In February 2021, a winter storm that swept
through Texas caused one of the most severe power crises in American history. The cold
weather created shockingly high electricity demands as people tried to keep their homes
warm. But it also caused problems with the power supply because power plants themselves
and their supporting infrastructure weren’t adequately protected against freezing weather.
The result was that Texas couldn’t generate enough power to meet demand. Instead they
would have to disconnect customers to reduce demands down to manageable levels. But before grid
operators could shed enough load from the system, the frequency of the alternating
current dropped as the remaining generators were bogged down, falling
below 59.4 hertz for over 4 minutes. It might not seem like much, but that is a
critical threshold in grid operations. It’s 1% below nominal. Power plants have relays that keep
track of grid frequency and disconnect equipment if anything goes awry to prevent serious damage.
If the grid frequency drops below 59.4 hertz, the clock starts ticking. And if it doesn’t
return to the nominal frequency within 9 minutes, the relays trip! That means the Texas
grid came within a bathroom break from total collapse. If a few more large
power plants tripped offline or too few customers were shed from the system in
time, it’s likely that the frequency would have continued to drop until every single
generator on the grid was disconnected. Thankfully, that nightmare
scenario was avoided. Still, despite operators preventing a total collapse, the
2021 power crisis was one of the most expensive and deadly disasters in Texas history. If
those four minutes had gone differently, it’s almost impossible to imagine how serious
the consequences would be. Let’s put ourselves in the theoretical boots of someone waking
up after that frigid February night in Texas, assuming the grid did collapse, and find out.
I’m Grady, and this is Practical Engineering. In today’s episode, we’re talking about the
impacts of blackouts on other infrastructure. Every so often some loud noise
wakes you from your sleep: a truck backfiring on the street outside, a
baby crying, a cat knocking something off a shelf. But it’s a very different thing
altogether to be awoken by silence, your unconscious mind telling you that the
sounds you should be hearing are gone. It only takes a groggy minute to piece it together. The
refrigerator is silent, no air is flowing through the heating register, the ceiling fan above your
head is slowly coming to a stop. The power is out. You check your phone. It’s 4AM. Nothing you can really do but go back to sleep and
hope they get it fixed by daylight. Most of us have experienced a power outage at some
point, but they’re usually short (lasting on the order of minutes or hours) and they’re mostly
local (affecting a small area at a time). A wide area interconnection - that’s the technical
term for a power grid - is designed that way on purpose. It has redundancies, multiple paths that
power can take to get to the same destination, and power users and producers are spread
out, reducing the chance that they could be impacted all at once. But having everyone
interconnected is a vulnerability too, because if things go very wrong, everyone is affected.
We’re in the midst of a deep dive series on wide scale outages to the power grid, and a mismatch
between supply and demand (like what happened in Texas) is only one of the many reasons that
could cause a major blackout. Natural disasters, engineering errors, and deliberate attacks can
all completely collapse a grid, and - at least for the first few hours of an outage - you might
not even know that what you’re experiencing is any more serious than a wayward tree branch tripping
the fuse on the transformer outside your house. You wake up 3 hours later, cold, sunlight
peeking in through your bedroom window. The power is still off. You grab your cell
phone to try and figure out what’s going on. It has a full battery from charging
overnight, and you have a strong signal too. You try to call a friend, but the call
won’t go through. You try a few more times, but still, nothing more than a friendly
voice saying “All Circuits Are Busy.” There is a vast array of pathways that
information flows between people across the globe, and they all use grid power to
function. Fiber networks use switches and optical terminals distributed throughout the
service area. Cable TV and DSL networks have nodes that service around 500 to 1000 customers
each that require power. Cellular networks use base stations mounted on towers or rooftops.
Major telecommunications facilities are usually on prioritized grid circuits and may even have
redundant power feeds from multiple substations, but even during a blackout where the entire grid
is completely disabled, you might still have service. That’s because most telecommunication
facilities are equipped with backup batteries that can keep them running during a power
outage for 4 to 8 hours. Critical facilities like cellular base stations and data-centers
often have an on-site backup generator. These generators have enough fuel to extend the
resiliency beyond 24 to 48 hours. That said, major emergencies create huge demands on
telecommunication services as everyone is trying to find and share information at once,
so you might not be able to get through even if the services are still available. In the US, the
federal government works with telecommunications providers to create priority channels so that
911 calls, emergency management communications, and other matters related to public safety can
get through even when the networks are congested. Since you’re trying to make a personal call and
you aren’t enrolled in the Telecommunications Service Priority program, you’re not getting
through. Just then, an emergency alert appears on your screen. It says that there’s a power grid
failure and to prepare for an extended outage. The reality of the situation is just starting to set
in. Since most people have a cell phone, wireless emergency alerts have become an important addition
to the Emergency Alert System that connects various levels of government to tv, radio,
satellite, and telephone companies to disseminate public warnings and alerts. During a blackout,
sharing information isn’t just for likes on social media. It’s how we keep people safe, connect
them with resources, and maintain social order. Two-way communications like cell phones and the
internet might not last long during a grid outage, so one-way networks like radio and television
broadcasts are essential to keep people informed. These facilities are often equipped with more
backup fuel reserves and even emergency provisions for the staff so that they can continue to
operate during a blackout for weeks if necessary. Jump ahead a couple of days.Your circumstances
start to dictate your experiences heavily. Even an outage of this length can completely upend your
life if you, for example, depend on medication that must be refrigerated or electrically-powered
medical equipment (like a ventilator or dialysis machine). But for many, a blackout on the
order of a day or two is still kind of fun, a diversion from the humdrum of everyday life. Maybe
you’ve scrounged together a few meals from what’s remaining in your pantry, enjoyed some candlelit
conversations with neighbors, seen more stars in the night sky than you ever have in your life. But
after those first 48 hours, things are starting to get more serious. You ponder how long you can stay
in your home before needing to go out for supplies as you head into the kitchen to get a glass of
water. You open the tap, and nothing comes out. A public water supply is another utility highly
dependent on a functioning electrical grid. Pumping, cleaning, and disinfecting water
to provide a safe source to everyone within a city is a power-intensive ordeal. Water is
heavy, after all, and just moving it from one place to another takes a tremendous amount of
energy. Most cities use a combination of backup generators and elevated storage to account for
potential emergencies. Those elevated tanks, whether they are water towers or just ground-level
basins built on hillsides, act kind of like batteries to make sure the water distribution
system stays pressurized even if pumps lose power. But those elevated supplies don’t last forever.
Every state has its own rules about how much is required. In Texas, large cities must have at
least 200 gallons or 750 liters of water stored for every connection to the system, and half
of that needs to be in elevated or pressurized tanks so that it will still flow into the pipes
if the pumps aren’t working. Average water use varies quite a bit by location and season, but
that amount of storage is roughly enough to last a city two days under normal conditions. Combine
the backup storage with the backup generation system at a typical water utility, and maybe they
can stretch to 3 or 4. Without a huge mobilization of emergency resources, water can quickly become
the most critical resource in an urban area during a blackout. But don’t forget the related
utility we depend on as well: sewage collection. Lift stations that pump raw sewage and treatment
plants that clean it to a level where it’s safe to release back into the environment are energy
intensive processes as well. Most states require that lift stations and treatment plants have
backup power supplies or enough storage to avoid overflows during an outage, but usually those
requirements are for short-term disruptions. When power is lost for more than a day or two, these
facilities won’t be able to continue functioning without additional fuel and maintenance.
Even in the best case scenario, that means raw wastewater in the sewers will have to bypass
treatment plants and be discharged directly into waterways like rivers and oceans. In the worst
case, sewers and lift stations will overflow, exposing the people within cities to raw
sewage and creating a public health emergency. Flash forward to a week after the start of
the blackout, and any fun from the change of pace is long gone. You still keep your
cell phone battery charged from your car, but you rarely get a signal and phone calls
almost never connect. Plus, your car’s almost out of gasoline and the fuel at filling stations
has long been sent to backup generators at critical facilities. You are almost certainly
running low on food and water after a week, even if you’ve been able to share or barter with
neighbors or visit one of the rare stores that was willing to open their doors and accept cash.
By now, only the most prioritized facilities like hospitals and radio stations plus those
with solar or wind charging systems still have a functioning backup power supply. Everything
else is just dead. And now you truly get a sense of how complex and interconnected our systems of
infrastructure are, because there’s almost nothing that can frustrate the process of restoring power
than a lack of power itself. Here’s what I mean: Power plants are having trouble purchasing fuel
because, without electricity to power data centers and good telecommunications, banks and energy
markets are shut down. Natural gas compressors don’t have power, so they can’t send fuel to
the plants. Railway signals and dispatch centers are down, so the coal trains are stopped. Public
roadways are snarled because none of the traffic signals work, creating accidents and reducing
the capacity at intersections. Even if workers at critical jobs like power plants, pipelines, and
substations still have gas in their vehicles, they are having a really hard time actually getting
to work. And even if they can get there, they might not know what to do. Most of our complicated
infrastructure systems like oil and gas pipelines, public water systems, and the electrical grid
are operated using SCADA - networked computers, sensors, and electronic devices that perform a
lot of tasks automatically… if they have power. Even if you can get people to the valves,
switches, pump stations, and tanks to help with manual operations, they might not know
under which parameters to operate the system. The longer the outage lasts, the more reserves of
water, fuel, foods, medicine, and goods deplete, and the more systems break down. Each of these
complicated systems are often extremely difficult to bring back online alone, and nearly impossible
without the support of adjacent infrastructure. Electricity is not just a luxury. It is a
necessity of modern life. Even ignoring our own direct use of it, almost everything we
depend on in our daily lives, and indeed the orderly conduct of a civil society, is undergirded
by a functioning electrical grid. Of course, life as we know it doesn’t break down as soon as the
lights go out. Having gone without power for three days myself during the Texas winter storm, I have
seen first hand how kind and generous neighbors can be in the face of a difficult situation.
But it was a difficult situation, and a lot of people didn’t come through on the other side of
those three days quite as unscathed as I did. Natural disasters and bad weather
regularly create localized outages, but thankfully true wide-scale blackouts have
been relatively few and far between. That doesn’t mean they aren’t possible, though,
so it’s wise to be prepared. In general, preparedness is one of the most important roles
of government, and at least in the US, there’s a lot we get right about being ready for the worst.
That said, it makes sense for people to have some personal preparations for long-duration power
outages too, and you can find recommendations for supplies to keep on hand at FEMA’s website.
At both an institutional and personal level, finding a balance between the chance of disaster
striking and the resources required to be prepared is a difficult challenge, and not everyone
agrees on where to draw the line. Of course, the other kind of preparedness is our ability
to restore service to a collapsed power grid and get everyone back online as quickly as possible.
That’s called a black start, and it sounds simple enough, but there are some enormous engineering
challenges associated with bringing a grid up from nothing. That’s the topic we’ll cover in
the next Practical Engineering video, so make sure you’re subscribed so you don’t miss it. Thank
you for watching, and let me know what you think.
