If We Built It Today (2019–…): Season 2, Episode 11 - Hoover Dam - full transcript
[narrator] The Hoover Dam, the
crown jewel of American infrastructure
and one of the most ambitious
projects of the early 20th century.
It was a bold idea, on a scale
that truly had not been seen
in dam construction before.
[narrator] At the time
of its completion,
it was the largest electric
power generating site
and concrete structure
in the world.
Today the Hoover Dam
plays an instrumental part
in providing water to over
25 million people.
But now, we're curious.
With modern technology,
could we update the original and
bring it in line with today's energy needs?
[Joe Zhou] Could we rebuild
the Hoover Dam?
I think we can. Should we build the
Hoover Dam? That's a different question.
A more complex question.
With the climate crisis, we're going to
need to be making some big changes
to the way we do things.
[narrator] Here's the plan. We're
enlisting the world's top engineers.
In situations where a hydro
dam already exists,
math is always gonna prove out very solidly
on the side of refurbishing and updating.
[narrator] Implementing
the heaviest machinery.
Hoover Dam can be
retrofitted. We have explored
the challenge and
we know we can do it.
[narrator] And all
the money it would take
to revive one of the greatest feats
of engineering ever constructed.
[narrator] Imagine the world's
greatest wonders, reimagined.
We're wondering,
wow long would it take?
How much would it cost?
How many workers would we need?
Could we even do it
if we built it today?
[intense music playing]
[narrator] The southwestern
United States is hot, dry, and barren.
But today, this desert
landscape is home to the most
rapidly growing population
in the country...
all thanks to this
marvel of engineering.
[John Ochsendorf] The Hoover
Dam represented progress.
Moving forward,
electrification, irrigation
in a remote region
of the United States.
The dam was very typical of
American expansion into the west.
It was a conquest, it was
a controlling of nature,
and turning nature's power
to beneficial ends.
[narrator] The Hoover
Dam was built along the
Colorado River between
Arizona and Nevada.
It's the lifeblood
for 18 million people,
providing not just a constant
flow of electricity,
but also regulating the precious
water supply from the Colorado River.
Today, it's a popular
tourist destination,
drawing nearly one million
visitors every year.
The Hoover Dam is
an incredibly striking dam.
It's iconic for good reason.
It's the tallest
concrete dam in the US.
[narrator] The Hoover Dam stands
as high as a 60-story skyscraper,
and its base is thicker than
the Washington Monument is tall.
The power plant's 17 generators
produce enough electricity
to power 1.3 million homes.
All that power comes
from the Colorado River,
entering the dam
through four intake towers.
Each one is about the same
height as the Empire State Building.
From there, the water spills
into two 30-foot diameter pipes,
racing toward the power plant
at 87 miles an hour.
This monsoon of water
generates electricity
at a three-million
horsepower clip.
Or, the same engine power
as 5,000 semi trucks.
Construction on
the Hoover Dam began in 1931,
just as the country was
entering a new and dark chapter.
The stock market crashed.
And the Great Depression started,
leaving Americans desperate for
work and desperate for some sign
that the promise of the
country was still there.
The Hoover Dam is born
of its time in the Depression
as a leap of faith into the future,
but also as a short-term investment,
and putting people back to work.
[narrator] As the Great
Depression unfolded,
hopeful laborers descended
on the barren desert job site.
For them, building the Hoover
Dam was more like a Gold Rush
than a construction project.
You can imagine for the
laborers who built the Hoover Dam
in a remote site,
to see this gargantuan...
project in concrete rising up
from the canyon floor.
It was unlike anything
they'd ever seen before.
[narrator] But soon
laborers realized
they'd signed up for a
near-impossible task,
taming the mighty
Colorado River.
The biggest problem in building
a dam is what to do with the water
during the construction
of the dam.
[Ochsendorf] The builders
developed an ingenious system
of tunneling through the bedrock
to carry the water around
the construction site.
This enabled the construction
to continue and not be flooded.
[narrator] When two
of the tunnels were complete,
the workers used
the excavated rock
to form two massive
cofferdams, or temporary dams
to divert the water
through the tunnels.
[Ochsendorf] These were
enormous undertakings
that enabled the
construction site to stay dry
and to proceed on schedule.
[narrator] But the greatest
achievement of all
was building the massive
concrete dam.
It required 6.6 million tons
of concrete,
enough to build a four-foot sidewalk
around the Earth at its equator.
[narrator] The triumphant story of the
Hoover Dam's construction is legendary.
But for civil engineers
Francisco Tesi and Kathleen King,
the Hoover Dam is a testament to
how engineering can reshape the world.
As a dam engineer, this is one
of the most iconic jobs that exists.
[Kathleen King] At the time of its
construction, in the early 1930s,
nothing like it had been achieved before,
and many thought it couldn't be done.
[narrator] So, what if we wanted to build
a 21st century version of the Hoover Dam?
We construct large dams
because they're useful
for things like flood
protection and storing water,
for drinking water,
and irrigation water,
and other municipal and
industrial uses of water.
But other water users like, you
know, the critters downstream
have come to rely
on the natural hydrology.
[narrator] Hydrology is the science of
water movement, distribution and management
with the natural environment.
And the Hoover Dam
had a massive impact
on the native hydrology
of the Colorado River,
by creating Lake Mead, the
largest reservoir in the United States.
The biggest challenges of
building a large dam nowadays is
the environmental aspect of it.
[Ochsendorf] A large dam project
on the scale of the Hoover Dam
causes environmental devastation,
flooding, changing ecosystems.
[narrator] Look no further
than China
to see the massive environmental
impact of the world's largest dam.
Completed in 2003, the Three Gorges
Dam is five times the size of Hoover.
But its construction displaced
1.3 million people...
and created a reservoir over
one-third the size of Rhode Island.
NASA estimates that the dam and reservoir
even slowed the rotation of the Earth,
making each day approximately
16 nanoseconds longer.
Many engineers, myself
included, are conflicted today
because the benefits of a
low-carbon electricity source
are really powerful.
[narrator] So now we have to figure
out, do the benefits outweigh the risks?
There's no denying
the power of hydropower.
It's the planet's number one
source of renewable energy,
accounting for over 50%
of all green power
and nearly 20% of total power
generation capacity worldwide.
Entrepreneur Kevin Mullen
sees a groundswell of opportunity
in the dams we've already built.
In situations where
a hydro dam already exists,
the environmental
impact is, you know...
It's a no-brainer that
it's been done already,
and therefore, to be able to use it
and increase utility of that location,
that's gonna make a lot of
sense in a lot of locations.
[narrator] The idea of a Hoover
Dam retrofit excites engineers,
who see the potential to integrate a
technology called pumped storage,
a mega-scale form of energy storage
capable of recycling hydropower.
In a pumped storage project,
you have two water bodies,
and those water bodies are
separated by some elevation difference.
So you got an upper reservoir
and a lower reservoir.
[narrator] The two bodies of water are
connected, and water can be pumped
from the lower body of water to
be stored in the reservoir above.
[King] For a traditional hydroelectric
project, water flows downstream,
and the pressure of that
flowing water moves a turbine,
which is connected
to a generator,
which generates electricity
to put on the grid.
Rather than letting that water
continue to flow downstream,
some of that water would be
diverted and pumped back upstream
so that it can be released later
when more generation is needed.
[narrator] But all that pumping
churns through a lot of electricity.
So, these days engineers are using
renewable energy to fuel the pumping,
creating what's known as
a clean battery.
A clean battery is something
that we can use to store generation
from renewable resources
like solar and wind
so that we can
use that generation
when the wind's not blowing
and the sun's not shining.
Pump storage is
a great way to do this.
You're charging the battery
when you pump water up,
and the battery is discharging
when you release water
from the upper water body
to the lower water body.
[narrator] Overhauling the Hoover Dam
into a clean battery is a radical proposal.
Is it even possible?
As an engineer, I can
tell you Hoover Dam can
be converted into a
pump storage facility.
There are other things that
impact whether we can do it,
but let's say
the big statement is... Yes.
[narrator] So, can we imagine
how we transform the Hoover Dam
into a pump storage facility?
Could it generate even more
electricity than before?
And how would it even work?
It's gonna be an epic feat
of engineering,
lining up all the parts,
pieces and people we'd need...
if we built it today.
[narrator] We're imagining
what it would take to build
one of the great engineering
feats of the 20th century.
The Hoover Dam.
The Hoover Dam was an
attempt to control the water,
particularly to control the mighty
Colorado River, which ripped through
the canyons of the west
at an incredible speed.
It was an amazing
technological accomplishment.
[narrator] The Hoover Dam
helped transform the American West,
providing unemployed laborers with
work during one of history's darkest times.
But these days, there's another
uncertain future on the horizon
when it comes to our
rapidly changing environment.
We're gonna need
to be making some big changes,
and part of that is thinking
a little bit outside the box.
[narrator] With that in mind, how
could our 21st century dam build
help curb carbon emissions?
Like the Hoover Dam, the scale of
the clean energy transition is immense.
And we need solutions that can deliver at
that scale to make sure we do this on time.
[narrator] Joe Zhou
is an entrepreneur
focused on carbon-free renewable
energy and energy storage.
Storage is gonna play a key role in
how we decarbonize the electricity sector.
[narrator] Because the sun doesn't
always shine and winds can be inconsistent,
clean batteries have
the ability to transform
unreliable energy sources
into reliable power,
keeping the electrical
grid stable.
As energy consumers,
we might take for granted
that at every moment,
grid operators have to balance
the supply of electricity
with the demand.
[narrator] For a grid
operator, pump storage is like
always having a spare battery
charger in your back pocket.
[King] A lot of generators like nuclear
power plants or coal power plants
don't like to be ramped
up and down.
They sort of just like to be set
at their output and stay that way.
[narrator] Tapping into a clean
battery is as easy as flipping a switch.
Other forms of grid-scale battery
storage are being experimented with,
but right now there's only 1.2
gigawatts of large-scale battery storage
connected to the electrical
grid in the US.
That's barely enough to power
400,000 homes a year.
Pumped storage tech is an
essential part of an ambitious goal
set by climate experts to double
energy storage capacity by 2050.
So, what if instead of imagining
how we'd build a new Hoover Dam,
we reimagine this one?
Here's the plan.
Let's imagine how
we could create the
biggest pumped storage
facility in the world.
That mission will guide
every decision we make
for our 725-foot tall makeover
of the Hoover Dam.
But can we really design the most
efficient energy storage solution on Earth?
We can improve the
efficiency and maybe
produce 20% to 40% more
power in the same spot.
[narrator] And we've got to figure
out how we could put it all together.
You would be undertaking
a significant effort
to construct a tunnel
to move water.
[narrator] We need
to figure out how many
people we'd need and
how long it might take.
Then it's time to add up
the final price tag.
But before we start
calculating costs
for this blockbuster remodel
of the Hoover Dam,
we need to put together
a design plan.
So let's start
from the beginning.
The Roman Empire, with their
ancient aqueduct system,
were the dam-building masters
of the ancient world,
using highly advanced hydro engineering
to fight flooding and store drinking water.
But dam building know-how
stalled out through the Middle Ages,
before going electric during the
Industrial Revolution in the 19th century.
It's the same ancient principle
as a water wheel, but electrified.
As water flows over the blades
of a turbine, it spins this turbine,
which in turn spins a generator,
which then produces
electricity for the power grid.
[narrator] But over five
millennia of dam design
culminated with the
construction of the Hoover Dam.
[Ochsendorf] The Hoover Dam
is an arch-gravity dam,
which means it can resist the
force of water through two ways.
The force of the water pressure
wants to move the dam out of the way.
It wants to push it downstream, the
water pressure wants to turn the dam over.
Engineers use two strategies to
push back against the water pressure.
An arch, which pushes against the cliff
on each side of the canyon, and gravity.
Sheer weight.
The heavy mass of the concrete
weighs the dam down,
and it's too heavy for the
water, which tries to push it over.
By using two strategies
to resist the water pressure,
the engineers of the Hoover Dam
dramatically overdesigned the dam.
[narrator] It's been estimated
that the Hoover Dam
could easily stand
for another 10,000 years.
But now we're trying
to imagine a bright new future
for this epic slab of concrete.
Can we draw up a design plan
to transform the Hoover Dam
into a gigantic clean battery
if we built it today?
[narrator] We're trying
to figure out
how to remodel the 90-year old
Hoover Dam,
creating the ultimate clean battery
that stores renewable energy as H2O.
To release as needed,
and generate hydro power.
That's the big idea behind a
system known as pumped storage.
Now, we need to draw up
a design for a mega makeover
of one of the world's
most famous mega projects.
Building a pumped
storage plant is more like
putting together a machine
than building a structure.
There's a whole bunch of different
parts that have gotta work together
to make it hum.
A pumped storage facility
has four main components.
It has an upper body of water,
which we call the upper reservoir.
That's where we store the
water, in this case, our energy.
It has a lower body of water. That's where
the water goes after we generate power.
It has the conduit that ties the
upper with the lower reservoir,
where there is a tunnel
or a pipe,
and then the pipe will go
into this powerhouse.
The powerhouse is where the magic
happens. That's where the turbines are.
[narrator] The Hoover Dam
already has an upper reservoir...
Lake Mead.
And it's got a powerhouse too.
There are 17 total turbines
down here.
Eight on the Nevada side
and nine on the Arizona side.
But what the Hoover Dam doesn't
have are bi-directional turbines
that can be used to
both generate electricity
and pump water back up to the
reservoir at the top of the dam.
[Tesi] When you look at a pump storage,
you're looking at two lakes, connected.
And, either we're generating
power in a given time,
or we're pumping the water
back up
from the lower body of water
to the upper body of water.
[narrator] But we might be able to get
away with skipping a powerhouse overhaul.
Another type of pump storage facility would
be what's called a pump back facility.
And rather than trying to
reconfigure the existing powerhouse
to have reversible equipment,
instead you can install a pump station
or construct a pump station
at another location
to use in conjunction
with the existing generators.
[narrator] And it's been
done before.
Welcome to Washington state,
home of the Grand Coulee Dam,
Hoover's lesser known
younger sibling,
built along the Columbia River,
a 1,250 mile-long
stretch of water
that runs from the rocky
mountains to the Pacific Ocean.
Grand Coulee is an example
of another mega dam
where pump back facility
was added.
[narrator] Construction
originally began in 1933
by blocking the Columbia River
and creating a massive reservoir.
The idea was to pump water
up into the Grand Coulee,
an ancient riverbed formed
by Ice Age era flooding.
The goal was
to reflood the basin
and irrigate an area twice
the size of greater Los Angeles.
But the farmers
would have to wait.
After America joined
World War II,
the Grand Coulee Dam's
secondary function,
electrical generation, was fast
tracked to power the war effort.
After the war, they began work
on the original plan.
Just as the pumping plant was
being installed in the early 1960s,
pump storage technology was
gaining major steam in the US.
Engineers decided to put in
reversible pumps.
And back then, they weren't
thinking about cutting back on carbon.
They were trying to make money.
Historically, pump storage was
used for what's called energy arbitrage.
So, when electricity
is very cheap,
you use that electricity to pump
water upstream in your upper reservoir,
and then when electricity
is very expensive,
you release that water
you generate
and then you're making money
by doing that.
[narrator] The reversible
pumps at Grand Coulee
are still used to play
the energy market.
And we could employ
a similar principle
with pumps powered
by renewable energy.
That's the sort of
configuration that could be
used at Hoover Dam if converting
Hoover Dam to a pump storage project.
You could make use of the
existing powerhouses at Hoover Dam
and then downstream, perhaps
along the Lower Colorado river,
build a pump station that would pump
the water back behind Hoover Dam.
[narrator] We have Lake Mead, which
is the lake formed by the Hoover Dam.
But we still need
a second body of water.
Will we be able to find
the perfect lower reservoir
or are we in over our heads
if we built it today?
[narrator] We're wondering how we could
re-engineer the world's most iconic dam
by turning it into a pump
storage hydro-powerhouse.
But in order for this to work,
we'll need to install a pump station
at another location.
[Tesi] The biggest challenge
we will have nowadays
is to find where
that other reservoir will be.
We have Lake Mead, which is
the lake formed by Hoover Dam.
Now we need
a second body of water.
[narrator] Lucky for us, the
perfect lower reservoir already exists
18 miles downstream.
Lake Mohave.
Okay, so here's our design plan.
We use the powerhouse
inside the Hoover Dam,
and Lake Mead
is our upper reservoir.
Our lower reservoir
could be Lake Mohave.
And we could build
a pumping plant and a pipeline
to connect the two bodies
of water.
But there's a problem.
Water is a very sensitive
resource in this area.
They're into a 20-year
drought now.
[narrator] Before 2001, the water line
was 12 storeys higher than it is today.
Retrofitting the Hoover Dam for
pump a storage facility is going to have
meaningful impact on how the
river downstream of the dam flows.
The environmental
and regulatory processes
associated with that type of change
can take several years to process.
[narrator] So how energy efficient
could a Hoover Dam remodel be?
[King] In some ways,
pump storage can seem
like that water could
perhaps just cycle forever.
However, it takes more electricity
to move a volume of water
to the upper reservoir
than you generate from
that same volume of water
when you really sit to
the lower reservoir.
I think when it comes to repurposing
the Hoover Dam for pump storage facility,
it's important for us to look at the
overall operating efficiency of the system.
The plans for this retrofit
require tens of miles of pipelines.
And on top of that, you also have
to spend energy to push the water
through those pipelines all the
way back to the top of the dam.
[narrator] So, before we
get started,
we better do some due
diligence into our alternatives.
And that brings us
to Medina County, Texas.
Well, you gotta have energy storage
because renewable energy is intermittent.
But the wind doesn't always
blow, sun doesn't always shine.
So, if you want to
have base load power
so the power's always there
when you need it,
you gotta have a way
to dispatch it.
[narrator]
Meet Howard Schmidt,
the energy storage innovator
behind geo-mechanical pump storage.
A different kind
of clean battery.
Geo-mechanical pump storage
is physically
basically identical
to regular pump storage.
[narrator] But the big difference
is groundbreaking. Literally.
Instead of pumping water
from a lower altitude
to store it at a higher altitude
when there is excess energy
on the electrical grid,
you charge the battery by pumping
water from a large artificial pond
down 1640 feet into the earth,
storing it between layers of
rock in a highly pressurized state.
Well, we're actually
deforming the rock
and then lifting it ever so
slightly, so that adds pressure.
When you need power, you let the
water come back up through the well.
It goes into a turbine
and then that water is then
discharged into the pond.
So it's a closed cycle system.
[narrator] The spinning turbine
sends electricity to the grid.
The powerhouse here
is still under construction.
But with the flick of a switch,
you can see the power of geo-mechanical
pump storage on full display.
It's just a pressure test
right now,
pumping water up from over
100 storeys below ground.
But if this water stream
was generating electricity,
it could produce as much
energy as a single wind turbine.
This is the revolutionary technology
behind this clean energy storage startup.
[Zhou] Traditional pump storage
requires the use of mountains,
which isn't
available everywhere.
I lead a team
of really talented people
trying to transform the way we store
energy and decarbonize the power grid.
[narrator] But how does
geo-mechanical pump storage rank
on the energy efficiency scale?
Geo-mechanical pump storage
actually operates at higher pressures
than traditional pump storage.
This allows you to use less
water and be more efficient.
[Schmidt] We've actually observed
90% hydraulic efficiency in this one.
We think we can improve that.
[narrator] So, instead of
using excess power
to pump water
back behind the Hoover Dam,
could we just build a geo-mechanical
pump storage facility right next door?
Turns out, this rugged terrain
would be a big issue.
Mountains are
not particularly good
'cause you're getting ununiformed
pressure gradients underground.
Best place for what we're doing
is sort of flat, sedimentary terrain,
which is probably two thirds
of North America.
Ideally, the best place for us
to start would be some place
where there's been
an oil and gas business,
so we kind of know what the
rocks are like underground.
[narrator] So geo-mechanical
pump storage won't work here.
But there's another new
energy storage solution
that could blow pumped
hydropower out of the water.
Lithium ion batteries.
That's right, the same tech that
keeps your smartphone charged
may someday power entire cities.
Large scale battery plants
are currently under construction
in New York, Florida
and California.
Lithium batteries have the
potential to lose less power,
and they're expected to get up
to the 95% retention of power.
[narrator] So could we just
build a battery farm
to store the excess power
from the Hoover Dam?
[Mullen] There is a cost to building
the battery that's large enough,
but then there's also
how long does that asset last.
If we're looking at things like
large-scale lithium ion batteries,
maybe that would be more like
a 10 year period,
at which time you will have to
deal with disposal and replacement
of those batteries.
[narrator] For longevity,
lithium ion can't hold a candle
to the Hoover Dam's
good old-fashioned hydro.
[King] Pump storage,
the infrastructure itself
could last for 100 years
or more.
It's something that's gonna
be around for generations.
[narrator] If our clean battery can
add another century to Hoover's life,
it's gonna be a good investment.
[Schmidt] That would be
actually a very useful project.
It represents a titanic amount of
energy, so it's hard to duplicate that.
So it's worth doing.
[narrator] The experts agree.
If renewables are ever going
to replace fossil fuels,
we need as much energy storage
as possible.
We have a lot of challenges in
terms of moving in to the future,
and part of that is thinking how
we can take what we have right now
and repurpose it in a more
sustainable way.
[Mullen] We can improve the efficiency
by using the most modern technology.
What we do is we bring in the most modern
turbines, generators, operating systems,
and then the software
and actuators for automation.
[narrator] So, we'll start
at 80% energy efficiency,
but aim for 90%
in the next decade.
Now we gotta figure out
how long it would take
and how many people we need
if we built it today.
[narrator] We're on the Nevada
and Arizona border,
imagining how we could transform
the Hoover Dam into a clean battery
to store renewable energy.
It would be a huge job,
but we think we could build
an energy storage project
with a 100-year life span.
But how long would it take
and how many people
will we need?
To answer those questions,
let's flash all the way back...
to the 1930s,
when the greatest engineering
project of the 20th century
rewrote the rules
of dam building forever.
[Ochsendorf] So
the idea of sending
thousands of people
to the middle of nowhere
to build a dam
essentially in the desert
was a radical idea.
The construction site would
have been a fascinating place.
Truly a melting pot of people
from every different walk of life.
[narrator] Twenty-one thousand
laborers worked on the Hoover Dam.
And not only did they build a
dam, they built an entire city too.
Boulder City came out of
providing housing for these workers
who had formally
been in a shanty town.
And this whole city
grew out of that.
[narrator] Today, the population
of Boulder City is about 15,000
or just over two thirds of the 21,000
people who built the Hoover Dam
in the middle
of the Great Depression.
It took that
massive workforce two years
just to drill the tunnels
and build the temporary dams
needed to prepare the job site.
But the greatest achievement was pouring
nearly 800 billion gallons of concrete
in less than two years.
[Baker] A dam that large,
that immense,
it was gonna take 125 years for
the concrete necessary to harden.
[Ochsendorf] Concrete sets,
it gets very warm.
And in the structure the size of
the Hoover Dam, it becomes so hot
that it can even start fires.
[Baker] The solution which
the dam's designer came up with
was 230 separate wooden
molds, boxes five feet deep
into which they poured
the concrete.
In the boxes were thermometers
and one-inch thick pipes.
Five hundred eighty two miles
of these little pipes
into which they pumped
cold water to cool the concrete
so it can harden gradually
and not pull it apart.
And it's gone on hardening.
Samples taken of the dam in 1995
showed that it was still getting harder,
probably will be decades,
maybe hundreds of years
before the dam
is at its hardest.
[narrator] The dam
was completed in 1936,
just five years
after construction began.
[Ochsendorf] The life of
a laborer was not easy.
And yet, they got
the project done
in a record time,
on a record scale
because of a drive to invent
something new.
[narrator] So how long would
it take us to get the job done?
[Zhou] To retrofit the Hoover
Dam for pump storage facility
with all the environmental and
regulatory processes required,
it could take up to a decade
before construction even begins.
Working out the downstream
impacts of water use
could be a permanent process
that takes several years.
[narrator] So, let's say
it'll take15 years,
a decade to work out
the environmental impact,
and another five years
to build it.
But how many people
will we need?
[Zhou] To retrofit the Hoover
Dam for a pump storage facility,
it would take
thousands of people,
and likely equal parts lawyers
and construction workers.
[narrator] Let's put
the number at 2,100,
10% of the workforce that built
the Hoover Dam 90 years ago.
But how are we gonna put it
all together?
It would be a big challenge
in constructing the overall pump
storage scheme using Hoover Dam.
The tunnels are key.
[narrator] At the time
of its construction,
the Hoover Dam was the most
expensive engineering project in history.
And that was nearly
a century ago.
It cost about $49 million to build
the Hoover Dam when it was built,
or about $833 million
in today's money.
It's inconceivable that it would
cost that little to build it today.
[narrator] So exactly how much cash is
this Hoover Dam retrofit gonna vacuum up
if we built it today?
[narrator] So you wanna turn
the Hoover Dam
into a clean battery.
What would it take?
We're imagining a pumped hydro
plant to take water from downstream
and divert it back into
the Lake Mead reservoir.
It's gonna take 2,100 workers
15 years to complete.
But it'll last
for at least a century.
So where do we start?
[Schmidt] What I would do is I
would leave the turbines in place
because it's a great facility.
It'd be tricky to retrofit the turbine
room at the bottom of the dam.
So I would go down
to Lake Mohave
and put in pumps there and then
pump the water back up to the lake.
It's about 30 miles away, so
you need a bit of a pipeline.
[narrator] Transporting water 30 miles
between Lake Mohave and Lake Mead
is the biggest and most
challenging part of the job.
You would be undertaking a
significant effort to construct a tunnel.
[narrator] Today we could
burrow through the desert ground
using a specialized process known
as Horizontal Directional Drilling.
Here's how it works.
First, a small pilot hole
is drilled below the ground,
marking the path of the pipeway.
Next, a larger drill head
called a reamer
is installed and pulled back
through the pilot hole,
carving the tunnel
to the appropriate length.
Then the tunnel is lined
with hollow tubes.
Once the pipeline's done,
we'll build a pumping station
to draw water from Lake Mohave and
send it back behind the Hoover Dam.
But we're not done yet.
Once we have our work come,
identifying the body of water
and connecting the two,
the third point will be how
much alternative energy
or all the renewable energy in the system
access that can be brought to Hoover Dam.
[narrator] If this is ever going to
become the world's greatest clean battery,
it needs to be rechargeable.
As we try to decarbonize
the economy,
a big part will be to try to
decarbonize the power system...
A lot of how that's done today requires
the use of solar energy and wind energy,
which isn't available
all the time.
So we need energy storage
to store the energy
when solar's shining
and wind is blowing
and then discharge the energy
back on to the grid
when it's not windy
or it's not sunny outside.
[narrator] What if we built a world
record-breaking solar farm right here?
The Hoover Dam sees about
4,000 hours of sunshine per year,
over 30% higher than
the international average.
We could also use solar panels
to help out with a major
evaporation problem at Lake Mead,
which is 12 storeys lower
than it was in the year 2000.
There are technologies
that exist today
that can mitigate some of
the evaporation issues.
There are solar panels
that float, that can be used,
and that reduces evaporation and
also produces additional electricity.
[narrator] If we could install 3,000
megawatts of generating capacity,
it'd be the most powerful
solar plant on earth,
surrounding the greatest dam
of all time.
Imagine that.
The Hoover Dam reinvented as a
clean battery to store renewable energy.
It would take 1,200 workers to do
the job and cut through all the red tape.
But we'd get it done
in 15 years.
So, how much would it cost?
This looks like a project
that's in the billions of dollars.
[narrator] But the three billion won't
include the cost of our solar farm,
which, on average, costs
about $1 million per megawatt.
So, building our 3,000 megawatt
plant would cost $3 billion.
We'll budget $3 billion to turn the
Hoover Dam into a clean battery
and another $3 billion
for our solar farm.
Final price tag?
$6 billion.
There's no question that's
a hefty chunk of change,
but in the end, the future of wind,
solar and even ocean electricity
will depend on
energy storage projects.
[Zhou] Transitioning to
a clean energy future
is one of the toughest
challenges that we have today.
Energy storage plays
a critical role to make sure
that our grid is not only
clean but also reliable.
[narrator] The world of electricity
is changing before our very eyes.
But the Hoover Dam proves
if you get the job done right,
you'll always pass
the test of time,
standing tall as a reminder of the
power we hold to reshape the future,
and the high watermark
we can achieve
if we built it today.
crown jewel of American infrastructure
and one of the most ambitious
projects of the early 20th century.
It was a bold idea, on a scale
that truly had not been seen
in dam construction before.
[narrator] At the time
of its completion,
it was the largest electric
power generating site
and concrete structure
in the world.
Today the Hoover Dam
plays an instrumental part
in providing water to over
25 million people.
But now, we're curious.
With modern technology,
could we update the original and
bring it in line with today's energy needs?
[Joe Zhou] Could we rebuild
the Hoover Dam?
I think we can. Should we build the
Hoover Dam? That's a different question.
A more complex question.
With the climate crisis, we're going to
need to be making some big changes
to the way we do things.
[narrator] Here's the plan. We're
enlisting the world's top engineers.
In situations where a hydro
dam already exists,
math is always gonna prove out very solidly
on the side of refurbishing and updating.
[narrator] Implementing
the heaviest machinery.
Hoover Dam can be
retrofitted. We have explored
the challenge and
we know we can do it.
[narrator] And all
the money it would take
to revive one of the greatest feats
of engineering ever constructed.
[narrator] Imagine the world's
greatest wonders, reimagined.
We're wondering,
wow long would it take?
How much would it cost?
How many workers would we need?
Could we even do it
if we built it today?
[intense music playing]
[narrator] The southwestern
United States is hot, dry, and barren.
But today, this desert
landscape is home to the most
rapidly growing population
in the country...
all thanks to this
marvel of engineering.
[John Ochsendorf] The Hoover
Dam represented progress.
Moving forward,
electrification, irrigation
in a remote region
of the United States.
The dam was very typical of
American expansion into the west.
It was a conquest, it was
a controlling of nature,
and turning nature's power
to beneficial ends.
[narrator] The Hoover
Dam was built along the
Colorado River between
Arizona and Nevada.
It's the lifeblood
for 18 million people,
providing not just a constant
flow of electricity,
but also regulating the precious
water supply from the Colorado River.
Today, it's a popular
tourist destination,
drawing nearly one million
visitors every year.
The Hoover Dam is
an incredibly striking dam.
It's iconic for good reason.
It's the tallest
concrete dam in the US.
[narrator] The Hoover Dam stands
as high as a 60-story skyscraper,
and its base is thicker than
the Washington Monument is tall.
The power plant's 17 generators
produce enough electricity
to power 1.3 million homes.
All that power comes
from the Colorado River,
entering the dam
through four intake towers.
Each one is about the same
height as the Empire State Building.
From there, the water spills
into two 30-foot diameter pipes,
racing toward the power plant
at 87 miles an hour.
This monsoon of water
generates electricity
at a three-million
horsepower clip.
Or, the same engine power
as 5,000 semi trucks.
Construction on
the Hoover Dam began in 1931,
just as the country was
entering a new and dark chapter.
The stock market crashed.
And the Great Depression started,
leaving Americans desperate for
work and desperate for some sign
that the promise of the
country was still there.
The Hoover Dam is born
of its time in the Depression
as a leap of faith into the future,
but also as a short-term investment,
and putting people back to work.
[narrator] As the Great
Depression unfolded,
hopeful laborers descended
on the barren desert job site.
For them, building the Hoover
Dam was more like a Gold Rush
than a construction project.
You can imagine for the
laborers who built the Hoover Dam
in a remote site,
to see this gargantuan...
project in concrete rising up
from the canyon floor.
It was unlike anything
they'd ever seen before.
[narrator] But soon
laborers realized
they'd signed up for a
near-impossible task,
taming the mighty
Colorado River.
The biggest problem in building
a dam is what to do with the water
during the construction
of the dam.
[Ochsendorf] The builders
developed an ingenious system
of tunneling through the bedrock
to carry the water around
the construction site.
This enabled the construction
to continue and not be flooded.
[narrator] When two
of the tunnels were complete,
the workers used
the excavated rock
to form two massive
cofferdams, or temporary dams
to divert the water
through the tunnels.
[Ochsendorf] These were
enormous undertakings
that enabled the
construction site to stay dry
and to proceed on schedule.
[narrator] But the greatest
achievement of all
was building the massive
concrete dam.
It required 6.6 million tons
of concrete,
enough to build a four-foot sidewalk
around the Earth at its equator.
[narrator] The triumphant story of the
Hoover Dam's construction is legendary.
But for civil engineers
Francisco Tesi and Kathleen King,
the Hoover Dam is a testament to
how engineering can reshape the world.
As a dam engineer, this is one
of the most iconic jobs that exists.
[Kathleen King] At the time of its
construction, in the early 1930s,
nothing like it had been achieved before,
and many thought it couldn't be done.
[narrator] So, what if we wanted to build
a 21st century version of the Hoover Dam?
We construct large dams
because they're useful
for things like flood
protection and storing water,
for drinking water,
and irrigation water,
and other municipal and
industrial uses of water.
But other water users like, you
know, the critters downstream
have come to rely
on the natural hydrology.
[narrator] Hydrology is the science of
water movement, distribution and management
with the natural environment.
And the Hoover Dam
had a massive impact
on the native hydrology
of the Colorado River,
by creating Lake Mead, the
largest reservoir in the United States.
The biggest challenges of
building a large dam nowadays is
the environmental aspect of it.
[Ochsendorf] A large dam project
on the scale of the Hoover Dam
causes environmental devastation,
flooding, changing ecosystems.
[narrator] Look no further
than China
to see the massive environmental
impact of the world's largest dam.
Completed in 2003, the Three Gorges
Dam is five times the size of Hoover.
But its construction displaced
1.3 million people...
and created a reservoir over
one-third the size of Rhode Island.
NASA estimates that the dam and reservoir
even slowed the rotation of the Earth,
making each day approximately
16 nanoseconds longer.
Many engineers, myself
included, are conflicted today
because the benefits of a
low-carbon electricity source
are really powerful.
[narrator] So now we have to figure
out, do the benefits outweigh the risks?
There's no denying
the power of hydropower.
It's the planet's number one
source of renewable energy,
accounting for over 50%
of all green power
and nearly 20% of total power
generation capacity worldwide.
Entrepreneur Kevin Mullen
sees a groundswell of opportunity
in the dams we've already built.
In situations where
a hydro dam already exists,
the environmental
impact is, you know...
It's a no-brainer that
it's been done already,
and therefore, to be able to use it
and increase utility of that location,
that's gonna make a lot of
sense in a lot of locations.
[narrator] The idea of a Hoover
Dam retrofit excites engineers,
who see the potential to integrate a
technology called pumped storage,
a mega-scale form of energy storage
capable of recycling hydropower.
In a pumped storage project,
you have two water bodies,
and those water bodies are
separated by some elevation difference.
So you got an upper reservoir
and a lower reservoir.
[narrator] The two bodies of water are
connected, and water can be pumped
from the lower body of water to
be stored in the reservoir above.
[King] For a traditional hydroelectric
project, water flows downstream,
and the pressure of that
flowing water moves a turbine,
which is connected
to a generator,
which generates electricity
to put on the grid.
Rather than letting that water
continue to flow downstream,
some of that water would be
diverted and pumped back upstream
so that it can be released later
when more generation is needed.
[narrator] But all that pumping
churns through a lot of electricity.
So, these days engineers are using
renewable energy to fuel the pumping,
creating what's known as
a clean battery.
A clean battery is something
that we can use to store generation
from renewable resources
like solar and wind
so that we can
use that generation
when the wind's not blowing
and the sun's not shining.
Pump storage is
a great way to do this.
You're charging the battery
when you pump water up,
and the battery is discharging
when you release water
from the upper water body
to the lower water body.
[narrator] Overhauling the Hoover Dam
into a clean battery is a radical proposal.
Is it even possible?
As an engineer, I can
tell you Hoover Dam can
be converted into a
pump storage facility.
There are other things that
impact whether we can do it,
but let's say
the big statement is... Yes.
[narrator] So, can we imagine
how we transform the Hoover Dam
into a pump storage facility?
Could it generate even more
electricity than before?
And how would it even work?
It's gonna be an epic feat
of engineering,
lining up all the parts,
pieces and people we'd need...
if we built it today.
[narrator] We're imagining
what it would take to build
one of the great engineering
feats of the 20th century.
The Hoover Dam.
The Hoover Dam was an
attempt to control the water,
particularly to control the mighty
Colorado River, which ripped through
the canyons of the west
at an incredible speed.
It was an amazing
technological accomplishment.
[narrator] The Hoover Dam
helped transform the American West,
providing unemployed laborers with
work during one of history's darkest times.
But these days, there's another
uncertain future on the horizon
when it comes to our
rapidly changing environment.
We're gonna need
to be making some big changes,
and part of that is thinking
a little bit outside the box.
[narrator] With that in mind, how
could our 21st century dam build
help curb carbon emissions?
Like the Hoover Dam, the scale of
the clean energy transition is immense.
And we need solutions that can deliver at
that scale to make sure we do this on time.
[narrator] Joe Zhou
is an entrepreneur
focused on carbon-free renewable
energy and energy storage.
Storage is gonna play a key role in
how we decarbonize the electricity sector.
[narrator] Because the sun doesn't
always shine and winds can be inconsistent,
clean batteries have
the ability to transform
unreliable energy sources
into reliable power,
keeping the electrical
grid stable.
As energy consumers,
we might take for granted
that at every moment,
grid operators have to balance
the supply of electricity
with the demand.
[narrator] For a grid
operator, pump storage is like
always having a spare battery
charger in your back pocket.
[King] A lot of generators like nuclear
power plants or coal power plants
don't like to be ramped
up and down.
They sort of just like to be set
at their output and stay that way.
[narrator] Tapping into a clean
battery is as easy as flipping a switch.
Other forms of grid-scale battery
storage are being experimented with,
but right now there's only 1.2
gigawatts of large-scale battery storage
connected to the electrical
grid in the US.
That's barely enough to power
400,000 homes a year.
Pumped storage tech is an
essential part of an ambitious goal
set by climate experts to double
energy storage capacity by 2050.
So, what if instead of imagining
how we'd build a new Hoover Dam,
we reimagine this one?
Here's the plan.
Let's imagine how
we could create the
biggest pumped storage
facility in the world.
That mission will guide
every decision we make
for our 725-foot tall makeover
of the Hoover Dam.
But can we really design the most
efficient energy storage solution on Earth?
We can improve the
efficiency and maybe
produce 20% to 40% more
power in the same spot.
[narrator] And we've got to figure
out how we could put it all together.
You would be undertaking
a significant effort
to construct a tunnel
to move water.
[narrator] We need
to figure out how many
people we'd need and
how long it might take.
Then it's time to add up
the final price tag.
But before we start
calculating costs
for this blockbuster remodel
of the Hoover Dam,
we need to put together
a design plan.
So let's start
from the beginning.
The Roman Empire, with their
ancient aqueduct system,
were the dam-building masters
of the ancient world,
using highly advanced hydro engineering
to fight flooding and store drinking water.
But dam building know-how
stalled out through the Middle Ages,
before going electric during the
Industrial Revolution in the 19th century.
It's the same ancient principle
as a water wheel, but electrified.
As water flows over the blades
of a turbine, it spins this turbine,
which in turn spins a generator,
which then produces
electricity for the power grid.
[narrator] But over five
millennia of dam design
culminated with the
construction of the Hoover Dam.
[Ochsendorf] The Hoover Dam
is an arch-gravity dam,
which means it can resist the
force of water through two ways.
The force of the water pressure
wants to move the dam out of the way.
It wants to push it downstream, the
water pressure wants to turn the dam over.
Engineers use two strategies to
push back against the water pressure.
An arch, which pushes against the cliff
on each side of the canyon, and gravity.
Sheer weight.
The heavy mass of the concrete
weighs the dam down,
and it's too heavy for the
water, which tries to push it over.
By using two strategies
to resist the water pressure,
the engineers of the Hoover Dam
dramatically overdesigned the dam.
[narrator] It's been estimated
that the Hoover Dam
could easily stand
for another 10,000 years.
But now we're trying
to imagine a bright new future
for this epic slab of concrete.
Can we draw up a design plan
to transform the Hoover Dam
into a gigantic clean battery
if we built it today?
[narrator] We're trying
to figure out
how to remodel the 90-year old
Hoover Dam,
creating the ultimate clean battery
that stores renewable energy as H2O.
To release as needed,
and generate hydro power.
That's the big idea behind a
system known as pumped storage.
Now, we need to draw up
a design for a mega makeover
of one of the world's
most famous mega projects.
Building a pumped
storage plant is more like
putting together a machine
than building a structure.
There's a whole bunch of different
parts that have gotta work together
to make it hum.
A pumped storage facility
has four main components.
It has an upper body of water,
which we call the upper reservoir.
That's where we store the
water, in this case, our energy.
It has a lower body of water. That's where
the water goes after we generate power.
It has the conduit that ties the
upper with the lower reservoir,
where there is a tunnel
or a pipe,
and then the pipe will go
into this powerhouse.
The powerhouse is where the magic
happens. That's where the turbines are.
[narrator] The Hoover Dam
already has an upper reservoir...
Lake Mead.
And it's got a powerhouse too.
There are 17 total turbines
down here.
Eight on the Nevada side
and nine on the Arizona side.
But what the Hoover Dam doesn't
have are bi-directional turbines
that can be used to
both generate electricity
and pump water back up to the
reservoir at the top of the dam.
[Tesi] When you look at a pump storage,
you're looking at two lakes, connected.
And, either we're generating
power in a given time,
or we're pumping the water
back up
from the lower body of water
to the upper body of water.
[narrator] But we might be able to get
away with skipping a powerhouse overhaul.
Another type of pump storage facility would
be what's called a pump back facility.
And rather than trying to
reconfigure the existing powerhouse
to have reversible equipment,
instead you can install a pump station
or construct a pump station
at another location
to use in conjunction
with the existing generators.
[narrator] And it's been
done before.
Welcome to Washington state,
home of the Grand Coulee Dam,
Hoover's lesser known
younger sibling,
built along the Columbia River,
a 1,250 mile-long
stretch of water
that runs from the rocky
mountains to the Pacific Ocean.
Grand Coulee is an example
of another mega dam
where pump back facility
was added.
[narrator] Construction
originally began in 1933
by blocking the Columbia River
and creating a massive reservoir.
The idea was to pump water
up into the Grand Coulee,
an ancient riverbed formed
by Ice Age era flooding.
The goal was
to reflood the basin
and irrigate an area twice
the size of greater Los Angeles.
But the farmers
would have to wait.
After America joined
World War II,
the Grand Coulee Dam's
secondary function,
electrical generation, was fast
tracked to power the war effort.
After the war, they began work
on the original plan.
Just as the pumping plant was
being installed in the early 1960s,
pump storage technology was
gaining major steam in the US.
Engineers decided to put in
reversible pumps.
And back then, they weren't
thinking about cutting back on carbon.
They were trying to make money.
Historically, pump storage was
used for what's called energy arbitrage.
So, when electricity
is very cheap,
you use that electricity to pump
water upstream in your upper reservoir,
and then when electricity
is very expensive,
you release that water
you generate
and then you're making money
by doing that.
[narrator] The reversible
pumps at Grand Coulee
are still used to play
the energy market.
And we could employ
a similar principle
with pumps powered
by renewable energy.
That's the sort of
configuration that could be
used at Hoover Dam if converting
Hoover Dam to a pump storage project.
You could make use of the
existing powerhouses at Hoover Dam
and then downstream, perhaps
along the Lower Colorado river,
build a pump station that would pump
the water back behind Hoover Dam.
[narrator] We have Lake Mead, which
is the lake formed by the Hoover Dam.
But we still need
a second body of water.
Will we be able to find
the perfect lower reservoir
or are we in over our heads
if we built it today?
[narrator] We're wondering how we could
re-engineer the world's most iconic dam
by turning it into a pump
storage hydro-powerhouse.
But in order for this to work,
we'll need to install a pump station
at another location.
[Tesi] The biggest challenge
we will have nowadays
is to find where
that other reservoir will be.
We have Lake Mead, which is
the lake formed by Hoover Dam.
Now we need
a second body of water.
[narrator] Lucky for us, the
perfect lower reservoir already exists
18 miles downstream.
Lake Mohave.
Okay, so here's our design plan.
We use the powerhouse
inside the Hoover Dam,
and Lake Mead
is our upper reservoir.
Our lower reservoir
could be Lake Mohave.
And we could build
a pumping plant and a pipeline
to connect the two bodies
of water.
But there's a problem.
Water is a very sensitive
resource in this area.
They're into a 20-year
drought now.
[narrator] Before 2001, the water line
was 12 storeys higher than it is today.
Retrofitting the Hoover Dam for
pump a storage facility is going to have
meaningful impact on how the
river downstream of the dam flows.
The environmental
and regulatory processes
associated with that type of change
can take several years to process.
[narrator] So how energy efficient
could a Hoover Dam remodel be?
[King] In some ways,
pump storage can seem
like that water could
perhaps just cycle forever.
However, it takes more electricity
to move a volume of water
to the upper reservoir
than you generate from
that same volume of water
when you really sit to
the lower reservoir.
I think when it comes to repurposing
the Hoover Dam for pump storage facility,
it's important for us to look at the
overall operating efficiency of the system.
The plans for this retrofit
require tens of miles of pipelines.
And on top of that, you also have
to spend energy to push the water
through those pipelines all the
way back to the top of the dam.
[narrator] So, before we
get started,
we better do some due
diligence into our alternatives.
And that brings us
to Medina County, Texas.
Well, you gotta have energy storage
because renewable energy is intermittent.
But the wind doesn't always
blow, sun doesn't always shine.
So, if you want to
have base load power
so the power's always there
when you need it,
you gotta have a way
to dispatch it.
[narrator]
Meet Howard Schmidt,
the energy storage innovator
behind geo-mechanical pump storage.
A different kind
of clean battery.
Geo-mechanical pump storage
is physically
basically identical
to regular pump storage.
[narrator] But the big difference
is groundbreaking. Literally.
Instead of pumping water
from a lower altitude
to store it at a higher altitude
when there is excess energy
on the electrical grid,
you charge the battery by pumping
water from a large artificial pond
down 1640 feet into the earth,
storing it between layers of
rock in a highly pressurized state.
Well, we're actually
deforming the rock
and then lifting it ever so
slightly, so that adds pressure.
When you need power, you let the
water come back up through the well.
It goes into a turbine
and then that water is then
discharged into the pond.
So it's a closed cycle system.
[narrator] The spinning turbine
sends electricity to the grid.
The powerhouse here
is still under construction.
But with the flick of a switch,
you can see the power of geo-mechanical
pump storage on full display.
It's just a pressure test
right now,
pumping water up from over
100 storeys below ground.
But if this water stream
was generating electricity,
it could produce as much
energy as a single wind turbine.
This is the revolutionary technology
behind this clean energy storage startup.
[Zhou] Traditional pump storage
requires the use of mountains,
which isn't
available everywhere.
I lead a team
of really talented people
trying to transform the way we store
energy and decarbonize the power grid.
[narrator] But how does
geo-mechanical pump storage rank
on the energy efficiency scale?
Geo-mechanical pump storage
actually operates at higher pressures
than traditional pump storage.
This allows you to use less
water and be more efficient.
[Schmidt] We've actually observed
90% hydraulic efficiency in this one.
We think we can improve that.
[narrator] So, instead of
using excess power
to pump water
back behind the Hoover Dam,
could we just build a geo-mechanical
pump storage facility right next door?
Turns out, this rugged terrain
would be a big issue.
Mountains are
not particularly good
'cause you're getting ununiformed
pressure gradients underground.
Best place for what we're doing
is sort of flat, sedimentary terrain,
which is probably two thirds
of North America.
Ideally, the best place for us
to start would be some place
where there's been
an oil and gas business,
so we kind of know what the
rocks are like underground.
[narrator] So geo-mechanical
pump storage won't work here.
But there's another new
energy storage solution
that could blow pumped
hydropower out of the water.
Lithium ion batteries.
That's right, the same tech that
keeps your smartphone charged
may someday power entire cities.
Large scale battery plants
are currently under construction
in New York, Florida
and California.
Lithium batteries have the
potential to lose less power,
and they're expected to get up
to the 95% retention of power.
[narrator] So could we just
build a battery farm
to store the excess power
from the Hoover Dam?
[Mullen] There is a cost to building
the battery that's large enough,
but then there's also
how long does that asset last.
If we're looking at things like
large-scale lithium ion batteries,
maybe that would be more like
a 10 year period,
at which time you will have to
deal with disposal and replacement
of those batteries.
[narrator] For longevity,
lithium ion can't hold a candle
to the Hoover Dam's
good old-fashioned hydro.
[King] Pump storage,
the infrastructure itself
could last for 100 years
or more.
It's something that's gonna
be around for generations.
[narrator] If our clean battery can
add another century to Hoover's life,
it's gonna be a good investment.
[Schmidt] That would be
actually a very useful project.
It represents a titanic amount of
energy, so it's hard to duplicate that.
So it's worth doing.
[narrator] The experts agree.
If renewables are ever going
to replace fossil fuels,
we need as much energy storage
as possible.
We have a lot of challenges in
terms of moving in to the future,
and part of that is thinking how
we can take what we have right now
and repurpose it in a more
sustainable way.
[Mullen] We can improve the efficiency
by using the most modern technology.
What we do is we bring in the most modern
turbines, generators, operating systems,
and then the software
and actuators for automation.
[narrator] So, we'll start
at 80% energy efficiency,
but aim for 90%
in the next decade.
Now we gotta figure out
how long it would take
and how many people we need
if we built it today.
[narrator] We're on the Nevada
and Arizona border,
imagining how we could transform
the Hoover Dam into a clean battery
to store renewable energy.
It would be a huge job,
but we think we could build
an energy storage project
with a 100-year life span.
But how long would it take
and how many people
will we need?
To answer those questions,
let's flash all the way back...
to the 1930s,
when the greatest engineering
project of the 20th century
rewrote the rules
of dam building forever.
[Ochsendorf] So
the idea of sending
thousands of people
to the middle of nowhere
to build a dam
essentially in the desert
was a radical idea.
The construction site would
have been a fascinating place.
Truly a melting pot of people
from every different walk of life.
[narrator] Twenty-one thousand
laborers worked on the Hoover Dam.
And not only did they build a
dam, they built an entire city too.
Boulder City came out of
providing housing for these workers
who had formally
been in a shanty town.
And this whole city
grew out of that.
[narrator] Today, the population
of Boulder City is about 15,000
or just over two thirds of the 21,000
people who built the Hoover Dam
in the middle
of the Great Depression.
It took that
massive workforce two years
just to drill the tunnels
and build the temporary dams
needed to prepare the job site.
But the greatest achievement was pouring
nearly 800 billion gallons of concrete
in less than two years.
[Baker] A dam that large,
that immense,
it was gonna take 125 years for
the concrete necessary to harden.
[Ochsendorf] Concrete sets,
it gets very warm.
And in the structure the size of
the Hoover Dam, it becomes so hot
that it can even start fires.
[Baker] The solution which
the dam's designer came up with
was 230 separate wooden
molds, boxes five feet deep
into which they poured
the concrete.
In the boxes were thermometers
and one-inch thick pipes.
Five hundred eighty two miles
of these little pipes
into which they pumped
cold water to cool the concrete
so it can harden gradually
and not pull it apart.
And it's gone on hardening.
Samples taken of the dam in 1995
showed that it was still getting harder,
probably will be decades,
maybe hundreds of years
before the dam
is at its hardest.
[narrator] The dam
was completed in 1936,
just five years
after construction began.
[Ochsendorf] The life of
a laborer was not easy.
And yet, they got
the project done
in a record time,
on a record scale
because of a drive to invent
something new.
[narrator] So how long would
it take us to get the job done?
[Zhou] To retrofit the Hoover
Dam for pump storage facility
with all the environmental and
regulatory processes required,
it could take up to a decade
before construction even begins.
Working out the downstream
impacts of water use
could be a permanent process
that takes several years.
[narrator] So, let's say
it'll take15 years,
a decade to work out
the environmental impact,
and another five years
to build it.
But how many people
will we need?
[Zhou] To retrofit the Hoover
Dam for a pump storage facility,
it would take
thousands of people,
and likely equal parts lawyers
and construction workers.
[narrator] Let's put
the number at 2,100,
10% of the workforce that built
the Hoover Dam 90 years ago.
But how are we gonna put it
all together?
It would be a big challenge
in constructing the overall pump
storage scheme using Hoover Dam.
The tunnels are key.
[narrator] At the time
of its construction,
the Hoover Dam was the most
expensive engineering project in history.
And that was nearly
a century ago.
It cost about $49 million to build
the Hoover Dam when it was built,
or about $833 million
in today's money.
It's inconceivable that it would
cost that little to build it today.
[narrator] So exactly how much cash is
this Hoover Dam retrofit gonna vacuum up
if we built it today?
[narrator] So you wanna turn
the Hoover Dam
into a clean battery.
What would it take?
We're imagining a pumped hydro
plant to take water from downstream
and divert it back into
the Lake Mead reservoir.
It's gonna take 2,100 workers
15 years to complete.
But it'll last
for at least a century.
So where do we start?
[Schmidt] What I would do is I
would leave the turbines in place
because it's a great facility.
It'd be tricky to retrofit the turbine
room at the bottom of the dam.
So I would go down
to Lake Mohave
and put in pumps there and then
pump the water back up to the lake.
It's about 30 miles away, so
you need a bit of a pipeline.
[narrator] Transporting water 30 miles
between Lake Mohave and Lake Mead
is the biggest and most
challenging part of the job.
You would be undertaking a
significant effort to construct a tunnel.
[narrator] Today we could
burrow through the desert ground
using a specialized process known
as Horizontal Directional Drilling.
Here's how it works.
First, a small pilot hole
is drilled below the ground,
marking the path of the pipeway.
Next, a larger drill head
called a reamer
is installed and pulled back
through the pilot hole,
carving the tunnel
to the appropriate length.
Then the tunnel is lined
with hollow tubes.
Once the pipeline's done,
we'll build a pumping station
to draw water from Lake Mohave and
send it back behind the Hoover Dam.
But we're not done yet.
Once we have our work come,
identifying the body of water
and connecting the two,
the third point will be how
much alternative energy
or all the renewable energy in the system
access that can be brought to Hoover Dam.
[narrator] If this is ever going to
become the world's greatest clean battery,
it needs to be rechargeable.
As we try to decarbonize
the economy,
a big part will be to try to
decarbonize the power system...
A lot of how that's done today requires
the use of solar energy and wind energy,
which isn't available
all the time.
So we need energy storage
to store the energy
when solar's shining
and wind is blowing
and then discharge the energy
back on to the grid
when it's not windy
or it's not sunny outside.
[narrator] What if we built a world
record-breaking solar farm right here?
The Hoover Dam sees about
4,000 hours of sunshine per year,
over 30% higher than
the international average.
We could also use solar panels
to help out with a major
evaporation problem at Lake Mead,
which is 12 storeys lower
than it was in the year 2000.
There are technologies
that exist today
that can mitigate some of
the evaporation issues.
There are solar panels
that float, that can be used,
and that reduces evaporation and
also produces additional electricity.
[narrator] If we could install 3,000
megawatts of generating capacity,
it'd be the most powerful
solar plant on earth,
surrounding the greatest dam
of all time.
Imagine that.
The Hoover Dam reinvented as a
clean battery to store renewable energy.
It would take 1,200 workers to do
the job and cut through all the red tape.
But we'd get it done
in 15 years.
So, how much would it cost?
This looks like a project
that's in the billions of dollars.
[narrator] But the three billion won't
include the cost of our solar farm,
which, on average, costs
about $1 million per megawatt.
So, building our 3,000 megawatt
plant would cost $3 billion.
We'll budget $3 billion to turn the
Hoover Dam into a clean battery
and another $3 billion
for our solar farm.
Final price tag?
$6 billion.
There's no question that's
a hefty chunk of change,
but in the end, the future of wind,
solar and even ocean electricity
will depend on
energy storage projects.
[Zhou] Transitioning to
a clean energy future
is one of the toughest
challenges that we have today.
Energy storage plays
a critical role to make sure
that our grid is not only
clean but also reliable.
[narrator] The world of electricity
is changing before our very eyes.
But the Hoover Dam proves
if you get the job done right,
you'll always pass
the test of time,
standing tall as a reminder of the
power we hold to reshape the future,
and the high watermark
we can achieve
if we built it today.