Read that again: a 6-GW shortfall covered by 43 GW of batteries.
Bennett’s response to this rather obvious mismatch is to reframe the question entirely. Instead of asking whether batteries can cover peak demand windows — which is what they’re designed to do — he converts the entire battery fleet into a single energy metric: 77 GWh, which he says is “equivalent to running a single 1 GW thermal power plant for the duration of this three-day storm.” It’s a striking comparison. It’s also irrelevant to how batteries actually operate in ERCOT.
Nobody designs, operates, or dispatches battery storage as a 72-hour baseload resource. Batteries are designed to shave peaks, provide rapid frequency response, and bridge the morning and evening demand ramps when solar output is low. A 43-GW battery fleet can inject enormous amounts of power during exactly the narrow peak windows that Bennett’s own Figure 2 identifies as the problem periods. During Winter Storm Heather, ERCOT’s post-storm analysis confirmed that batteries were “partially supplementing the lack of solar generation available” during the coldest pre-sunrise hours — the exact scenario Bennett says they can’t handle.
The thermal backbone he takes for granted
Perhaps the most revealing aspect of Bennett’s analysis is what he doesn’t discuss: the massive existing fleet of gas, coal, and nuclear generation that forms ERCOT’s backbone. He projects 103,802 MW of firm winter output in 2030. That fleet — overwhelmingly fossil and nuclear — carries the grid through the vast majority of every storm hour in his model. The assumed thermal outage rate is only 12% — a figure drawn from ERCOT’s reliability assessments — meaning 88% of the thermal fleet performs through the modeled storm.
Bennett constructs a scenario in which batteries fail by defining success as continuous 72-hour discharge, while simultaneously taking for granted the thermal fleet of 80-plus GW that keeps the lights on during the bulk of his modeled event. The batteries aren’t replacing that fleet. They’re supplementing it during the peak demand windows that the thermal fleet alone can’t quite cover — which is precisely the role that ERCOT’s system planning envisions for them.
None of these experts are claiming the grid faces zero risk. ERCOT’s probabilistic risk assessment, as reported in NERC’s winter reliability assessment, puts the chance of controlled load shed this winter at about 1.8% — low, but not zero. The question is whether Bennett’s framework for evaluating that risk is sound, and on that point, the data he himself relies on says no.
The agenda behind the analysis
Bennett’s piece concludes that ERCOT needs “market design changes that redirect revenue away from wind and solar and toward resources that can work in all types of weather conditions.” That’s a policy preference dressed up as an engineering conclusion. His own data doesn’t support it.
What his data actually shows is that ERCOT has a manageable peak-demand gap that battery storage is well positioned to address, supplemented by a massive thermal fleet that provides the overwhelming majority of firm capacity during winter events. The December 2025 launch of ERCOT’s Real-Time Co-optimization Plus Batteries (RTC+B) market is specifically designed to optimize exactly this kind of coordination — dispatching storage where and when it creates the most grid value.
The real question isn’t whether batteries can run for 72 hours straight. No one is asking them to. The question is whether the combination of 100-plus GW of firm thermal capacity, a rapidly growing battery fleet, improving demand-response capabilities, and better weatherization standards can keep the lights on during winter storms. The last five years of actual performance — including three consecutive record-breaking winter peaks — provide a clear answer.
Bennett’s analysis works only if you accept his premise that battery storage should be evaluated as a baseload replacement rather than what it actually is: a fast-dispatching, peak-shaving complement to the thermal fleet, which helps dramatically in firming up renewables like wind and solar. Reject that premise, and his crisis narrative dissolves into the numbers he himself provides.
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Great Job Tam Hunt & the Team @ Canary Media for sharing this story.
