Spot wholesale electricity prices from Maine to Virginia declined as cloud coverage and periods of heavy rain helped reduce demand.
Northeast prices reversed gains as demand slipped below day-earlier levels. New York prices had surged earlier after the state grid operator issued a thunderstorm alert from 8:45 a.m. until 12:55 p.m. that reduced the city’s power imports while exports to New England increased following the shutdown of the Pilgrim reactor in Massachusetts.
The regions saw scattered rain today, with temperatures averaging 2 to 4 degrees Fahrenheit (1.1 to 2.2 degrees Celsius) above normal in the Northeast and 3 to 5 degrees higher in the mid-Atlantic states, according to WSI Corp. in Andover, Massachusetts.
Spot on-peak electricity for New York City dropped $7.60, or 13 percent, to $49.39 a megawatt-hour as of 4 p.m. from yesterday’s full-day average, grid data compiled by Bloomberg showed. Prices briefly surged to $293.28 at 9 a.m. On-peak hours are from 7 a.m. until 11 p.m.
Boston on-peak average prices fell $6.07, or 13 percent, to $40.76 a megawatt-hour. The premium for New York power versus Boston narrowed to $7.19 from $10.16 yesterday.
The amount of power flowing onto the New York Independent System Operator Inc. network from Quebec climbed back to more than 1,400 megawatts after plunging to 679 megawatts at 8:35 a.m., the grid operator’s website showed. Exports to ISO New England Inc. totaled 496 megawatts at 4:14 p.m. after jumping to 964 megawatts five hours earlier.
Entergy Corp. took the Pilgrim reactor off line at 7:55 a.m. today “due to an electrical fault associated with the plant’s feedwater pumps” that supply water to the reactor, Carol Wightman, a spokeswoman for the company in New Orleans, said in an e-mailed statement. “Operators will restart the plant after a review of the cause of the electrical fault and any necessary repairs are complete.”
The unit was shut based on plant procedures and back-up pumps were automatically activated to maintain reactor water levels, she said.
Pilgrim, about 4 miles (6 kilometers) east of Plymouth, was operating at 99 percent of capacity early today, Nuclear Regulatory Commission data show. Pilgrim’s summer capacity is 685 megawatts, according to data from the Energy Information Administration.
“The combination of a sharp real-time drop in output from Pilgrim and a thunderstorm alert in New York City during the same hour” had driven up prices earlier in the day, said Matt Oatway, a Boston-based analyst with Genscape Inc., which tracks real-time power data.
Power for the 13-state PJM Interconnection LLC network, serving more than 60 million people from New Jersey to North Carolina and Illinois, dropped as demand slumped and moved below forecasts. The on-peak average at the Western hub, which includes deliveries to Washington, declined $15.81, or 30 percent, to $37.66 a megawatt-hour as of 4 p.m. from yesterday’s average.
Spot prices in Texas, the Midwest and California also declined.