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Trash Batteries & 4 Other Weird Ways to Store Energy
Trash Batteries & 4 Other Weird Ways to Store Energy
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0:00
Are you one of those people who starts stressing
0:01
out when their phone battery drops below 50%?
0:04
Or do you like living on the edge,
0:05
regularly seeing a single digit number up in that corner?
0:09
Either way, you probably think about energy storage a lot.
0:12
But probably not as much as the people who are
0:14
responsible for maintaining our municipal power grids.
0:17
There’s a huge variation in how much energy
0:19
gets used at certain times in certain places.
0:21
And whether you’re storing energy to power
0:24
a city or your iPhone, it requires batteries.
0:26
Typical batteries store energy in the chemical
0:29
bonds within materials, usually a set of metals.
0:32
To get this energy out, other materials in the battery chemically
0:36
react with these metals to remove some of their electrons,
0:40
which are then used to generate electricity.
0:42
Hence the name electrochemical batteries.
0:45
But if we get creative, we can store energy using
0:48
way more and potentially way weirder methods.
0:52
Like using water, rocks, and even soil!
0:55
So let’s break down 5 weird ways to store energy.
0:58
[♪INTRO]
1:02
The first example on our list today
1:03
is called pumped storage hydropower.
1:06
Or, more informally, water batteries.
1:08
As you might have guessed, water batteries store energy in water,
1:12
and they do this through the power of gravity. Here’s how it works:
1:15
We start off with a large reservoir of water.
1:17
When we want to store energy, we pump the water from this
1:20
reservoir up to another reservoir on higher ground using a turbine.
1:24
Because we had to fight against gravity to get that water up there,
1:27
it now holds energy in a form called gravitational potential energy,
1:32
which is kind of like an energy IOU with gravity.
1:35
When we want to use this energy,
1:36
we cash in this IOU by having gravity take over
1:39
and letting the water flow back down to the lower reservoir.
1:43
All that moving water is used to spin a turbine and generate electricity.
1:47
Water batteries are usually ginormous in scale,
1:50
both in terms of physical size and in terms
1:52
of how much energy they can store.
1:54
And as long as the top reservoir is fully enclosed,
1:57
these batteries can basically store energy for forever
2:01
without any loss due to evaporation or leaks.
2:04
This means they’re often used in the power grid to store backup
2:07
energy in case of emergency, like storms or equipment failures,
2:11
or just when demand gets a little too high.
2:13
Also, if the grid has inconsistent energy sources,
2:15
like solar or wind power, water batteries can
2:18
save any excess energy for later
2:21
like when it’s dark or, you know, not windy.
2:24
In fact, water batteries are so good at storing
2:27
backup energy they’re used almost everywhere.
2:30
More than 90% of grid energy storage in
2:32
the world uses water batteries!
2:34
And right now, the largest is located at the
2:37
Fengning power plant in northern China.
2:39
Physically, the upper reservoir can hold 45 million cubic meters of
2:43
water, which is enough to fill around 18,000 Olympic swimming pools.
2:48
That amount of water translates to about 40 gigawatt-hours of energy,
2:52
which is enough energy to meet 340,000 people’s needs for a week.
2:56
But as gigantic as Fengning seems, there’s another water battery
3:00
under construction in Australia that should shatter this record.
3:04
This project, called Snowy 2.0, is an expansion upgrade
3:07
to the existing pumped-hydro power plant called Snowy.
3:11
Snowy 2.0 is supposed to begin operation in 2029,
3:14
and is designed to store nine times more energy than Fengning.
3:19
That brings it to a storage capacity of 350 gigawatt-hours,
3:23
which is enough for 3 million people for a week.
3:26
Now, it’s worth noting that water batteries
3:28
aren’t a perfectly efficient form of energy storage.
3:31
You expend a lot of energy pumping the water into that upper reservoir
3:35
that you don’t get back out when you let the water flow back down.
3:38
For example, over the course of one year,
3:40
the plant at Fengning uses about 8.7 terawatt-hours
3:44
of energy to generate about 6.6 terawatt-hours of energy.
3:48
That translates to an efficiency of 76%, which isn’t
3:52
amazing for a water battery, but it’s certainly not terrible.
3:55
And anyway, I’d rather have an inefficient backup than no backup at all.
3:59
Water batteries aren’t the only way we can store energy using water.
4:02
Another way turns the concept of water batteries upside down.
4:05
This technology, called geomechanical storage,
4:08
stores energy by pumping water 300 to 600 meters
4:12
underground into pockets between rocks.
4:15
The pressure from the water pushes against the rocks, slightly
4:18
deforming them, and it’s within this deformation that energy is stored.
4:22
To retrieve the energy, we release the pressurized water
4:26
out of the ground and, once again, use it to spin a turbine.
4:29
Like water batteries, geomechanical storage is intended for
4:32
large-scale grid applications, serving as backups for blackouts or
4:37
energy supplements for inconsistent renewable energy sources.
4:40
This tech is also fairly new. One company called Quidnet Energy
4:44
has been working over the past several years on a
4:47
megawatt-hour-scale commercial storage system.
4:50
Recently, they demo’d storing 35 Megawatt-hours of energy for
4:54
six months, enough energy for 300,000 people for a week.
4:58
Quidnet predicts that their final system
5:00
will have an energy efficiency of around 50%.
5:03
While that number might sound like
5:04
a major downgrade from Fengning’s 76%,
5:08
the technology’s selling point is that it’s much
5:10
easier and cheaper to install than water batteries.
5:13
You know what’s also cheaper than building a battery
5:15
big enough to support a city’s worth of people?
5:17
Making a YouTube video about those batteries.
5:20
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6:03
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6:06
An energy storage technology that’s further along than
6:09
those water-plus-rock batteries are thermal batteries,
6:12
which store energy in the form of heat.
6:14
To do this, we first generate heat by operating
6:16
what is essentially a giant toaster, running an
6:20
electric current through a highly resistive material.
6:22
The heat this generates is used to warm the thermal
6:25
battery to a blazing hot temperature, which can range from
6:28
around 500 to 1700 degrees Celsius
6:31
depending on the material we’ve chosen.
6:33
Also, to prevent that heat from escaping,
6:35
we also need to insulate this hot material really well.
6:38
When we want to access that stored energy,
6:40
we just open the insulation, or blow air across
6:43
the hot material to carry the heat away.
6:46
This hot air can then be used to do work,
6:48
such as heating a space directly, or turning water into
6:52
steam that can then be used to, yet again, spin a turbine.
6:56
Why does everything come back to turbines?
6:58
For their heat-storing materials,
7:00
thermal batteries typically use bricks, rocks, sand, or molten salts.
7:04
These all have a high specific heat capacity,
7:07
meaning they can absorb a ton of energy before getting hot,
7:11
allowing thermal batteries to pack more energy into less space.
7:14
Because thermal batteries naturally output energy as heat,
7:18
they work best for industrial manufacturing processes
7:21
that can directly use that heat, such as furnaces or kilns.
7:25
And in such cases, thermal batteries can
7:27
operate with very high efficiency, like around 95%.
7:31
Meanwhile, if we want to turn the released heat back into electricity,
7:34
things get a little bit more complicated.
7:36
As I said earlier, we could do this with a steam turbine.
7:40
But this only works for the batteries operating at lower temperatures.
7:43
Above 1500 degrees Celsius, turbines
7:46
literally start falling apart from the heat.
7:49
So instead, some researchers are looking into
7:51
a technology called thermophotovoltaics, or TPVs.
7:55
This technology basically works like solar cells,
7:57
but instead of turning sunlight into electricity,
8:00
it turns infrared radiation into electricity.
8:03
Which our sun also emits, but TPVs are
8:05
focused on more down-to-Earth sources.
8:08
The efficiency’s still fairly low, though.
8:10
One of the best prototypes still only hits about 44%.
8:14
But even without a great way to turn heat into electricity,
8:17
thermal batteries are still operating in the real world.
8:20
Today, the largest operating thermal battery is in
8:22
the Ouarzazate Solar Power Station in Morocco.
8:25
It can store 2800 Megawatt-hours of energy using molten salt…
8:30
which I should probably clarify is not, like,
8:33
regular table salt, but a mix of other salts.
8:36
Which are not just inedible, but can be hazardous if swallowed.
8:41
So sadly, no. You can not use this battery as a salt lick.
8:45
But heat isn’t the only way to store energy.
8:47
We can also crank the temperature all
8:49
the way down and make ice batteries.
8:51
To do this, we first freeze water or some other liquid into ice.
8:55
We then use that ice to cool a place down.
8:58
To extend the ice’s reach, we can also use it to cool a liquid
9:02
that then gets sent off to circulate somewhere farther away.
9:05
Now technically, we aren’t really storing energy here,
9:09
at least not in the same way I’ve talked about previously.
9:12
Because when we freeze stuff, we’re actually pulling energy
9:15
out of the material, not pumping it in to be accessed later.
9:18
We can still colloquially refer to this system as “energy storage”
9:22
because we’re doing work to make ice now so we don’t have to do the
9:26
work again later when we actually want to make something colder.
9:30
To get the best ice batteries, we want to use materials that have a
9:33
high latent heat of fusion, which means they require a lot of energy to
9:37
physically switch from being a liquid to a solid, or vice versa.
9:42
That way, the ice can provide a larger
9:45
“cooling energy” stockpile to draw from later on.
9:48
Many ice batteries rely on good ol’ H2O, water.
9:51
But pure water famously freezes at the
9:53
relatively low temperature of 0 degrees Celsius.
9:56
Since an ice battery also needs to maintain this temperature to work,
10:01
you might want to use something with a higher melting point,
10:04
like paraffin wax.
10:05
Meanwhile, other ice batteries use salt hydrates,
10:08
which is basically just a fancy way of saying you’ve
10:10
got a bunch of salt crystals with water molecules
10:13
incorporated into them, rather than a bunch of salty water.
10:16
While some salt hydrates freeze at higher temperatures than water,
10:19
they also tend to freeze and melt unevenly,
10:22
which hurts their effectiveness as ice batteries.
10:24
Plus, all that salt can corrode the battery’s equipment,
10:27
which isn’t great unless you’re an HVAC company
10:30
looking to put some planned obsolescence into your tech.
10:33
But with all that said, ice batteries are still helpful
10:35
for making our A/C needs more manageable.
10:38
At night, we can stockpile ice when electricity is cheaper to use.
10:41
Then, during the day, when electricity costs are at a premium,
10:44
we can rely on the ice for cooling instead
10:46
of drawing electricity to power the A/C.
10:48
So not only do ice batteries save us money,
10:51
but they also help keep our power grid happy
10:53
by reducing the strain on it during peak usage hours.
10:56
And yes, ice batteries are also out there in the real world,
10:59
though they’re not super common.
11:00
One example system is at 11 Madison Avenue in New York City.
11:04
Every day, the building freezes 227,000 kilograms of ice,
11:08
enough to fill three city buses.
11:10
That ice equates to “storing” 22.5 Megawatt-hours of energy,
11:15
enough to last 193,000 people for a week.
11:19
And just like the molten salt battery,
11:21
I do not recommend sticking your tongue against the ice block,
11:24
even if it’s one made of just water.
11:26
Nor do I recommend licking the final energy storage system on this list.
11:30
Remember the very beginning of this episode
11:31
when I said energy can be stored in chemical bonds?
11:34
Well our final piece of tech takes
11:36
advantage of this type of energy again.
11:38
But this time, we’ve got microorganisms to help us get the energy out,
11:42
and a microbial fuel cell or microbial battery.
11:45
In microbial batteries, microorganisms such as bacteria, algae, and
11:49
fungi digest biomass by stripping electrons off the biomass’s atoms.
11:54
These electrons are then directly used to generate electricity.
11:57
The “biomass” in these batteries is typically soil or wastewater.
12:01
And with wastewater, we get the added
12:03
bonus of reducing our giant piles of, well, waste!
12:07
So yeah, don’t lick the sewage battery…
12:10
Unlike the energy storage systems I’ve covered so far,
12:13
microbial batteries put out way less power.
12:15
Instead of sustaining an entire city’s worth of people for several days,
12:19
or even a single building, they work best for smaller scale applications,
12:23
like powering irrigation switches that control water sprinklers on farms,
12:28
or powering sensors for measuring wastewater pollution.
12:31
But researchers are working on ways to boost
12:33
how much power a microbial battery can pack.
12:36
Some are testing different architectures,
12:38
some are looking for new materials.
12:40
One state-of-the-art microbial battery described in a paper from
12:43
2024 achieved a power density of 10 milliwatts per square centimeter,
12:48
which is about 100 times less than a top-tier wireless phone charger.
12:52
But let’s let ‘em cook. Maybe one day, we’ll be living in a
12:55
world where you can buy your own microbial fuel cell…
12:58
Feed it like a sourdough starter,
13:00
give it a name like your sourdough starter….
13:02
And then you can thank it when it saves
13:04
you after you realize your phone is at 3%.
13:07
[♪OUTRO]
