If renewables like wind and solar energy are ever going to truly make a difference in the
energy game, we’ll need to solve one major issue — energy storage.
There are all kinds of proposed solutions — from the classic lithium-ion batteries
to more ambitious ideas like pumped hydro and other mechanical batteries. But what if
we could store the energy produced by wind turbines and solar panels… in sand?
One energy company in Finland has developed the world’s first sand battery! But how
will this battery impact the day-to-day lives of people in Finland? Could this breakthrough
be the energy storage solution we’ve been looking for, or is it just another pie in
the sky fantasy bound to come crumbling down?
Let’s dive in.
Energy storage is a bit like Goldilocks and the three bears. There are solutions that
are energy dense, but too expensive. There are options that are cheaper, but can’t
store as much power. That leaves researchers and companies on the look out for the solution
that’s juuust right.
Finnish energy company Vatajankoski have made a major breakthrough in renewable energy storage,
and it just might prove to be an utter gamechanger in the way European families heat their homes.
The company calls it the world;s first “sand battery.” At a power plant in the town of
Kankaanpää, sits an enormous silo, 13 feet (four meters) in diameter and about 22 feet
(seven meters) high. But, instead of grain or food products, this massive tower is filled
to the brim with 100 metric tons of sand — that’s the equivalent weight of about 46 Tesla Model
S’s!. The sand is nothing special in and of itself, standard, low-grade sand typically
used in construction, but you might be surprised at how much potential lives inside something
so simple.
See, sand has an incredibly high melting point — above 1700°C (3090°F), which is about
how hot the space shuttle gets as it re-enters earth's atmosphere! For reference, ​​the
melting point of iron alloys and the melting point of steel occur between 2,200-2,500 Fahrenheit
(°F) / 1,205-1,370 Celsius (°C). LINK Which means sand can take quite a bit of heat and
still keep its form!
But not only can sand quite literally take the heat, it can hold onto that heat for a
very long time. Sand has what’s known as a of 0.06W/m²·°С, which increases its
ability to hold heat for a prolonged time. A 1-kilogram container of sand will cool from
104 degrees F to 68 degrees F in 5 hours, 30 minutes.
Basically, sand can retain heat for extended periods of time, that’s why beach sand can
still feel hot on your bare feet even after the sun has gone down!
Why does all this matter? Well, because heat is just one form of energy. As we’ve mentioned
in past videos, energy can neither be created or destroyed, it simply changes form.
What this Finnish energy company has done is found a way to harness power generated
from renewable sources like wind and solar and store it as heat in these sand silos!
Essentially, electricity from wind and solar is converted into heat using what’s known
as resistive heating. This is a process by which an electric current passes through a
conductive material (the resistor) where the heat is released. The greater the resistance
of electricity encounters, the more heat is created. LINK
Like any other storage systems, when the renewable sources produce more energy than required,
its directed into the sand. Instead of trying to move electrons from one electrode to theother,
or power pumps to send water into a reservoir, a sand battery uses resistive heating to increase
the air temperature, which then gets transferred into the sand via a heat exchanger.
When energy prices are high, the system discharges heat that then warms water for Vatajankoski’s
district heating system. That water then gets pumped to homes, offices, and even the town’s
swimming pool! LINK
The current model of the sand battery has a capacity to store up to 100 kW of heating
power in addition to 8 MWh of energy storage! Right now, the current sand battery provides
service for around 10,000 people.
But, the company says this is just the initial phase. Eventually, they plan to build batteries
20 meters across and 10 meters high! This could increase capacityto roughly 1 GWh, or
1 million kWh. LINK
So, at this point you might be asking… why sand? And that’s a great question. PLAY
VIDEO 00:02-00:04
For one thing, the process is incredibly low cost. Right now, as of 2022, the average price
of construction sand in the US is about $10 per metric tone! Compare that to , the average
price of battery-grade lithium carbonate which was estimated at 17,000 U.S. dollars per metric
ton in 2021! LINK
This also makes the process easily scaleable — want more heat? Just add more sand!
The battery also uses no consumables and runs fully automated. Polar Night Energy, one of
the companies behind the battery, claims the setup costs are less than $10 per kWh.
So how does this stack up to other energy costs? According to the National Renewable
Energy Laboratory’s Cost Projections for Utility Scale Battery Storage for 2021, the
low, mid, and high cost projections for a 4-hour battery system Cost $143/kWh, $198/kWh,
and $248/kWh in 2030 and $87/kWh, $149/kWh, and $248/kWh in 2050. These numbers factor
in maintenance costs, lifetimes, and efficiencies.
Now, some of these systems are designed to last longer. The sand battery, in its current
state, is rated to last “tens of years.” A pretty short life cycle. But, with material
costs not only incredibly cheap, but also incredibly abundant, sand batteries do seem
to be the more cost effective route.
Heating and cooling sand in a “charge cycle” each day, will do almost nothing to harm the
sand, and therefore the sand of a sand battery won’t degrade like a lithium ion battery
that’s rated for between 1200-5000 cycles depending on the chemisty.
Now while the sand has no real lasting effects charge cycle to cycle, there might be other
components that won’t last so long. “Tens of years” is a pretty vague amount of time.
But, consider that a Tesla battery currently lasts between 21 and 35 years but cost roughly
$132/kWh.
The truth is though, right now this sand battery really doesn’t compare to Lithium Ion batteries
for a few reasons that we’ll get to in a minute.
But, sand batteries have some other strengths when compared to other energy production nd
storage methods.
Right now in Finland, the vast majority of homes and businesses use electric heat pumps.
As of 2018, roughly 70% of newly built small homes used heat pumps. So, in many ways, Finland
is already ahead of the curve in phasing out gas and oil heaters. As we’ve talked about
on this channel, heat pumps are incredibly efficient, in many ways difficult to beat.
Still, during long, grueling winter months, Finns tend to run their heating systems more
often, driving up energy usage as heaters are working overtime to maintain safe and
comfortable temperatures.
According to reports, during the cold winter days, where temperatures can drop well below
freezing, peak energy consumption in Finland reaches about 15,000 MW. But, the available
domestic market-based production capacity is roughly 10,700megawatts, which just doesn’t
quite cut it. As it stands, Finland generally imports alot of its electricity from outside
countries. We’ll dive more into that in a sec. But, suffice it to say, the gruelling
winters can put a major strain on energy grids in the EU.
Much of the EU’s power is generated by Natural Gas, which, compared to coal and oil burning
plants is much cleaner — emitting 50% and 30% fewer emission respectively. But, since
2005, natural gas combustion has risen nearly 43%, totalling roughly 505 million metric
tons. So while natural gas is a cleaner alternative to some energy production methods, it’s
hardly the cleanest.
As the EU plans to reach carbon neutrality by 2050, the search for cleaner production
and storage methods is vital!
So, while heat pumps use energy very efficiently, they still derive most of their energy from
the grid, which in Finland is mostly powered by natural gas.
The Sand Battery could provide an emissions free means of providing heat energy that doesn’t
strain the grid!
Think about the statewide energy emergency that hit Texas in 2021, where an unprecedented
polar vortex cost residents statewide to lose power, resulting in hundreds of people losing
their lives.
While the cause of that particular tragedy is multifaceted, it could have potentially
been resolved in Texans had an alternative means of generating heat that didn’t require
overloading the power grids.
A sand battery could store excess energy and redistribute it even if the entire grid went
down.
Then there’s the geopolitical element. Right now, many countries in Europe, including Finland,
get much of their gas and electricity from Russia. As the conflict in Ukraine has proven,
that kind of reliance on global superpowers can create an imbalance of power. Ifcountries
like Finland can reduce their reliance on centralized power (in more ways than one),
it could help reduce the number and severity of conflicts like the on in Ukraine.
So, to recap — we have cheaper heat powered by renewables that doesn’t rely on grid
power or carbon emitting sources? Sounds like a win win. But,of course, we always have to
look at the other side.
In this case, the sand batteries greatest shortcoming is that while it is excellent
for storing and distributing heat, it’s not so great as a means of storing electricity.
Right now, the process to convert heat back into electricity is an incredibly inefficient
process.
So, really, this technology would only serve as a means of providing heat using clean renewable
sources. At least for now.
Other companies are exploring the potential of sand in othe battery applications, but
those are still very much in the experimental phase.. Since it is such a cheap and abundant
material with so much potential for storing heat energy, its worth exploring other applications.
But for now, even as a means of storing and distributing heat, the sand battery holds
alot of promise.
But what do you think? Could a sand battery help solve some of our energy storage needs?
Where do you think this technology could be used most?
Sound off in the comments below!