Oil-fired power plants have dominated the New England electric grid as a brutal cold and a heavy winter storm gripped the region.
Climate-polluting oil generators are often used as backup in periods of intense demand. Over the weekend, however, oil plants contributed more than a third of the region's power, according to a review of data from grid operator ISO-New England.
Dan Dolan, president of the New England Power Generators Association, said that oil generators are often turned on to provide auxiliary power in cold periods when more natural gas is being used to heat homes, instead of produce electricity. Gas typically provides about half the region's electricity.
But this surge of oil generation is remarkable, Dolan said.
"What is unusual about the current situation is the duration and the scale of some of that fuel switching that has had to occur," Dolan said.
"This is an unusually high oil burn period," he added. "Driven both by subarctic temperatures across a wide geographic scale as well as increased natural gas prices that have increased much higher than is normal during these winter periods."
At around the same time oil plants were firing up, New England also lost a major source of renewable electricity as the brand-new transmission line through Maine linking the region to Quebec hydropower was taken offline.
HydroQuebec spokesperson Ben Dudley said low water levels and intense demand from its own customers led the company to keep power on its side of the border over the weekend.
"Temperatures in Quebec are the coldest on the planet right now because of a polar vortex," Dudley said. "So this is an exceptional moment, the ability of HydroQuebec to supply this contract throughout the year is not in question."
The New England Clean Energy Connect line was activated in mid-January after years of legal and political battles over its construction.
The hydropower company has 20-year contracts with electric distributors in Massachusetts to provide enough electricity down the line to power about one million homes.
Looking forward, ISO-New England projects continued high demand as frigid temperatures persist in the region throughout the week.
The grid operator over the weekend secured federal environmental waivers that allow power plants to ignore limits on air pollution and other environmental restrictions in order to achieve maximum output. More than 30 power plants are on a federal waiver list.
ISO-New England spokesperson Mary Cate Colapietro said the order from the U.S. Department of Energy will help keep the system stable during a period of intense demand.
"It's important to note that we are not in an emergency situation at the moment but these waivers would let generators operate above normal limits if they are needed to maintain reliability," Colapietro said.
The federal order expires at the end of the week.
