Opinion of Advocate General Rantos delivered on 13 October 2022.#RWE Power Aktiengesellschaft v Hauptzollamt Duisburg.#Request for a preliminary ruling from the Finanzgericht Düsseldorf.#Reference for a preliminary ruling – Taxation of energy products and electricity – Directive 2003/96/EC – Article 14(1)(a) – Second and third sentences of Article 21(3) – Electricity used to produce electricity and to maintain the ability to produce electricity – Exemption – Scope – Opencast mining operations – Electricity used in order to operate fuel bunkers and means of transport.#Case C-571/21.