Massive failures of methane gas- and coal-fired power plants during “Winter Storm Elliott” left PJM — the country’s largest grid operator — more than 40 gigawatts short over the Christmas weekend officials said during a public meeting Wednesday. Methane gas plant failures accounted for 70% of PJM’s total outages, with some plants giving little or no warning of impending failure.

“Generation outages were unacceptably high and they occurred at the worst possible time,” Donnie Bielak, senior manager of dispatch at PJM, said during the presentation. “A large portion of our generation fleet failed to perform.” PJM said it may issue as much as $2 billion in fines for power plants that failed to deliver on their obligations to provide power during the storm.

“Yet again, system-wide fossil fuel plant failures came close to causing a major disaster,” Tom Rutigliano of NRDC said in a statement. “PJM must plan accordingly, and reform rules that subsidize fossil fuel power plants by pretending they’re more reliable than they really are.”

Electricity shortfalls and fossil fuel failures were not at all limited to PJM during the holiday storm. An estimated 1.6 million customers lost power nationwide and ISO-New England also issued $39 million in fines to power generators who failed to meet their obligations, but refused to disclose how many or which power generators underperformed. (PJM: Bloomberg $, Politico Pro $; ISO-NE: E&E $)