01x06 - Solar

[bunniefuu]

[mellow techno music]

Here we are on the top of the tower,



And here you see all the solar field

with the 10,600 mirror,

which will be aiming the light of the Sun

to the top of the receiver.

And that is increasing the temperature

to 560 degrees Celsius.

[mellow techno music]

A global industrial revolution is underway.

Yes, we have a technological challenge

for our environment, for the well-being

of the population of the
planet, for civilization.

Driven by passionate, dedicated individuals

intent on shaping a new world.

I do it because I look at my kids,

and I honestly, I'm
convinced that this is the way.

A cleaner world.

There is a way forward

other than burning fossil fuels

out of our funnels.

A greener world.

This wind farm is producing
more hours of power

into the grid than all wind farms in the UK

and probably in the world.

What we've done in the past

is not going to solve these challenges.

We need to find new ways.

And I think the only way to do that

is to bravely step forward
and implement technology.

Together, they are pushing engineering

to its limits,

to create extraordinary machines

that can protect our planet

for the future.

[dramatic music]

We face one of the greatest challenges

in the history of humanity,

to eliminate the fuels
that have driven progress

and technology for over a century,

[tense energetic music]

while our thirst for energy only grows.

[pensive music]

Could the solution lie

with an ancient and distant power source?

It's without question
that in our Solar System,

the Sun is the greatest source of energy.

And the better we can
take advantage of that,

the better it is for us as a civilization.

It's like a nuclear reactor in the sky,

and it provides endless power.

And if we can harvest
just fractions of this,

it can power all our consumption.

[pensive music]

Giant strides have been made

in capturing the Sun's energy,

but to replace fossil fuels,

solar power needs to step up a gear.

We've got a long way
to go, the way I see it.

We've only got 2% of
the world's energy is solar.

So there's a massive opportunity there,

and this technology is made for it.

Engineers are racing to capture

more of the Sun's power,

to open vast new expanses for solar panels,

and even to make solar electricity

available through the night.

This is the full cycle that allow us

to keep generation 24 hours

using 100% only renewable energy,

the light from the Sun.

This is the future.

[mellow techno music]

The vast majority of solar power today

is generated by silicon solar panels.

These are made of many individual cells.

Each cell has two thin
layers of crystalline silicon,

which have been altered so that one

is slightly negatively charged

while the other is positive.

The magic happens when light falls on it.

Electrons in the silicon atoms

absorb the energy and break free.

The negatively charged electrons

are then drawn towards the positive layer.

Once connected to a circuit,

this flow of electrons becomes electricity.

[energetic music]

Solar panels like this are
on rooftops all over the world,

producing clean, green
electricity to power our homes

and charge our gadgets.

[upbeat music]

But transportation is a
much tougher challenge.

It's still overwhelmingly
powered by fossil fuels.

[sparks sizzling]

A tech startup in Holland

has gone right back to the drawing board,

inventing a new car from first principles

that could revolutionize personal travel.

[energetic music]

Their goal is to prevent billions of people

buying gas-powered cars
by offering them a vehicle

that charges itself for free.

Everybody said we couldn't do it.

And that's what makes it interesting.

So, I think that's one,

actually, one of the
things that motivates us,

that it seems like an impossible challenge.

Actually, if we look back at the beginning,

it all started with [indistinct] challenge.

[tense energetic music]

Their story began at a
race across Australia.

Every two years, a
fleet of futuristic vehicles

can be seen streaking across the desert.

[tense energetic music]

This 1800-mile race is powered by the Sun,

with cars built by students
from around the world.

[fast car swooshes]

In 2012, a Dutch team from Eindhoven,

including electrical engineering
student Arjo van der Ham,

decided to enter for the first time.

I think most people were
there for the adventure

and for actually building
something with your own hands,

during your studies, and seeing it work,

and then trying to win
the race in Australia.

[metal clicking]
[team laughing]

[mellow techno music]

In previous years,

all entries had been one-seaters

built purely for speed,

but that year, the team
decided to enter a new category

that awarded extra points
for comfort and practicality.

[mellow techno music]

The idea was to encourage the development

of a commercially viable solar-powered car.

[mellow techno music]

We said, "Okay, let's
build a four-seater car."

And that became Stella,

the world's first solar-powered family car,

but also a car that had a flat roof,

especially because of the
efficiency of the solar panels.

Furthermore, it was very aerodynamic.

It was very lightweight.

It was made almost
completely out of carbon fiber.

The team had just over
a year to fully design

and build a radical new
solar car that could also be

a practical family
vehicle for everyday use.

Stella, they hoped, would be the blueprint

for the car of the future.

People would be sleeping
actually at the university,

waking up, build a solar car,

go back to sleep for six hours,

wake up, and go build again.

So, this was really an intense period

for most of the people in the team.

[mellow techno music]

On the 6th of October 2013,

the only family-sized car in the race

crossed the starting
line in Darwin, Australia.

[energetic music]

For the next six days,
Stella would be racing

through the desert powered by the Sun.

Or be it accompanied by
gas-powered support vehicles.

During the race, we had the solar car,

and then in front of that,

we had a small van called the strategy van

and was packed with computers.

And we had two guys, so me and my buddy,

modeling and calculating exactly how fast

should we drive with the solar car

such that at the end of the day,

our battery is exactly empty.

[energetic music]

Everyone expected the
comfortable four-seater

to be much slower than the others.

[energetic music]

But by day three, she'd
hit 75 miles per hour,

[energetic music]

so fast, the team bus couldn't keep up.

[speaking in foreign language]

[energetic music]

Before long, she'd overtaken

their leading competitor,
Tim Bochum from Germany,

despite carrying twice as many people.

[speaking in foreign language]

But the following day,

the car ran into difficulty,

and needed an emergency pit stop.

The team fixed the issues,
but they'd lost precious minutes.

And on day five, they lost
even more time to their rivals.

[melancholic music]

[speaking in foreign language]

By the morning of the final day,

the race was still tight,

but Arjo had a trick up his sleeve.

[speaks in foreign language]

[energetic music]

Stella crossed the line in Adelaide,

having driven 1,900 miles in 40 hours,

with an average speed of 47 miles per hour,

the second fastest in the category.

But the cars weren't only judged on speed.

They could earn extra points

for the number of passengers carried,

and how it would fare in the real world.

And it's here that Stella
came into her own.

A jury would take your car and see

if they can parallel-park it easy,

how many suitcases would fit in,

are there any cupholders,

how easy is it to get in
and get out, et cetera.

And they would score points on that

for all the different cars.

And then all of these scores
combined would make up

the final winner of the Cruiser Class.

With bonus points for
real-world credentials,

the team squeezed ahead of the competition,

and took first place
with a family-sized car.

[mellow music]

But they knew that to
really make a difference,

the hard part was still ahead of them.

At that point, you're not
really changing anything, right?

You're just making one car

and driving it through
the desert of Australia.

And there's five trucks behind it

to carry all the spare parts.

So, you really have to
take a concept to the market

to really make an impact

and try and improve the plan in that sense.

[mellow music]

Arjo and four other team members decided

to make the dream a reality,
and launched Lightyear,

to make solar-powered cars for the public.

In one year, the entire fleet of cars

throughout the world, they will drive

one Lightyear worth of kilometers.

And the mission of the
company is to get that

to one Lightyear of
sustainable kilometers by 2035.

[upbeat techno music]

To achieve their mission,

they set about turning
Stella's outlandish design

into something more
attractive to consumers,

while still keeping the radical approach.

We came up with our own scoring formula,

what will make this car better.

And the key metric that we
optimize the Lightyear One for

is the amount of miles you
can drive each year on the sun,

so the amount of miles
you can drive for free,

and that also guided all the decisions.

So if you have to decide

whether the car should be a bit wider

to accommodate more solar panels,

or whether it should be a bit smaller

to make it more aerodynamic.

You calculate how much solar kilometers

would option one give,

and how many solar kilometers

would option two give,

and then make your decision.

So this is what guided

the development of the Lightyear One.

[upbeat techno music]

As chief technical officer,

Arjo has overseen the
design of the solar panels.

At their workshop in the Netherlands,

Lightyear are fixing them in place.

With panels on the roof and the bonnet,

they cover 54 square feet in total.

But although they work in the
same way as a standard panel,

Arjo has altered the structure
to maximize the power.

A special technique can reveal the design.

We can actually show
the structure of the panels

and any defects at the panel at the lab

using an EL test, and with an EL test,

you actually use the
solar panel in reverse.

So normally, the solar panel

would turn sunlight into electricity,

but if you actually do
it the other way around,

and you provide the
electricity to the panel,

it will work as a light source,

and it will light up an infrared spectrum.

And now we make it dark in the room,

so we turn off the lights.

We take a picture with
a camera that's modified

to actually show up the IR lights.

And then we can see the groups lighting up.

[mellow techno music]

You see all of the cells lighting up,

with just a couple of exceptions.

So this is actually an old panel

that we used already for last test

and we abused quite a bit.

So that's also the places where

the solar cells themselves
don't work anymore.

Like an X-ray,

as well as showing what's broken,

the image reveals the inner structure.

So to increase the power
output of the solar panel,

we've done lots of small tricks,

like putting all the solar
cells pretty close to the edge.

We've cut them to a smaller size

and that way, we can
place them closer together.

Lightyear claim,

these are the most efficient
solar panels on any car,

with the improvements
gaining them 20% more power.

And as well as squeezing more solar cells

into every square foot,

Arjo has divided them into groups.

To see the benefit of
that, you need sunlight.

Luckily for countries like Holland,

the panels even work on a cloudy day.

First, Arjo is connecting
this regular solar panel

to a volt meter.

This will reveal what
impact shadows can have

on the power they produce.

So we've connected the panel to the meter.

And if I put a shadow on it,

you will see this number dropping,

and it actually doesn't
matter where I put the shadow.

You lose the same amount of energy.

If a shadow falls on even one solar cell,

the power generated by every other cell

drops by the same amount,

even if they're in sunlight,

because they're all connected.

So the whole panel
becomes much less efficient.

This doesn't matter much
for panels on rooftops

that rarely have shadows fall on them,

but cars regularly drive
under trees or past buildings.

On this panel, we've
actually divided the panel

into 11 very small panels.

These 11 very small panels allow us that

if one of them is in the shade,

one cell, it will only shut down

one small group of the
panel and not the entire panel.

And we can actually demonstrate this.

And if I go over it with this board,

then I create a shadow on the front,

and then only the first meter

will show that it actually drops,

and the older meters, they
still show the same value.

And then if I move it along,
the value on the first meter

actually comes back, and it
drops on the second meter.

And then if I move even farther along,

the same thing happens on the third meter.

So, as I go over to different groups,

I will only shut down the
performance of that group

and not have the entire roof,

which you would see on a regular panel.

[mellow techno music]

As if reinventing the solar panel

wasn't enough, the Lightyear team

have an even bigger engineering goal:

making the car one of the
most efficient ever produced.

The lights, you want
us to design to maximize

the amount of miles you can
drive each year on the sun.

And if you break that down,

and the biggest factor is aerodynamics.

So making the car more aerodynamic

is where you can save the most

on the energy consumption of the car.

[mellow techno music]

Most of the design process

happens using computer simulations.

[mellow techno music]

But now, the team must prove

how streamlined the car really is.

Annemiek Koers is responsible

for Lightyear One's aerodynamics.

We are currently in the [indistinct],

with the prototype of Lightyear One,

to test how it performs
at different speeds.

So, we test the air flow over the car,

how much drag does it produce,

and what effect that has on
the range eventually of the car.

[energetic techno music]

The tests will reveal the drag coefficient,

a number that tells you

how much wind resistance the car has.

The target is to get down to
about 0.2, which would equal

the most streamlined
production car ever made.

With such low drag, it
could drive much farther

with the precious solar energy it collects.

But compared to a regular car,

the team faced an extra challenge.

As well as being streamlined,

the shape must also fit enough panels.

The aerodynamics are a bit
constrained by the solar roof,

and it needs to be
quite flat surface on top,

instead of having very curved surfaces,

which would be maybe
better for aerodynamics.

But the team have managed to find a profile

that boosts both the
solar power and efficiency,

one that gives a larger
area for the panels,

while also reducing drag.

You can see that we
have a very shallow slope

going to the rear, and the flow can stay

at that slope over that full length.

If you have a shorter car,

we will have a steeper slope,

and that will detach the flow,

and will create a lot of drag.

[energetic techno music]

The team analyzed and modified

every inch of the car,

replacing bulky wing mirrors
with streamlined cameras,

and fixing covers over the back wheels.

[energetic techno music]

[mellow piano music]

Eventually, the team get
the drag coefficient down

even further than they'd hoped, below 0.2.

So, we again claim to be

the most efficient production car

by the time we get to production,

but that's, of course, the first time.

[mellow techno music]

This world-beating efficiency means

the solar energy can go much further,

even in cool, cloudy countries.

The solar panel will actually
give you enough energy

to drive somewhere around


in the Netherlands.

It doesn't sound like that
much, right, 8,000 kilometers?

But the average car in the Netherlands

actually drives only 11,000.

For California, they drive much more,

but there's also much more sunlight,

so you get again around 70%
of your annual energy needs,

you get from the solar panel.

For the other 30%, the Lightyear One

can be plugged in and charged
like a regular electric car.

For now, to pre-order one will set you back

well over $100,000.

But it could also save
thousands at the pump.

Towards the future, we will be developing

an affordable version of the Lightyear One.

And we see energy efficiency is the key

to the price in the longer term.

[mellow techno music]

But while solar cars

may still have a premium price tag,

the cost of standard solar
panels has already plummeted.

The main mineral used to make solar panels,

quartz, is abundant and cheap.

And by mass-manufacturing
in large factories

with automated production lines,

they also cost less to make.

Solar power now is the most
affordable source of power.

It's just a matter of
capturing this energy,

and solar power now beats

coal-fired power diesel generators.

And now, hundreds of
millions of the solar panels

are manufactured every year.

[funky music]

With such cheap panels available,

solar farms have mushroomed.

Many are so large
they're visible from space.

Some generate over
two gigawatts of electricity,

enough to charge 400 million
phones at the same time.

And yet, solar power still produces

only 2% of the world's electricity.

That's because although panels are cheap,

they need the right kind of location.

So one of the challenges,

and this is now starting to happen,

with the very high number of solar panels,

we are searching for
new places to put them,

and it's a quest to find
these areas in good positions.

[taut techno music]

As solar farms get bigger,

they start to compete
with other uses for the land,

such as recreation, farming, forests,

and other wildlife habitats.

It's questionable whether to set aside

big surfaces for the solar farms,

and it's becoming more and more difficult

to find good spots for at
least very large solar plants.

[mellow techno music]

To solve this conundrum,

an entirely different approach
is starting to make waves.

Borge Bjorneklett is the
founder of Ocean Sun,

a company making platforms
for solar panels that float.

Borge realized that there are water bodies

all over the world with a
readily available sunlit surfaces.

Many, like the Magat
Reservoir in the Philippines,

are next to hydropower
dams, which has a big benefit.

One very nice thing about combining

floating solar power and
the hydroelectric power

is the very short distance
from producing solar power

to delivering it out to the grid,

because the infrastructure
is already in place

at the power station.

The solar panels generate electricity

when it's sunny,

while the dam makes power when it rains.

It has the flexibility over the seasons.

For the rainy season and the dry seasons,

you can make a more
steady power production.

So this combination is
a fantastic application.

Other companies are also targeting lakes

and reservoirs.

[mellow music]

But Borge has set his sights

on a much bigger body of water, the sea.

[mellow music]

The main obstacle is the ocean waves.

[mellow music]

The challenge is very much to create

a protective environment
for the solar panels,

and also to cope with the
waves and also strong winds

that can occur on the water surfaces.

Ocean Sun tested their design

off Norway's coast.

The most critical piece of engineering

that protects the panels
is also the simplest,

the thin polyethylene
membrane that forms the surface.

This is the fabric of our system,

which we place the solar panels on top.

As you can see, it's less
than one millimeter thick.

It interacts with the surface tension

of the water to create two
curious and powerful effects.

Firstly, it boosts the
strength of the material.

This fantastic effect that this layer has

when we put it on top, and it
came to us as a big surprise,

that you could actually walk
around on the water surface

through this very thin fabric.

And secondly, Borge discovered

that the membrane
changes how water behaves.

It has a dampening effect

on the motion of the waves,

and it serves as an ideal surface

for placing solar power on top of it.

In January 2019,

the floating system had
a chance to prove itself.

In the winter, we had a pretty bad storm

coming in over Norway.

Bridges were closed
and the ferries stopped,

and we really got to test our system

in quite bad conditions.

The floating solar array

was hit by high winds and waves.

[tense music]

Once the storm had blown over,

the panels emerged unscathed

and still generating power.

Having proved it can survive
harsh ocean conditions,

sea-based solar seems perfectly placed

for an energy revolution,

as nearly half the world's population

lives near the coast.

Many big cities, like here in Oslo,

have the ocean right on their doorstep.

And if we can use the surfaces here

for floating solar power,

you have a very short
transmission to the consumers.

[mellow music]

Research is underway to minimize

any negative impact on marine life.

So far, results have
shown that floating panels

appear to reduce damaging algae blooms.

With water surfaces now
available as well as land,

experts estimate that


are being laid every hour,

equivalent to a thousand
soccer fields a day.

But although solar is already the world's

fastest-growing energy technology,

it could be generating even more power.

Standard solar cells can only convert

about 1/5 of the energy

that's available in
sunlight, into electricity.

A fundamental problem with
your standard solar panels,

it captures a little bit for electricity,



If that percentage were increased,

we could accelerate the
transition to clean energy sources.

[bright strings music]

In Victoria, Australia, a
company called RayGen

think they have found a way

to harness more of the Sun's power.

[bright strings music]

Inventor John Lasich came
up with part of the solution

as a student way back in 1975.

I was pretty ambitious for a young lad,

and I thought if you're gonna make perhaps

a quarter or even half
of the world's energy

from solar energy, you
have to have something

that is highly efficient
and very, very powerful.

In the 1970s, solar panels were small

and even less efficient
than they are today.

But John had a simple idea
how to supercharge them.

He calculated that a parabolic dish

with a reflective surface

could focus sunlight
onto one small solar cell,

concentrating the power of the Sun,

like a magnifying glass.

So he had a parabola-shaped bowl

made for him in pottery class,

and then ingeniously lined it

with a reflective bag from a box of wine.

I put those two items together

and produced a solar concentrator.

We produced several
hundred times more power

out of that cell.

And at that moment, I
knew we're onto something.

Briefly, it seemed John had found

the perfect way to
capture the Sun's energy,

but he'd overlooked one thing.

Unfortunately, about 10 seconds later,

the cell fell to pieces

because of the very
high intensity in the heat,

it reached several hundred degrees.

[mischievous music]

To overcome this, John developed

a way to protect the
cells from overheating,

a system he still uses today.

Normally, we'd expose these
to 750 sounds of intensity.

And what we have to do is have a modulator

that tough it can stand a blowtorch.

It's the equivalent of


[tense music]

The apparatus keeps the solar module cool

even when blasted with heat
intense enough to melt steel.

The secret system involves
pumping high-pressure water

through the back of a panel.

[indistinct] That shows how effective

the cooling is, and stone cold.

With the heat problem solved,

John scaled up his idea
into bigger and bigger dishes.

[taut music]

Eventually, he found a system

that could focus even more sunlight.

[taut music]

At RayGen's pilot plant
in Bendigo, Victoria,

instead of focusing
sunlight with a parabolic dish,

they use giant mirrors.

These reflect sunlight onto solar modules

at the top of three tall towers.

What we do is we put
an array of these modules

into a large receiver
that has a field of mirrors

that focus a massive
beam of light to that receiver,

where we can produce
megawatts of electricity

out of that array of modules.

[taut music]

The receivers are exposed to 750 times

more sunlight than they
would be on their own.

And this allows another
major technological advance.

Their solar modules consist
not of normal solar cells,

which turn around 20%
of sunlight into electricity,

but of a special type
called multijunction cells,

which produce far more power.

This is the flash test that
we're about to demonstrate

and this measures the power

and the performance of the module.

So we take a module and
we place it into the chamber.

This machine simulates the Sun.

We have a flash can at the top,

which provides the highly intense light.

We simply run the process,

and the machine collects

the vital information about the module,

so the main indicators being
the power, 2.27 kilowatts,

the efficiency, of an astonishing 36.9%.

[mellow music]

Multijunction cells can turn around



nearly double what
conventional ones achieve.

This is because sunshine consists

of many different
wavelengths or colors of light.

Standard solar cells have
one pair of silicon layers,

which can only absorb a small
range of those wavelengths.

The rest is wasted.

Multijunction cells, on the other hand,

have several pairs of layers,

each made of different materials

that can absorb different wavelengths,

so more of the Sun's power is harvested.

Although multijunction cells
are around twice as efficient,

their price is also higher.

So they're normally only used

to power specialist equipment,

like space satellites.

[mellow music]

But by concentrating the sunshine,

RayGen only need a small number

to capture a vast amount of light.

The trick that we have is, yes, we pay


centimeter for the cell,

but we get 1,500 times more power

out of the cell in our system.

When the Sun is focused on them,

just two of these can
produce as much electricity

as 20 full-size solar panels

covering the roof of a large house.

John has plans to scale up his pilot plant

to produce gigawatts of power,

and they can even share
the land it's on with others.

All we can do is spread
the collectors out a little bit,

which makes the system very efficient,

but it allows the grass to grow

and we can actually run
stock at the same time.

So, you've got a solar farm

and you've got an agricultural farm

running on the same land.

The beauty of a light footprint.

RayGen hope to disrupt the industry

with their radical approach,

harnessing even more of the plentiful power

we receive from the Sun.

But despite its success, solar energy

currently has a major drawback.

Demand for power surges in the evening,

just as the Sun is setting.

Unlike fossil fuel power stations,

most solar farms can
only produce electricity

when the Sun is shining.

[pensive music]

In the arid Atacama Desert in Chile,

a major new development is
aimed at solving the dilemma,

Cerro Dominador.

Like the RayGen plant in Australia,

Cerro Dominador has a
tower surrounded by mirrors

that will track the Sun
and collect its energy.

But the system works in a
fundamentally different way,

and on a far bigger scale.

[mellow music]

Once complete, the tower will rise

as high as a 70-story skyscraper.

[mellow music]

Francisco Viscaino is project director

of this groundbreaking venture.

It is very important to
develop project like this

because if we really want to
turn page on the fossil fuels,

we need to create green
energy, renewable energy,

that is able to work 24 hours in the night.

When the electricity is really needed,

in the evening, and you turn on your light,

this is what we need.

Cerro Dominador is designed

to produce solar
electricity 24 hours a day,

and more of it than
anywhere else in the world.

Northern Chile is the perfect place

for this kind of solar installation,

as the Atacama Desert
is the driest place on Earth

outside the poles.

That causes the solar radiation here

to be uniquely intense.

In Chile, the Sun is much more powerful

than any other place in the world,

not only because of the power
of the Sun, which is strong;

also because there is not
water in the environment,

it's very dry.

So, the light is coming
directly to the ground

without any reflection on
the water in the environment.

Even if the temperatures are not very high,

the power that we are receiving
from the Sun is tremendous.

But there is a price to pay

for choosing the sunniest spot on Earth.

Firstly, it's also one
of the windiest spots,

meaning, the mirrors need
frequent cleaning from dust.

And secondly, Chile
sits in one of the planet's

most seismically active
zones, and holds the record

for the world's most powerful earthquake.

One of the most challenging things

by constructing this kind of plants

in the desert, with this big tower,

is the earthquakes.

The seismic movements,
we need to control it

by doing a special design
and special engineering

and a special construction.

For the 820-foot-high
tower to be quake-proof,

its foundations must be 24 feet deep.

[taut techno music]

Once the main structure was complete,

an enormous receiver
was assembled for the top.

This is where the sunlight
will be reflected onto.

[upbeat music]

But the 72-hour-long
procedure to lift it into place

had never been attempted before.

Lifting up this equipment

was one of the biggest engineering

and construction maneuvers
in South America all time.

It was one of the most tense moments

in our life in construction.

We have been lifting the receiver,

taking care of the
earthquakes and the wind,

and it was a very, very difficult maneuver.

By lifting 3,000 tons
equipment from the ground

to 150 meters to the top of the tower

was challenging, was
difficult, but was very nice.

The receiver, which weighs

as much as a Navy frigate,

was lifted by 16 powerful hydraulic jacks.

For safety, it had to be moved

no faster than 16 feet per hour.

[mellow music]

After three days, the
receiver reached the top,

and was successfully fixed in place.

Once complete, the tower became

the second tallest
manmade structure in Chile,

and the fifth highest on the continent.

[taut music]

[mellow music]

As well as building the giant tower,

the workers have a huge
job assembling and calibrating

over 10,000 giant mechanical
mirrors, called heliostats,

spread over an area of 1,700 acres.

Each one is the size of a helipad

and can tilt in any direction.

[mellow music]

Today, the team in the control room

are calibrating the heliostats.

[speaking in foreign language]

Jose Romero

is the solar field commissioning manager.

He must ensure that every heliostat

can eventually reflect the
Sun's radiation accurately

onto the receiver at the top of the tower.

But as the Sun moves through the sky,

the heliostats must also move
to keep the reflected sunbeam

trained on exactly the right spot.

[mellow music]

If they're even a fraction
of a degree out of position,

the whole system could fail.

[speaks in foreign language]

For each heliostat to be able

to automatically track the sun,

the team must first train
the reflected beam of light

onto a target on the tower.

[speaks in foreign language]

Once the light spot has been locked

into position, the system will be able

to find the black receiver automatically.

One down, 10,599 to go.

The best view of the heliostat field

is from the top of the central tower.

To get there takes a


Here we are on the top
of the tower, 220 meters.

And here you see all the solar field

with the 10,600 mirror,

which will be reflecting
the light of the Sun

to the top of this tower,

just where we are right now.

It's very, very nice when in the morning,

they wake up, and like some flower,

they are following the Sun

and aiming the light of the Sun

to the top of the receiver.

[mellow music]

From here, you can see the big difference

between this site and
conventional solar power plants.

There are no solar panels anywhere.

At Cerro Dominador,
they will generate electricity

a completely different way.

[mellow music]

A special liquid made from salt

is pumped to the receiver

at the top of the tower.

[taut music]

Here, the reflected heat from the Sun

raises the liquid's temperature

to a whopping 1,040 degrees Fahrenheit,

as hot as lava.

[taut music]

That molten salt is then
pumped back down the tower

where it's used to heat water
and make high-pressure steam.

That steam drives the
turbine and makes electricity.

[taut music]

Cerro Dominador is
not the first solar plant

to generate electricity this way,

but it aims to be one of the first

to produce power reliably
on demand 24 hours a day.

[taut music]

Conventional batteries
are much too expensive

to use on this scale.

So to generate electricity
through the night,

Cerro Dominador has two giant storage tanks

at the bottom of the tower.

Here we have the tanks.

The salt today is here melted,



waiting for being pumped
to the top of the tower.

[taut music]

The salt from a nearby
mine in Northern Chile

consists of sodium and potassium nitrates,

which have the ideal properties

to store heat safely and reliably.

Once on site, the salt was melted,

then the liquid was stored in a tank.

Despite being 600 degrees Fahrenheit,

this is known as the cold tank.

In the morning, we have all the salt

there in the cold tank,


During the day, the salt is being pumped

to the top of the receiver,
to the top of the tower.

In the receiver, we heat the salt,

and we start to fill the hot tank.

So during the day, the
cold tank is getting empty,

and the hot tank is getting full.

In the hot tank,

the salt is stored at


The tanks are so well-insulated

that the temperature only
drops one degree per day.

During the full night,
we are using that salt

to generate the steam.

And at the end of the night,

again, we have the cold
tank completely full of salt,

and this is the full battery cycle

that allow us to keep
the generation 24 hours

using 100% only renewable energy,

the light from the Sun.

[taut music]

Solar tower technology
with molten salt tanks

can generate solar
electricity on demand 24/7,

but they only work efficiently in countries

with intense sunlight, near the equator.

If power from the Sun is
to truly replace fossil fuels,

we need solar-generated electricity

available day and night, everywhere.

[mysterious music]

A team at the US Naval Research Laboratory

is working on a way to supply solar power

to any place any time.

[dramatic music]

It's called space solar,

and it sounds like something
from a science fiction movie.

The idea of space solar is that

instead of collecting
sunlight on the ground

using a solar panel
the way we usually do it,

is we take that solar panel instead

and put it in space and then send it

to where you need it on Earth.

We kind of take it for granted now

that we can go anywhere on this planet

and take out your phone
and it tells you where you are.

And we can do that because
we have a system of satellites,

the global positioning satellites,

which was also created here

at the Naval Research Laboratory.

And we're talking about
doing the same thing for energy.

Imagine if you could
just go anywhere on Earth

and you wouldn't have to worry
about charging your batteries

or where are you going to plug in,

and just have energy
no matter where you are.

Dr. Paul Jaffe

is the lead engineer on the project.

In 2019, his team set out

to demonstrate a vital
part of the technology

at one of the world's biggest
marine testing facilities,

a prototype system to transfer power

over long distances without using wires.

Instead, the power will
be sent as a laser beam.

So we have here today, a
two-kilowatt laser transmitter.

And we have a receiver that
is made out of photovoltaics,

similar to what you
would find in a solar panel.

And this is really a remarkable capability

that unlocks all kinds
of amazing possibilities.

So the power beam itself is
invisible and completely silent.

The way that we can help show where it is

is with this $20,000 infrared imager.

You can see the transmitter

sending the beam over 325 meters,

so the receiver at this end of the basin,

which converts that back
to electricity for us to use.

You'll notice, though, that
you cannot see the beam

if you just look without an imager.

The aim is to ultimately use

a scaled up version to
send beams of solar energy

collected in space, back to Earth.

The transmitter would be on a satellite,

with the receiver down
in the Earth's surface.

Imagine if we could take the
boundless sunlight in space,

send it effectively to the
ground wherever we need it,

whether it's a refugee camp,

whether it's a developing country,

places that are difficult and expensive

to get energy to today,

if we could do that in a effective way,

it would be truly revolutionary.

[mellow music]

But firing a giant laser beam

at Earth, from space,
might naturally cause alarm.

So Paul's team have
developed a safety mechanism

and are testing it out today.

The system should detect when something

or someone enters the beam,

and instantly shut down.

[mysterious music]

This solar circuit breaker
means the technology

could be used on a much
bigger scale in the future.

[mysterious music]

For now though, Paul's
team are happy to use

the beamed electricity to
make a simple Cup of Joe.

This demonstration has exceeded

our expectations many times over.

We are opening people's eyes

to the prospect for this
revolutionary technology.

[energetic music]

As well as creating safe power beams,

Paul's team have been working for 10 years

on a prototype space
solar module called PRAM.

Its job is to generate solar power

and convert it to a form of energy

that could be beamed to Earth.

To check that the module would
work outside the atmosphere,

the team simulated space inside the lab.

Liquid nitrogen matched the extreme cold,

a vacuum chamber removed the air,

while xenon lamps
mimicked the intense sunlight.

But although space conditions are harsh,

there's more energy available to harness.

In space, it's always daytime

and it's always brighter
than anywhere on Earth.

So you not only have


but it is also brighter.

You never have to worry
about clouds, or nighttime,

or rain, or anything that would interfere

with the collection of solar energy.

[mysterious music]

The next step was space itself.

T minus.

Three, two, one,

and liftoff.

[dramatic music]

After more than a decade's work,

in May 2020, the module launched

aboard the US Air Force
X-37B Orbital Test Vehicle.

[dramatic music]

It almost felt surreal
to think of how it started

as just like a kind of crazy
idea that we proposed,

and got the funding and
resources and support to build,

and finally made it to a point

where we're actually
launching it into space,

and it's operating on orbit,

and it's sending us data,

that we're now going to use

to continue to push
this technology forward.

[mysterious music]

Paul's team are laying the groundwork

for a potential energy
revolution in years to come.

In the meantime, other solar technologies

are already powering ahead.

Solar towers capable
of generating electricity



in sunny countries around the world,

[energetic music]

from Israel to South Africa,

[dramatic music]

while advances in technology capture

more and more of the Sun's energy.

In Australia, RayGen
plan to start harnessing

the heat from their cooling system

to produce another critical
resource alongside electricity.

That byproduct heat, we use

to disseminate water, very cheaply,

and that produces the two
most important resources

that any community needs, power and water.

With power and water, you can do anything.

[dramatic music]

Lightyear have plans for a car

that's so cheap to run
that billions of drivers

would choose solar-powered transportation.

That became the mission of the company,

clean mobility for everyone.

That's what they're working towards.

And first by making, unfortunately,

a rather expensive car
to test the technology,

to show everybody that this is working.

And then the next step is to make it

available to everyone,
to fulfill the mission.

And the spread of solar panels

from land onto lakes and oceans

is opening up an almost
limitless opportunity

to generate clean electricity from the Sun.

I'm very optimistic.

I think technology can
provide the solutions

that we can develop this,

and that we can make this transition.

It's doable, and the
technology is almost there.

[dramatic music]

When it comes to solar,

the future looks bright.

[dramatic music]

[mellow techno music]