Constellation Mystic Power v. FERC, No. 20-1343 (D.C. Cir. 2022)
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Constellation Mystic Power, LLC (Mystic)—a subsidiary of Exelon Generation Company, LLC (ExGen), which itself is a subsidiary of Exelon Corporation (Exelon)—announced its intention to retire the Mystic Generating Station (Mystic Station). ISO New England entered into a cost-of-service agreement with Mystic and ExGen to keep two of Mystic Station’s generating units, referred to as Mystic 8 and 9, in service between June 2022 and May 2024. The parties filed the proposed agreement (Mystic Agreement) with the Federal Energy Regulatory Commission (Commission or FERC). The Commission ultimately approved the terms of the Mystic Agreement.
At issue are Commission orders related to its approval of the Mystic Agreement. Two groups of petitioners sought review: Mystic and a group of New England state regulators (State Petitioners). The DC Circuit dismissed Mystic’s petition for review in part and denied it in part; the court granted the State Petitioners’ petitions. The court held that the Commission’s application of the original cost test to determine Mystic 8 and 9’s rate base was not arbitrary and capricious. The court dismissed Mystic’s objection to the Commission’s selection of capital structure as moot in light of the Commission’s May 2022 Order. The court further concluded that the Commission properly included historical rate base components in the true-up mechanism but also find that the Commission failed to respond to the State Petitioners’ request for clarification.
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