New England’s electric power supplies are projected to be adequate to handle demand this summer, but several unexpected events could result in localized problems that could lead to tight power supply situations, ISO New England, operator of the region’s electric power grid, said last Monday in its annual summer forecast.

To hedge against these unexpected events, ISO New England said that it is implementing practical strategies to reduce electrical demand this summer, including a conservation program that provides financial incentives for large commercial users to reduce their power consumption during periods of high demand.

“Since the deregulated wholesale power marketplace opened in 1999, New England has added more than 4,000 MW of new generating capacity, bringing the total available to more than 28,000 MW. This provides a solid foundation for meeting the region’s energy needs,” said Stephen G. Whitley, ISO New England’s chief operating officer. “However, we still face several challenges: We need regular imports of power from Canada to ensure we have adequate supply, and we need to address transmission congestion that could cause capacity deficiencies in southwest Connecticut and Boston.”

Challenges this summer could include:

Whitley said that long-term contracts for power imported from Quebec expired last year and have been replaced by a number of smaller, shorter-term contracts. Approximately 1,700 MW can be imported from Quebec to New England. While ISO New England expects that this power will be available, that is contingent upon wholesale power marketers executing contracts.

Constraints on the transmission system represent another major challenge. Most of the region’s new power plants are located outside areas of high demand, such as southwest Connecticut and greater Boston, and the transmission systems serving these areas are often inadequate.

Southwest Connecticut has one of the nation’s most severe reliability problems. The situation is so acute that the loss of a major transmission facility or power plant in southwest Connecticut could lead to the disruption of electricity supplies. Similar, but less severe, constraints could occasionally affect the Boston area.

The failure of transmission lines near Stratford, CT, on a moderately hot day last summer nearly resulted in blackouts that were averted only through an emergency dispatch of power from Long Island. Conversely, several hundred megawatts of generation were “locked in” in Maine during a heat wave last summer and unavailable for delivery to the rest of New England.

ISO New England last week warned that while Connecticut’s overall capacity situation would ordinarily be adequate to meet summer peak demand, the inadequate transmission system serving southwest Connecticut could create critical power supply reliability problems for the area’s 51 cities and towns.

In a conference call last Monday, Whitley noted that the ISO has been working with participants and states in the region on the siting process for new energy facilities. “The most critical project right now is in southwest Connecticut, the establishment of a 345 kV loop from northern Connecticut — two directions — into southwest Connecticut on existing right of way,” Whitley said.

“We’d love to have that project online right now, but we’re probably going to go through at least three more summers before it gets online because of the siting process and all the factors that you have to go through to get the facility sited and built,” the ISO executive went on to say. “We’re now serving that region of our system, which is the second biggest load pocket [of] the New England area, at 115 kV, which isn’t real efficient to be hauling that much power on,” Whitley said.

“Electricity supplies have outpaced demand here in New England, but it’s also a matter of location, location, location,” said Whitley in a prepared statement. “Until more improvements are made to the region’s transmission system, ISO New England will have to carefully manage power system operations during peak demand periods this summer and for the next few years.”

Other factors that could exacerbate this summer’s power situation include seasonal power plant maintenance overruns and forced outages at power plants and transmission substations. In addition, if drought conditions persist, water supplies to power plants could limit their output. Any one of these reasons, coupled with periods of very hot and humid weather, could require consumers to conserve electricity for short periods of time this summer. Historically, public appeals to conserve electricity have proved beneficial in helping balance supply and demand on the region’s bulk power system.

To further reduce power use during peak demand periods, ISO New England has expanded the load response program, which provides medium-to-large commercial users with financial incentives to curtail their consumption of electricity during peak demand periods. In addition to the standard incentives, large users in transmission-congested areas of Boston, southwest Connecticut and Vermont will receive bonus incentives to participate. In addition, to supplement the load response program in southwest Connecticut, 80 MW of demand reductions and temporary generation has been contracted to help alleviate the demand in that transmission-congested area.

Based on historical weather and electricity use data, summer peak demand is expected to reach 24,200 MW on at least one day this summer under assumed normal weather conditions. An extended heat wave could drive peak electrical demand to 25,500 MW. The current record is 24,967 MW, set on August 9, 2001.

New England’s summer electricity use typically ranges between 19,000 MW and 23,000 MW. In addition, ISO New England maintains a reserve of at least 1,700 MW to cover unexpected power plant or transmission line outages.

For the sixth straight year, ISO New England will be using its public appeal program, which issues conservation requests to reduce demand on the power grid. Modeled on the National Weather Service’s storm advisory system, the emergency warning system has two levels of public appeal: Power Watch and Power Warning. Last year, five Power Watches and two Power Warnings were implemented.

A Power Watch is invoked to request that customers voluntarily reduce electricity use, in ways consistent with health and safety, when the region’s electricity supplies are expected to be tight. A Power Warning is a more urgent appeal, issued when there is a concern that utilities may have to disconnect customers to reduce local demand on the power grid so that the integrity of the entire power grid is maintained.

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