A major new transmission line across Minnesota won approval recently from state regulators, who required that it carry a substantial amount of wind-generated electricity to the Twin Cities from the Buffalo Ridge area of southwestern Minnesota.

The line, which will run from Brookings, S.D., to Hampton Corners in the metro area, is part of the CapX2020 project — a trio of 345 — kilovolt lines that constitute the first major expansion of the state’s high-voltage transmission system in a quarter-century. All three were granted certificates of need by the Minnesota Public Utilities Commission, which has spent nearly a year reviewing applications by 11 utilities including Xcel Energy, Minnesota Power, Great River Energy and Otter Tail Power Co.

Beth Soholt, director of Wind on the Wires, praised the PUC’s action as forward-thinking. She said it showed that the commission “understood the importance — at least for the Brookings line — of providing as much certainty as possible that renewables would use the new capacity on the transmission lines. It’s clear that significant transmission will be needed to reach Minnesota’s Renewable Energy Standard and the Commission took an important step in granting the utilities the ability to construct the pieces of the transmission system that will deliver renewables to Minnesotans.”

The other two lines — running from Fargo, N.D., to Alexandria, St. Cloud and Monticello, and from the Twin Cities to Rochester and La Crosse, Wis. — were approved without the requirement that they carry renewable energy. But all three must be built as “double-circuit ready,” meaning that they can be strung with a second set of high-voltage lines as demand grows — without requiring new towers or transmission corridors.

Clean energy advocates including the Minnesota Center for Environmental Advocacy, Fresh Energy, Izaak Walton League of America and Wind on the Wires took the position that building CapX2020 — with appropriate requirements for renewables — was critical to achieving Minnesota’s mandate that 25 percent of the state’s electricity be generated from renewable sources by 2025. That mandate aims to reduce the state’s contribution to global warming by reducing emissions from conventional coal-fired power plants.