During the bitter cold weather around Christmas, the Calpine-owned Bethlehem Energy Center was permitted to increase its production for the power grid. (Courtesy of Calpine)

For those depending on electricity for heat, this past Christmas could’ve been a very cold one. Thanks to a power plant in Bethlehem, many were able to stay warm, and keep the holiday light displays on. Generator Gas Natural

Calpine, which owns the Bethlehem Energy Center off of Applebutter Road, was given special permission from the U.S. Department of Energy to ramp up production as the energy grid was beginning to strain with high demand that caused some power plants to fail.

PJM Interconnection, which monitors the reliability of individual utility systems such as PPL, Met-Ed and PECO, made the request. PJM, which is based in Montgomery County and manages the bulk electric grid in the Lehigh Valley, serves as sort of an air traffic controller for the power grid in a region spanning 13 states plus the District of Columbia.

“At the request of PJM to ensure grid reliability, our Bethlehem and York Energy Centers operated for a handful of hours on Christmas Eve” with higher generating limits, Calpine spokesperson Brett Kerr said. “We thank our plant operations staff for their hard work to help meet increased electricity demand brought on by the bitter cold weather.”

The emergency order was effective Dec. 24 through noon Dec. 26. It authorized all electric generating units in the PJM region to operate up to their maximum generation output levels under limited, prescribed circumstances, even if doing so exceeded their air quality or other permit limitations.

PJM spokesperson Jeffrey Shields said consumers were asked to conserve electricity that weekend for the first time since a cold snap and a snowstorm in January 2014.

“The greatest factor really was the cold, not so much the Christmas lights per se. It was the way the cold came on so quickly,” Shields said. “And we also had generators that were having difficulty performing, because of the cold itself or because they couldn’t get fuel supply, that kind of thing. So we had more generators out than we expected and the generators that were left were asked to run at full capacity.”

On Dec. 23, the temperature in the Lehigh Valley almost hit 60 in the morning, but dropped into single digits in the evening. The next day, the high was 13 degrees before the temperature gradually increased over the next week.

The Bethlehem Energy Center was opened in 2003 and is a combined-cycle power plant fueled primarily by natural gas. Houston-based Calpine acquired the facility in 2010 as part of its purchase of the Conectiv Energy assets.

On its website, Calpine said the plant consists of two power blocks, each consisting of three combustion turbine-generator sets, three heat recovery steam generators and a steam turbine generator.

PJM’s service area has more than 85,000 miles of transmission lines and at full capacity, the plants in the region can generate 185,442 megawatts.

Shields said that the network normally doesn’t reach capacity, but on the evening of the 23rd, the load was up to 135,000 megawatts. An extra 45,000 megawatts was needed because of power plant outages.

While the call went out for conservation, Shields said, the chance of having to institute rolling blackouts was remote. The last time that happened was in January 1994, when a deep freeze increased usage in the Mid Atlantic states.

“We were several steps away from having rolling outages,” he said. “We would try not to impact one area too much. We have a big footprint and that’s something we haven’t done since 1994.”

Gas Generator Set Morning Call reporter Evan Jones can be reached at ejones@mcall.com.