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Minnesota's largest power companies and several other Upper Midwest utilities will study how their transmission network must be bolstered to meet increasingly aggressive renewable-energy goals.

The study is being launched at a time when space on the region's Midwest grid is already tight — even after a $2 billion transmission expansion that was completed just a couple of years ago.

That project, called CapX2020, was the work of Xcel Energy, Great River Energy, Minnesota Power, Otter Tail Power and seven other electricity providers in Minnesota, Wisconsin and the Dakotas. CapX2020 took more than seven years to complete and included 800 miles of new high-voltage lines.

Ten of the 11 utilities involved in the earlier project Monday announced the "CapX2050" study, which they are aiming to complete in January. The study "will look at maintaining a safe, reliable and cost-effective electric grid as the system adds more carbon-free energy," the utilities said in a statement.

CapX2020 was the largest transmission project in the Upper Midwest since the 1970s, and it was aimed partly at freeing up power-line capacity for burgeoning renewable-energy production.

The U.S. electrical grid was built to serve large centralized power plants, but wind and solar farms are more dispersed, often requiring transmission build outs. Xcel has stated plans to produce 100% carbon-free power by 2050, while other utilities also are planning for significantly more renewables.

Also, Minnesota's DFL Party has strongly backed raising Minnesota's overall carbon-free energy goal to 100% by 2050.

The CapX2020 project isn't enough to meet those long-term needs and the grid is essentially "at capacity," an energy analyst at the Union of Concerned Scientists told the Star Tribune last year.

Xcel's latest long-term resource plan, filed this spring, came to a similar conclusion.

"Many of these (CapX2020) lines planned in the early 2000s and completed over the recent past are already fully-or-nearly-fully subscribed," the plan said.

Mike Hughlett • 612-673-7003