Summary

Global environmental problems have attracted a great deal of public attention. Reduction of environmetal impact has been require all over the world. The problem in Japan has come to be tackled gradually in railways. It includes not only train-induced noise and ground vibration known in general, but also evaluating synthetically the environmental impact on railway systems throughout the life cycle of the train. Life cycle assessment(LCA) has been a focus of attention recently. It is a technique for evaluating the environmental impacts associated with a product throughout its life cycle. Though the methodology of LCA is still under development, it is very important to appreciate the concept of LCA. Thus, the preliminary investigation for LCA of Shinkansen vehicle was carried out. And then, trial applications of LCA of Shinkansen vehicle for energy consumption and CO₂ emission were performed on the basis of data acquired in this investigation. As the result, life cycle energy consumption and CO₂ emission in running stage were found the highest of all stages. This study will contribute to future study on LCA for railway vehicles.

Key Words : Shinkansen vehicle / LCA

Environmental protection is one of the most important global issues in recent years. For example, the problem on the reduction of CO₂ emission regarded as the major cause of global warming has attracted a great deal of public attention. Figures 1 and 2 show energy consumption and CO₂ emission for various transport modes in Japan respectively [Japan Transport Economics Research Center, 1996]. Railway is the best transport for environment in terms of energy consumption and CO₂ emission. For the purpose of the sustainable development of human society, however, we have to grasp the environment impact induced by human activities, and make efforts to minimize it.

LCA is now recognized as an effective tool for quantification of the environmental impact of various products. Standardization of the methodology of LCA has been undertaken by ISO (ISO14000s). However, LCA has not been established yet. Thus, to establish a basis for the future railway vehicles LCA study, we carried out a preliminary investigation for LCA of Shinkansen vehicles.

Figure 3 shows a universal life cycle flow of a certain product. The life cycle of the product consists of the following 4 stages generally: material mining, manufacturing, use/maintenance and recycling/final disposition. Raw materials, energy, water, etc. are inputs and airborne emission, waterborne emission, solid waste, etc. are outputs in each stage of life cycle. LCA is a method to evaluate the environmental impact throughout the life cycle of a product, and is the decision support tool in reducing the environmental impact.

Figure 4 shows the LCA framework. It consists of the following 4 phases:

(1) The goal and scope of the LCA study are defined.

(2) Inventory analysis(LCI) involves data gathering and calculation procedures to quantify all relevant inputs from and outputs into the environment at every stage.

(3) Impact analysis is aimed at evaluating the environmental impact after classifying the inventory data into impact category.

(4) Interpretation means evaluating the results of inventory analysis and impact analysis individually or synthetically.

There is intimate relationship among different phases on LCA framework. This means that LCA is not a linear but a cyclical process. Thus, the correspondence between different phases must be verified while LCA is being performed.

Railway system consists of different elements of vehicles, track, construction etc. Ultimate goal is the performance of LCA covering all such elements. As the first trial of LCA on railway field in Japan, a case study on a railway vehicle has been carried out.

Figure 5 shows the life cycle flow of a railway vehicle. This case study takes account of 3 following stages; manufacturing, operation/maintenance and final disposition, assuming that transportation from step to step is not included in the scope of evaluation. Raw materials, energy, water, etc. are inputs and airborne emission, waterborne emission, solid waste etc. are outputs in each stage.

In performing LCA, it would be ideal if inventory analysis and impact analysis could be performed, covering all categories of environmental impact over the whole life cycle. However, a railway vehicle has a large number of component parts and is produced through multiple processes. And also, many kinds of expendables occur at maintenance stage. Therefore, it is difficult to take account of all the processes and all component parts in the scope of evaluation. Furthermore, the process from recycling to final disposition is not grasped accurately as things now stand. That is why it is difficult to quantify all the relevant inputs and outputs at every stage. Moreover LCA has not been established yet and the basic Japanese data on life cycle inventory concerning material manufacturing, power generation and so on are not standardized. For the above-mentioned reasons, it is extremely difficult to perform a perfect LCA, therefore considered nearly impossible.

Thus, a preliminary investigation was carried out to establish a basis for railway vehicles LCA study. Then the following items are summarized using the data acquired ; energy consumption, CO₂ emission. The object in this investigation is a series 0 Shinkansen vehicle, which has been operated on Tokaido/Sanyo Shinkansen. And to compare the difference in the type of vehicle, series 100, 200 and 300 were also investigated partially. Table 1 shows Shinkansen vehicles in this investigation.

Data on energy consumption and CO₂ emission were investigated at each life cycle stage of Shinkansen vehicle.

Manufacturing stage

It is difficult to quantify the electric consumption for all component parts and processes at manufacturing stage, because the railway vehicle has a large number of component parts and is producted through multiple processes. Thus, the kinds and weights of major materials constituting series 0 and 200 Shinkansen vehicles were investigated to estimate the electric consumption for producing raw materials from the difference in the component materials of the body,. The body of series 0 Shinkansen vehicle is made of steel. That of series 200 Shinkansen vehicle is made of aluminum alloy. Figure 6 shows kind and mass of major materials constituting each vehicle. Both vehicles are constituted of steel, aluminum and copper in more than 90mass%.

Operation / Maintenance stage

The electric consumption per 1km running for Shinkansen vehicle in 16-cars shown in Table 2. The objects for the investigation are series 0, 100 and 300 Shinkansen vehicles. We should be aware of the difference in the electric consumption for each vehicle. The reason will be described in next chapter. A large-scale inspection of Shinkansen vehicles is carried out every 450,000km run. It is nearly impossible to gather the data on each process of the inspection. Thus, we assume that the electric consumption at the whole workshop is equal to the electric consumption for maintenance stage. It is calculated that the electric consumption per car for inspection is about 11,000kWh.

Final disposition stage

Series 0 Shinksnsen vehicle is the oldest of the present Shinkansen vehicles. Therefore, this Shinkansen vehicle is due for final disposition and replacement. It is nearly impossible to gather the data on each process of the final disposition similar to maintenance stage. Thus, it is calculated that the electric consumption per car due for scrap is about 3,100kWh.

Trial applications of LCA to a Shinkansen vehicle on energy consumption and CO₂ emission were performed on the basis of data acquired in chapter 4. As conditions for calculation it was estimated that life cycle distance run of series 0 Shinkanse vehicles was 8 million km and life cycle inspections were 20 times. Unit of energy consumption was estimated at 24450kcal/kWh, unit of CO₂ emission, at 392g/kWh. Calculation took account of the production of raw materials at manufacturing stage. Energy consumption for production of raw materials was calculated using unit of energy consumption for each material production as shown in Table 3 [The Society of Non-Traditional Technology, 1995]. Unit of energy consumption for steel production is estimated in terms of the average for hot-rolled steel plate, thick plate, bar steel and wire rod. Figures 7 and 8 show life cycle energy consumption and CO₂ emission per one series 0 Shinkansen vehicle respectively. CO₂ emission was calculated on the basis of energy consumption. Life cycle energy consumption and CO₂ emission in running stage are the highest of all stages and those in other stages are low as compared with running stage. This fact suggests that the development of energy-saving in railway vehicles will translate to reduction of the environmental impact.

As shown in Figure 6, the component materials differ with different series of Shinkansen vehicle. Figures 9 and 10 show the results of the comparison between series 0 Shinkansen vehicle and series 200 one in energy consumption and CO₂ emission at production of raw materials respectively. Energy consumption and CO₂ emission of series 200 Shinkansen vehicle are higher than those of series 0 one because the former is made of aluminum and production of aluminum consumes more electric power than that of steel. However, their differences are remarkably small as compared with energy consumption and CO₂ emission in running state as shown in Figures 7 and 8.

Figures 11 and 12 show the results of comparison among series 0, 100 and 300 Shinkansen vehicle in energy consumption and CO₂ emission at running stage respectively. Life cycle distance run of each Shinkansen vehicle was 8 million km. Whenever the new type Shinkansen vehicle is thrown into service, energy consumption and CO₂ emission of Shinkansen vehicle are reduced. It is estimated that the reduction is caused by a decrease in vehicle weight, performance improvement of main circuit control, use of regenerative braking and a decrease in running resistance as shown in Table 4.

A preliminary investigation for LCA of Shinkansen vehicle was carried out. Trial applications of LCA of Shinkansen Vehicle for energy consumption and CO₂ emission were performed on the basis of data acquired in this investigation. As a result, we reach the following conclusions:

(a) Life cycle energy consumption and CO₂ emission in running stage are the highest of all stages and those in other stages are low as compared with running stage. This result suggests that the development of energy-saving in railway vehicles will lead to reduction of the environmental impact.

(b) LCA has not been established yet and has been performed with some assumptions using imperfect data at the present time. However, it is very important to appreciate the concept of LCA as one of the methods for evaluating the environmental impact. At least it can be said that this study will give a chance for the railway to reflect on its own responsibility for environmental impact.

We acknowledge with sincere gratitude the kind cooperation of Central Japan Railway Company and West Japan Railway Company which helped us very much in the present study.

[1] Japan Transport Economics Research Center: Research report about economics load step for environmental load decrease in transport, Japan, 1996, in Japanese

[2] The Society of Non-Traditional Technology, Ecomaterials Forum: Basic investigation for building up environmental load estimation system, Japan, 1995, in Japanese