b'FOGHORNFOCUS: MARINE PROPULSIONFUEL TYPE EMISSIONS AVAILABILITY SAFETY ENERGY DENSITY COSTDiesel Baseline High Proven 12.9 kWh/kg InexpensiveVegetable Oils/ Lower SOx, LowerRenewable but envi- Safe 10.9 kWh/kg Moderate and Biodiesel Particulates ronmental impact fromcompetes with monocrop. food cropsLiquified NaturalLower SOx, LowerPlentiful but no marineCryogenic Fuel with10.8 kWh/kg but effectively 1/3InexpensiveGas Particulates infrastructure low flash point butto 1/5 of diesel due to cryogenic well-establishedstorage tankregulationsMethanol Lower SOx, LowerIndustrial uses only Low flash point 6.4 kWh/kg Liquid at atmosphericLowParticulates no infrastructure pressure and temperatureAmmonia High energy cost toWidespread use asToxic 5.17 kWh/kg Moderateproduce fertilizerHydrogen None if created byIndustrial use primarily,Very low flash point 39.4 kWh/kg but effectively 1/3Highrenewable energy some automotive useto 1/5 of diesel due to cryogenic but no marine infra- storage tankstructureUranium 235 Small amount dueTightly regulated Nuclear fuel with22,500,000 kWh/kg Hugely expensiveto refining process well-established regulationsfuel. Other fuel types, such as ammoniaOne way to reduce environmen- for various types of vessels. This can or hydrogen require the use of fuel cellstal impact is to use less energy. At thebe achieved through better hull forms, to convert the fuel into electricity whichInternational Maritime Organizationdecreasing the hotel load, slowing the can then be used for propulsion. Fuel(IMO), the Marine Environmentalvessel speed, installing more efficient cells have higher operating efficien- Protection Committee has introducedengines, or increasing the carrying cies than internal combustion enginesthe concept of the Energy Efficiencycapacity for the same CO2 emissions. (50% to 55% efficient versus 40% toDesign Index (EEDI). This index isWhile the EEDI only applies to certain 45% efficient) but the electrical conver- a measure of how much energy atypes of vessels (tankers, bulk carriers, sion offsets some of the advantages.ship uses. IMO has set targets for thecontainer ships, general cargo ships, Fuel cells are a mature technology inindustry to reduce over time the EEDIetc.) on international routes, the EEDI bus operations and stand-by power generation. There are demonstration projects underway to apply fuel cells to the marine environment. The promise of a quiet, emission free, propulsion technology is very appealing.attention to detailNuclear power is listed above as a potential fuel because it is a proven technology. The USS Nautilus first demonstrated the feasibility of such propulsion in 1955. Since then, several hundred vessels have safely operated on nuclear power. New reactor designs could further improve safety and reduce the lifecycle cost to the point where it is economically viable. A large container ship could operate at high speeds for up to 20 years with no emissions and no need to refuel. Nuclear power may not be suitable for smaller vessels, but we can expect to see its continued application in vessels with high power requirements, such aswww.beurteaux.comice breakers.OCTOBER 2020FOGHORN 23'