Methanol as a Fuel for Marine Diesel Engines

Maritime transportation is the most important transportation type since 90% of world trade is carried. There are 96,295 ships in operation all over the world, and more than 300 million tons of fuel is consumed annually. A significant amount of emissions are emitted when ships are in operation. There are strict emission rules and regulations that are entered into force by the International Maritime Organization. To reduce shipping emissions and comply with the emission rules and regulations, there are various technologies and methods, including engine modifications, after-treatment systems, and alternative fuels. In today’s maritime transportation, the use of alternative fuels on ships increases its popularity. Methanol is one of the promising alternative fuels for future maritime transportation. Although methanol-fueled ships are low in number now, methanol has the potential to increase in usage on ships in the future. There is a scant amount of study and a lack of knowledge about methanol usage on marine diesel engines since it is the new fuel for maritime transportation. The methanol combustion at marine diesel engines is needed to be discussed because it is a unique fuel that can provide high engine efficiency and low emissions than diesel fuel. This chapter covers information about the status of maritime transportation, international maritime emission rules and regulations, emission mitigation technologies and methods, methanol at maritime transportation, methanol properties, and combustion concepts, and the methanol partially premixed combustion strategy for maritime transportation. Lastly, the summary section comprises the chapter results. One of the main findings of the chapter is using methanol as an alternative fuel can reduce the different types of regulated emissions at maritime transportation at once without applying additional equipment while providing more efficient marine diesel engines. Another finding is the methanol partially premixed combustion (PPC) strategy showed high engine efficiency than the conventional marine gas oil-fueled diesel engine with lower CO₂ and NOX emissions. The sulfur-free structure of methanol does not emit SOX emissions and the low-carbon chain structure of the methanol molecule extremely decreases PM emission formation. This chapter confirms that the methanol PPC can be a solution for marine engines to comply with emission regulations and more efficient engine operation from low load to high load.