Largest US electric grid ramps up warnings amid hot temperatures

PJM, the largest U.S. grid operator, issued warnings of transmission line congestion and high electricity costs due to soaring temperatures and heavy energy loads.

Largest U.S. grid operator PJM ​on Wednesday issued a series of ​warnings as temperatures soared and transmission ‌line ​congestion increased the spot price of wholesale electricity.

PJM, which serves 67 million people in the Mid-Atlantic, South and Midwest, issued ‌warnings about low voltage and heavy energy loads on transmission lines. PJM data also showed transmission line congestion, including around northern Virginia, home to the largest collection of data centers ‌in the world. On Tuesday, PJM reported that the cost to secure enough electricity supplies ‌to cover the highest-demand days on the grid would be more than $16 billion, according to its latest annual capacity auction results. But without price caps, the cost would have been nearly $30 billion, PJM said.

The ⁠auction fell ​short of meeting ⁠PJM's reserve margin target by about 7 GW, weakening the grid's buffer against wild weather and other unforeseen ⁠events. “This year’s auction confirms an unacceptable trend: data center load growth is outpacing new electricity ​supply, degrading reliability, and keeping prices at the cap," said Claire Lang-Ree, a climate ⁠and energy advocate at National Resources Defense Council.

For Wednesday, PJM forecast electricity demand would reach 164.1 gigawatts about ⁠6 ​p.m. EDT as air conditioning use surged. Temperatures in PJM's region hovered around 90 degrees Fahrenheit (32 degrees Celsius) in Chicago, Philadelphia and Washington, D.C., for example. PJM ⁠set an-all time demand record of 168.2 GW on July 2. With heavy transmission line congestion, ⁠spot electricity prices surged ⁠to more than $300 per megawatt hour around noontime Wednesday. Earlier in the day, prices were around $30 per MWH, before residents and businesses ‌cranked up ‌their air conditioning use.

(Reporting By Tim McLaughlin, Editing ​by Nick Zieminski)