Alternative Fuel Technologies Diesel fuel contains environmentally damaging matter. Once the fuel is consumed during the combustion process, SOx, PM, and NOx are vented through the exhaust system to the atmosphere. By decreasing the amount of harmful agents within the fuel, generally through further refinement, fewer harmful agents are vented to the atmosphere following the combustion process. However, challenges remain. Primarily, the sulfur content in marine diesel fuels, known as heavy fuel oil (HFO), acts as a lubricant and cooling agent in the fuel delivery systems of modern C2 marine diesel engines. This cooling and lubricating function is critical to engines operating in extreme weather climates such as Alaska or the Caribbean. Secondarily, land-based, low sulfur diesel fuels can have a lower flash point than standard marine diesel fuels. According to international standards, marine diesel fuels must have a flash point greater than 60° Celsius. For this reason, on-highway diesel fuels were not considered in the analysis, as they do necessarily meet this standard consistently. Finally, since fuel switching mandates the use of separate fuel storage, delivery, and injection systems, options such as dual-fueled engines, or the utilization of those fuels which require substantial capital conversion costs, such as emulsified, or Fischer–Tropsch diesel fuels, were not considered a viable option in our analysis. Due to the regulatory and mechanical constraints presented by the current marine environment and the challenging commercial applications in which marine diesel engines operate, this report will evaluate only three potentially feasible alternative fuel technologies: biodiesel, low sulfur fuel, and ultra-low sulfur fuel. Table 3: Selected properties of certain diesel fuels Fuel Type A.K.A. Defined By Maximum Sulfur Price Premium/Gal Heavy Fuel Oil (Int'l) Bunker C MARPOL 45,000 ppm (4.5%) Baseline Heavy Fuel Oil (US) HFO EPA 29,000 ppm (2.9%) Baseline Low Sulfur – U.S. MDO EPA 500 ppm (0.5%) $0.02 Low Sulfur - EU MGO EU 200 ppm (.2%) $0.02 Ultra Low Sulfur ULSF EPA 15-30 ppm (0.015 – 0.030%) $0.05 20% Biodiesel B20 n/a 0 ppm $0.25 Biodiesel is produced from an animal or vegetable fat base. During the refining process, glycerol and fatty acids are removed, and a methyl or ethyl ester remains as a combustion fuel source. The utilization of biodiesel significantly reduces dependence on fossil-based, non-renewable fuel sources, and it significantly decreases PM. However, serious issues remain before this will be a viable fuel source. While particulate matter content decreases following the combustion process, (-50%), the level of NOx content in exhaust gases increases, (+10%). Furthermore, availability of this fuel is limited and current distribution outlets cannot viably support the marine industry. Although blending biodiesel with traditional diesel fuels has been field trialed successfully, cost remains an issue. Biodiesel is currently selling at a $0.25 per gallon premium over HFO. Low Sulfur diesel fuel is defined in the U.S. as containing fewer than 500 parts per million (ppm) sulfur (0.5%). Low sulfur marine gas oil, (MGO), is a readily available fuel that possesses 0.2% sulfur content, on average, conforming to the EU’s definition of low sulfur fuel. Consuming low sulfur fuel as opposed to HFO can result in up to 55% PM reductions. However, NOx emissions do not decrease as a result of consuming MGO. Furthermore, a capital investment is required to re-equip a vessel’s fuel storage and delivery system, (cleaning tanks and fuel lines, and replacing fuel filters), in order to switch to the new fuel. Finally, MGO fuel has a flashpoint of 57-69 degrees Celsius. Special controls must be incorporated into distribution schemes that restrict distribution of MGO fuels to at least a 60 degree flashpoint level. Low sulfur diesel fuel is currently selling at a $0.01 per gallon premium over HFO. This fuel type (120 – 140 ppm sulfur content), is currently being mandated for use in captive fleet operations in California and EU waterways. In California, the California Air Resource Board (CARB) specified fuel properties to California petroleum refineries following the passing of the low sulfur-only fuel requirement, and a standardized CARB low sulfur diesel is currently the only fuel allowable for captive fleet operations. Although a few negative side effects resulted in the 19 initial fuel conversion, such as excessive injector O-ring and fuel system seal wear, the subsequently-specified blending of lubricity agents to the base fuel quelled these issues.27 Ultra-Low Sulfur diesel fuel is defined to contain fewer than 30 ppm sulfur (0.03%). Consuming ultra-low sulfur fuel (ULSF) as opposed to HFO can result in 75% PM reductions. However, NOx emissions do not decrease as a result of consuming ULSF. Furthermore, a capital investment is required to re-equip a vessel’s fuel storage and delivery system, (cleaning tanks and fuel lines, and replacing fuel filters), in order to switch fuel types. Finally, although ULSF is well within international flash point limits, it does not contain enough sulfur to provide lubrication and cooling to marine diesel engines. For this reason, it is recommended that a synthetic lubricant additive be mixed with the fuel prior to use. Ultra-low sulfur diesel fuel is currently selling at a $0.03 per gallon premium over HFO. Current proposed CARB-sponsored legislation in California is requesting that this fuel type (15 ppm sulfur content), be mandated for use in captive fleet operations in California beginning in 2007-2008. Once approved, CARB will specify the ULSF fuel requirements, (sulfur content, contained lubricity agents, and minimum flash point), to petroleum refineries for distribution. The California ferry system is successfully field-testing ULSF across the entire fleet.28 The EU is mandating ULSF for its entire captive fleet by 2008.