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The International Marine Organization (IMO) has a goal of reaching 40% reduction of GHG emissions by 2030 and target of a full 50% reduction in marine fleet wide GHG emissions by 2050, while other organizations and governments desire to develop a path to Net-Zero GHG emissions by no later than 2050. To accomplish this, engines with near zero GHG emissions must be developed now. In addition to new ships, there is a large existing fleet of diesel fueled engines in the market today which are candidates for retrofit. Ammonia fueling of a diesel engine using dual-fuel combustion represents a viable zero-carbon fuel and combustion strategy suitable for long-haul / heavy-duty transportation due to its favorable storage properties of liquid at low tank pressure. The challenge, however, is ammonia is hard to ignite, slow to burn, and cool when it does burn which creates a significant challenge from a combustion point of view. Conventional dual fuel (CDF) will not be able to burn more than 50% NH3-Diesel ratios efficiently with acceptable combustion quality, thus, combustion enhancement is required to get ammonia to ignite and burn at higher substitution rates. Woodward has developed a fueling and combustion control strategy using diesel pilot injection as the ignition source and combustion accelerant. And using RCCI combustion (Reactivity Controlled Compression Ignition) controlled by Active Combustion Control (ACC) high ammonia-diesel substitution ratios (GSR) is demonstrated to burn as fast or faster than the baseline diesel. With the proportional reduction of carbon in the fuel and an appropriate ammonia slip catalytic technology, it is demonstrated that ammonia can be used as a GHG reduction fuel in dual-fuel diesel engines which can contribute to reduction in GHG emissions proportional to the NH3 substitution ratio. This is a technology which can be deployed today on both retrofit of existing engines as well as on new engines to meet the marine fleet average GHG emissions goals. |
