The United States has enough resources to meet peak electric demand this summer in all areas except for the Electric Reliability Council of Texas, according to the North American Electric Reliability Corp. The anticipated reserve margin, or the projected amount of unused electric generating capacity at the time of peak load, ranges from less than 11% in the Electric Reliability Council of Texas to about 33% in the PJM Interconnection.
North American Electric Reliability Corp. is a nonprofit that oversees regional electric reliability organizations in the lower 48 states, Canada and parts of Mexico. It publishes a summer reliability report that shows peak electricity demand, supply changes, unique regional challenges or expected conditions that might impact the bulk power system.
The anticipated reserve margin is the difference between capacity and net internal demand and is shown as a percentage of net internal demand, according to the U.S. Energy Information Administration. Net internal demand is the difference between total internal demand and demand response systems that should be available during peak demand. A reserve margin of 15% means about 15% of a region’s electric generating capacity would be available to meet peak hourly load in the event of unexpected generation or transmission outages.
Planning reference margins are reserve margin targets based on load in an area, generation capacity and transmission characteristics. Sometimes, planning reference margin levels are required by states, provinces, system operators or regulatory agencies. Most reliability organizations have planning reference margins of about 15% and aim to have their anticipated reserve margins exceed the planning reference margins.
The only U.S. reliability organization in which the anticipated reserve margin is lower than the planning reference margin is the Electric Reliability Council of Texas. Its planning reference margin is 13.75%, while the anticipated reserve margin is 10.9%, which equates to a capacity shortfall of about 2,000 megawatts.
Anticipated reserve margins are highest in the PJM and Little Rock-based Southwest Power Pool in which the margins exceed 32%. Reserve margins that significantly exceed planning reference margins are helpful for reliability but indicate the region might have excess generating capacity, according to the EIA.