報告書番号

Y11036

タイトル（和文）

米国における発送電分離が電気事業に与えた影響－主要な自由化州を対象とした事例調査－

タイトル（英文）

Impacts of Unbundling on the Electric Utility Industry in the US -Case Studies for the Representative Restructured States-

概要 （図表や脚注は「報告書全文」に掲載しております）

これまで垂直統合の維持を前提としてきたわが国の電気事業体制を見直す議論を踏まえ，本報告では，米国で発送電分離を行った代表的な州の経験から，発送電分離の実施が事業運営をどのように変化させ，競争の促進や電力の安定供給，電気料金にどのような影響を与え，どのような課題に直面しているのかについて，いくつかの具体的な事例を通じた考察を行った。発送電分離を実施した後，新規参入が活発な州において，電気料金が全米平均と比較して下がっているという明確な傾向は認められない。一方で，分離後に信頼度が低下するといった明確な傾向も認められないが，これは2003年の北米大停電以降，全米で信頼度の向上が重視されてきたためである。発送電分離後は，分離した様々な組織の間でいかに連携をとるかが重要な課題になるが，米国の場合には，ISO/RTO（独立系統運用者・地域送電機関）の権限を強化することで対応している。

概要 （英文）

This report discusses the issues in vertical unbundling in the U.S. electricity industry to identify the potential benefits and challenges of separating generation from transmission. In the U.S., the unbundling and restructuring efforts have been jointly led by federal and state authorities, involving the operational unbundling of transmission activities from generation businesses at the federal level and the unbundling of competitive generation from distribution at the state level. We selected three different states (Texas, New York, and Illinois) for case studies on the process of unbundling and its impact on the industry. The type of unbundling implemented across different states varies depending on the position of the legislators/regulators and the business strategies pursuant to the restructuring plans at that time. All three states have been successful to facilitate competition in retail market as well as wholesale market, due at least in part to the market design. However, the competition did not necessarily lower electricity prices. Thus far, there has been no clear indication that vertical unbundling led to a serious deterioration of reliability, although the potential risk on the security of supply might have been increased. As a result of unbundling, the functions and responsibilities of the former vertically integrated utilities become shared among different entities, and it seems that in the U.S., ISO/RTOs without asset ownership have been more responsible for coordinating generation and transmission in both the short-term and long-term, and this is becoming a cause of concern as it might increase inefficiency in the long-run.

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