Special Lecture
To Stop Global Warming and Prospects of Future Marine Engines*
by Masaru Hirata**
1. To stop the Global Warming and Contribution of Ships
The total emission of carbon dioxide (hereinafter, abbreviated as CO2) in Japan was 336 million tons in 1997 FY, which was already increased by about 9.4% compared with the total emission of 307 million tons (in terms of carbon) in 1990 FY. If the emission will be increased in this manner, the target reduction in 2010 in Japan (reduction by 6%), which was incorporated in the Protocol of The Third Conference of the Parties of the United Nations Framework Convention on Climate Change (COP3, Prevention of Global Warming, Kyoto Protocol) in December, 1997, will be absolutely impossible. In particular, the objective gases for reduction this time included six kinds including not only CO2 but also methane, dinitrogen monoxide, HFC (hydro-fluorocarbon) as alternative to fron and PFC (per-fluorocarbon), and sulfur hexafluoride (SF6), and since the reducing method for HFC, PFC, SF6, etc. is not clear, it is expected that the reduction of CO2 itself be larger than the value of 6%.
In the case of ships, methane is mainly emitted from the engines at low load conditions, and through the evaporation from the LNG tankers and crude oil tankers. Most of dinitrogen monoxide is derived from the combustion of fuel. HFC is mainly derived from the leakage of the refrigerant of the refrigerator container. PFC is derived from that used in cleaning electronic parts, and SF6 is mainly derived from that used for the insulation gas in transformers, and these are less related to ships directly. These gases were selected from the ratio contributing to the global warming effect (the absolute quantity in the atmosphere x warming effectiveness), the annual rate of increase, the service life in the atmosphere, etc., and at present, the contribution of CO2 is the maximum, which is effective about three times that of methane, about 10 times that of dinitrogen monoxide and the alternative fron, and about 800 times that of SF6. In this paper, discussion will be focused on CO2.
The Environment Agency established the "Working Group on Evaluation of Suppression Thethods of Air Pollution from Ships" under the commission of the Marine Engineering Society in Japan since 1992 FY, and has continued its examination. On the other hand, the Ministry of Transport established the "Committee of Evaluation on the Present Status of the Influence of Ship Operation on Atmospheric Environment and its Preventive Technologies" in 1990 and 1991 FY, the "Committee of Evaluation and Research on the Standards of Measurement of NOx, etc. from Ships" in 1992 and 1993 FY, and the "Committee of Evaluation of the Influence of Exhaust Gas from Ships on the Global Environment and its Preventive Technologies" in 1998 FY under the commission to Ship and Ocean Foundation. These committees were chaired by the author, and the evaluation has been performed mainly on the actual condition of emission of SOx and NOx, and its technological countermeasures.
According to the result of evaluation on the total quantity and its contribution ratio in 1996 FY of the air pollutants emitted from ships, SOx of 238,000 tons/year (23%), NOx of 945,000 tons/year (37%), CO2, of 34,21 million tons/year (3%) were emitted from all ships navigating in waters within 200 nautical miles from Japan (including fishing boats and pleasure boats), and SOx of 9.02 million tons/year (6%), NOx of 15.17 million tons/year (13%), and CO2 of 528.19 million tons/year (2%) on the global basis. Higher contribution ratio of ships to the emission of SOx and NOx in Japan is noticeable, which indicates that the regulation on emission to the land-based sources of generation becomes more stringent, and the degree of contribution of ships which have been free from regulation can not be neglected. The degree of contribution to CO2 seems relatively small for the time being, but it will be noticeable sooner or later when others are decreased similar to SOx and NOx. Efforts for reduction should be paid from now on.
* Translated form Journal of MESJ Vol.35, No.1 At 63rd Autumn Academic Lecture Meeting (October 13, 1999)
** Honorary Member
Professor of Shibaura Institute of Technology Professor Emeritus of The University of Tokyo (1135-1, Shikoda, Kashiwa, Chiba, Japan 277-0862)
