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King County Washington home

Fuel

Transportation accounts for roughly one-third of annual greenhouse gas emissions in King County. Transitioning to alternative fuels—such as biodiesel, renewable diesel, and electric power—can significantly reduce this impact and help lower overall emissions.

King County Metro and other King County agencies are expanding the use of renewable diesel and other renewable fuels across their fleets to reduce greenhouse gas emissions and transition away from fossil fuels. Plans include scaling renewable diesel to 100 percent use in the Metro bus fleet by 2030, piloting and fully converting the primary water taxi fleet by 2026, and expanding renewable fuel use in Paratransit as vehicles and infrastructure allow. In addition, King County Solid Waste has already transitioned its heavy-duty equipment and trucks to renewable diesel, and Wastewater Treatment will continue piloting and increasing renewable fuel use for its operations as availability permits.

Policy and Goals:

From King County’s 2025 Strategic Climate Action Plan (SCAP),

  • GHG 71. Plan for transition of County facilities away from fossil fuel consuming equipment
  • GHG 81. Transition light, medium, and heavy-duty vehicles to zero-emission vehicles
  • GHG 85. Use alternative fuels when zero emission vehicles are unavailable

Quick Tips

Choose

  • Biodiesel fuels
  • Ultra-Low Sulfur Diesel (ULSD)
  • Electric or hybrid vehicles
  • Alternative-fuel conversion kits for existing vehicles
  • Audit and optimize current travel practices
  • Encourage online meetings and conferencing tools to reduce travel
  • Purchase third-party certified carbon offsets to compensate for impact
  • Implement a certified Environmental Management System (EMS), such as ISO 14001

Avoid

  • Hard acceleration and braking
  • Excessive idling
  • Improperly tuned engine
  • Underinflated tires
  • Speeding

End of Life/Spill Practices

  • Use EMS tools to monitor fuel consumption, idling, and vehicle emissions
  • Clean up any fuel spills immediately using absorbent materials or containment methods
  • Dispose of used absorbents and contaminated materials through approved hazardous waste programs
  • Report large spills to environmental safety staff or local authorities as required

Types of Fuels

Alternative Fuel Description
Electric (EV) Runs entirely on batteries that power the motor. Offers lower fuel costs and reduces greenhouse gas emissions.
Hybrid-Electric (HEV) Uses both gasoline and a battery that recharges during braking. Improves fuel efficiency and reduces emissions.
Biodiesel (B99-B100) Made from animal or vegetable fats mixed with alcohol. Can be blended with petroleum diesel, such as B20 (20% biodiesel, 80% diesel).
Biodiesel (B20) A common blend: 20% biodiesel and 80% petroleum diesel. Reduces emissions compared to conventional diesel.
Liquefied Natural Gas (LNG) Natural gas cooled into a liquid. Modern engines achieve emissions similar to gasoline or diesel vehicles.
Ethanol (E85) Made from corn or other plant materials. Usually blended with gasoline for a cleaner burn; lower energy content reduces fuel economy.
Compressed Natural Gas (CNG) Natural gas compressed to less than 1% of its volume. Mostly methane; colorless, odorless, and tasteless. Offers emissions similar to gasoline and diesel.
Propane (LPG) Liquefied petroleum gas stored as a liquid. Often used in high-mileage vehicles; can reduce maintenance costs.
Renewable Diesel Produced from fats or vegetable oils, alone or blended with petroleum, and refined through hydrotreating. Provides a lower-emission diesel alternative.

Fuel Guidance

Fuel Guidance - The EPA, U.S. Department of Energy, and U.S. Department of Transportation certify fuel economy labels for all new vehicles sold in the U.S. These labels show a vehicle’s fuel economy, fuel cost, greenhouse gas rating, and smog rating.

Anti-idling requirements Train drivers and use idle-reduction equipment to save fuel and reduce emissions.
Route Optimization Use GPS and route-planning software to minimize travel distance and improve efficiency.
Fuel Use Tracking Implement monitoring systems to track consumption, detect leaks, and identify inefficient vehicles or equipment.
Right Sizing Match the size and type of vehicle or machinery to each project to lower fuel use and greenhouse gas emissions.
Preventative Maintenance Regular tune-ups, proper motor oil, and timely repairs improve fuel efficiency.
Ridesharing/Carpooling Encourage carpool programs to reduce vehicle trips and overall fuel consumption.
Vehicle Retrofits Install devices such as diesel particulate filters (DPFs) or diesel oxidation catalysts (DOCs) to reduce emissions.
Fuel-Efficient Vehicle Procurement Purchase vehicles with higher miles-per-gallon or energy-efficient ratings to reduce fuel needs.

Technical Specification Language

High Performance Buildings Guide: Transportation and Automotive

National Biodiesel Board

U.S. Department of Energy: Alternative Fuels Data Center

California Air Resources Board: Carbon Intensity Lookup table

West Coast Climate and Materials Management Forum: Climate Friendly Purchasing Toolkit

Western Washington Clean Cities: Alternative Fuels

Atlas Public Policy: Fleet Procurement Analysis Tool