﻿Say you wanted to power the entire Earth with solar power. I estimate you would need
around 112,000 square kilometers of at least moderately-efficient photovoltaic panels.
If that sounds like a lot, that’s because it is, but it’s also not. Because those panels
could also all fit in just a little more than 1% of the Saharan desert.
And with the falling cost of solar panels,
it could be done waaaay more cheaply than making the same amount of power with nuclear fuel.
But like we talked about last time, in episode 3, there’s a big problem with relying on renewable
resources like solar and wind: What happens to our electricity when the sun goes down?
Sometimes the rotation of the Earth can be a real bummer.
Another problem? We need reliable ways to store and transmit electricity,
so that it’s available when and where we need it.
And that is going to require a lot more technology and a lot more space.
Hi hi! I’m M Jackson, and this is Crash Course Climate and Energy.
[INTRO]
Electricity rules our lives.
We use it from the moment we wake up and check our phones, when we cook, when we work, wind down,
when we watch YouTube videos, all the way to the end of the day when we switch off the lights…
and watch more YouTube. And then eventually go to sleep.
Electricity won this MVP status thanks to its versatility as an energy carrier.
As tiny particles called electrons flow within conductive materials — think copper,
aluminum, gold, or really any metal — they push energy from one place to another.
And that energy can be used to do anything you could dream of,
or at least, design for. It can heat your home,
it can heat your takeout. It can even help power those agricultural processes
that lead to your takeout, and manufacture the plastic container your takeout comes in.
So, decarbonizing electricity could go a long way to decarbonizing many adjacent industries,
like construction, agriculture, transportation.
But like you can probably guess by this point, that’s easier said than done.
Right now, all of our homes and industries are connected to their electricity supply by
a vast electric grid. Last time, we compared that electric grid to a bucket of water.
Imagine this time the bucket is the grid, and the electricity is the water.
Power plants put water into the bucket, and then,
when you flip the lights on, that water flows through a hose to wherever you are.
Crucially, the utilities companies are the bucket managers: It’s their job to control
the flow of electricity in and out of the bucket and make sure it stays full throughout the day.
Traditionally, power plants that use fossil fuels have produced electricity on-demand,
to effectively pump water back into the bucket to replace whatever is used up.
But as we lean more on renewable resources like wind and solar, we won’t have that flexibility.
We don't get to pick when the sun shines or when the wind blows. And that can lead
to overproduction. Basically, on a really sunny or really windy day,
so much water could be poured into the bucket that it could overflow and damage the whole system.
To avoid this, utility companies do something called curtailment,
where they selectively switch off solar panels or wind turbines at their most productive times.
If you’ve ever noticed a wind turbine not spinning on a pretty windy day and wondered why…
Well, there’s a good chance that’s why.
Let’s head to the Thought Bubble.
The amount of electricity a neighborhood uses varies during the day, depending on
people’s habits. And as much as we like to feel unique, we really are habitual creatures.
In the morning, you and your neighbors get up, turn the lights on, make coffee,
watch YouTube videos. So the load on the electric grid gradually ramps up.
After that, things tend to stay pretty constant during the day, because you’re either gone,
or because you’re working at home with the same lights and same devices drawing power.
But then, comes evening.
People are coming home, it’s getting dark,
so you’re turning on more lights around the house, cooking food, playing music,
chilling in front of the TV. So, the load on the grid peaks to its highest level of the day.
Then, as everyone goes to bed, electricity usage tails off to its lowest levels.
But this curve of “rise, flat, peak, and drop” changes when you add solar panels.
Panels produce most of their electricity during the day,
so they easily meet the demand of the mid-day plateau.
In fact, the electric grid is being asked to supply less power than what’s being produced,
so wind and solar power plants may even switch off to avoid overproduction.
But then comes evening…and it’s like one minute you’re jogging at a comfortable pace,
and the next you’re sprinting full speed away from a bear… or, towards an ice cream truck.
Peak demand happens right when the sun goes down. So, good night, solar power.
The baseload fossil fuel and nuclear power plants suddenly have to step
in to supply all the electricity, ramping up production very quickly to pick up the slack.
This pattern of midday sag and steep evening incline has a name: the Duck Curve —because
if you squint and tilt your head to the side, it kinda looks like a duck?!
Look, we don’t make the names here.
Thanks, Thought Bubble!
As cute as it sounds, the Duck Curve spells trouble for the electricity grid.
It’s really inefficient and definitely not economical
for power plants to keep switching off and then ramping up supply so quickly.
That doesn’t mean solar panels are a bad idea—they’re still carbon-free,
renewable energy! But the way we do electricity just wasn’t made for them.
Now, one way to get around this is to change our habits. That’s called load shifting.
Basically, we could start using most of our electricity when it’s cheapest to generate.
That could mean running the washing machine in the
middle of the night when there’s less demand on the grid. Or it could mean
switching on an electric heater in the day when solar power is most plentiful.
Those individual changes add up! But, as we talked about before and we’ll talk about again,
tackling climate change isn’t just about you; it’s about collaboration.
And even if everybody did midnight laundry,
that wouldn’t be enough to completely flatten the Duck Curve.
Plus, what about when you really need to binge a nature show during peak evening hours?
Or, at any time of the day or night, when a hospital needs electricity
to perform surgeries, take x-rays, keep vital sign monitors running?
For that, there’s another solution: We could level out the Duck Curve by storing
electricity when it’s made in excess, and dishing it out when we need it the most.
For example, any extra electricity solar panels make during the day
could be stored and then used in the evening so power plants don’t have to work as hard.
And there are already multiple ways we could make this happen.
First, you’ve got electrochemical storage, a.k.a. your everyday battery.
Batteries contain charged particles. And when you plug in your phone,
those particles go from one end of the battery to the other and hang out there until you need them.
Then, when you unplug your phone and start scrolling through cat photos,
the particles release energy by whipping back to the other side of the battery,
generating an electric current as they go.
Batteries are fast and easy to charge, they’re relatively safe and portable,
and they can hold their energy for a very long time.
The trouble is, electrochemical batteries often use metals that are rare on Earth,
so assembling enough of them to store electricity for an entire grid would be costly.
To extract these rare Earth minerals, you would need big mining operations that would
damage the environment. Which is kind of the opposite of what we’re going for here.
So instead, excess electrical energy could be stored by chemical means.
We’d use extra electricity to split water molecules into hydrogen and oxygen,
in a process called electrolysis. Then, when we needed electricity later,
we could generate it using a hydrogen fuel cell.
Here, the hydrogen enter a chamber with a special membrane. The membrane lets part
of the hydrogen atoms pass through: their positively-charged protons.
But the negatively-charged electrons have to take a different path to the other
end of the fuel cell. And that stream of electrons creates an electric current.
The only waste product here is water, so this is a carbon-free option that
uses and regenerates one of the Earth’s most abundant resources.
The catch? Hydrogen is a really lightweight gas, meaning, its molecules are quite spread out.
So, it takes up a lot of space and is difficult to compress into small containers for storage.
So, there’s a third option that’s carbon-free,
and it deals with regular, un-split water: it’s called mechanical energy.
When there’s electricity to spare,
water is pumped to the top of a big hill and kept there in a reservoir.
Then, when the electricity is needed again,
water is released to turn a turbine and generate power on-demand.
This is basically the same technology as a hydroelectric dam: You just add
an uphill pump. So, this is something we could actually develop relatively easily.
But it’s not the most efficient technology.
You need a huge space and at least one big hill for a reservoir,
if you’re going to rely on gravity alone. Sorry, Kansas.
So, the last option is thermal energy storage.
Here, excess electricity is used to heat a material with a high
boiling point, like molten salt. Some salts don’t melt until they
reach several hundred degrees Celsius, so they’re really not something you want to
put on your fries… because your food would immediately catch explosion, pardon, fire.
But these salts are a good heat source.
So, when the demand for electricity increases, the heat from the salt can be transferred to
water to make steam, turn turbines, and generate the electricity we need.
It seems simple, and existing fossil fuel plants could even be repurposed
to contain thermal storage and steam generators.
Except, molten salt also has a bad habit of corroding everything it touches. And fighting
that is a constant, expensive battle, so is keeping the salt hot enough to stay liquid,
especially if you want to do that with renewable energy.
As great as they are, renewable energy sources like wind or solar just don’t
have a high energy density compared to fossil fuels.
In other words, to generate the same amount of energy as a fossil fuel power plant using
solar panels, you’d need anywhere from 25 to 2000 times as much space.
Compared to fossil fuels, all these storage options can have
a high Green Premium, or upfront cost difference.
So, there is one more path: We start sharing buckets across locations, even time zones.
In other words, instead of saving spare electricity for when we need it,
we could transmit that electricity to somewhere that needs it right now.
Connecting grids over wider areas would allow utility companies to deliver electricity more
efficiently and more equitably. And it could overcome some of the limitations with renewable
energy: One region that’s super sunny could send power to a city that’s a bit more overcast. [Phone rings]
This is Seattle… Hey Phoenix!
Unfortunately, this is hard with the grids we have at the moment.
Our buckets only serve certain regions. Unless you happen to
be near Indianapolis right now, my region’s electricity bucket, not connected to yours.
But this is starting to change!
For instance, the TransWest Express in the US (say that three times fast) is planning to take
wind power from Wyoming and deliver it all the way to California, over a thousand kilometers away.
Big regional projects like this will help each state reduce its emissions,
while requiring fewer solar panels and wind turbines than if each state powered itself alone.
You know what they say: Team work makes the dream work!
In the end, decarbonizing electricity won’t have a single solution,
like filling part of the Sahara with solar panels.
I mean, if transmitting electricity between states is hard right now,
imagine the challenge of transmitting electricity from one part of Africa
to the rest of the world! And that’s not even mentioning how we’d store it.
So obviously, collaboration will be key here.
Some regions might work on advancing batteries,
while others might focus on connecting grids. And you — you might contribute to research,
or policy, or tech, that furthers the conversation in areas you’re interested in.
Figuring out the best ways to store and transmit electricity
won’t be easy. But the payoffs will be huge.
Because whatever strategy we come up with won’t just help us make carbon-free
electricity. The advancements will affect all other big, carbon-emitting sectors,
like transportation or heating our homes.
We’ll get into that next time.
Special thanks to Harry Brisson, this episode’s combination bucket manager, wind turbine wrangler,
and duck curve illustrator. You really held it down this episode, Harry.
Thanks for keeping the lights on and the buckets from overflowing — and for supporting us on Patreon.
Crash Course Climate and Energy is produced by Complexly with support provided by Breakthrough
Energy and Gates Ventures. This episode was filmed at the Castle Geraghty Studio
and was made with the help of all these nice people. If you want to help keep
Crash Course free for everyone, forever, you can join our community on Patreon.