The Winter Texas Blackout of 2021
Texas was four minutes and 37 seconds away from a complete blackout- one that would have taken almost a month to recover from. The gravity of the situation is severe; 70 people have lost their lives, people were without power for days in below freezing temperatures, and experts say the cost will likely be more expensive than Hurricane Katrina. Yet, I feel like I never got a real resolution on exactly what the main drivers were for this disaster. After doing some research, we decided to create a Flow to help explain it for folks confused like myself.
In order to dive deeper into this story there are two components you need to understand:
- The generators at the power plants use Alternating Current (AC), which is the same type of electricity coming into our homes, and there is a specific frequency (60 Hertz) that all the current needs to stay synced up on. If it’s even a little bit off, it can cause damage to the generators and many of the appliances in our homes. For that reason, the power plants have a threshold set so if the frequency drops below that threshold for more than nine minutes, the circuit breakers trip- which results in a complete grid blackout.
- Texas is its own grid that doesn’t cross interstate boundaries, and therefore doesn’t need to adhere to their regulations. They still need to follow EPA and some federal regulations.
Let’s jump right into the night of February 10th, where temperature is clearly a big piece of the puzzle. Noted by the pink line, it’s typically around 54 degrees this time of year in Texas- but on the 11th, temperature started to dip below freezing.
Shifting the perspective to electrical demand, and keep in mind: people are freezing. So they’re cranking up their furnaces to generate heat, and in turn, using more electricity. The demand is at 40 gigawatts here on the beginning of the 10th, and by the 15th, it’s up to 72 gigawatts. Just as a reference point, the previous maximum demand was 59 gigawatts during the 2011 winter outage.
Now if we examine the electrical supply: 108 gigawatts seems to be plenty to cover our demand, right? We’ve broken up power generation into components of gas, wind, coal, solar, and nuclear with percentages showing the differently weighted contributions to total supply (in white). On the 10th we see the first sign of something going wrong- wind power drops down to 61% of its total capacity. Therefore, overall capacity is impacted, falling to 94 gigawatts.
Moving things forward to the 15th, temperature is starting to affect all of these energy sources and capacity falls to 85 gigawatts.
Another thing about Texas having their own grid is their unique energy economy. There are a variety of different power companies in competition, which is more similar to a free market than the rest of the states. Normally, more competition drives the price down, but let’s see how that plays out when Texas can’t borrow any power from neighboring states. The price on the 10th is around $30 and then on the 13th, that price increases ten times over. Even though everyone still has power, the price of electricity is $300.
I want to show you what happened on the 15th just to give you a sense of the magnitude of what is going on here. If you look up past all of the charts, you’ll see just how astronomical prices were for power- reaching $7,000.
It’s the early morning of the 15th that things started to really go wrong. Supply officially drops below the demand, power plants are able to produce 67 gigawatts worth of power, meanwhile, 72 gigawatts are being requested. Shown in the curves of the chart, a majority of that power loss is driven by outages from natural gas plants. However, I do want to point out that while natural gas was the major contributor to overall capacity loss, there were still some losses from nuclear, solar, coal, and as we mentioned earlier, wind. It’s all these things working together that contribute to the capacity shortage.
Moving our focus to the frequency chart on the right, we’re going to take a closer look into what was happening at the power plants the early morning of February 15th. At 1:20 AM official order was made to turn off the first gigawatt worth of customers. When customers are turned off, it sheds load to decrease the demand on the system- which in turn helps the frequency increase back to normal levels. Unfortunately, this was not the case here due to the demand still outweighing the supply of electricity, putting a big strain on generators. Frequency continued to plummet rapidly.
At 1:51 am, just after frequency dropped past that important threshold, another order was made to turn off an additional three gigawatts worth of customers. If you can, try to imagine being in that room as you are nine minutes away from the whole grid going offline. These are very nerve-racking minutes- even at 1:55 am, with only 5 minutes left until the circuit breakers flip, the frequency is still below the threshold. Just then, 3.5 more gigawatts were turned off.
As a reference point, in 2011 there was a winter outage that only consisted of four gigawatts of shed load for the entire event. So, these aren’t small little areas without electricity- this is manually turning off electricity to millions of homes.
Eventually, the generators increased their frequency back to a stable enough level that the grid didn’t completely collapse. Phew.
Not such an easy sigh of relief. What now? We know this can and will happen again. What can be done moving forward? What steps can we take right now to ensure we don’t get this close to a blackout ever again?
