine cable that runs along the seafloor through the harbor to bring power to the terminal. This approach not only avoids the need to dig up busy streets on the downtown waterfront but it’s also cheaper.

This project is anticipated to be complete by the 2024 cruise season and is supported in part by nearly $3 million in grant funding from the U.S. Environmental Protection Agency Diesel Emissions Reduction Act, the state of Washington Department of Ecology, and the TransAlta Centralia Coal Transition Board. 

Pier 66 Shore Power map

How many ships are equipped to use shore power in the 2023 season?

2023 Cruise Season Preview

  • 289 cruise ship calls (275 calls by homeport cruise ships, 14 calls by in-transit cruise ships)
  • 2 of 3 Port of Seattle cruise berths offer shore power
  • 38% (111/289) of total sailings expected to plug into shore power 

Related to FAQs about Cruise Ship Emissions

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