of the world's estimated 1.4 billion vehicles

run on fossil fuels,

releasing a whole bunch of pollutants.

Can you believe that a typical car

emits roughly 4.6 metric tons of CO2 every year?

Fortunately, momentum to take gas vehicles off the road

is building around the world

with many countries planning to phase out

fossil fuel powered vehicles in the coming years.

And at the forefront of this shift

towards alternatively powered vehicles

are the teams competing in the World Solar Challenge.

By now, we know all about the sun and the technology

like the batteries, solar cells and aerodynamic structures

that are being used to harness the sun's power.

We even understand the mechanics

of how to power a solar car.

And don't worry, if you're fuzzy on the details here,

then you can go watch our previous videos

in this Learning Playlist

where we talk about all of that stuff.

So, now, let's explore what's it gonna take

to power all of our cars using the sun.

It all comes down to pretty much one thing.

The amount of solar power

that a car is able to generate

compared to the amount of power it uses up.

Electric cars, gas powered cars,

self-driving cars, you name it,

have pretty big power demands.

So while incorporating solar technology

into lightweight vehicles

like e-bikes and drones is relatively easy,

the same can't be said for larger vehicles like cars

which can easily weigh at least 2,000 kilograms

and need to be able to maintain

constant power at high speeds.

Plus, most commercial cars today are also outfitted

with power draining AC units,

radio systems and complex computer circuits.

This poses a bit of a problem for photovoltaic systems,

which as we've learned in previous episodes,

are by their very nature only as powerful

as the amount of photons they're able to absorb.

The more photons a solar cell absorbs into its material,

the more electricity can be produced.

And basically, cars require a lot of energy to work.

And if we want to power them with solar energy,

there's not a whole lot of surface area to work with.

And then there's the fact that the solar cells we use

out in the real world today

don't often reach their already limited efficiency.

Right now, the best research-grade solar cells

are still at, like, 30%.

And that's in a lab environment,

like, a teeny tiny solar cell.

MAREN: With that said, we've certainly made huge strides

in improving the conversion rate of solar cells.

And work is underway to push their potential even further,

whether that's through finding new materials configurations,

developing more sophisticated anti-reflective coatings

to let the cells capture more light,

or even figuring out how to manipulate light waves

so that they're easier for the cells to absorb.

But until solar cells reach their maximum efficiency

and then some,

designing solar vehicles to be as aerodynamic

lightweight and efficient as possible

will remain the primary focus.

So, while powering a car on sunlight alone

does remain a challenge,

it's certainly not impossible,

because solar cars are a reality right now.

I've been given a pretty unique opportunity

to ride in a solar car

while it is going around the figure eight track.

This is the Minnesota team. They've drafted me.

And who's spot am I taking?

MAN: Uh, you're taking Chris' spot around here.

-DEREK: Chris? -MAN: Yeah.

-[CHUCKLES] -That's okay.

Is there something I should know?

-You'll figure it out. -[ALL LAUGHING]

DEREK: The Eos II is a two-door, two-seater,

so kinda like a concept solar coop.

Man, this is intense. [CHUCKLES]

WOMAN: All right, solar car to Ricky. Am I clear to start?

DEREK: Keep in mind that the Eos II is a concept car.

Clearly, it's not quite ready for production.

But the ride is surprisingly smooth,

though very loud.

-Now I'm feeling the speed. -WOMAN: Yep.

And before you know it...

There we go. That was the end of it.

-That's it? -That was the official rounds.

-Wow! -I know.

That was easy. [CHUCKLES]

That was very nicely done.

Hurray!

While I wasn't able to fly over to Australia

to ride around in a solar cruiser, unfortunately,

I did get the chance to speak

with a few Stanford Solar team members

about whether they see solar cars

taking off beyond the race track.

Yeah, I think that there's a chance

that solar technology could make its way

into mainstream automobiles.

There's always the chance that, you know,

some company comes out with a great innovation

that really pushes the industry forward.

There are definitely limitations

especially with the efficiency of solar powered cells

and how much energy it takes to actually run a car.

But if you make your car aerodynamic,

and you make your car light,

and you make your array really good,

then you're gonna be hard to beat.

If there's one thing that I hope for,

with solar cars specifically,

I really hope that it makes more people excited

about working on these new sources

for renewable and sustainable energy.

MAREN: But solar cars aren't just

at the Stanford Solar Car team's garage,

or racing across the Outback at the World Solar Challenge.

We've actually got a little known

but rapidly growing solar vehicle commercial market.

Startups like Sono Motors and Lightyear

are going all-in on solar.

ARJO: And what excites me the most

about making commercial solar cars

is showing to the world

that we can be much more efficient

with the energy that we have available

without having to compromise

on the convenience you get every day.

You improve the aerodynamics a bit,

you improve the weight a bit,

you increase the solar panel array a bit,

you increase the efficiency of the solar panel a bit,

and then combining all of that,

you basically match energy consumption and energy yield.

We're not 100% there yet, but we're getting pretty close.

The closer you get,

the more practical the car becomes to use every day.

MAREN: Established companies like Hyundai and Toyota

are also developing ways

to incorporate solar panels into their cars.

Albeit mainly as a way

to lend cars a few extra miles of range

or power some of the auxiliary system.

It's a little less ambitious, sure,

but it's certainly a step in the right direction.

And research teams all over the world

are working tirelessly

to make the next revolutionary breakthrough

in solar panel technology,

which could be exactly what our cars need to level up.

There's just too much at stake here

to let that big beautiful star above our heads go to waste.

So, there you have it, folks.

That's a wrap for our Light Speed Learning Playlist.

I hope you learned a lot

and that you enjoyed the ride as much as I did.

Now, go outside and get some sun.