- The Niagara River with its magnificent waterfalls and rapids, is not only a natural wonder, but it's also one of the world's greatest sources of hydroelectric power.

It launched Nikola Tesla's victory in The War of the Currents, and it lit up the dazzling Pan-American Exposition.

But here's the question, how do you turn a waterfall into electricity?

The process begins with the diversion of water from the high elevation of the Niagara River, through tunnels to power generation stations where it's converted into electricity.

The churning river provides the driving force for 2.6 million kilowatts of electricity on the American side, and almost 2 million kilowatts of electricity from a number of power plants on the Canadian side.

In this episode of "Compact Science," we'll explore how potential energy and kinetic energy drive this incredible system, and how the mighty Niagara River helps power our world.

(logo whooshing) We use electricity pretty much every day, from televisions and computers to phones and even cars.

Our modern world depends on it.

But where does all that power come from?

Some methods burn materials that you can find deep underground, like coal, oil or natural gas.

However, once you burn it, it's gone forever and it takes a long time to make more.

These are called non-renewable energy sources, and we use them faster than we make them.

Other methods generate power from the forces of nature around us.

Windmills convert the energy from the wind into electrical energy.

Solar panels convert the energy from the sun into electricity, while hydroelectric power plants use the energy of water to power our world.

Speaking of hydropower, here in New York State, the biggest electricity producer is Niagara Falls.

New York's Niagara Power Project includes two power plants, (arrow whooshing) the Robert Moses Niagara Power Plant, and the Lewiston Pump Generating Plant.

These facilities can create as much as 2.6 million kilowatts with 25 turbines spun by 748,000 gallons of water per second.

That's like lighting 26,000,000 100-watt light bulbs all at the same time.

Hydropower is one of the oldest and largest sources of renewable energy, but how does it work?

(video whooshing) I'm here at the Niagara Power Vista with Chris Carey, an engineer and operations superintendent who seems to know it all.

Hey Chris, do you mind walking me through the process?

- Absolutely.

For us, it all starts with the diversion of water.

We have two intake structures that bring water upstream of Niagara Falls.

It goes underground in two tunnels.

They're about 4.3 miles, 44 feet by 66 feet, and water comes right in here to our forebay.

- So you're telling me like underneath all of that land, there's tunnels of water flowing through it.

- Exciting, isn't it?

- Oh, that's so cool.

- So once water comes into our forebay, we can determine based off of load what we're going to do with that water.

We have two options.

We can either pump it up into our reservoir or we can bring it, let water fall through and go through our Robert Moses plant.

- It's a two for one deal, isn't it?

Look at that.

- Sort of, sort of, sort of.

So the amount of water that we can take is dictated by an international treaty between the U.S.

and Canada.

That treaty dictates the amount of water that has to flow over the falls.

So during the summertime, during the day, a hundred thousand cubic feet per second of water has to flow over the falls.

- It's a lot of water.

- Think of a cubic foot as a basketball.

- That's a lot of water.

That's a lot of basketballs.

- It is, it is, it is.

At nighttime and during the wintertime, only 50,000 cubic feet per second of water has to flow over the falls.

- [Sarajane] It's a whole lot of basketball.

- That water that's left over gets split between us at the New York Power Authority and Ontario Power Gen for power generation.

I don't know if you picked up or not, but we could take the most amount of water at night, when usually load is the lowest.

That's where this pump plant here is extremely important for us.

Think of this as a huge battery.

So when load is low, when the demand is low, we can actually capture water, we pump it up into the pump plant.

We'll do that through the nighttime, as the day goes on, load starts to go up, the power demand starts to rise.

We can actually use the same units, we can run 'em as generators.

We can generate power to fall into the forebay and then let it fall through the Robert Moses Plant.

So we actually get to use the water twice.

As load goes up and down throughout the day, we can actually buffer that load and we can adapt accordingly.

- So unlike days where it's really hot and everyone's using their air conditioning, you can change it, whatever, like, oh, that's super cool.

So how do we use the water to create electricity at this plant?

- So as water comes down our forebay, it travels into our penstock.

The penstock is just a big tube that brings water down into the turbine.

Water then flows through the turbine, which causes it to spin.

- [Sarajane] Kind of like a big old water reel.

- At that point, you're converting your water energy or the flow of falling water into mechanical energy.

As that turbine spins, it's connected to a shaft.

The shaft is connected to a rotor.

The rotor is made up of many electromagnets.

And then on the outside of that, you have what's called a stator, which is essentially just coils a copper.

And that electromagnetic theory that's happening is what is really allowing the conversion of mechanical energy into electrical energy.

And then it travels out of the stator, goes up to a transformer where we step the voltage up, and then from there it goes through tunnels up to our switch yard, and from there it distributes out to the world.

- That is such cool science and engineering.

Like there's so many parts that go into it, oh, I love it.

Chris, this was super cool and I'm really excited to see the rest of this place.

So you want to go on an adventure?

- Absolutely, let's go.

- All right.

(bright music) (muffled speaking) (energetic music) Yoo.

Niagara Falls is often called the cradle of hydroelectric power, because it was one of the first places where water was harnessed on a large scale to generate electricity.

It was also the stage for a scientific showdown that changed the world.

The War of the Currents.

On one side was Thomas Edison, champion of direct current, or DC.

On the other was Nikola Tesla, backed by George Westinghouse, fighting for alternating current or AC.

DC current, like the kind from a battery, flows steadily in one direction.

It works, but it loses energy quickly over long distances.

That made it hard to bring electricity from a place like Niagara Falls to cities miles away.

AC power was different.

Instead of flowing one way, it zips back and forth, alternating direction many times per second.

That simple zigzag makes it perfect for sending electricity long distances with very little loss.

It was a game changer.

In 1896, Tesla and Westinghouse proved their point.

Power from Niagara Falls traveled 26 miles to Buffalo, lighting up the city and dazzling the world.

It was the first large scale hydroelectric transmission ever, and the beginning of the electric age.

So who won the war of the currents?

AC did.

And thanks to that victory.

The energy of Niagara Falls doesn't just thunder here, it travels.

Powering home, schools, cities, even your video game console.

(logo whooshing) All the energy in the world can be divided into two categories- potential and kinetic.

Potential energy is stored energy.

While we find kinetic energy, when something is moving.

Think about this.

I have a rubber band.

I will use the energy in my body to stretch the rubber band.

Right now the rubber band isn't moving, but it has a lot of stored potential energy.

So what happens if I let it go?

(rubber band clanging) Yay.

That potential energy is converted to kinetic energy and the rubber band goes flying.

- Ouch.

- Here's another way to see potential and kinetic energy at work, using nothing more than popsicle sticks.

Okay, so the idea with this is, they're made out of wood, but I can bend them.

So kind of that bending that tensileness, that's where I'm going to use to the potential energy.

So it's very similar to the water being held back in Niagara Falls.

Basically, I'm going to cross them and I'm going to weave them.

But in the weave I'm going to, if it wants to go up, I'm pushing it down, if it wants to go down, I'm pushing it up.

And if we keep going, and I'm actually putting a lot of my own energy into it by holding it down.

So if that tells you how much power I can kind of store in these things.

So this is just a little one.

This one's just a little one.

And if I were to let go, you can actually see it pulling up a little bit.

If I were to let go, (popsicle sticks snapping) it comes apart.

It's like a little bitty kersplosion, if you will.

That was all well and good, but what if I made it a little bit larger?

Oh.

Fingers crossed, three, two, one.

Ah, yes.

It happened.

It's like the potential energy burst into kinetic energy.

Motion you can see, and that's exactly how Niagara works.

Stored water energy suddenly released, transformed into motion, and finally into electricity.

So the next time you see something waiting to spring, remember it's just potential energy ready to burst into kinetic motion.

(bright music) We learned that Niagara Falls is not just a breathtaking natural wonder, but it's also a superhero of science that helps us make electricity using water.

And we explored the difference between potential energy and kinetic energy.

If you're interested in learning more about potential and kinetic energy, check out our Compact Science Viewer Challenge.

We have a fun experiment that you can try at home to test the energy of rubber bands.

Get all the instructions on our website and be sure to share back your results in the comments.

I'm Sarajane Gomlak-Green, and you've been watching "Compact Science."

Until next time, stay curious.

(upbeat music) - [Narrator] Compact science is funded in part by the Joy Family Foundation.

- Niagara Falls is often called the crado, crado, cradle, okay.

Mulligan.

- Someone broke it.

- I'll help them, - Oh, jezz, oh jezz some are on fire.

- Something is on fire.

What's on fire?

- I blame him.

- And it lit up the dazzling Pan American Expo - Exposition, sorry.

Gimme the hairspray, we need to keep this.

(bright music)