A study by two researchers at Sandia National Laboratories has concluded that building and operating a high-speed passenger ferry solely powered by hydrogen fuel cells within the context of the San Francisco Bay is technically feasible, with full regulatory acceptance as well as the requisite associated hydrogen fueling infrastructure. . . .
- In the course of the study, we examined over 10 major issues where feasibility was initially unknown. SF-BREEZE sailed through them all.
—Lennie Klebanoff, Sandia co-author of the SF-Breeze study
Tom Escher, president of San Francisco’s Red and White Fleet, first conceived of the project when he asked if it was possible to do away with emissions altogether on one of his ferries.
- This is a game changer. We can eliminate environmental pollution from ships. This could have a major impact on every shipyard in the country.
—Tom Escher
. . . .
The SF-BREEZE study set out to discover whether it is technically feasible to build a large, fast vessel; could meet maritime regulations; and could be economically competitive with modes of transportation already available in the San Francisco Bay area.
The group drew up conceptual specifications: a 150-passenger commuter ferry that would travel four 50-mile round-trip routes each day at a top speed of 35 knots (~39 mph) about 60% of the time. The ferry could refuel midday, between the morning and afternoon commutes. . . .
Through examination of the options, the project team selected proton exchange membrane (PEM) fuel cells for the powerplant due to their low weight and volume, commercial availability, proven track record, zero emission characteristic, and acceptable power performance. The fuel cell base model chosen for this case study was the Hydrogenics HyPM HD30.
Liquid hydrogen (LH2) was selected for on-board storage in order to minimize the weight that is so critical for performance of a high-speed vessel.
The final specifications for the SF-BREEZE were:
Passenger capacity: 150 (the maximum allowed by Subchapter T regulations).
Top Speed: 35 knots.
Total installed power: 4.92 MW (4.4 MW for propulsion at top speed, 120 kW for auxiliary power, and the remainder for margin) consisting of (41) 120 kW PEM fuel cell racks, each rack containing four 30 kW PEM fuel cell stacks.
Fuel: 1,200 kg (~4,500 gallons) of LH2 contained in a single Type C (pressurized vessel) storage tank on the top deck, enough for two 50 nm round trips before refueling, with 200-400 kg margin.
Electrical architecture: DC power from the fuel cells converted to AC power for the motors. Either one or two motors per shaft.
Propulsors: Waterjet or Voith linear jet.
Amenities: Standard passenger cabin with restroom and snack bar.
Zero greenhouse gas and criteria pollutants during operation. . . .
Emissions. The project team investigated the SF-BREEZE GHG emissions associated with five LH2 fuel production pathways including renewable and non-renewable (fossil-fuel based) methods. While hydrogen PEM fuel cell technology has zero emissions at the point of use, it is important to consider the fuel production pathway and delivery emissions in a “well-to-waves” (WTW) analysis. The team found that the
WTW GHG emissions for the SF-BREEZE using non-renewable LH2
are significantly higher than for the diesel-fueled Vallejo ferry on a per passenger basis.
Due to the higher weight of the SF-BREEZE compared to the comparable diesel ferry, the SF-BREEZE has more on-board power in order to make 35 knots. This higher power makes the ferry consume more hydrogen, and when combined with the fact that making LH2 is much more energy intensive than making diesel fuel. However,
using renewable LH2, WTW GHG emissions for the SF-BREEZE ferry are reduced 75.8%
compared to the diesel-fueled Vallejo. . . .
The hydrogen ferry would cost about twice as much as a comparable diesel ferry with today’s prices. Much of that cost is in the fuel cell system.
- Right now, we can’t achieve economic parity with a comparable diesel ferry. But this is a question we need to explore further. Is economic parity necessary from the outset? Lessons from the automotive market tell us maybe not.
—Joe Pratt, Sandia co-author. . . .