A power substation near a data center in Ashburn, Virginia. Photographer: Nathan Howard/BloombergBusinesses and households served by the largest US power grid will spend a record $16.1 billion to ensure electricity supplies amid a massive AI-driven demand surge.The payouts to generators topped last year’s record $14.7 billion, according to PJM Interconnection LLC, which operates the grid stretching from the Midwest to the mid-Atlantic. That puts the capacity price per megawatt each day at $329.1...