As millions of Texans head into a third day of freezing temperatures and no electricity, they have, no-doubt, asked themselves a simple question: How?
The story of the blackouts is a story of supply and demand. The winter weather came on Sunday and everybody turned up their heaters. That takes electricity and, often, natural gas. The same weather that caused demand to skyrocket also ruined the supply.
To oversimplify only a bit: Things froze up and broke at Texas power plants.
“Out in West Texas we’re hearing reports that natural gas wells are actually freezing up and not being able to provide more gas to the system to keep the lines pressurized,” said Josh Rhodes, a research associate at UT Austin who studies the state's energy grid. “If the lines become depressurized, some natural gas power plants have to turn off.”
Coal, nuclear, wind and solar plants were also affected. The Electric Reliability Council of Texas, or ERCOT, says as of Tuesday a total of about 16,000 megawatts of renewable electricity and close to 30,000 megawatts of so-called thermal generation (coal, natural gas, nuclear) has been forced offline because of the cold and snow.
ERCOT’s job is to maintain the “integrity” of the grid. That means it needs to keep a balance on the grid between supply and demand. If that balance is not maintained, it could break the grid and lead to even longer term blackouts.
So, early Monday morning, ERCOT started cutting people’s power to balance out that supply and demand.
“The thing that really shifted matters was that ... we saw a large drop in the amount of supply available,” Sunday night, ERCOT CEO Bill Magness said.
How Do They Decide Where To Cut Power?
ERCOT farms the decisions about where to cut power to regional electricity suppliers. In Austin, that's Austin Energy; in other parts of the state, it could be a private company or a rural power cooperative.
ERCOT tells those groups to cut power use by a certain amount, and they chose where to cut. But they are not going to cut power in places where there are hospitals or other essential facilities or infrastructure. That’s why you still see some parts of town have power.
Why Has The Blackout Lasted So Long?
You might hear experts refer to what's happened as “rolling blackouts” or “rotating outages.” The idea is that everybody gets their power cut for a little while to share the burden, so the grid remains stable and no one is left without power for too long.
That's clearly not what’s happening in Austin or elsewhere, where people have been without power for two days now.
The reason the outages have lasted so long is that there is still very little power available to the grid, and the places getting power are often those “essential infrastructure” areas where power cannot be shut off.
“At the same time we’ve been adding supply to the grid from certain generators [coming back online], we’ve also been losing other generators," Dan Woodfin, senior director of system operations at ERCOT, said. “So we haven’t been able to add as much back during the course of the day as we’d like to have.”
When Will This End?
ERCOT says it's working with power companies to get their plants back online. But it’s hard to see power being fully restored until closer to the end of the week when the weather gets better.
Officials at ERCOT are hopeful demand will drop as things heat up. But the wintery weather forecast for Tuesday into Wednesday could also knock some more electric supply offline.
What Role Did Wind Power Play?
When there is a failure with the grid in Texas, opponents of renewable energy often try to blame wind power. In this instance, that criticism does not hold water.
Almost twice as much gas, coal and nuclear power dropped offline this week than wind power.
“That may be a way of answering the question” about wind’s role, Woodfin said. “There are significantly more megawatts [out of commission] in that thermal unit category than in the renewable category."
Rhodes adds that wind generation does not make up a sizable enough part of Texas' electricity mix in the winter to be blamed for the blackouts.
“We're not really counting on wind to be there to ride us through these winter events," he said. "But we do count on our thermal fleet to be highly available."
What Happens Next?
Texas Gov. Greg Abbott has already called for “reform” at ERCOT in response to the blackouts. What shape that takes depends on who does the reforming.
Some believe Texas should change the way it manages its de-regulated electricity market to pay generators public money to build more power plants to be kept in reserve.
The debate about renewable versus fossil fuel power could also be part of the discussion, due, in part, to the strength of the state's fossil fuel lobby.
Finally, ERCOT itself is already talking about rewriting the rules for how power plants weatherize.
This happened back in 2011, when a winter storm caused rolling blackouts. After that, ERCOT instated new policies to protect power generators from breaking down in wintery weather. Clearly, those policies did not stand the test of this week’s storms.
