MAREN:
The sun releases more energy
in just 1.5 millionth of a second
than we humans on planet Earth consume in a year.
That's a lot of power.
Which is why solar will likely play a huge role
in our quest for a cleaner, more secure energy future.
The sun generates all of this energy
through a process called fusion.
But what exactly is fusion,
and how does the sun generate so much energy?
The sun is a massive nuclear powerhouse
that can raise temperatures in the Australian Outback
to an incredible 50.7 degrees Celsius.
That intense energy is perfect for fueling race cars
competing in the World Solar Challenge.
DEREK:
As you can see,
this is a very inhospitable environment.
You know, it's funny being out here,
you feel the power of the sun.
It gets so stinking hot.
And of course, it is that very energy
which is propelling these cars down the road
at incredible speeds.
And in the World Solar Challenge,
cars from over 20 countries
have to power across the whole continent,
going 3,000 kilometers, over 1,800 miles,
to claim the title
of world's fastest solar vehicle.
MAREN:
that makes all of this possible
is 150 million kilometers away
and involves subatomic particles.
You may know that atoms, which make up all matter,
have a nucleus at the center
made up of protons and neutrons,
with electrons zipping around the nucleus in a small cloud.
Fusion happens when two atomic nuclei
are forced together
in extremely high-energy conditions.
Now, keep in mind,
this is different from what happens
when atoms link together using their electrons,
like when two hydrogen atoms and an oxygen atom
come together to form water.
That's called bonding.
But in fusion,
the nuclei of the atoms themselves
need to smash together to form a single nucleus,
and this process releases massive amounts of energy.
Okay, so, now that we've got our heads wrapped around
the very basics of how fusion works,
let's take a look at how it happens in the sun.
First off, it takes a lot of energy
to force the nuclei to come together
in the first place,
because protons, all with the same positive charge,
repel each other.
You know, like magnets.
You may recall that principle
that like charges repel
while opposite charges attract.
However, the sun is so massive,
roughly 1.392 million kilometers in diameter,
that it has an insane amount of gravity,
meaning there's an incredible amount of pressure
exerted on all those hydrogen atoms
that make up the sun.
Now, solar fusion happens inside the sun's core,
where the pressure is so intense
and the density is so great
that those like-charged protons
of those hydrogen nuclei
smash together to form helium.
If we want to break things down
in even greater detail, which we do,
we'll have to talk about something
called the proton-proton cycle.
The energy radiated by the sun
is really the result of a series
of thermonuclear reactions.
The first step in the reaction...
two hydrogen nuclei collide
to produce what's called deuterium,
a hydrogen nucleus
with one proton and one neutron.
See, most hydrogen atoms have only one proton
and no neutrons.
Next, a third hydrogen proton
smashes into the deuterium nucleus
to make a tritium nucleus, or a triton,
a nucleus with one proton and two neutrons.
When two of these tritium nuclei fuse together,
they form a helium-4 nucleus
with two protons and two neutrons.
This fusion also releases two protons,
allowing the cycle to continue.
Two hydrogen protons collide,
a third hydrogen proton joins the party,
two of these tritium nuclei fuse together,
two protons are released.
Repeat, and repeat, and repeat
until the sun runs out of hydrogen.
Got it? Great.
It is a complicated process.
After all, it's literally thermonuclear physics.
So, if you want to go and run that animation back,
go ahead and rewatch
that proton-proton cycle animation.
Now, you may be asking,
how much energy does this process generate?
Well, scientists have calculated
that at any given moment,
the sun releases
an estimated 384 yotta watts of energy.
Never heard of a yotta watt before?
Because me neither.
But using scientific notation,
that's 3.84 times 10 to the 26th power.
So, 384 with 24 zeros behind it.
We barely have enough screen
to actually show all of those zeros.
Saying that's a "yotta" power
would be a gross understatement
and a groanable pun.
And because nuclear fusion doesn't produce unstable,
long-lived radioactive waste like nuclear fission does,
that's the splitting of an atom,
instead, fusion results in a stable,
non-radioactive by-product of helium.
So, scientists are exploring
how to develop this as a viable energy source.
But as many of our secret viewers have noted,
fusion technology always feels like
it's just a few decades away.
Now, while most of the sun's energy
is scattered across our solar system,
researchers have estimated that 430 quintillion joules
of the sun's energy
hits the surface of the Earth
roughly every hour, or hour-and-a-half.
With current estimates
of total world energy consumption
at 580 million terajoules annually,
that means, theoretically,
if we could effectively harness all of the sun's energy
that hits Earth for just two hours,
we could power our entire planet
for more than a year.
Clearly, this isn't a reality, at least not anytime soon,
but solar energy is helping power a worldwide shift
to cleaner, more sustainable energy.
And there have been some
incredible innovations in recent years
as the technology has become more and more efficient.
So, next up, we take a closer look at solar panels
and break down the technology
that powers our homes and cities,
and can transform sunlight into horsepower.