A controversial high-voltage power line across southern Minnesota to the metro area now faces a two-year delay as regulators decide who will pay for the $700 million-plus price tag.

The utilities developing the 240-mile power line have asked state utility regulators to move the date for the Brookings transmission line to become operational from 2013 to 2015, citing "considerable uncertainty" about the tariff structure they'll be allowed to use to recover development and construction costs, according to a filing the utilities made with the Minnesota Public Utilities Commission (PUC) last week.

The line is one leg of CapX2020, a network of high-voltage power lines that Xcel Energy, Great River Energy and other utilities plan to build across Minnesota. The $1.7 billion project, one of the largest grid expansions in the state's history, would add about 700 miles of overhead wires. The utilities want to delay the Brookings line, they said, until they know what kind of new tariff structure will be in place, a formula officials at the Midwest Independent System Operator (Midwest ISO) have until July 15 to file with federal regulators. Federal regulators must then approve it.

The utilities want the PUC to allow them to fund it the old-fashioned way: by simply folding costs into ratepayers' bills over decades. That's how they plan to pay for the other CapX2020 lines.

However, the Midwest ISO, which operates the grid of power lines over the Midwest, determined the utilities had to use a particular tariff formula because that line is not necessary for making electricity service more reliable, but is mainly for hooking up new power generation, such as wind farms. The tariff it had in place for that has been hotly debated for putting too heavy a burden on one player or another, so the Midwest ISO has been hammering out a new one.

The new tariff will somehow divvy up the cost of building new transmission lines between parties such as wind developers and other power generators wanting to hook up to the line, and the multitude of retail customers throughout the region who get some small part of their electricity from it.

The Brookings line is a 345-kilovolt cable that would stretch 240 miles from Brookings, S.D., through Minnesota's prime wind country to Hampton in Dakota County. It's expected to help ease some of the current wind energy jam-ups on the grid.

The Citizens Energy Task Force said the delay concerns them because by 2015 the high electricity demand forecasts on which the whole CapX2020 project is based will be more than a decade out of date. It has filed an appeal asking the PUC to re-evaluate the need for the huge project.

Jennifer Bjorhus • 612-673-4683