U.S. power giants NextEra Energy and Dominion Energy announced plans Monday to merge in the largest electricity deal — by far — since the mainstreaming of AI.Why it matters: The deal, if approved by regulators, would enable massive scale as the industry looks to expand generation and related infrastructure to meet rising demand.The all-stock merger "creates the world's largest regulated electric utility business by market capitalization and one of the world's largest energy infrastructure companies," the companies said in a joint announcement.The potential merger would expand NextEra's presence in the fast-growing PJM grid region of the Midwest and mid-Atlantic.Stunning stats: The combined company would serve about 10 million utility customer accounts across Florida, Virginia, North Carolina and South Carolina, and own 110 gigawatts of generation from a wide array of energy sources, the announcement states.It would be the world's largest player in renewables and battery storage, and would lead the U.S. in total power generation, the companies said.That means it would be the largest company in natural gas-fired power, and No. 2 in nuclear.Driving the news: NextEra — which has a market capitalization of $195 billion — owns the utility Florida Power & Light, and has renewables, battery, gas and other projects nationwide.Richmond-based utility Dominion serves what's currently the largest data center market — Virginia — and operates in several other states. Its current market cap is $54 billion.The big picture: The deal lands amid U.S. electricity demand that's rising thanks to AI, re-shoring of manufacturing and the growth of electric cars, among other reasons.Power prices are also rising in many areas, putting pressure on utilities and regulators to enact new consumer protections.The companies said customers would benefit from increased scale and efficiency. They're also proposing to provide $2.25 billion in electric bill credits spread over two years for Dominion customers in Virginia, North Carolina and South Carolina.Catch up quick: It would be the latest in a growing number of very large deals, notably Constellation's $29 billion acquisition of Calpine completed in January that greatly expanded its gas-fired fleet.Scale is becoming increasingly important, "not only to compete but also to access capital and execute transactions efficiently," Deloitte analysts wrote in a report on U.S. power deals.What they're saying: While both NextEra and Dominion have a range of assets and project pipelines, power entrepreneur Jigar Shah says the deal would be important for expanding NextEra's battery storage skillset."Dropping NextEra's storage expertise onto Virginia's data center load could be transformative," Shah, who led the Energy Department's loan program in the Biden-era, posted on X over the weekend.What we're watching: The deal could face legal and regulatory challenges getting approved by federal and state officials. The companies hope to close the transaction in 12 to 18 months.