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.