NEW YORK (Reuters) - About half of the United States is at increased risk of power supply shortfalls in the next decade that could lead to outages and electricity conservation measures, the North American Electric Reliability Corporation said on Tuesday.

As U.S. power consumption rises from AI data centers and the electrification of buildings and transportation, efforts to add electricity generation have fallen short, creating an intensifying supply-demand imbalance, NERC said in its annual Long-Term Reliability Assessment.

"We are seeing demand growth like we haven't seen in decades," said John Moura, director of NERC's Reliability Assessment and Performance Analysis. "Our infrastructure is not being built fast enough to keep up with the rising demand."

The Midcontinent Independent System Operator, which operates the electrical grid in 15 states, was at high risk of shortfalls even at normal peak demand periods, NERC said.

Other grid operators at elevated risk, in which shortfalls may happen during extreme heat or cold, include PJM Interconnection, ISO New England, Texas and California operators. Parts of the northwest, northeast, southeast and midwest were better positioned to keep the lights on over the long term, NERC said.

Accelerated electricity demand contributed to the high-risk and elevated-risk areas, along with planned fossil-fired power plant retirements, which may exit service before new supply comes online.

NERC found that there are 78 gigawatts of confirmed generator retirements, and another 37 gigawatts with announced plans for retirement, through 2034.

One gigawatt of capacity can power as many as 1 million U.S. homes.

NERC is a North American nonprofit regulator that develops industry standards, assessments and forecasts focusing on the reliability and security of the electric grid.