when they realize that they are about to embark

on something that will define their future.

For many here today, this is that moment.

The start of the race will be a very special day for us

'cause we'll have worked for this for so many months,

and then we're finally there with the car,

and you can see it taking off.

I just can't wait to get started on this race.

I'm very excited.

The launch of the World Solar Challenge in Australia

is moments away.

MAN: Ready now.

[CHEERING]

These cars will leave downtown Darwin

and travel all the way across the continent

to the city of Adelaide,

covering almost 1,900 miles,

powered only by light.

Whoever arrives first will be crowned champion,

and they'll garner the attention of the engineering world.

Teams will depart in 30-second intervals

in an order determined by their qualifying laps yesterday.

Top Dutch from the Netherlands

leads the start line.

Any team that wants to win this race

will have to overtake them to do it.

[CHEERING]

Top Dutch gets the final countdown...

and the World Solar Challenge is underway.

ANNOUNCER: As the first car takes to the streets...

Next up, Sonnenwagen from Germany,

then Kogakuin from Japan,

Agoria from Belgium,

and Twente from the Netherlands.

Each team has a large convoy surrounding their solar car.

There's a lead car keeping an eye

on everything directly in front of the solar car.

There's also a chase car directly behind.

Race to convoy, we have teams over the track.

It houses what teams call the brains of the operations,

tracking all the data, like energy in and out,

battery readings, and the car's performance.

They also track all aspects of the weather,

so it can be factored in to strategy adjustments.

Most decision making is done here in the brains car.

Yeah.

-That's how it should be. -Okay. Problem solved.

Currently moving out. Following volunteer instructions.

Our car just started moving

and we're about to catch up with it at the start line.

Uh, I'm feeling good. Obviously, nervous,

but that should be natural at this point, I think.

NARRATOR: Stanford had a rough time making it through qualifying,

and they're happy to finally be getting into the race.

Yup.

Okay.

Car shut off.

Yeah.

It's powering back on.

Car keeps shutting off.

I'm, like, at the starting line.

I have started the race...

I guess.

Stanford's underway,

and their convoy is anxious to join their car.

Yeah, this is us. Go over there.

Over there, over there.

All right, good to go.

What should my speed be?

Solar car copies.

Before the lead teams have even cleared the outskirts of Darwin,

they're already jockeying for position.

The traffic lights played in our favor...

Getting a good position for today's start is crucial.

These guys want to be out in front.

That's my boys.

In vehicles behind the solar cars,

there are a lot of department specialists,

each in charge of specific components of the race and car,

mechanics, electricians, the works.

And, there are entire crews

in charge of camping and food for everyone.

These teams are big.

In total, with the solar car,

we're with eleven cars.

Yeah, it's a pretty big logistical operation.

So the total group of people travelling with us

from Darwin to Adelaide are 40-49.

We have one amazing solar car,

and then, eleven petrol cars which follow.

NARRATOR: I have to say, in order to prove the tech

in these ridiculously efficient cars,

they're leaving a pretty big carbon footprint across the outback.

I guess that's the price you pay for progress.

There are challenges, there are risks in participating.

So, as a pilot, you really need to trust your friends

on what they design and what they build,

and even yourself.

So, with the team, with the drivers,

with everyone, we try to minimize the risks.

But you never know.

As teams forge their way through the Northern Territory,

the sun is intense,

providing as much energy as a solar race could ask for.

But the trade-off is,

it's really hot.

Like, humid and a hundred hot.

Due to weight and massive power consumption,

these cars don't have any kind of air conditioning,

and I really wonder how these drivers are gonna hold up.

Solar energy is absolutely amazing

when the sun is shining.

But to be useful at all times

requires battery storage.

These solar car teams

are advancing storage tech out of necessity.

The race limits them to only 20 kilograms of battery weight.

That's pretty small.

For that reason, the battery of choice

for most teams is lithium-ion.

It has a very high energy density,

meaning it stores more energy in less space.

That's why we use them everywhere,

from our smartphones, to drones,

to cutting-edge solar cars.

However, this reactivity also makes them volatile.

Inside, a very thin semi-permeable layer

separates the positive and negative electrodes.

If that barrier is damaged, a cascade of reactions

could cause the highly-flammable electrolyte

to expand and combust.

So, while these batteries are great for storage,

any breach or over-taxing

can cause a four-alarm fire.

Stanford has cleared Darwin,

and they're running at highway speeds.

But only six miles in, something isn't right.

I smell a not-good smell.

I could hear, "You need to pull over right now, get out of the car."

I'm like, "Oh, no. This is not good."

[CORI CRIES]

With just seconds to spare,

Stanford's driver, Julia, is safely out of the car.

Her teammates have wrestled the overheated battery

out of the vehicle as well,

and things are going downhill fast.

Guys, move away from the car.

Everyone, away, please.

It's okay, it's okay.

I'm so glad you're okay.

You could tell immediately something was looking severely wrong,

and the next call we hear is, battery fire,

everyone needs to come back now.

Um... And that was awful.

I don't think I'm ever gonna forget that moment

ever in my entire life.

Okay, smoke's toxic. Stay out.

NARRATOR: Stanford's World Solar Challenge is over

almost faster than it began.

They will have to tow their car

all the way to the finish in Adelaide.

We think there may have been some changes

that we had to make to the car to pass the rules

that could have caused an issue.

There could have been something we did on our pack that was an issue.

We got the driver out safely,

which is the most important thing.

I think everyone's gonna be sad about the car for a while.

You just gotta figure out a way through it

and move forward.

And that's, I guess, what we also have to do

as a group.

NARRATOR: Back on the road, Twente is still on a tear,

but so is team Agoria.

They have each passed two cars coming out of Darwin,

and are just behind Top Dutch,

who is barely hanging on to their lead.

Twente is keeping up a blistering pace.

The question is, can they catch the leader

on the very first day?

This desolate place is Katherine,

the site of the first control stop

where all of the solar cars must come in here

and stop for a half hour.

I'm excited to see them after this significant part of the journey.

Control stops are mandatory, mostly for driver safety.

They force teams to change out their drivers,

and they also give convoy vehicles a chance to refuel.

Katherine is only the first of nine control stops along the way,

and much to my surprise, first in is Twente.

Remarkable. They started five cars back in Darwin,

and they've already pulled into the lead.

These control stops are really interesting

because the drivers have to pull in here,

and they can make any adjustments they want

to the vehicle as they get out.

But once they leave the car, they cannot come back to it.

No one from the team is allowed to touch the car

for a half hour.

It's gonna charge up just from the sun,

and then, if it's all good, the driver hops back in

and they'll take off down the road.

Each driver must make their way to the officials' tent

and trigger a button, starting their half hour.

Nicely done. Congratulations.

In past events,

some teams would use the control points as pitstops

to make repairs and modifications while off the clock.

To force teams to build more robust cars,

race officials created the no touch rule,

forcing teams to implement fixes

on their own time, or not at all.

So, what I think is interesting is, obviously, this race

is about harnessing the power of sunlight.

But when you start in Darwin, you have a full battery.

Yes.

So, one strategy that one could employ for day one

would be to drain that battery

and get out fast, ahead of everyone.

So, I guess what I'm curious about is,

how much energy is left in your battery?

I'm not going to say anything about that, I'm sorry.

It is true that we start with a full battery,

and of course, the remaining four days

we can only charge with solar energy.

It's on day one where this car could be bluffing,

could be using a lot of battery,

but we won't know until a few more days...

Exactly.

...whether it's really running on sort of a neutral energy balance.

Is there a risk of going out too hard on day one?

Like, is it possible to drain that battery too much?

Yeah, of course, there's always a risk.

I mean, there's also a risk

if you don't drive too fast on day one,

that you are way back.

But of course, there's also a risk if you drive too hard.

Next in is Top Dutch,

who have not been able to hold on to their starting position.

[SPEAKS DUTCH]

So, we're talking, like, 25 minutes behind.

They're 25 minutes behind.

And then, Agoria.

It is a very hot day, being a driver in this car...

The temperature in that cockpit

is at least ten degrees hotter than it is out here,

and it is roasting today.

This is due to the same process

that traps heat in our atmosphere and warms our planet:

the greenhouse effect.

As light energy from the sun enters the cockpit

as short, visible waves,

some reflect back out,