14 JULY 2017 • FOGHORN FOGHORNFOCUS: ENVIRONMENTAL ISSUES trical requirements when underway are approximately 1,020 kW. Allowing for some reserves for increased speed to make-up schedule, EBDG assumed that 10 fuel cell units of 120 kW each plus one unit in reserve would form the basic power plant. The reference vessel has sufficient fuel for 35 days of operation, due to the client’s desire for reserves in the event of a major earthquake. The fuel cell version cannot carry large quantities of liquid hydrogen (LH2) since LH2 has much less energy density than diesel fuel. EBDG sized the LH2 storage tank to suit a resupply every four days with a 20 percent margin from a standard tank truck with a capacity of 3,200 kg of LH2. EBDG adjusted the weight estimate Figure 5. 120 kW Fuel Cell Rack (Source: Hydrogenics) for the vessel to remove the propul- sion diesels and the diesel generator sets and then added the weights of the cryogenic storage tank, the cold box, the fuel cells, the electrical conversion equipment, and the electric motors. EBDG also deducted the weight of the diesel fuel and added the weight of the LH2. The resulting vessel had a larger light ship weight than the reference vessel (774 Long Tons versus 733 Long Tons) but a lesser Full Load Displacement (966 Long Tons versus 996 Long Tons) due to the decreased fuel weight. The capital cost of the fuel cell ferry is approximately $7.5 million greater than the reference vessel due to the electric propulsion equipment, the fuel cells, and the cryogenic tank. This cost difference will shrink as demand for fuel cell technology increases but fuel cells are competing with a technology (geared diesel engines) that is mature, with many competing vendors, and a large base of applications. The key ad- vantages of fuel cells driving electric motors are extremely low maintenance and, of paramount importance, the zero emissions. The current cost of LH2 is roughly $6.35/kg to $7.40/kg depending upon the annual demand. This is significantly greater than current marine diesel oil at $0.48/kg. (Based on New York Harbor Ultra-Low Sulfur No. 2 Diesel Spot Price of $1.564 per gallon as on June 1, 2017). Note that the diesel fuel price does not include the cost of delivery to the vessel whereas the LH2 price is inclusive of trucking.) After accounting for the energy density difference (a kg of LH2 has 2.9 times the energy content of a kg of diesel) and the efficiency dif- ference (a fuel cell is somewhat more efficient than a diesel engine at con- verting chemical energy into electric- ity) the fuel costs for hydrogen for a ferry operating 350 days per year are approximately three times the costs for a diesel fueled vessel. In conclusion, this investigation demonstrated that using hydrogen fuel cells to power a conventional ferry did not result in any loss in capacity