A Study on Relation between CO2 Emission and Weight of Machinery Equipment by Using Input-Output Tables: For Simplified Estimation of CO2 Emissions
2008 Volume 4 Issue 4 Pages 349-358
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2008 Volume 4 Issue 4 Pages 349-358
Background and Aim. CO2-emission from production process of energy equipments is often a trade-off for CO2-emission in operation. A simplified method would be useful for estimating approximate CO2-emission from production process of energy equipments. On the other hands, the authors have been trying to evaluate energy systems and technology from the viewpoint of material use. We have used weight as a measure of material use, as it is relatively easy to get weight data of energy equipments. Therefore, if the weight of energy equipments has a positive correlation with the CO2-emission, the weight would be a good measure in a simplified estimation of CO2-emission. From this point of view, in this paper we discuss relations between weight of energy equipments and CO2-emission from their production process, by using input-output tables.
Results and Discussion. In this paper, we use input-output tables (year 2000) as a common data source of weight of energy equipments and CO2-emission. We chose 15 from 400 categories of input-output tables, most of which are energy equipments and industrial machines. Studies by “National Institute for Environmental Studies”, show that most of CO2-emission is from metals, e.g. iron and steel, and power supply. We therefore, estimate weight of the metals, for selected 15 categories. We calculate the weight from the weight of intermediate categories that was calculated from the weight of the metals by using material tables. The resultant relation between weight and CO2 emission from production process is approximated as following, c = 1.99 m + 1.50 p where c : CO2-emission (t), m : material weight of the product (t), p: producer price of the equipments (million yen) The weight coefficient 1.99 is approximately equal to the CO2 emission per unit weight of pig iron, 1.50, implying that most of CO2-emission is from metals, e.g. iron and steel. The price coefficient 1.50 corresponds to CO2-emissons form electric power for production process and energy for transportation, etc.
Conclusions. Simple approximate relation between CO2-emission from production process and total weight of energy equipments, has been derived. This approximate method is useful to evaluate CO2-emission from production process, when only limited information about equipment, e.g. the equipment weight is available.
