Based on the so-called MARPOL 73/78 Treaty “the International Convention for the Prevention of Pollution From Ships, 1973 as modified by the Protocol of 1978” so called MARPOL 73/78 Treaty, the Protocol of 1997 and 1973, which includes Annex VI titled “Regulations for the Prevention of Air Pollution from Ships”, was adopted and came into effect on 18 May 2004. The emission regulations of NOx and SOx from ships started with this protocol. After that, the severe sulfur regulation was discussed and adopted at MEPC58 held in October 2008. This paper presents the production process and the expected quality of low sulfur marine fuels that will be used in specified sea areas after 2015 and in general sea areas after 2020. This paper also presents the future unconventional fuels.

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 With regard to global warming, efforts toward the reduction of carbon dioxide(CO₂) emissions need to be undertaken with great urgency. It is difficult to reduce CO₂ emissions with further improvement of the thermal efficiency since the diesel engine’s thermal efficiency is already high. For this reason, it is realistic to restrain the use of fossil fuels by using bio-fuels (raw vegetable oil, waste cooking oil) as a countermeasure against global warming. In this paper, the authors studied the emission characteristics of a high speed, naturally aspirated, 4 stroke cycle diesel engine using gas oil, marine diesel oil(MDO), raw rapeseed oil, raw palm oil and waste cooking oil. The effect of fuel injection control on bio-fuel combustion using an assist injection system: new fuel injection system composed of a common rail system and a cam drive pump was also investigated. The findings are the following: (1) CO emission of bio-fuels is higher than that of gas oil or MDO. (2) Smoke from bio-fuels is lower than that of gas oil or MDO. (3) Assist injection system is effective to improve bio-fuel combustion by suppressing the maximum cylinder pressure and rapid premixed combustion.

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 This paper describes an experimental study on the burning time of suspended single droplets of fuel oils in high temperature air. The fuel oils used in the experiment were marine diesel oils and light cycle oils. The results show that the burning time of a single droplet is determined by the mass of droplet at ignition and the evaporation rate during burning, and that it decreases under both lower and higher ambient temperatures. The burning time was a maximum at an ambient temperature of 1000K. The burning times were compared and the mechanism of the burning process of these droplets was observed.

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 Natural gas produces less carbon dioxide, nitrogen oxides and sulfur oxides per unit heat released than other fossil fuels such as oil and coal. In line with efforts to preserve global environment and to promote sustainable development of world economy, the demand for natural gas has steadily increased. This study was conducted to analyze the risk of GHG (greenhouse gas) release caused by accidents involving natural gas carriers. LNG, which stands for Liquefied Natural Gas, is composed mainly of CH₄, so the composition of LNG was assumed to be 100% CH₄. Also, the other components of natural gas are not recognized as GHG. To estimate the maximum environmental impact, “Q-Max” which is currently the largest LNG carrier was used as the reference ship. For comparison, CO₂ emissions from the propulsion engine were calculated. The environmental impact due to accidents was insignificant compared with the impact of CO₂ emissions from the propulsion engine.

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