Abstract
Enlarging the fleet of gas carriers would make it possible to respond to the growing demand for hydrocarbon gases, but it will increase carbon dioxide emissions. The International Maritime Organization (IMO) has developed the energy efficiency design index (EEDI) with the objective of carbon emission reduction for new ships. In this paper, thirty gas carriers transporting liquefied natural gas (LNG) and liquefied petroleum gas (LPG) and equipped with various types of main engines are considered. As shown by the calculation of the attained EEDI, 2 of the 13 LPG carriers and 6 of the 17 LNG carriers under study do not comply with the EEDI requirements. To meet the stringent EEDI requirements, applying thermochemical regenerators (TCRs) fed by main engine exhaust gases is suggested. Mathematical modeling is applied to analyze the characteristics of the combined gas-turbine-electric and diesel-electric power plant with thermochemical recuperation of the exhaust gas heat. Utilizing TCR on gas carriers with engines fueled by syngas produced from boil-off gas (BOG) reduces the carbon content by 35% and provides the energy efficiency required by IMO without the use of other technologies.
Highlights
Human demand for energy will continue to grow to satisfy various needs
The novelty of this article is the idea to apply thermochemical regenerators (TCRs) fed by main engine exhaust gases to improve the energy efficiency of gas carriers, whose propulsion engines are fueled by the boil-off gas (BOG) cargo, which in addition to natural gas consisting largely of methane, contains heavier alkanes such as ethane, propane, and butane
As shown by the calculation of the attained efficiency design index (EEDI) for 13 considered modern liquefied petroleum gas (LPG) carriers, 11 ships comply with the EEDI requirements, but only two of them meet the requirements of the most stringent Phase 3
Summary
Human demand for energy will continue to grow to satisfy various needs. According to the International Energy Outlook data (US Energy Information Administration 2017), global energy consumption will grow by 28% between 2015 and 2040. Mitienkova: Analysis of the Impact of Thermochemical Recuperation of Waste Heat exporters and importers, and the level of gas transportation technologies development, it can be argued that pipeline and LNG transportation are preferred technologies This is supported by the opinions of the energy market experts. There are two main types of ship power plants for gas carriers: 1) Those with a re-liquefaction system 2) Those with compressors, which are used for supplying pressured gas derived from the BOG to the installed engines. The novelty of this article is the idea to apply TCR fed by main engine exhaust gases to improve the energy efficiency of gas carriers, whose propulsion engines are fueled by the BOG cargo, which in addition to natural gas consisting largely of methane, contains heavier alkanes such as ethane, propane, and butane. With regard to the level of CO2 emission controlled by IMO (IMO 2015), gas carriers rank sixth among all the types of ships (Figure. 4)
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