When Dominion first sought SCC approval for the line in 2012, it said it was needed to meet long-term electricity demand on the Peninsula. The utility said that need became more urgent when tougher new federal limits on the mercury and toxic gases power plants emit took effect, since they meant it had to close down its two coal-fired units at its Yorktown power station. State and federal regulators gave Dominion temporary permission to operate the plants through April, even though their emissions exceeded the federal standard. This summer the U.S. Department of Energy issued an emergency order allowing the plants to continue to operate if necessary to meet summer demand.