This article was contributed by: Mary Culnane, San Franisco’s Bay Area Water Transit Authority (WTA) and Chris McKesson, John J. McMullen Associates (JJMA).

San Francisco’s Bay Area Water Transit Authority (WTA) is actively developing a fuel cell powered ferry in order to move toward a zero-emissions future. The envisioned vessel will showcase the marine application of fuel cells for propulsion and provide an opportunity to gain essential operational experience. The vessel is intended to serve Treasure Island, approximately three miles from the San Francisco city front.

WTA awarded a contract to John J. McMullen Associates (JJMA) to develop design drawings for the vessel. JJMA’s stated intent is to keep the points of innovation to a minimum, insofar as that is consistent with the fuel cell concept. This means that it will not develop a specialized hull design, but will instead attempt to develop a propulsion package that is compatible with a number of suppliers’ "catalog" ferry designs.

Further, JJMA intends to use an off-the-shelf fuel cell in its design. Following acceptance of the design, WTA will procure the vessel in a conventional bid process, and the major fuel cell components will be owner furnished.

The design is focused on fuel cell "engines" being developed for use in transit buses. For example, two 200 kW bus "engines" would be sufficient to drive a 49-passenger ferry at about 12 knots, even after accounting for the weight of the system.

Another, potentially larger, issue is the matter of fuel storage. Again, following a philosophy of "minimum innovation", the current thought is to simply carry compressed hydrogen gas to fuel the cell. As with the transit bus units, the ferry would carry a roof-mounted "tank farm" of hydrogen cylinders, amounting to some 80,000 standard cubic feet of gas. This tank farm would encompass a volume of 20 feet by 20 feet by 3 feet.

An issue not yet fully addressed is regulatory approval of a hydrogen fuel system. The U.S. Coast Guard has approved natural gas fuel for ferries in some cases, and it is hoped that the same design techniques used for natural gas would result in approval of hydrogen. In this connection, it should be noted that both gases are lighter than air and both have been carried in liquefied and compressed forms (although at present only compressed hydrogen is being considered for the ferry).

WTA’s fuel cell ferry design project is scheduled for completion in early to mid 2003. At that time, WTA will hopefully be positioned to obtain funding for construction of a true zero-emission ferry and to lead the way in exploring a possible new future for ferry propulsion.

MARAD has joined forces with NAVSEA-Philadelphia in a Navy Emission Test Program. Commencing January 2003, the testing of five fuels and six emission reduction technologies (see below) will be conducted by the Ship Systems Engineering Station’s Marine Engine Test Laboratory. All equipment and fuels will be tested on a reconditioned, naturally aspirated, two-stroke, 12V-71, Detroit Diesel engine.

Program objectives are to assess performance and criteria pollutants generated by the various fuels and abatement technologies under controlled laboratory conditions. Subsequently, a shipboard evaluation will be conducted to assess reliability and durability of one or two combinations of optimal technologies. Particular attention will be given to NOx and PM emissions. The engine model is very common within the workboat fleets of the Navy, Army, other federal agencies, and commercial maritime industry. Results will be disseminated to all interested fleet operators.

The test plan incorporates a total of 25 configurations utilizing International Organization for Standardization (ISO) 8178 propulsion, generator, and auxiliary engine test cycles. Performance data will be collected in addition to emission measurements of NOx, PM, hydrocarbons (HC), carbon monoxide (CO) and opacity. Particulate matter will be broadly characterized both physically in terms of size and chemically in terms of composition.

Other partners for the testing program include the Office of Naval Research, California Air Resources Board, South Coast Air Quality Management District, Environmental Protection Agency, and Department of Energy.

In June 2002, Blue and Gold Fleet and the San Francisco WTA released the results of emission testing conducted on the 400-passenger ferry MV OSKI. The OSKI is powered by twin two stroke, 12V-71, Detroit Diesel engines. The testing established NOx and PM emissions for baseline operation with low sulfur diesel fuel, for a 20% blend of biodiesel, for 100% biodiesel, and for a continuous water injection system with both low sulfur diesel and 100% biodiesel fuel.

The biodiesel fuel was a soy based methyl-ester type. Biodiesel is a renewable energy source that reduces greenhouse gases and particulate matter. However, biodiesel often increases NOx emissions. In order to reduce NOx, a continuous water injection system was installed to inject finely atomized water droplets in the engine’s intake air system. Water injection reduces maximum combustion temperatures and consequently reduces NOx emissions.

Available bar charts provide brake specific NOx and PM emissions for each condition tested. At the data points tested, B20 produced a NOx increase ranging from 2-11% and the B100 increase ranged from 5-20%. The water injection system, which was only operated at higher powers, reduced NOx by averages greater than 20%. B100 generally reduced PM emissions by over 50%.

Exhaust gas composition was measured with an Enerac Model 300 portable emission analyzer. PM was measured by weighing the accumulation of particulate on a quartz filter with no dilution tunnel. Formal fuel performance tests were not conducted, but the operator stated there was no noticeable change in consumption when the continuous water injection system was applied.

Blue and Gold, a ferry operator in San Francisco Bay, managed the project with MARAD as a co-sponsor. The water injection equipment was purchased from MA Turbo/Engine Ltd. of Vancouver, British Columbia. The biodiesel fuel was purchased from World Energy, Inc. Testing and test reports were by Walther Engineering.

We welcome the opportunity to publish on our web site the status and/or results of demonstration projects in which you are engaged. If you are willing to share such information with our readers, please contact MARAD’s Office of Shipbuilding and Marine Technology.