If, in any general rate proceeding filed by an electric utility before June 1, 2018, the utility includes a request for recovery of any amount related to the implementation of an emissions reduction and capacity replacement plan and recovery of such an amount would result in an increase in the electric utility’s total revenue requirement of more than 5 percent, the utility must propose a method or mechanism by which such excess may be mitigated. The Commission may accept or reject such a rate method or mechanism. If the mitigation method or mechanism is approved by the Commission, the utility shall record any deferred revenue in a regulatory asset account and may calculate carrying charges on the unamortized balance of the regulatory asset.