According to a new report from the North American Electric Reliability Corporation (NERC), problems with the operation of gas-fired plants contributed greatly to power outages associated with last winter’s Polar Vortex. With even more natural gas slated to be used by U.S. power producers due to new EPA carbon dioxide regulations, the grid problems associated with extreme weather events might become more commonplace.
The Polar Vortex on January 6th saw the nation’s average daily temperature plummet to less than 18 degrees, with the following day producing record low temperatures at forty-nine locations across North America. According to NERC’s report, gas-fired power generators in the Midwest and Southeast saw an abnormally high rate of outages during the weather event. A number of power producers struggled to obtain adequate natural gas supplies. Others had trouble bringing units back online after operating plants at maximum output for extended periods of time.
“System operators had many challenging decisions to make as a result of lost capacity from both weather conditions exceeding the design basis of generating units, and from the lack of availability of natural gas,” the report states. “They successfully maintained reliability through extensive training and preparation.”
Training and preparation were certainly key to keeping the lights on, and utility workers nationwide are to be commended for their efforts, but another factor played a critical role during the event: the availability of coal-fired generation. Power systems across the Southeast and Midwest relied heavily on electricity generated by coal during the Polar Vortex, in part because coal-fired power plants were more likely to be running. In fact, while natural gas plants represented 55% of the outages during the weather event, coal and nuclear power represented 26% and 3% of the outages, respectively. In some systems, far more than half of all electrons generated during the bitter cold came from coal.
During the Polar Vortex, the grid lost 19,500 megawatts of generation capacity due to cold weather conditions, with more than 17,700 of those megawatts lost due to frozen equipment. NERC’s report documents equipment failures from a variety of causes, including iced gear boxes and frozen cooling water.
While NERC’s report does make a number of recommendations, such reviewing natural gas supply and transportation issues, considering winter preparation site reviews, and the revising temperature design basis for some plants, those measures are unlikely to mitigate the long-term consequences of shifting significant amounts of coal-fired power to natural gas. By entering into a future with fewer energy options, U.S. power producers will likely be less able to cope with major weather events or to maintain the sort of price stability to which customers have grown accustomed.
Warnings about sustained electricity price increases caused, in part, by more reliance on natural gas are already coming true. Grid operators, too, are raising warning flags about reliability issues caused by EPA rule-making. The next Polar Vortex-like event could bring such warnings into even greater focus. Let’s hope it doesn’t happen this winter, and let’s also hope U.S. policy makers have the good sense to take precautions before American power customers are left in the dark.