Winter storms put the US power grid to the test. It failed.

 Vox -    In many states, utilities and grid operators only narrowly averted greater disaster by asking customers to conserve their energy or prepare for rolling blackouts (when a utility voluntarily but temporarily shuts down electrical power to avoid the entire system shutting down). Some of the largest operators, including Tennessee Valley Authority and Duke Energy, used rolling blackouts throughout the weekend. Others, like National Grid, experienced some outages and asked some consumers to reduce gas usage. Texas also barely got through the emergency. ... Officials probably could have met the higher demand if not for another predictable event that overwhelmed the system. Because of the extreme conditions, coal and gas plants and pipelines froze up too, taking them out of commission to deliver energy in areas that run mostly on gas.