Berkeley is poised to embrace one of the dirtiest, highest-carbon, globally-destructive forms of transportation: diesel-powered high-speed commuter ferries. 

The numbers speak for themselves: A modern fast ferry is a carbon hog, using about 2,300 BTU of liquid fossil fuel energy per passenger mile. Compare that to commuter buses at 130 BTU per passenger mile, light rail at 91 or BART at only 68. Even an older gasoline-powered car, 20 mpg in a four-person carpool, leaves a lighter carbon footprint than the ferry at 1,750 BTU/passenger mile. 

Modern battery-electric cars, single-occupancy, have an energy consumption range from 853 to about 1,180 BTU equivalent per passenger mile. Also, consider that private vehicles have no reverse commute; with public transportation, a half-load in the reverse commute direction doubles the per-mile carbon footprint. If our high-speed diesel ferry averages 50% passenger load throughout the day (probably optimistic), then the ferry’s actual carbon footprint per passenger mile is doubled. 

While it’s true that modern “Tier 4” emission controls remove particulates from diesel exhaust, they do nothing for carbon dioxide, the primary greenhouse gas produced when petroleum fuel is burned. The carbon footprint tracks closely with the energy content of the liquid fossil fuel burned, so BTU per passenger mile is a good measure of the carbon footprint of a diesel ferry. (Electric vehicle energy is more commonly given as kilowatt-hours rather than British Thermal Units, but the conversion is easy: 1 kWh = 3,412 BTU.)

Now, look at the latest purchase by our local ferry authority, WETA: Two diesel engines of 2,557 HP each, 36 knots at full load, 320 passengers. It works out to 2,719 BTU per passenger mile, assuming every seat is occupied in both commute directions. 

Meanwhile, California is aggressively pursuing full electrification of our transportation fleet. New cars must be all-electric by 2035. We’re transitioning to zero-emission buses. Electric ferries are in the works worldwide (Seattle, Vancouver, New York, Europe, and Asia). Norway is particularly progressive: A new 27-knot, 150-passenger all-electric ferry is now operational, joining a fleet of 70 zero-emission ferries. It runs at a relatively efficient 927 BTU/passenger mile. 

Closer to home, BC Ferries is already operating hybrid car ferries in Puget Sound, and the Federal Trade Commission is funding low-emission ferries in seven states. Washington State Ferries, the largest ferry operator in the U.S., has initiated a $4 billion program to electrify its fleet. 

Even the humble Tiburon-Angel Island ferry will be electrified next year, moving 400 passengers at only 256 BTU/passenger-mile — less than one-tenth of the per-passenger per-mile energy of WETA’s newest diesel ferries.

The proposed Berkeley-San Francisco ferry service is well suited to electrification. It’s a short route at only 6.5 miles, with a long enough dwell time at each end for useful recharge. 

Before proceeding with plans for a major ferry terminal at the Berkeley Marina, we need a firm contractual guarantee from WETA that only electric ferries will operate from Berkeley. Yes, WETA has made this promise, but their cost projections are based on diesel. We need an enforceable agreement that we can hold them to. We need realistic costs and revenue projections based on all-electric boats. 

A ferry has a useful life of 30 to 40 years. In 2050 and beyond, do we really imagine that we will still be supporting a diesel fleet for the short run from Berkeley to San Francisco? Diesel will cost more in the long run and contribute to disastrous climate change. It’s easy to see why the City Council would love to take credit for bringing ferry service back to Berkeley. But diesel-powered boats will leave a different legacy: A regressive climate policy and an inexcusable disregard for the future.

Paul Kamen is a naval architect who loves clean ferries and clean air. He has served six terms as chair of the Berkeley Waterfront Commission.