Dominion Resources, Inc. (DRI) has asked the Federal Energy Regulatory Commission (FERC) to declare its proposed "impacted megawatt mile (IMM)" tariff a just and reasonable method of pricing transmission service.
The IMM tariff would base electric transmission prices on the actual flows that result from each transmission service, taking account of the size and distance of power flows on all affected lines, the direction of the flows, line loadings, and the costs of relieving any congestion. Prices would reflect incremental capital and operating costs, with the capital costs derived from the current duplication costs of the lines used for service. Consistent with the FERC's proposed rules on capacity reservation, the IMM tariff would require reservation of the transmission capacity required for all firm service, including utility service to native loads.
According to Everard Munsey, DRI's vice president of public policy, DRI presented IMM pricing to the FERC in its 1993 inquiry on transmission pricing. Utilities have been reluctant to adopt IMM pricing without assurances that it is acceptable under the Federal Power Act.