Four San Francisco Ferries Refit with Cleaner Engines

The San Francisco Bay Area Water Emergency Transportation Authority (WETA) and Bay Area Air Quality Management District (Air District) announced that WETA’s Gemini Class Clean Air Conversion Project has been completed, resulting in a substantial decrease in air pollution emissions from four San Francisco Bay Ferry vessels serving Oakland, Alameda and Richmond.

In September 2021, WETA's Board of Directors approved a $5.5 million project to upgrade the engines and reduce emissions on the agency’s four Gemini-class vessels. The conversion to cleaner engines was completed over the course of 2022 and early 2023 at JT Marine in Vancouver, Wash.

Funding for the Gemini class project came from the Air District’s Carl Moyer grant program and proceeds from the Alameda County Transportation Commission’s (Alameda CTC) sales tax Measure BB.

The four vessels were built with U.S. Environmental Protection Agency (EPA) Tier 2 engines about 15 years ago. The conversion project replaced those engines with U.S. EPA Tier 4 certified engines, the cleanest available. Nitrogen oxide (NOx) and hydrocarbon (HC) emissions are 73% lower and particulate matter (PM) emissions are 80% lower on each of the four vessels.

WETA pursued this project outside of regulatory requirements in its push to green its fleet. The vessels can be used on any of San Francisco Bay Ferry’s six routes, but are most frequently used in Oakland, Richmond, South San Francisco and Alameda. The new Tier 4 engines were manufactured by Germany-based MAN Engines.

The project continues work that WETA started in 2019 when the agency built the nation’s first high-speed passenger ferry with Tier 4 certified engines. Today, 12 of the 16 ferries in the San Francisco Bay Ferry fleet are powered by Tier 4 engines, making it the cleanest high-speed, high-capacity passenger ferry fleet in the nation.

"Reducing emissions from San Francisco Bay Ferry vessels has always been a top priority for WETA," said Jim Wunderman, Chair of the WETA Board of Directors. "We were the first to adopt the cleanest diesel technology available, and soon we’ll be the first in the nation to operate high-speed, zero-emission electric ferries. We have a responsibility to give the Bay Area a transportation option that improves air quality and public health in the communities we serve and all of this work is connected to that goal."

WETA has raised nearly $100 million to pioneer the operation of zero-emission ferry service in the U.S. Those funds will support construction of five small battery-electric ferries to serve Alameda, Oakland and San Francisco’s waterfront neighborhoods including the downtown core, Treasure Island and Mission Bay. Construction of the zero-emission vessels is expected to begin later this year.

"Oakland is committed to reducing greenhouse gas emissions so we can address the climate crisis and reduce pollution in our communities," said Oakland Mayor Sheng Thao. "I’m proud to stand with our partners as we celebrate the completed conversion of the Gemini class ferries serving our city. Now residents and visitors can enjoy our ferries even more, knowing that they’re supporting climate-friendly transportation."

"The Gemini Ferry project offers residents a clean transportation option to cross the Bay while reducing harmful emissions in communities that are most impacted by air pollution," said Dr. Philip Fine, executive officer of the Air District. "The Bay Area continues to lead by deploying the cleanest equipment to preserve air quality, protect the climate and safeguard the health of our communities."

"Two of Alameda CTC’s top priorities are shifting away from single-occupant vehicles and advancing clean transportation, with special focus on reducing the environmental impact in low-income communities and communities of color," remarked Alameda CTC Executive Director Tess Lengyel. "That’s why Alameda CTC is thrilled to help fund the Gemini ferry project through Measure BB funds and deliver on the promises made to Alameda County voters."