The Explainer: The Big Freeze

We asked Daniel Cohan, who studies air, climate and energy at Rice, to explain what factors led to February’s cascading power failures in the wake of extreme winter cold.

By Daniel Cohan

After an Arctic blast blew through Texas and nearby states in February, millions were left without electricity, heat and water for days or even weeks. In Texas, more than 100 people died, and property damage was estimated in the billions.

Q. What were the chief reasons the Texas grid did not meet the demand for electricity during the winter storm?
A. Every single component of the power supply was producing less than expected at precisely the same time as demand was hitting an all-time peak for a Texas winter. More than all other factors combined was the fact that natural gas failed to generate as much electricity as expected exactly when we needed it most.

Q. In what ways did the natural gas system fail the electrical system, and vice versa?
A. We saw how mutually vulnerable gas and electricity systems are to each other. One piece of the problem was that the electrical compressors needed to compress gas and keep it moving through the pipeline system lost power and stopped working. That created cascading problems — gas power plants weren’t producing power, which meant that electrical compressors in the gas system went down, which meant there was even less gas supplied to the power plants.

Q.What actions could have prevented this series of events?
A. There’s a lot that could have been done to head off some of these problems. It appears the regulators and companies involved in both the gas and power systems hadn’t listed electrical compressors as priority critical infrastructures — what you need to make sure power doesn’t get shut off. There’s gas production that happens in North Dakota and Siberia. There are ways to weatherize and protect gas supply systems, but at a cost. With the cost of natural gas so cheap in recent years, many companies neglected investments that would have protected the system.

Q.What’s the difference between “winterization” and “weatherization?”
A. Winterization focuses on refighting the last battle. It’s preparing ourselves for a repeat of another Arctic blast, the type of storm you’d expect to get every 10 or 20 years in Texas. Our gas, power and water systems are vulnerable to a wide range of extreme events. The majority of those come in summertime — heat, drought, floods and hurricanes. Steps taken to prepare us for the next Arctic blast won’t necessarily prepare us for other extreme events. For many of those other events, the climate science is quite clear — climate change is likely to make them worse and more frequent. To focus all of our attention on winterization won’t prepare us adequately for the full spectrum of extreme events to come.

Q. What steps should water suppliers take to increase reliability?
A. Everything from our wastewater treatment to drinking water plants are heavily dependent on electricity to operate. The Arctic blast highlighted the need to have backups of power when the grid goes down. Houston learned that lesson, in part, after Harvey when the power went out, and that affected our water systems. So they bought backup generators — but [in February] the generators froze.

Q. What role can individual consumers play?
A. We all have a role to play. One of the biggest stressors that our water systems faced was that pipes were bursting all over town, causing the water pressure to go down and adding extra strain on our water system, just at the time when they were struggling to get that power to operate. If we were using more efficient heating systems in better-insulated homes, we would have been able to get through the storm with far fewer blackouts. Not enough attention is going to how we make our homes more resilient, efficient and weatherized.

Q. What role can policy play?
A. A lot of the homeowners unable to make these investments live in homes that are the least insulated and have the biggest energy bills when the storms come through. There could be a role [for policy] to make it easier for low-income families to better weatherize their pipes and homes; all of us would benefit. In Texas, we have 60% of homes heated by electricity. If we can make it easier for families to switch to the most efficient available electric heat pumps, that would take a lot of strain off the grid.

Q. During and after the storm, a lot of people seized on to this phrase, “fixing the grid.” Is that too narrow?
A. What we really had is an energy and water systems failure that goes beyond the grid. If we only focus on the grid alone, we’ll miss the fact that the gas supply systems failed to deliver gas to the power plants that needed to burn it. The biggest shortfalls appear to have come from natural gas power plants that were ready to operate but didn’t have any gas to burn.

There were certainly some frozen wind turbines. There was one nuclear reactor that went down, coal piles that froze and gas power plants that had equipment fail, so they couldn’t have worked even if they had gas supply. But a huge part of the outages came from the lack of gas making its way to the power plants. It might be counterintuitive, because for people who heat their homes with gas, they probably kept gas service through the entire blackout. Homes, hospitals, churches and schools get prioritized for the gas supply, and they only need it at low pressures. The gas power plants are further back in the line and need a high-pressure, consistent supply of gas that comes from hundreds of miles away.

If we only focus on the grid alone, we’ll miss the fact that the gas supply systems failed to deliver gas to the power plants that needed to burn it.

Each of our energy sources have their own unique vulnerabilities. I think people neglected that very unique vulnerability of gas, and it’s a vulnerability where you won’t just have one power plant go down at a time. You can have a systemic failure of gas systems, and that isn’t the case for coal or nuclear or some other sources. ERCOT was counting on a single fuel, natural gas, to supply two-thirds of peak demand. So we were overly reliant on a single fuel that we thought was more firm and reliable than any other, and we left ourselves vulnerable to systemic failure.

Q. What would a more diversified portfolio of power sources, including renewables linked with robust transmission lines, look like in Texas?
A. The more that we have a diversified mix of sources, the more likely we’ll be able to keep the lights on in an extreme event — and be able to reduce costs and emissions throughout the year. The real value of wind and solar comes less at the peak of the storm, when it may be dark and not very windy, than from providing us the cheapest and cleanest forms of electricity throughout the year. This would help reduce consumption of gas and coal throughout the year and conserve them for when we need them most.

Q. What’s keeping us from having more available wind and solar power; is it transmission?
A. Transmission has become the leading stumbling block to wind and solar. My research group has a paper under review, and we find that if you built a mere fraction of the wind and solar farms in the queue, meaning they’ve been proposed and want to connect to the ERCOT grid, that would be enough to replace the electricity from every coal power plant in Texas. So we could avoid the many hundreds of deaths that come from the air pollution of Texas coal plants every year. There are developers who have projects lined up that they want to build, but the majority of those plants probably won’t get built until there’s more transmission lines to bring their power to consumers.

Texas led the nation in transmission investment with a program called the CREZ (competitive renewable energy zones) about a decade ago. Through this program, $7 billion was invested in new transmission lines, targeted toward some of the windiest parts of the state. That led to a boom in construction of wind farms that have now brought wind to surpass coal, for the first time, as Texas’ second leading source of electricity. Now we’ve gotten to the point where those lines that we built are filling up, and there’s been a real slowdown in adding new lines.

Q. During the Arctic blast, the cost of electricity spiked to $9,000 per megawatt hour. What are the implications of such spikes?
A. The average price of power last year was $21 and went to $9,000 for several days on end. Companies weren’t prepared for that. But to me, whoever wins and loses on certain days, it’s a sign of a broken market, and I think we all lose.

We’ve really allowed our power markets to be turned into a casino. I liken it to selling electricity for lottery tickets. The majority of the time, those tickets are nearly worthless. Power prices are extremely low, and then every once in a while, they hit the jackpot with these astounding prices for power. We’re only meant to hit these types of prices a few hours a year. The entire market was unprepared for staying there for days.

Allowing prices to swing by factor of 500 with such unpredictability doesn’t put anybody in a position to make wise decisions. Texas probably won’t ever go back to a fully regulated market, but there are certainly ways even with the deregulated market to operate without such enormous jackpots.

Q. How did you and your family do during the freeze?
A. The east-west streets of our neighborhood, which we were on, kept power, and the north-south streets lost power. It was very much a fluke — who had power and didn’t. We had very low water pressure and had to boil water like everyone else. My wife works in a hospital where she was seeing more carbon monoxide poisoning in those days than in her entire career. They were working without running water or functioning toilets. We were affected in those ways, but a lot of people had it far worse. It was a terrible tragedy for the region.

— Interview by Lynn Gosnell

Daniel Cohan is an associate professor of civil and environmental engineering. This interview was recorded in early March and has been edited for clarity and length. An expanded version can be found at