Building the world's largest (and most controversial) power plant - Alex Gendler
In 2018, a single power plant
produced more energy
than the world’s largest coal-powered
and gas-powered plants combined.
And rather than using finite fossil fuels,
this massively powerful plant relied on
a time-tested source of renewable energy:
running water.
Stretching over 2.3 kilometers,
China’s Three Gorges Dam isn’t just
the world’s largest hydroelectric plant.
It’s capable of producing more energy
than any other power plant on Earth.
So what allows Three Gorges
to generate all this power?
And how do hydroelectric plants
work in the first place?
A hydroelectric dam is essentially
a massive gate,
which redirects a river’s natural flow
through a large pipe called a penstock.
Rushing water flows through the penstock
and turns the blades of a turbine,
which is attached to a generator
in an adjacent power station.
The turning of the blades spins coils
of wire inside a magnetic field,
producing a steady supply of electricity.
Because the penstocks can be sealed
at any time,
a dam can hold back excess water
during stormy seasons,
and save it for dry ones.
This allows hydroelectric dams
to produce power
regardless of the weather,
while simultaneously preventing
floods further downstream.
These benefits have long appealed
to China’s Hubei Province.
Located near the basin
of the Yangtze River,
this region is prone to deadly floods
during rainy seasons
when the Yangtze’s flow is strongest.
Plans to build a dam that would
transform this volatile waterway
into a stable source of power circulated
throughout the 20th century.
When construction finally began in 1994
the plans were epic.
The dam would contain 32 turbines—
12 more than the previous record holder,
South America’s Itaipu Dam.
The turbines would supply energy
to two separate power stations,
each connecting to a series of cables
spanning hundreds of kilometers.
Electricity from Three Gorges would
reach power grids as far away as Shanghai.
However, the human costs
of this ambition were steep.
To create the dam’s reservoir,
workers needed to flood over
600 square kilometers of land upstream.
This area included 13 cities,
hundreds of villages,
and over 1,000 historical
and archaeological sites.
The construction displaced roughly
1.4 million people,
and the government’s relocation programs
were widely considered insufficient.
Many argued against this controversial
construction,
but others estimated that the lives
saved by the dam’s flood protection
would outweigh the trauma
of displacement.
Furthermore, raising the water level
upstream
would improve the river’s navigability,
increase shipping capacity,
and transform the region
into a collection
of prosperous port towns.
When the project was completed in 2012,
China became the world’s largest
producer of electricity.
In 2018, the dam generated 101.6 billion
kilowatt-hours.
That’s enough electricity to power
nearly 2% of China for one year;
or to power New York City
for almost two years.
This is a truly astonishing amount
of energy.
And yet, two years earlier,
another dam less than half the size
actually generated more electricity.
Despite Three Gorges record-setting scale,
the Itaipu Dam still produced more power.
To understand why Itaipu can outperform
Three Gorges,
we need to look at the two factors
that determine a dam’s energy output.
The first is the number of turbines.
Three Gorges has the world’s highest
installed turbine capacity,
meaning it’s theoretically capable
of producing over 50% more power
than Itaipu.
But the second factor is the force
and frequency of water
moving through those turbines.
Three Gorges spans several deep, narrow
ravines surging with powerful water.
However, the Yangtze’s seasonal changes
keep the dam from reaching
its theoretical maximum output.
The Itaipu Dam, on the other hand,
is located atop what was previously
the planet’s largest waterfall by volume.
Although the dam’s construction destroyed
this natural wonder,
the constant flow of water allows Itaipu
to consistently generate more
power each year.
This dam rivalry is far from over,
and other projects like the Inga Falls Dam
in the Democratic Republic of Congo
are also vying for the title
of most powerful power plant.
But whatever the future holds,
governments will need to ensure
that a power plant’s environmental
and human impact
are as sustainable as the energy
it produces.
