Eastern U.S. Power Gains as Warm Weather Drives Use

Power prices from Boston to Baltimore advanced as warm weather swept through the region, triggering consumption to run air conditioners during a period when power plants are undergoing seasonal maintenance.

The temperature in Boston reached 81 degrees Fahrenheit (27 Celsius), 19 above the normal high, while Philadelphia reached 77 degrees, 10 more than average, according to AccuWeather Inc. of State College, Pennsylvania.

The six-state New England market was forecast to see 8,325 megawatts of planned and forced plant outages and reductions during the peak hour of the day, representing 25 percent of regional capacity, according to ISO New England Inc.

“A thin supply stack in New England due to seasonal outages, including Millstone nuclear unit, in combination with limits on Hydro Quebec imports is resulting in strong real time power prices,” said Natalia Mestvirishvili, a regional director for Boston-based Genscape Inc.

Spot wholesale electricity at the Boston and Northeast Massachusetts hub jumped $41.24, or 65 percent, to average $105.05 a megawatt-hour during the hour ended at 3 p.m. New York time from the same time yesterday, grid data compiled by Bloomberg showed.

Electricity output in the U.S. for the week ended Oct. 10 climbed 1,964 gigawatt-hours, or 2.8 percent, from a year earlier to average 72,215 gigawatt-hours, the most for the time of year since 2008, data from an Edison Electric Institute report today showed.

Nuclear Plant

Dominion Resources Inc. shut its Millstone 3 reactor on Oct. 13, according to the U.S. Nuclear Regulatory Commission. The plant, located about 3 miles (5 kilometers) southwest of New London, Connecticut, has a nameplate capacity of 1,253 megawatts, data from the Energy Information Administration showed.

Power prices also advanced in the Eastern hub of the PJM Interconnection LLC system, where the grid manager said yesterday that 35,148 megawatts, or 19 percent, of the installed capacity on the entire 13-state system will be out of service today.

“Constrained operations are expected” in the American Electric Power, Allegheny Power, Baltimore Gas and Electric, Delmarva Power and Light, Commonwealth Edison, PECO Energy, Dominion Virginia Power, and Public Service Electric and Gas zones today and tomorrow, PJM said on its website.

In PJM’s Eastern hub, which includes deliveries to New Jersey, eastern Pennsylvania, Maryland and Virginia, power jumped $3.87, or 8.2 percent, to average $51.14 a megawatt-hour at 3 p.m. after climbing to $98.62 an hour earlier.

In New York City, higher-than-expected demand saw power jump $29.77, or 65 percent, to average $75.29 a megawatt-hour, after rising to as high as $113.52.

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