These numbers are not exact, but here’s the math:
- Texas has about 72,500 megawatts of power plant capacity.
- ERCOT told me about 12,000 megawatts of capacity was offline going into Wednesday for regularly scheduled maintenance. This is work that has to be pre-approved weeks or months in advance. It usually happens in the cold-weather months.
- That means about 60,500 megawatts of power were expected to be ready to go on Wednesday.
- The projected peak demand for Wednesday morning was 57,200 megawatts. That means there was a 3,300 megawatts cushion, or a reserve margin of about 5.7 percent.
- If you add the two demand-response programs ERCOT has, where large power users agree to shut-down in an emergency (which appears to be about 1,400 megawatts) you get about 4,700 megawatts or a reserve margin of about 8.3 percent.
Losing 7,000 megawatts of capacity — about 11.5 percent of what was expected to be online — is certainly unprecedented and unexpected. But was ERCOT operating under an unusually low reserve margin going into Wednesday?
According to a report from the North American Electric Reliability Council – a quasi-private entity that oversees all of the country’s power grid operators — ERCOT’s winter maintenance was not expected to top more than 4,568 megawatts at any one time this winter. If that was the case, ERCOT would have had about 10,700 megawatts of capacity in reserve,or a reserve margin of 18 percent.
So what was really going on Wednesday morning?
Is it a case of ERCOT mismanaging the grid? Was it an attempt to manipulate the market? Was it a conspiracy by either providers or transmitters to force through rate increases? Or was it simply an overreaction to a problem that should have been anticipated?
One thing is for certain - there was ample warning of the Arctic storm that hit Texas.
For ERCOT's side of the story, click here.
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