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Measuring Greenhouse Gas Emissions at Port of Seattle

COVID-19 and travel at SEA Airport More Information

About the Port's Greenhouse Gas Emissions Inventories

The Port conducts two separate greenhouse gas (GHG) emissions inventories: one for GHG emissions associated with the Seattle-Tacoma International Airport (SEA) and the other for GHG emissions from its maritime-related sources, which include the Port's Maritime and Economic Development Divisions' lines of business separate from SEA. Both Port inventories follow the GHG Protocol Corporate Accounting and Reporting Standard to estimate Scope 1, Scope 2, and Scope 3 emissions, which represent sources directly and indirectly controlled or under some degree of Port influence.

Inventories track progress toward the Port's Century Agenda GHG reduction targets. In October 2021, the Port updated its GHG targets to accelerate Scope 1 & 2 reductions to net zero or better by 2040 from carbon neutral or negative by 2050, and increase ambition of its Scope 3 reductions to carbon neutral or better by 2050 from 80 percent. The updated targets respond to the urgency of the climate crisis, build on reduction initiatives already underway, and affirm Port leadership to facilitate the clean energy transition and zero-emission port operations.

Port of Seattle Century Agenda GHG Targets
Scopes 1 and 2 Scope 3
Port-controlled and Port indirect emissions Emissions the Port has influence over but not direct control
  • 15 percent below 2005 levels by 2020
  • 50 percent below 2005 levels by 2030
  • Net-zero of better by 2040
  • 50 percent below 2007 levels by 2030
  • Carbon neutral or better by 2050

(1) Net-zero means any carbon dioxide released into the atmosphere from a company’s activities is balanced by an equivalent amount being removed

(2) Carbon neutral or carbon negative means emissions can be offset with a reduction that could include buying carbon offsets to make up the difference

The SEA GHG Emissions Inventory is verified by the Airport Carbon Accreditation Program. The Port's Maritime GHG Inventory is newer and not yet verified, but the Port may seek verification for future maritime inventories. Port of Seattle conducts GHG emissions inventories annually for the previous calendar year. Starting with the year 2019, historical and prior year inventory results will be publicly posted online each year as soon as the inventory process is complete. The Port is committed to data accuracy and transparency and the inventories represent a best estimate of emissions sources. As new information or inventory best practices become available, the Port may update historical data or inventory methods to better reflect its sources and their contributions. 

Port-Wide Greenhouse Gas Emissions

Scope 1 and 2 GHG Emissions

Scope 1 and 2 emissions include direct emissions from sources under the Port's control (scope 1) or indirect emissions produced to generate the electricity used by the Port (scope 2). The Port conducts inventories for Scope 1 and 2 emissions annually. 

Scope 1 Sources Scope 2 Sources
  • Fossil fuel used in Port-owned vehicles and equipment, and employee vehicles for Port business
  • Fossil natural gas used in Port-owned buildings, and not metered and sold separately to tenants. 
  • Purchased electricity used by the Port of Seattle in Port-owned buildings, and not metered and sold to tenants
  • Purchased steam used in Port-owned buildings, and not metered and sold to tenants

Graph showing port-wide Scope 1&2 emission levels for 2005, 2015-2020, and the level of GHG emissions the Port needs to reach by 2030 to achieve the 50% reduction target.
Port of Seattle’s Scope 1 & 2 GHG emissions from both aviation and maritime operations combined for the 2005 baseline and 2015-2020. The Port aims to reduce GHG emissions 50 percent by 2030.

Trends

Port-wide Scope 1&2 GHG emissions have decreased approximately 20 percent as of 2020 compared to the 2005 baseline due to a combination of factors.  In October of 2020, SEA Airport became the first airport in the country to purchase thermal renewable natural gas (RNG) derived from waste to heat SEA terminals and power the Airport’s bus fleet. This decision to use RNG will continue to significantly reduce the Port's Scope 1 and 2 GHG emissions, allowing the Port to meet its 2030 goal by the end of 2021.  SEA also joined Puget Sound Energy’s Green Direct electricity program to purchase energy from renewable sources, and the Port used renewable diesel in its aviation and maritime fleet vehicles and equipment.

The COVID-19 pandemic led to many changes in the Port’s day-to-day operations that impacted GHG emissions. Use of maritime fleet vehicles and natural gas use at maritime properties declined. While thermal natural gas use increased at SEA during COVID-19 due to more energy required to heat the Terminal with fewer passengers, this was offset by a reduction in transportation natural gas use in employee parking and rental car buses.

Port of Seattle Scope 1 and 2 GHG Emissions Data
Airplane icon SEA Airport Scope 1 and 2 Emissions Inventory Data (2020)
Sailboat icon Port of Seattle Maritime Scope 1 and 2 Emissions Inventory Data (2020)

 

Scope 3 GHG Emissions

Scope 3 GHG emissions are indirect sources of emissions that are a consequence of the Port's activity but are owned or controlled by another entity. Scope 3 emissions sources include energy used by Port tenants, airplanes, ground transportation to and from the airport, cruise ships and other ocean-going vessels, cargo-handling equipment, rail locomotives, waste transport and disposal, employee business travel by air, and even Port employees commuting to and from work. 

Trends

The COVID-19 pandemic dramatically reduced air travel. As a result, Scope 3 emissions for Aviation decreased by 35 percent in 2020 compared to 2015. Decreased air travel also reduced related emissions from ground transportation and tenant operations.  However, Scope 3 emissions steadily increased prior to 2020 due to increasing demand for air travel and associated services.

GHG emissions from maritime supply chain (ocean-going vessels, commercial harbor vessels, recreational vessels, locomotives, cargo-handling equipment, cruise buses on terminals) are not quantified annually.  GHG and air emissions from these sources are quantified every five years through the Puget Sound Maritime Air Emissions Inventory. While the Port does not have GHG data for these sources in 2020, GHG emissions associated with the maritime supply chain declined significantly from the cancellation of the 2020 cruise season in response to COVID-19.

Prior to COVID-19 and as of the last Maritime scope 3 inventory for the year 2016, Maritime-related Scope 3 emissions had declined 20 percent since 2005.  This decline was largely due to new international and national regulations, such as the North American Emissions Control Area, increased use of shore power by cruise vessels, improved vessel and equipment efficiency, and successful port policies and programs that encouraged replacement of older equipment and use of cleaner maritime fuels.

Port of Seattle Scope 3 GHG Emissions Data
Airplane icon SEA Airport Scope 3 Emissions Inventory Data (2020)
Sailboat icon Port of Seattle Maritime Scope 3 Emissions Inventory Data*

*Note: Data on GHG emissions from maritime supply chain (ocean-going vessels, commercial harbor vessels, recreational vessels, locomotives, cargo-handling equipment, cruise buses on terminals) comes from the Puget Sound Maritime Air Emissions Inventory. Completion of this inventory occurs every 5 years and is complex as the Port does not own or manage the vessels and equipment. The 2020 Maritime Scope 3 Emissions data uses 2016 GHG emissions levels for maritime supply chain sources because 2016 is the most recent year that data from these sources is available. The next Puget Sound Maritime Air Emissions Inventory will be complete for year 2021. 

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