Dawn broke Sunday in Sandwich, Massachusetts with the air minus 18°C. Out on Freezer Road, the Canal Generating Station was burning fuel oil to make electricity.  It was a rare moment of combustion for the 50-year-old power plant. Oil typically accounts for a tiny fraction of the fuel mix behind New England’s electricity. But in the past week, oil-fired stations such as Canal were generating more than one-third, according to the grid operator. As energy demand soared during a record-breaking cold snap, oil made sense despite being a dirtier fuel.

After spot prices for natural gas soared in the region and a winter storm knocked out a large nuclear power plant, using oil suddenly became an economical way to keep the lights on.  The shifts reveal the fragility and complexity of US energy markets, even at a time of overall abundance. And they put a spotlight on efforts to maintain reliable energy supplies while addressing greenhouse gas emissions from fossil fuels.  As the cold weather took hold, ships imported liquefied natural gas to Atlantic coast ports. The ISO New England grid operator warned late Sunday that managing the region’s power system “continues to be challenging”, noting that some of the region’s oil-fired generators were “quickly depleting their fuel supply”.

New England generates almost half its electricity from gas-fired plants, on average. But these plants were forced to compete for fuel with homeowners trying to keep warm as low temperatures crashed through records in cities such as Hartford, Connecticut and Providence, Rhode Island. Enbridge, a pipeline company, says it had to limit volumes from its recently-expanded Algonquin Gas Transmission system for customers that did not have firm contracts.