The Federal Energy Regulatory Commission rejected an agreement between Duke Energy Carolinas and Duke Energy Progress to share capacity, saying the deal would be discriminatory.

The two companies, subsidiaries of Duke Energy following its acquisition of Progress Energy, said they created the capacity agreement to provide savings to their native load customers in North and South Carolina.

The agreement would allow the companies to “make temporarily excess capacity available to each other for time periods when” one party “is projected to have more capacity than is required” to meet reliability standards.

The companies said the capacity agreement would allow them to minimize purchases of capacity and “commitment of additional generation.”

The companies also said the sharing would be done “for no additional monetary compensation” because of the reciprocal nature of the agreement.

FERC was not persuaded. “Applicants have failed to demonstrate how sharing capacity with an affiliate at a zero-price term to the exclusion of other parties is just and reasonable and not unduly discriminatory or preferential under [Federal Power Act] section 205,” the commission ruled (ER14-2356).

The ruling does not affect the companies’ agreement to share economic dispatch of their owned and purchased generating resources.