- This is 4,000 acres of mirrors.
As you drive south away from Las Vegas,
you come across enormous shining towers.
But the amazing fact is that the towers are actually
pitch black in color.
And the light is shining up from the ground
because this site is a $2.2 billion solar energy field.
I'm Dianna and you're watching physics girl,
and we're gonna go inside a power plant
with the same technology as that one.
I was approached by Toyota,
who offered to sponsor a series on renewable energy,
and you have made it to the final video in that series.
But why?
Why did we do a road trip for two weeks across California
on a car powered by hydrogen fuel cells?
We, I want a future with cleaner air,
a future where we were not using an energy source
that's gonna run out.
And I learned that the roadmaps to get us to zero emissions
by 2050 are very exciting, but we have a lot of work to do.
Most people think of photovoltaics
when they think of solar power,
the solar panels on your roof,
but there's a whole other technology.
Have you guys seen this?
This is not a simulation.
I've been pass the first
concentrated solar site that I ever saw.
And I was like, pull over.
We have to figure out what this thing is.
- So it doesn't convert sunlight directly to electricity
like photovoltaics does.
It uses lots of mirrors to generate heat
by concentrating the sunlight,
focusing it onto something to heat it up.
- I found out later that it's this technology called
concentrated solar power, CSP.
That's super promising.
It's been around for even longer.
And there's a ton of potential to pair it
with energy storage, which is the whole reason
we made the last video.
Plus those mirrors look so cool.
That's the technology we're gonna talk about
in this entire video.
I was like a kid in a candy store.
So how does concentrated solar power work?
I think that you guys, at the spine,
get the sense that nearly everything runs with a turbine,
Really? No?
Coal power plant? turbine.
Hydroelectric? turbine.
Grid-scale stuff that involves heat
often involves a turbine.
The same is true here.
The ultimate goal of concentrated solar power
is to drive a turbine.
The sun hits mirrors that then reflect
to a special material and heat it up,
and that material boils water,
and then the steam drives the turbine
that creates electricity.
And we took a look at this process during a tour
of the Mojave Solar Project.
To be clear, the plant that we toured looks very different
from the solar towers I was talking about.
It's actually parabolic mirrors instead of the towers,
but conceptually it's very similar.
Using mirrors to concentrate solar light.
And we got access to Atlantica's parabolic mirrors
to learn how concentrated solar power work.
- So we can work a little bit backwards
on how the energy actually gets to the grid.
And then it will work all the way back to the sun.
- So please, join us on the rewind tour.
As we started the tour there was a dress code.
We had to wear long sleeves, long pants.
When we went into some of the places
like the turbine room, earplugs.
- On the other end of the dark gray building
is where the steam turbine is.
- That was, I think, the loudest place we went.
- That's the high pressure turbine there.
And that's the exhaust of that turbine.
- So after we went to the turbine room,
I think he asked like, do we want to go to the top?
And before anyone could say,
I don't know if that's a good idea.
I was like, "Yes!, I wanna go to the top".
- Wanna go up there?
- Yeah, sure.
- All right.
- It was high. We were climbing rungs.
Holding these really thin rungs with super sweaty hands,
and through that, like, cage-like thing.
We didn't film any kind of interesting conversations,
but a couple of things that we could see
was out to the towers where the electricity
is transmitted to the grid.
And then we could finally see for the first time
how big these facilities are.
You get up to the top and then you look out over this ocean,
sea of mirrors out for one mile.
Turn around, another mile in the other direction.
I didn't mind that I couldn't hear anybody
'cause I just wanted to soak it all in.
A single plant like this can power over 200,000 homes.
We're talking, saving hundreds of thousands of tons
of CO2 emissions every year.
So going backwards.
so we've got turbine and we got one that go with steam.
So where the steam is created as where the material,
the hot material's coming in and creating steam.
These are the steam generators?
- Yep.
It's actually a natural circulation.
So the bottom part is where you're boiling the water.
The water is going up
and you have the steam drum on the top.
Is dripping back down
and creating a natural circulation loop.
So it's really cool stuff.
- I remember being really curious,
like I didn't really understand
how the material that came in,
they call it the heat transfer fluid,
how it came in and, you don't let it
just flow with the water.
- Inside here, if we were to take this out,
there's thousands of tubes.
The heat transfer fluid should be coming in here, all right?
They're at a U, and then it comes back and goes out.
- That was the really cool thing that I learned.
Is that it's not just creating steam,
is creating something called saturated steam,
where steam, which is like the gas form of water
and liquid water exists together at the same temperature
because it's at such high pressure.
And then that's a lot to expand out later,
once it gets to the turbine in order to push the turbine.
And then he pointed out where
the heat transfer fluid is coming in.
- It looks like we're coming in here
and then out this way, like that.
- So that's moving all the heat transfer fluid around.
- I have to talk about what is getting heated up
by the sunlight when it hits the mirrors.
Again, this plant works differently
than the solar towers near Vegas.
Instead of a big tower,
the light is being reflected at glass tubes near the mirror.
So there's these tubes that carry a synthetic oil
that they call it the heat transfer fluid or the HTF.
That oil gets up to about 400 degrees Celsius.
It's just continually flowing in a circle
around the entire power plant.
I can't believe they had all these numbers,
but there's 2 million gallons of this stuff.
Is it the same fluid that's been in there
since the beginning? - Yep.
- And then we went on to the best part.
Step number one on the energy process is the mirror itself.
Well, there's a sun, but you know, we didn't visit that.
Oh my gosh. Wow.
Oh my gosh. It's so bright.
Woo. That was so amazing.
One really interesting thing was that
the tubes carrying the heat transfer fluid
right up where the mirrors were,
they expand in length.
- It's going to grow maybe half a meter
when it goes from cold to hot.
That's like just having a little expansion,
like a slinky almost, except for it's seal
- The mirrors themselves are parabolic
and they track the sun so that the sun rays come in
and are reflected and focused up to the tubes
running across the center at the focal point of the mirrors.
- We have 282 kilometer of this too.
Right. So from here, if you wind them all up in a row,
you can go to Vegas.
- And they're exactly at the focal point,
the guy kept mentioning, he was like,
"Yeah, we can walk up to it,
and you'll start to feel when it gets hot."
And he was like, "I think we can get up to about here."
We got up to about there.
And we were like, oh, back up.
- You feel that, right? - Oh. Yeah.
That's hot - Oh yeah.
- [Woman] And our poor cameras kept over-heating.
- [Man] Oh, that's true
- So toolsty.
And we can tell, as soon as they took the mirror
that they moved down for us and focused it back,
that was, probably, the most magical moment for me.
Because the entire tube looked like it froze over.
Wow. Oh my gosh, that was cool.
Not every plant uses synthetic oil though.
In some of the solar towers,
the heat transfer fluid is molten salt.
In some of the towers, the light directly
heats the water to create steam.
And there are newer plants
looking at other materials like sand.
We're gonna get to that in a minute.
So why don't we see more of these sites?
Well, there's a few challenges
for concentrated solar power.
For one, photovoltaics are very cheap.
Also there's a limited number of contracts.
I came into this entire series being like,
"We're gonna learn about the best technology
and that's gonna be the one that goes in everywhere."
But I realized very quickly, it's not that simple.
There's a lot more involved in power purchase agreements.
So we talked in the last video about
how sometimes these renewable energy plants
can sometimes produce more energy than the grid needs.
And at this site, they told us they've done that
where they've turned down the turbine,
because if they produce more electricity
than they're contracted to,
they're gonna be charged money for it.
But the way a lot of experts are looking to get around this,
is by adding energy storage.
I was really curious about
what the future is gonna look like.
So I reached out to Cliff Ho,
who's a scientist at Sandia National Labs,
who is one of the lead researchers
in concentrated solar power.
- What you looked at, was called a parabolic trough.
And the difference between that
and these large towers that you might see,
it's the towers that are receiving more attention
to get to the higher temperatures
which can enable higher efficiency.
- So Cliff's project just got awarded
one of the biggest DOE grants.
This is what's different and exciting
about Cliff's technology.
- And so the department of energy, basically,
they put out a call earlier this year.
Secretary Granholm announced they had selected our team
and the Particle Pathway.
And it basically has the advantage
of going to very high temperatures,
well over 1,000 degrees celsius.
- The efficiency of your engine, your heat engine
depends on the temperature of it.
So the hotter you can get the hot thing,
the higher the efficiency.
This is just called the Carnot efficiency of a heat cycle.
So that's what they trying to do.
- [Dr. Cliff] The synthetic oils parabolic troughs
about 400 degrees Celsius.
A power tower, the towers with molten salt,
about 600 degrees Celsius.
And right now with our particles,
you know, we can get over 1,000 degrees Celsius.
- By using these particles that look like sand,
their falling particles, like a waterfall of sand.
- So everything is just gravity driven.
That's kind of cool. Everything just falls by gravity.
- And then the sun is all concentrated up to that sand,
heats that up directly.
And then the sand is brought back up on an elevator
and that's the innovation.
It seems pretty simple, you just heat up sand.
But the thing that's so innovative about it
is that it incorporates energy storage.
Because renewables are intermittent.
The sun only shines during the day
and the wind doesn't blow all the time.
And since our grid is on demand,
then you need storage for the other times.
- If you don't have storage
with concentrating solar thermal power,
you might as well just go with photovoltaics.
- So when I first heard about this, they're like,
"It's the solar energy that produces solar
after the sun goes down."
And I was like.
- So the existing systems, you know,
today there's nearly 30 gigawatt hours of storage globally
with the CSP systems that currently exist.
And in many of those existing systems,
they're storing it for 10 hours.
The discharge can be for over 10 hours
and sometimes are even 15 hours.
So in other words, you're running the turbine.
You're generating electricity at its capacity,
nameplate capacity for long period of time.
- It takes some time for the stuff to cool down.
You can just store heat in the sand or in the molten salt,
and then use it at night time.
And actually Atlantica, the company that owns
the Mojave Solar Project, owns another site
that already incorporate storage.
So that is the promise of concentrated solar power.
Basically this technology is looking to improve
cost of materials, availability of materials, efficiency,
so getting hotter.
And storage.
right now, what we're seeing
is it's starting to solve a modern problem.
As they say, in the energy sector,
"Modern solutions for old pollution."
They don't say that, but they should.
Thank you so much for watching.
If you haven't seen the rest of the videos in this series,
I will link them in the description.
Thank you to Toyota for sponsoring this series.
Thank you to you guys so much
for coming with me on the road trip.
Thank you everybody who contributed research.
I learned so much.
I hope you learned something too.
Happy phisicssing.
(Happy upbeat music)