報告書番号

Y00017

タイトル（和文）

電気事業の環境パフォーマンスを考慮した効率性の計測 ---DEA手法の適用---

タイトル（英文）

Measuring Efficiency of Electric Power Companies Considering Environmental Performance -- Application of the Modified Slack-Adjusted DEA Model --

概要 （図表や脚注は「報告書全文」に掲載しております）

本稿では、従来効率性分析に用いられてきた典型的な投入要素（資本・労働・燃料）や産出物以外の要因、特に環境問題関連のパフォーマンスを考慮した効率性の計測を行った。その際、環境関連の望まれない生産物（bads）を扱った先行研究で従来用いられてきた手法ではなく、badsの排出余剰に着目し、これを扱えるDEAモデル（改良型Slack-Adjusted DEA（SA-DEA）モデル）を用いて新たな指標を構築し、指標の整合性を検証した。その結果、本稿で提案する指標が、従来の指標よりも、環境パフォーマンスの実態により即した、実用的な環境を考慮した効率性指標であることが示された。この指標を日米の電気事業者に適用したところ、日本の電力会社9社の平均が、米国の平均を上回っており、環境を考慮しなかった場合よりも、その差はさらに大きくなった。

概要 （英文）

This study examines the efficiency index considering environmental performance using Data Envelopment Analysis (DEA). Several previous DEA studies exits, which measured efficiency of business entities considering not only desirable outputs (goods) but also undesirable outputs (bads) like Sulfur Dioxide (SOx) and Nitrogen Oxide (NOx) emissions from electric power plants. This study applies a modified Slack-Adjusted DEA (SA-DEA) model which incorporates an influence of slacks into the measurement of DEA efficiency and doesn’t use an assumption most previous studies applied, and introduces a new efficiency index considering environmental performance.Using a data set from US electric power companies, the behavior of the indices is examined and compared with ones introduced by Fare et al. (1996). In addition, these indices are also applied to Japanese electric power companies in order to compare with that of US.The results clarifies the fact as follows: ・the efficiency index considering environmental performance calculated by a modified SA-DEA model is more practical, while previous index under weak disposability assumption is not suitable for using solely and is valid only used with the other index, ・this efficiency index contains the environmental performance indicator that demonstrates good correlation with actual environmental performance, while such indicator included in previous efficiency index sometimes fails to do so, ・the results mentioned above show that the efficiency index calculated by the modified SA-DEA model is more useful and accurate, ・the average score of Japanese efficiency index considering environmental performance is much better than that of US, and the difference between Japanese and US averages gets larger than that in the case without considering environmental performance, and・the modified SA-DEA model used in this study would be applicable to measure efficiency considering other bads, like blackout, accident and negative services of companies.

報告者

キーワード