Objective. The project to produce BDF from waste cooking oil has started in some autonomous communities, Japan. In this study, the waste cooking oil potential was estimated by using data obtained by questionnaire survey and demonstration of collection from household. Furthermore, we apply life cycle analysis for accounting the environmental load of BDF production project. The variation of environmental load was showed by each uncertain factor in this analysis and the way of decreasing environmental load was considered.
Result and Discussion. Tahara city in Aichi prefecture was selected as the case study area. The recoverable waste cooking oil was estimated to be 2.4kL per year in Tahara city. CO₂ emission and energy consumption were estimated in the life cycle of BDF production system. The result shows that environmental load by transport between household and collection point was biggest factor in the life cycle when evaluate by using the default value. The condition of low environmental load was changed by the uncertain factors that are the distance between household and collection point, and the amount of waste cooking oil from household. The result showed that if collection frequency change to every two months, CO₂ emission became lower than diesel and it can get the net energy.
Conclusions. BDF production system was analyzed by applying life cycle analysis and we considered the conditional equations about CO₂ emission and net energy value. It was found that there is the situation of increasing environmental load by the project of BDF production from household waste cooking oil. It is important to consider about the uncertain factors in the BDF project.

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Background and Objective. In recent years, besides the domestics recycling, a part of Japanese post-consumer PET bottles are exported to and recycled in mainland China. In this study, life-cycle assessment was applied to the comparison of PET bottle recycling scenarios, including domestic recycling and transboundary recycling between Japan and China, from the viewpoint of CO₂ emission and fossil fuel consumption.
Results and Discussion. The following 10 scenarios based on our field surveys were evaluated: Japanese post-consumer PET bottles are (i) recycled into polyester staples in Japan, (ii) recycled into polyester filaments in Japan, (iii) recycled into polyester clothes in Japan, (iv) chemically decomposed and recycled into bottle-grade PET resin in Japan, (v) chemically decomposed and recycled into polyester filaments in Japan, (vi) (vii) recycled into polyester staples in two different flows in China, (viii) recycled into polyester clothes in China, (ix) incinerated and partly recovered as electricity in Japan, and (x) directly landfilled in Japan. The results showed that all the domestic and transboundary recycling scenarios had smaller impacts than the incineration scenario, and that the chemical recycling scenarios had larger impacts than the other recycling scenarios. The robustness of the results was examined against variability of background parameters for electricity supplies and against specification of virgin products substituted by recycled products.
Conclusions. The differences of CO₂ emissions and fossil fuel consumptions between domestic and transboundary recycling scenarios, other than the chemical recycling scenarios, were not large enough to be robust against the above-mentioned variability. In particular, the variability strongly influenced the results of the scenarios including cloth-manufacturing processes in their system boundaries.

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Objective. The present paper proposes a general compilation method of the interregional waste input-output table. As a case study of compilation, we estimated the interregional waste input-output table for Tokyo, which demonstrates the characteristic of waste emission and its treatment of Tokyo and other regions. We also indicate some critical issues and present some proposals, about the modeling of industrial waste treatment and the treatment of illegally-dumped waste in the interregional waste input-output analysis.
Results and Discussion. The compilation method of interregional waste input-output table consists of 4 steps, the estimation of the sectors of good and services, the waste input and output sectors, the environmental loads sectors, and the waste treatment sectors. The amount of waste and interregional transportation amount can be estimated by using the statistical data of local governments and Ministry of the Environment. The fourth step is the most important step. We present sub models to estimate the activity of waste treatment sectors by obtaining detailed information about waste treatment technologies from Tanaka and Matsuto et al. (Matsuto, 2005). The formulation of sub models depends on the characteristic of regions. We show a practical method of estimation and models in the case study of Tokyo. In the estimation of the interregional waste input-output table for Tokyo (TWIO), we assumed three types of sub models, which differ in the location and parameters of waste treatment facilities. The estimated TWIO table for 1995 demonstrates the characteristic of waste emission and its treatment of Tokyo and other regions. The sorts of waste of Tokyo are mainly composed of “Organic sludge”, “Construction debris”, “Inorganic sludge” and “Glass bottles and cullet”. Over 3 million tons of waste, which account for 12 %, emitted from Tokyo are transferred and treated in other regions. The tendency of the sorts of waste emission in Tokyo and in other regions is quite different. The sorts of waste of other regions are mainly composed of “Animal waste”, “Incineration ash”, “Molten slag” and “Inorganic sludge”.
Conclusions. The reliability of the interregional waste input-output analysis depends on the reliability of the compilation of its table. The sufficient disclosure and the quality of the related statistical data are the critical issues for the reliable compilation of the interregional waste input-output table. Especially the corroborative information for the modeling of the industrial waste treatment is needed. The improvement of the sub models for interregional waste transportation is also needed. The stock analysis of illegally accumulated dumped waste will also be an important subject.

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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.

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Objective. Water consumption is one of the environmental performance indicators and should be managed as a significant environmental aspect of business. Recently, huge water consumption outside Japan corresponding to the productions of imported goods, known as ‘virtual water’, is considered to be a serious environmental issue. The objective of this study is to estimate total water consumption of Japan, including the indirect water consumption in upstream processes of the supply chain.
Results and Discussion. Annual water consumption in Japan was estimated based on various statistics and allocated to the input-output table of Japan. Applying the input-output analysis method, embodied intensities of water consumption in Japan have been estimated. In order to clarify the data quality, they have been compared with results estimated by the process analysis method, focusing on grains, livestock and meat. In the case of differences in embodied intensities of water consumption, parameters of their estimation processes are discussed. In addition, total water consumption of Toshiba Group, which includes direct and indirect consumption, was calculated by using the embodied intensities estimated in this study. As a result, it was found that total water consumption was about 0.167 billion tons and indirect consumption was about 2.6 times larger than direct consumption.
Conclusion. In this study, embodied intensities of water consumption in Japan were estimated based on the latest input-output table of Japan. They were compared with results based on process analysis. A case study was also presented in which total water consumption of Toshiba Group was calculated. In future work, we intend to apply life cycle impact assessment method and, in order to make the embodied intensities of water consumption more useful for the environmental management, improve the data quality.

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Objective. The objective of this study is to investigate how to reduce the environmental load induced by consumers with ones’ minimum endurance, in other words, with a minimum reduction of utility. To carry this out, we firstly combined the environmental household accounting based on our input-output analysis with the demand function in the semi-flexible AIDS. Then we specified on the consumers’ lifestyle changes as subjective discount behaviors. We focused on the following changes: the high use of eating-out and recreation services, and the changes in the means of transportation which result from new traffic policies: the road pricing system and mobility management.
Results and Discussion. The increase in demand for eating out and using recreation services will increase both the utility level and the total amount of environmental load. But in the case when the eating-out demands change, the environmental efficiency of the consumption behavior decrease, while it increases along with the changes in recreation demands. The two types of changes in transportation means will increase the utility level and the utility per environmental load. The total amount of environmental load, however, will decrease by introducing the road pricing system, whereas it increases by the mobility management.
Conclusions. It is clear that reduction of the environmental load induced by consumers’ minimum endurance is very difficult. But some results in our simulation analysis show that some changes in our lifestyles improve the environmental situation as well as the utility level. We should seek such change of lifestyles and the device of consumption.

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It is necessary to collect a large amount of data of the material and mass, etc. to calculate LCA. Moreover, LCA calculation procedure is complicated. In the product development stage, the engineer calculates LCA repeatedly and must give a result quickly. Therefore, LCA support system that controls an increase in the man-hour by LCA calculation is indispensable for the engineer. This report describes LCA system (Eco-PLAS) which Toyota industries corporation developed originally. Various devices are incorporated in this system to control an increase in the man-hour by LCA calculation. Moreover, this system corresponds to recycling rate calculation and factor calculation. By introducing this system, the development of our environmentally friendly product is promoted.

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Objective. A Life Cycle Assessment (LCA) of a personal computer (PC) connected to Internet is required because it is concerned that environmental load will increase by worldwide glowing Internet population. This study was performed as a case study to evaluate the life cycle global warming impact of a PC under internet condition by LCA (with Process Analysis method).
Results and Discussion. The subject PC system was composed of a desktop PC coupled with a 15” liquid crystal display (LCD) and a router. During this study, several key data were obtained such as the foreground data of LSI manufacturing stage, the amount of power consumption of PC during use stage, and some components like CD-ROM, hard disk, keyboard, and so on. By this study it became clear that LSI emitted several hundred times amount green house gas (GHG) of its own weight during production stage, and also that the global warming impact by electrical parts were much higher than materials such as iron and resins. On the other hand, this study revealed the deficiency of the background data of electrical parts like that resistor, transformer, connector and circuit board and so on.
Conclusion. The foreground data of LSI and the data of the components of PC obtained in this study may be very useful for the analyses of many other electric devices. However, the deficiency of the background data of many electric parts was revealed. The background data of the electric parts should be collected more and more.

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