This February of 2021, a major winter storm
made its way through the U.S. central plains, setting all-time records for low temperatures
across the country. One of the biggest impacts of the storm happened
here in Texas where people across the state suffered extended outages of electricity and
water. It was one of the worst winter weather events
in history, creating loss-of-life and economic impacts that will take years to unfold. When disaster strikes, the flurry of political
positioning and fingerpointing can make it difficult to understand what really happened. This is especially true for the complex systems
of infrastructure like the power grid where most people really need a little more context
and background than can be provided in a 500-word news story, but a little more boiled down
than the discussions between economists and electrical engineers on twitter. So - for the first time ever on this channel,
by the way - I’m talking about a current event. This is a developing story, and we’re still
learning the details and consequences of what happened during the storm. But, I’ve received a lot of requests for
a video like this, and I hope it can provide some clarity and technical knowledge to elevate
the dialogue surrounding this disaster. I’m Grady and this is Practical Engineering. Today’s episode is the story of the 2021
Texas Power Grid Emergency. Before diving into the chronology of events,
I want to provide just a quick overview of some important technical topics. I actually have a series of videos explaining
the power grid in greater detail linked below, so check that out if you want to learn more. A wide-area interconnection, which is the
technical term for a power grid, is the solution to the number one problem of the supply and
demand of electricity: volatility. There aren’t many feasible ways to store
large quantities of electricity, so for the most part, the supply and demand have to be
matched simultaneously. Electricity is produced, transmitted, and
consumed all in the exact same instant. Managing those ebbs and flows is a very difficult
thing to do unless large groups of power producers and users are connected together, smoothing
out the volatility of demands (making them more predictable) and the supply (making it
possible to have larger, more efficient generation facilities). Interconnection increases the efficiency and
reliability of electricity supply, and the majority of Texans are served by a single
interconnection that covers most of the state. I’ll be referring to it as the Texas Power
Grid. Just because there are so many power producers
and users interconnected doesn’t mean that there is no volatility in supply and demand. These are some example demand curves on the
Texas grid. You can see that demand is always changing
throughout the day. When power demand drops due to mild weather
or at night when people are asleep, we need generators to shut down. Otherwise, the frequency of the AC power will
speed up above 60 hertz. When demand spikes, we need generators spun
up to match it. Otherwise, the extra load will bog down the
physical generators, and frequency of the AC power will fall below 60 hertz. The consequences of the AC frequency deviating
by too much are massive because every generator in the entire system is magnetically coupled. If parts of the system lose synchronization,
both generators and equipment connected to the grid can tear themselves apart. Because of that, most parts of the grid (including
generation facilities) have breakers that trip to isolate equipment if the frequency
deviates too far. The breakers in your house monitor electrical
current. If you plug in too many things to one circuit,
the breaker will trip. These work the same way except they monitor
frequency. And unlike in your house where restoring power
is a quick fix, large power generating stations don’t turn on and off with a flip of the
switch. So, matching supply and demand to maintain
a stable frequency is the most critical part of managing the power grid. In Texas, the entity in charge of this task
is ERCOT, the Electric Reliability Council of Texas. This is a non-profit corporation with board
members representing basically every segment of the electricity market from generators
to utilities to consumers. ERCOT’s job is to oversee the entire system. They don’t own or operate any facilities
themselves, but they tell the operators of generation facilities when to start and stop
running depending on the electrical demand. ERCOT also manages scheduled outages. Owners have to have approval from ERCOT before
they take facilities offline for maintenance. Finally, ERCOT manages the wholesale market
of electricity by setting prices and handling the transactions between power sellers and
buyers. The week before Valentine’s day 2021 had
already been a wintry one in many parts of Texas, but as the weekend drew near, the forecasts
started to make clear that the next week would be extraordinarily cold. On February 8, a full week before things really
hit the fan, ERCOT had already started issuing public communications about very high expected
electrical demands across the state. They canceled or delayed approval for a large
number of scheduled outages to make sure as much electrical infrastructure as possible
would be in service in anticipation of the storm. They worked with the Texas Railroad Commission,
which confusingly is in charge of the oil and gas industry, to increase the priority
of delivering natural gas to power plants. They also worked with the U.S. Department
of Energy to get permission for some power plants to temporarily exceed their emission
limits from the EPA during peak needs for electricity. All this to say, the folks managing the power
grid were expecting exceptional strain on the system and had already started working
the week beforehand to prepare. When the storm did hit on Valentine’s Day,
it really was one for the history books. Three major facts to illustrate this point:
First, it was extremely cold. This figure from the National Weather Service
shows the departure from normal temperatures for three historical winter weather events
in the southern U.S. plains. The one on the right is the 2021 event. Essentially the entire southern U.S. had average
temperatures more than 25 degrees Fahrenheit or 15 degrees Celsius below normal. All-time low temperature records were set
in nearly every city across the region. It was the coldest many places had practically
ever been. The next point which you can also see in this
figure is that it was not just a local event. The storm had significant impacts across the
entire state of Texas and beyond. Finally, the duration of frigid temperatures
was just so long. This figure from the National Weather Service
shows that large portions of the state were below freezing for more than 7 continuous
days. That might not sound like a lot to those of
you in northern climes, maybe even a welcome respite. But, in most parts of Texas, that is unheard
of. The state started Sunday with about a quarter
of its total electrical capacity already out of service, mainly due to weather the week
before. These outages were about half wind power and
half natural gas generators. Even with that lack of capacity, as night
began to fall that Sunday, Texas hit its all-time winter peak electrical demand of nearly 70,000
MW, and it met that full demand. The previous peak was 66,000. Everyone in the state was running their heaters
to the max trying to stay warm. As the evening continued, though, it became
clear to ERCOT and utilities that the amount of electricity available on the grid may not
be able to continue to meet the demand. An advisory was issued that electrical reserves
were low at around 11:30 PM. Not long after that, generation facility after
facility started to trip offline reducing the capacity to meet the high demand. Texas has a diverse portfolio of power generators. The largest segment of that is natural gas
making up about half of the capacity. The second segment is wind turbines at about
30%. The rest of the generation fleet is made up
mostly of coal powered plants, nuclear plants, and solar farms. This graph shows the outages of each generation
type during the winter storm. You can see that wind and natural gas make
up the majority of the lost capacity but no type of power plant was spared during the
storm. The most important part of this figure is
the natural gas line. Plant after plant went offline to the tune
of 15,000 MW of capacity within the span of 8 hours. All the details are still coming out about
what really happened, but there was a lot we know that went wrong. Natural gas wells and pipelines are particularly
vulnerable to cold temperatures. Not only does a gas stream contain water vapor
that can freeze by itself, that water vapor can also combine with hydrocarbons to create
hydrates that solidify at temperatures well above freezing. Combine this with the fact that many roads
were completely impassable during the storm, it was nearly impossible for some gas suppliers
to keep things flowing. That despite the fact that the wholesale price
of natural gas during the storm skyrocketed to more than 100 times its normal price due
to the incredible demand, with power plants competing with residential homes that use
gas for heat. At that price, suppliers were doing essentially
everything in their power to deliver gas to customers, but it just wasn’t enough. Or, in some cases, it was enough, but the
generators couldn’t afford to operate their plants with such a high cost for fuel. But it wasn’t just gas power plants that
struggled, and it wasn’t just about fuel. Wind turbines were shut down due to icing. Solar panels were covered in snow. One of the few nuclear units in Texas tripped
offline because of cold weather issues with its water supply. Basically, the entire system was ill-prepared
for a storm of this magnitude. Texas does have a few connections to other
power grids to help alleviate supply problems during emergencies, but those grids were suffering
under similar conditions without much extra electricity to spare. This graph shows the total outages during
the event. With that huge spike of generators going offline
the morning after Valentine’s day, the state had nearly half of its total capacity gone
during one of the highest periods of electrical demand on record. Without any remaining reserve of resources,
ERCOT had only one option left to keep supply and demand in sync: shed load. This is the technical term for what is essentially
turning off parts of the power grid (in other words, disconnecting customers) to reduce
total demands on the system. Here’s a simplified version of how it works:
ERCOT tells the transmission operators they need to take X megawatts off the grid. Those megawatts are distributed roughly evenly
between the operators you may have heard of, like Oncor, Centerpoint, CPS Energy, Austin
Energy, etc. based on their share of the total load. Each operator has a plan in place for how
to shed load within their own system when required. It’s not something they decide on the fly. Certain circuits critical to public health
and safety like hospitals are prioritized. The other non-critical circuits are usually
shut off in a rolling manner at 15-30 minute intervals. That way the inconvenience of lost service
is spread out more evenly across the entire service area. Of course, in many places during the storm,
that is not what happened. And, this graph is the key to why. As more and more resources tripped offline
so quickly, the frequency of the Texas power grid began to drop. ERCOT continued ordering additional load to
be shed from the system trying to keep up with both the rising demand from the cold
weather and the quickly failing power plants. At about 1:50 AM, the frequency fell below
59.4 hertz. It doesn’t sound that significant, but this
is a critical threshold for grid stability. Power plant controls are set to automatically
disconnect if the frequency stays below 59.4 hertz for more than 9 minutes. In such a situation, as each generator trips,
the frequency would quickly plummet until just about every circuit breaker on the grid
had disconnected. Four minutes and 37 seconds is all that separated
Texas from a complete grid collapse. Without the urgent action to continue shedding
load from the system, many might still be without power in Texas a month later. That’s because recovering from a complete
collapse, called a “black start” of the power grid, is an immense technical challenge. So much equipment would need to be inspected,
repaired or replaced from the damage caused by the collapse. Only then could we start bringing generators
and customers online slowly but surely to maintain balance between supply and demand
throughout the process. If anything goes wrong during a black start
and frequecy deviates too far, breakers will trip to protect the equipment and you have
to start all over. I am not an economist, but the energy market
is an important part of this story, so I’ll do my best to summarize the key points here. Unlike other markets that pay generators to
secure capacity for the future, the wholesale electricity market in Texas is energy-only. That means if you put power on the grid, you
get paid for it. You get no extra points for having generation
capacity when it wasn’t needed. The only reason it’s feasible to invest
in future capacity is the scarcity pricing of wholesale electricity. When demand is high, the price goes way up. In theory, this incentivizes generators to
not only make short-term investments to ensure their facilities are up and running during
peak demands but also long-term investments in plants that can spin up during these times
when prices are sky high to capitalize on the energy scarcity. This type of price model also favors intermittent
sources of electricity like wind and solar which would struggle to compete in a market
that valued firm capacity. While it normally varies between $30 and $50
per megawatt-hour on an average day, the wholesale electricity price went up to the cap of $9,000
per megawatt-hour during the storm and stayed that high for days. The result was that providers spent more money
on wholesale electricity in a week than would normally be spent in 4 average years. That’s with the extreme load shedding that
occurred and doesn’t include the incredible prices that some utilities paid for natural
gas. Most energy users won’t see those massive
costs, at least not right away. That’s because nearly every retail provider
offers a fixed or at least tiered rate for electricity to their customers, bearing the
dips and swings of the wholesale price using a wide variety of financial tools and long-term
contracts to try and hedge against the extreme volatility. Prudent planning can only take you so far
in an event like this, though, and at least one utility has already filed for bankruptcy
protection after the extreme energy bill came due. Other retail energy providers used a different
strategy to manage the market unpredictability: pass the risk on to their customers by offering
direct access to wholesale energy rates for a monthly fee. The idea is that some users may prefer to
manage their own demand, cutting back on electricity usage when rates are high and shifting usage
to times when rates are low. Unfortunately, many of these customers were
misled about or misunderstood the incredible volatility of the wholesale energy market
to which they were being exposed, and there are many reports of residential energy bills
in the thousands of dollars. During the peak of the event, ERCOT ordered
20,000 MW of load to be shed from the system. That’s the equivalent of turning off half
of Texas on a normal day. And the load shed orders lasted for three
days straight from early morning on the 15th to the end of the 18th. What should have been rolling outages couldn’t
roll because many utilities just didn’t have any non-critical circuits on their system
left to turn off. The result was that millions of Texans were
plunged into darkness, in some cases for days, without heat or light during one of the coldest
winter storms on record. My house lost power in the middle of the second
night of outages, and it was already 42 degrees Fahrenheit (6 degrees celsius) that morning
before we relocated to a family member’s house. And, we were the lucky ones. Many were not so fortunate to have friends
or family with power nearby or even to have roads clear enough to safely make the trek. The selection of which circuits were left
on versus off seemed arbitrary or even capricious to many. Water utilities started losing service, both
because of frozen lines and lack of power available for pumping, reducing the availability
of yet another basic human necessity to huge swaths of the population. Even though we had avoided the catastrophe
of a total grid collapse, we did not avoid a crisis. Many lives were lost, and the economic impacts
of this emergency are untold. I have my own opinions about what could have
or should have been done better during the storm and by whom, but this is not the place. My goal with this video is to try and summarize
the facts of this tragic event in a way that is approachable by people who don’t have
a working knowledge of the intricacies of the power grid. Many are still recovering from the storm and
will be for years to come. Please feel free to share your thoughts and
opinions in the comments below. All I ask is that you please be kind and respectful
to one another. Thank you for watching, and let me know what
you think!
Interesting to see how many aspects played a part in all this. The worst thing was the lack of real rolling blackouts, at least where I live. My grandmother is on oxygen and the compressor is powered by electricity. She has a portable compressor that has a 6-hour battery life and we had to do 1 hour on/off through nights and charge with a car battery during the day. I think our longest stretch with no power was about 30 hours...so not great rolling blackouts.
I will never forgive Ercot for what me and my family had to go through. Hope the whole company crumbles. Had to sleep in 35° house for 4 days straight. Bursted pipes and a flooded house when power was finally restored.
Good video, although it is missing the critical point of some combination of PUC and ERCOT keeping the price at max(arbitrarily, not letting the market set its own price) for an extended period which resulted in a lot of the surplus electricity costs.
Greed, Corruption, Price Fixing, Idiots
The people with the money were supposed to fix the problem 10 years ago
Well There's Your Problem also did a much longer, much less serious, and much more communist video about this.
Some of their unironic "car bad, train good" attitude is eye-rolling, but in this case, it's hard not to ask why the fuck electricity isn't treated as a public utility.