The short answer is that the Electric Reliability Council of Texas (ERCOT), which operates the grid, did not properly forecast the demand for energy as a result of the storm. Some say that this was nearly impossible to predict, but there were warnings of the severity of the coming weather in the preceding week, and ERCOT’s projections were notably short. Brownouts last summer had already demonstrated the grid’s lack of excess capacity, says George O’Leary of Tudor, Pickering, Holt & Co (TPH), an energy investment bank.
Many Republican politicians were quick to blame renewable energy sources, such as wind power, for the blackouts, but that is not fair. Some wind turbines did indeed freeze, but natural gas, which accounts for around half of the state’s electricity generation, was the primary reason for the shortfall. Plants broke down, as did the gas supply chain and pipelines. The cold also caused a reactor at one of the state’s two nuclear plants to go offline. Transmission lines may have also iced up, says Wade Schauer of Wood Mackenzie, a research firm. In short, Texas experienced a perfect storm of equipment failure.
Some of the blame falls on the unique design of the electricity market in Texas. Of America’s 48 contiguous states, it is the only one with its own stand-alone electricity grid—the Texas Interconnection. This means that when power generators fail, the state cannot import electricity from outside its borders.