A major one is that there isn’t enough transmission capacity to carry power from far-flung wind and solar farms to population centers. Many regions are at risk of blackouts during heat waves or powerful storms, which are expected to worsen with climate change. Aging infrastructure needs to be replaced.

Why the U.S. Electric Grid Isn’t Ready for the Energy Transition

The current system makes it hard to build the long-distance power lines needed to transport wind and solar nationwide.

The Energy Department’s report, the National Transmission Needs Study, looks at which places would benefit from new or expanded power lines. For example, customers in parts of Wisconsin and Michigan pay high prices because local grids are too congested to bring in cheaper power from elsewhere. The Mid-Atlantic’s grid is vulnerable to electricity shortfalls during winter storms because it lacks sufficient capacity to import power from its neighbors.

But there are major barriers to grid expansion. While the study found that new transmission capacity between different regional grids would have large benefits, hardly any such projects have been built in recent decades, since they can require approval from more than one state or jurisdiction, leading to disagreements over who should pay.

Pushing Past the Limit

New calculations add weight to the conclusion that we are cutting emissions far too slowly to have much hope of keeping warming below 1.5 degrees Celsius.

The federal government has limited authority to direct grid planning, in contrast to the way it oversaw the Interstate Highway System. Some regions, like Texas and the Southeast, have resisted expanding transmission ties with their neighbors. And some utilities are wary of new long-distance lines that might undercut their local monopolies. 

The Biden administration wants to use the limited tools at its disposal. As part of the bipartisan infrastructure law in 2021, Congress approved more than $20 billion to upgrade America’s power grids. The Energy Department has started sending much of that money out the door in recent weeks.

 As part of Monday’s announcement, the agency will negotiate a commitment to buy capacity from three proposed transmission projects: a 748-megawatt power line carrying renewable energy from New Mexico to Arizona, a 1,200-megawatt line bringing Canadian hydropower to Vermont and New Hampshire and a 1,500-megawatt line linking Utah and Nevada.

By acting as an initial customer, the agency hopes to give developers confidence to move forward with these projects. The government would later sell its rights to private customers and replenish its funds, so that it could help other grid proposals.

“This is an extremely promising program,” said Rob Gramlich, president of the consulting group Grid Strategies. He noted that many transmission projects are plagued by a “chicken or egg” problem: Developers won’t build power lines to windy or sunny regions until there are customers, but renewable projects won’t get built until after the lines are in place.

Still, Mr. Gramlich said, the agency’s $2.5 billion program to alleviate this issue can only support “a very small set of lines.”

Separately, the Department of Energy this month announced $3.5 billion in grants for 58 different projects to harden power lines against extreme weather, integrate batteries and electric vehicles into local grids and expand capacity for wind and solar power. That included $464 million for an effort to connect two large regional grids in the Midwest and Great Plains.

Together, those projects could help increase U.S. renewable energy capacity by 10 percent, Ms. Granholm said.