Application of Life Cycle Inventory Analysis to Manufacturing Process of Marine Main Engine in Japan
Hideyuki SHIROTA*, Katsuhide HIRAOKA*, Michihiro KAMEYAMA* and Takeshi KIHARA*
The authors made hearing surveys of energies/materials consumed in manufacturing processes and wastes/emissions to environment on three domestic private companies which manufacture marine main engines of major types. Also, they made a hearing survey in the same way on one cast/forged steel parts factory which mainly manufactures crankshafts. On the basis of these surveys, they made LCI analysis of a model engine by matrix-method and mainly evaluated in terms of CO2 emission. In the marine main engine manufacturing factory, nearly 95 (%) of the CO2 emission in manufacturing a unit of the engine is attributable to the land trial process, and about 5 (%) for the machining process and about 1 (%) for the assembling process. Including the CO2 emission from the production stages of materials such as cast/forged steel parts, steel plates, purchased equipments and other parts, the CO2 emission from the engine manufacturing factory accounts for about 10 (%). And on the basis of the results of surveys and calculations, several remarks in applying LCI analysis to the manufacturing processes of the marine main engine were listed.
Key word: Life Cycle Assessment (LCA), Life Cycle Inventory (LCI), Ship, Shipbuilding, Main Engine
Various problems of environmental pollution on a worldwide scale have been socially taken up recently. LCA (Life Cycle Assessment), a method of environmental management in which effects of products on the environment over life cycle are assessed, has begun to spread together with the international standard ISO 14000 series in the industrial world. When the LCA is applied to the domestic products, transport by ship should be taken into account, because most natural resources used for the products are imported by ship.
The LCI (Life Cycle Inventory) analysis is an important phase of the LCA involving the compilation and quantification of inputs/outputs for a given product system throughout its life cycle. The authors have begun with an LCI analysis of ship from production of materials to ship-dismantling, with an object of establishing a method of acquiring process data for transport by ship.
In shipbuilding process in shipyards in Japan, marine main engines, auxiliaries and equipments are not made in-house but supplied as finished goods from other makers. The manufacturing processes of them are much different from those in shipbuilding. Therefore, it is supposed that both inputs such as energies and materials used in manufacturing processes of the engine and outputs such as products, emissions and wastes are much different from those in shipbuilding process. A marine main engine is bigger and heavier and of more parts than auxiliaries and equipment's. From that viewpoint, the manufacturing process of the engine is considered to be examined independently.
The authors firstly made hearing surveys on some manufacturing factories of the marine main engines and made trial analytical research on the LCI of the engine . As the result, it was known that the cast/forged steel parts composing the engine such as crankshafts are not made in engine manufacturing factories. Secondly, they made a hearing survey on one cast/forged steel parts factory which mainly manufactures crankshafts.
On the basis of these surveys, they made analytical research on LCI of a model marine main engine in Japan.
This paper presents these results of the surveys and the analytical research.
2 MANUFACTURING OF MARINE MAIN ENGINES IN JAPAN
2.1 Subject of investigation
A 2-cycle diesel engine corresponding to a main engine loaded on an 85,000 (DWT) oil tanker which the authors are examining at present, was selected as the subject of investigation. And hearing surveys were made on three domestic private companies which manufacture marine main engines of major types. The items of surveys are as follows.
* statistics of products
* manufacturing processes and works
* energies consumed on each manufacturing process (electric power, fuel...)
* inputs/outputs of materials and parts
* wastes and emissions
2.2 Manufacturing processes
According to the surveys of the factories, manufacturing processes of marine main engines are categorized as shown in Table 1. These processes consist of some works listed in Table 1.
* Ship Research Institute, Ministry of Transport,
6-38-1, Shinkawa, Mitaka, Tokyo 181-0004, JAPAN
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