How to use gravity to store energy

Summary

Gravity batteries, a novel energy storage solution, harness the power of gravity to store renewable energy for times of low supply. Companies like Energy Vault are developing large-scale systems using concrete blocks or other materials, which can be lifted during energy surplus and lowered when needed, converting potential energy into electricity. Despite the high initial costs and lower energy density, these systems offer long-term storage capabilities and environmental benefits, positioning them as potential contenders in the future energy storage market.

Takeaways

• 🔋 Gravity batteries store energy by lifting heavy weights and can be a solution for long-term energy storage.
• 🌐 Companies like Energy Vault are developing large-scale gravity energy storage systems to address renewable energy supply shortages.
• ☀️ These batteries are particularly useful for storing excess energy produced during peak times, such as midday solar energy.
• 🏗️ The technology has been criticized for its high initial costs and the environmental impact of producing the concrete blocks used in some designs.
• 🌱 Energy Vault's gravity battery in China, which is taller than the Great Pyramid of Giza, demonstrates the potential of the technology on a large scale.
• 💡 The International Energy Agency predicts a significant increase in energy storage needs by 2040, highlighting the importance of developing new storage technologies.
• 🔩 Lithium-ion batteries, a current storage solution, face challenges such as environmental pollution from mining, safety issues, and limited storage duration.
• 💰 The cost of gravity batteries is currently higher than lithium-ion, but their proponents argue that their long lifespan could make them more cost-effective in the long run.
• 🏭 Underground gravity batteries, using the shafts of decommissioned mines, offer a potential solution to reduce costs and utilize existing infrastructure.
• ⏳ While gravity batteries are not yet mainstream, they may become one of several options for long-term energy storage, competing with other emerging technologies.

Q & A

What is a gravity battery?

A gravity battery is a form of energy storage that uses the force of gravity to store and release energy. It lifts a heavy weight when there is excess energy and then lowers it to release energy when needed.

How do gravity batteries store renewable energy?

Gravity batteries store renewable energy by using excess electricity to lift heavy weights during times of high supply. These weights are then lowered to generate electricity when there is a shortage of renewable energy, such as when the sun isn't shining or the wind isn't blowing.

What is the potential of gravity energy storage according to the International Energy Agency?

The International Energy Agency suggests that by 2040, more than 25,000 GWh of energy storage will be needed, which is enough to power countries like Paraguay or Tunisia for an entire year and is 2.8 times more storage than currently available.

What are the limitations of current energy storage methods like pumped storage hydropower?

Pumped storage hydropower, which makes up over 95% of current storage capacity, requires specific geographical features like hills and water, and is not easily scalable. It also involves significant construction work that can disrupt natural habitats.

What are the issues with lithium-ion batteries for energy storage?

Lithium-ion batteries have several issues, including environmental pollution from mining, potential for fires or explosions, rapid degradation, and limited storage capacity to cover only a few hours of energy demand.

How does Energy Vault's gravity battery system work?

Energy Vault's system involves lifting and lowering concrete blocks or other materials using cranes. When energy is abundant, the blocks are lifted; when energy is needed, they are lowered, and the potential energy is converted back into electricity.

What is the criticism Energy Vault's prototype faced?

The prototype faced criticism for not complying with building codes, potential inability to withstand extreme weather, and the use of thousands of tons of concrete, which is not climate-friendly.

What are the advantages of gravity batteries over lithium-ion batteries?

Gravity batteries have a longer lifespan, potentially up to 60 years, compared to lithium-ion batteries which degrade over time. They are also predictable like pumped hydro storage and can be built almost anywhere without the need for scarce resources.

Why are gravity batteries currently more expensive than lithium-ion technology?

Gravity batteries have a higher initial cost due to the need for larger infrastructure and more building materials to store the same amount of energy as lithium-ion batteries. They also have lower energy density, which contributes to their higher cost.

What is the potential of using abandoned mines for gravity energy storage?

Researchers propose using the shafts of decommissioned mines for gravity energy storage, which could offer a large capacity for energy storage with relatively low installation costs, as these mines already have the necessary infrastructure like road access and transmission lines.

What are some of the innovative designs for gravity batteries mentioned in the script?

Innovative designs for gravity batteries include sinking a giant piston into the ground, weights on wagons on rails going up and down a mountain, and an updated version by Energy Vault that resembles a ski lift with weights.

Outlines

00:00

🔋 Gravity Batteries: Storing Energy for a Greener Future

The paragraph introduces gravity energy storage, or gravity batteries, as a novel method of storing renewable energy. It explains how these systems work by lifting heavy weights during periods of energy surplus and then releasing the stored energy when needed. The concept is being pursued by several companies aiming to build large-scale versions, promising the ability to store large amounts of energy, which is crucial during periods of low renewable energy supply, such as when the sun isn't shining or the wind isn't blowing. The technology's potential to reduce CO2 emissions is highlighted, as it complements the need for more renewable energy storage solutions. The International Energy Agency's projection for energy storage capacity by 2040 is mentioned, emphasizing the significant growth required beyond current capabilities.

05:01

💼 Investor Interest in Gravity Batteries: Challenges and Potential

This paragraph discusses the financial backing and investor interest in gravity battery technology, including investments from Saudi Aramco and Leonardo DiCaprio. It outlines the advantages of gravity batteries over lithium-ion batteries, such as their longer lifespan and the ability to be constructed almost anywhere without the need for scarce resources. However, it also points out the high costs associated with gravity batteries due to their low energy density, which requires larger infrastructure. The comparison with lithium-ion batteries is further elaborated, noting that gravity batteries are currently more expensive but may become competitive over the long term due to lower maintenance costs and the potential for levelized cost of storage to be lower over the project's lifetime. The paragraph also explores the idea of installing gravity batteries in decommissioned mines, which could significantly reduce installation costs and provide a large-scale storage solution.

10:02

🏗️ Future Developments and the Role of Gravity Batteries in Energy Storage

The final paragraph looks ahead to future developments in gravity battery technology, including plans for more efficient systems like Energy Vault's updated design resembling a ski lift. It mentions the potential for gravity batteries to be installed in skyscrapers and the company's collaboration with an engineering firm to achieve this. The paragraph acknowledges that gravity energy storage is still in its early stages and faces competition from other emerging long-term energy storage technologies. It concludes by suggesting that gravity batteries may become one of many options for long-term energy storage but are unlikely to become mainstream due to their current costs and the existence of more cost-effective alternatives. The video invites viewers to explore other energy storage technologies by subscribing to the channel.

Keywords

💡Gravity Energy Storage

Gravity Energy Storage, also known as a gravity battery, is a concept where potential energy stored in a lifted weight is converted into electricity. This technology is central to the video's theme, which explores innovative methods for renewable energy storage. The script describes how companies are developing large-scale gravity energy storage systems that can harness the force of gravity to store energy, particularly useful during periods when renewable energy supply is low, such as when the sun isn't shining or the wind isn't blowing.

💡Renewable Energy

Renewable energy refers to energy sources that are naturally replenished on a human timescale, such as sunlight, wind, and water. The video discusses the importance of renewable energy in the context of gravity batteries, emphasizing the need for technologies that can store excess renewable energy for use during periods of low production. The script mentions how gravity batteries could be a solution for storing large amounts of renewable energy, highlighting their potential role in a sustainable energy future.

💡Pumped Storage Hydropower

Pumped storage hydropower is a method of energy storage that uses water pumped to a higher elevation to store energy, which can be released by allowing the water to flow back down through turbines. The video compares this traditional method with gravity batteries, noting that while pumped storage is effective, it requires specific geographical conditions and can be disruptive to the environment. The script points out that gravity batteries aim to mimic the principle of pumped storage but with more flexibility in terms of location and scalability.

💡Lithium-ion Batteries

Lithium-ion batteries are a type of rechargeable battery commonly used in electronics and electric vehicles due to their high energy density and efficiency. The video discusses the limitations of lithium-ion batteries for large-scale energy storage, such as their environmental impact from mining, potential safety hazards, and relatively short lifespans. The script contrasts lithium-ion batteries with gravity batteries, suggesting that while lithium-ion batteries are currently more cost-effective, gravity batteries offer a longer-term storage solution.

💡Energy Density

Energy density refers to the amount of energy that can be stored per unit of volume or mass. In the context of the video, the script mentions that gravity batteries have a lower energy density compared to lithium-ion batteries, which means they require more space and materials to store the same amount of energy. This lower energy density contributes to the higher initial costs of gravity batteries, making them less competitive for certain applications.

💡Levelized Cost of Storage

The levelized cost of storage is the average cost per unit of stored energy over the lifetime of a storage system. The video suggests that while gravity batteries have higher upfront costs, their long operational lifetimes and low maintenance costs could make them more cost-effective in the long run when considering the levelized cost of storage. The script uses this concept to argue that gravity batteries might become competitive with other storage technologies when their total cost over time is considered.

💡Decommissioned Mines

Decommissioned mines are mines that have ceased operations, often leaving behind infrastructure that can be repurposed. The video proposes the idea of using the shafts of decommissioned mines for gravity battery storage, which could provide a cost-effective and environmentally friendly way to store energy. The script highlights the potential of using these existing underground spaces for gravity energy storage, suggesting it as a creative solution to repurpose abandoned mining infrastructure.

💡Grid-Scale Storage

Grid-scale storage refers to large-scale energy storage systems that can support the electrical grid by storing excess energy and releasing it during periods of high demand. The video discusses the need for grid-scale storage solutions like gravity batteries to accommodate the fluctuating supply of renewable energy. The script emphasizes the importance of such systems in ensuring a stable and reliable energy supply, particularly as the proportion of renewable energy in the grid increases.

💡CO2 Emissions

CO2 emissions, or carbon dioxide emissions, are a major contributor to climate change and are often associated with the burning of fossil fuels for energy production. The video suggests that gravity batteries could help reduce CO2 emissions by providing a means to store renewable energy, thus reducing the reliance on fossil fuels. The script connects the potential of gravity batteries to the broader goal of reducing greenhouse gas emissions and combating climate change.

💡Long-Duration Energy Storage

Long-duration energy storage refers to systems that can store energy for extended periods, ranging from hours to days or even months. The video discusses the need for long-duration storage solutions like gravity batteries to address the intermittent nature of renewable energy sources. The script contrasts short-term storage options, such as lithium-ion batteries, with long-duration options like gravity batteries, emphasizing the importance of having a variety of storage technologies to meet different energy needs.

Highlights

Gravity energy storage, or gravity battery, is a novel method proposed by a handful of companies to store large amounts of renewable energy.

The concept involves lifting a heavy weight using excess electricity and then releasing it to generate power when needed.

Vision fund has invested 110 million dollars in gravity battery technology, indicating significant interest in its potential.

Gravity batteries could be a solution for storing renewable energy when the sun isn't shining and the wind doesn't blow.

The International Energy Agency predicts a need for more than 25,000 GWh of energy storage by 2040.

Current energy storage primarily relies on pumped storage hydropower, which is limited by geography and scalability.

Lithium-ion batteries, while popular, have issues with environmental pollution, safety, and rapid degradation.

Energy Vault, a leading developer in gravity energy storage, has built a prototype in Switzerland demonstrating the feasibility of the concept.

The first commercial gravity battery in Rudong, China, is taller than the Great Pyramid of Giza and stores energy in concrete blocks.

Gravity batteries have the potential to last up to 60 years, significantly longer than lithium-ion batteries.

The cost of gravity batteries is currently higher than lithium-ion, with lower energy density requiring more infrastructure.

Energy Vault plans to build 4 GWh of gravity batteries in China, a significant scale-up from existing projects.

Underground gravity batteries in decommissioned mines could provide a cost-effective and scalable solution for long-term energy storage.

Gravitricity and Green Gravity are companies exploring gravity batteries in mines with the aim of storing energy for up to 12 hours.

Innovative designs for gravity batteries include sinking a giant piston into the ground or using weights on wagons on rails.

Energy Vault is considering installing gravity batteries in skyscrapers, expanding the potential applications of the technology.

Despite the excitement, gravity batteries are not expected to become mainstream due to higher costs and the existence of more cost-effective alternatives.

Transcripts

This is a battery.

It might not look like one.

But this weight here stores the energy

it took to move it up here.

When it's released,

it can power this light.

A handful of companies want to build

large versions of this.

Really large.

High into the sky...

deep into the ground...

or up on mountains.

It's called gravity energy storage,

or gravity battery for short.

And the companies behind them

are making a buzz -

saying they'll be able to store

large amounts of renewable energy

for times when supply is short.

Like when the sun isn't shining,

and the wind doesn't blow.

"That's where

a novel new energy storage technology

comes to play."

"Vision fund announcing that

it is investing 110 million dollars."

"Why are we not spending trillions

right now to be building this stuff?"

So are gravity batteries going to make it big?

First, let's take a look at how these batteries work.

When we produce more electricity than we need -

like in the middle of the day,

when there's lots of solar energy -

we can use that energy

to lift a heavy weight.

It just hangs around until we lower it again.

The motor becomes a generator

and feeds electricity back into the grid.

This technology could be a good way

to cut CO2 emissions.

We need a lot of renewable energy -

and places to store it.

The International Energy Agency says

more than 25,000 GWh by 2040.

That's enough to power countries like

Paraguay or Tunisia for an entire year.

And it's 2.8 times more storage

than we have today.

But those numbers

don't fully capture the challenge.

Today, most energy storage

is pumped storage hydropower -

so, dams and reservoirs.

We'll talk about that in a moment.

But we won't be able to

nearly triple that kind of capacity.

So, actually we need to expand other storage

not 2.8 but at least 22 times more

than we can today.

Now, that's a challenge.

To achieve this huge growth

in storage capacity,

developers have mainly been looking

at lithium-ion batteries.

Like the one in your phone or laptop,

just a lot bigger.

It has a number of problems, though.

We've made a video about it

which you can find here.

In short:

lithium mining pollutes the environment

and exploits people.

Sometimes the batteries catch fire or explode.

They degrade rather quickly.

And today's grid-scale lithium-ion batteries

can store only a few hours' energy,

to cover daily peaks in demand.

But with more and more renewable energy,

we'll need even more reliable short-

and long-term storage.

That could be six hours, six days,

six weeks or even months.

Like I said earlier,

pumped storage hydropower

is great for this.

It's been around for more than a century

and still makes up over 95%

of our storage capacity.

You pump water up

when there's an energy surplus,

and let it flow down through turbines

when energy is needed.

Notice anything?

Yep, that's gravity at work.

Pumped hydro is tried and tested -

but doesn't work just anywhere.

It requires lots of construction work

and disrupts natural habitats.

And you need a hill and a lot of water.

It is not easily scalable.

But the gravity principle is.

"We basically mirror that same process,

but instead of water for one of our solutions,

we use blocks."

That's Robert Piconi,

co-founder and CEO of Energy Vault,

which currently is

the biggest gravity-energy-storage developer.

"And there's essentially,

depending on the size of the system,

can be up to thousands of them per systems."

Back in 2020,

Energy Vault built THIS prototype in Switzerland.

Six cranes stacked the concrete blocks

up to a height of 70 meters.

The prototype proved that the concept works.

But it also received criticism -

such as that the structure

didn't comply with building codes,

or might not withstand extreme weather.

And the thousands of tons of concrete

that went into the blocks

are anything but climate-friendly.

So Energy Vault came up

with this gravity battery building.

Thousands of blocks are lifted or lowered

and then stored horizontally,

as seen here.

The first battery of this kind went into operation

in Rudong, in Jiangsu province in China,

in May of this year.

It's taller than the Great Pyramid of Giza

and stores more than 3,500 blocks

weighing 25 tons each.

They were made on site from excavated soil,

but the company says it could use

waste materials such as coal, ash

or old wind turbine blades.

"And it's 100 MWh

so that you can think that equivalent

to powering about 35,000 homes."

But only for two or three hours.

The company plans to build

4 GWh of gravity batteries for China,

or 40 times this one.

Another smaller storage facility

is supposed to go online

in Snyder, Texas, this year.

And plans are underway in southern Africa, too.

The company has drawn

hundreds of millions of dollars

from investors,

including oil giant Saudi Aramco

and Leonardo DiCaprio.

Because you must admit -

it all sounds very promising.

It's predictable like pumped hydro storage,

but can be built pretty much anywhere.

It doesn't need scarce resources.

And it lasts a lot longer than lithium-ion storage.

That's because with lithium-ion

chemical processes,

aging and heat limit battery life

to no more than 15 years.

Look at your phone

and how long the battery lasts now

compared to when you bought it.

It's the same thing.

Gravity batteries could in theory

lift a weight and keep it up for 60 years.

The motors might need replacing,

but the weights and stored energy

would remain in place.

"The biggest drawback is the cost."

That's Evelina Stoiku,

Senior Research Associate

at Bloomberg NEF's Energy Storage team.

They recently published a study comparing

several long-duration energy storage solutions,

including gravity storage.

"And what we found is that

gravity batteries have the higher average cost

and higher cost range

from all the other long duration technologies.

One of the reasons

that they have a very high cost

is because they have very low energy density.

So, you need sort of larger infrastructure

in order to store the same energy

as you would need for a lithium-ion battery,

for example."

The gravity battery in Rudong

stores the same amount of energy

as this lithium-ion battery.

But the gravity battery

needs much more space

and building materials.

So the initial cost is higher.

It also loses out in other ways.

Storage operators earn their money

by discharging the energy and

selling it for more than they paid.

Chemical storage like with lithium-ion,

can react in milliseconds to market needs

Which allows for a lot of quick profit taking.

A gravity battery mechanically lifts and lower weight

which takes time and limits profit options.

So, gravity battery capacity is more expensive.

Right now,

its double the cost of lithium-ion technology.

But developers like Energy Vault

want to convince investors to think long-term.

"...because they have such

long lifetimes of 50-60 years,

which is considerably higher

compared to lithium-ion,

they make claims that levelized cost of storage

over the duration of the project lifetime is lower."

If the high start-up costs of gravity batteries

even out over time

partly due to the low cost of maintenance.

That might make them competitive in the long run.

But can we make these batteries cheaper now?

Let's go underground.

"The deeper the mine, the cheaper it is,

the more energy you can store."

Julian Hunt

has been researching gravity batteries

for a number of years.

He's proposing to put them

in the shafts of decommissioned mines.

"We looked at 1500 underground coal mines

and from these coal mines we estimate

capacity of 70 TWh of storage."

70 TWh of energy is HUGE.

It's what the entire world needs in a day -

and it's 700,000 times the capacity of THIS.

And that's just old coal mine shafts,

which are particularly deep.

Abandoned metal mines could also work.

Two companies from Scotland and Australia

have built small pilot projects above ground.

And want to install gravity batteries

in former mines in Europe and Australia.

The idea is

to have a small number of very heavy weights

moving up and down the empty shaft.

Installation costs

for this kind of gravity energy storage

could be fairly low...

"Underground mines

have the road access,

they have transmission lines into the mine.

So you can use that."

Gravitricity and Green Gravity

hope to go online

with this type of storage by 2027.

They say the energy could be stored

for up to 9 or even 12 hours.

But Julian Hunt

is looking for longer storage times.

Much longer.

"So for example, from one season to another,

from one year to another."

Energy could then be stored when it's really cheap...

and used when it's much more expensive -

which would make it a profitable solution.

Whether it's for hours or months,

we'll only know if this system works as planned

once it's been built.

There are also some even bolder designs

for efficient gravity batteries.

Like sinking a giant piston into the ground,

and raising and lowering it

with the water underneath.

The idea has been around for years,

but hasn't reached the pilot stage yet.

Another idea involves

weights on wagons on rails,

going up and down a mountain.

That idea is over ten years old,

but hasn't gone anywhere yet.

Energy Vault is planning an updated version,

which looks a bit like a ski lift with weights.

They say this system could be more efficient

than the standalone gravity batteries

they're making now.

"We don't do anything small in gravity.

In fact, 100 MWh in China

is the smallest we would ever do.

Everything we're looking at now

for these applications of

gravity leveraging slopes and things,

they're all multi-GWh."

And soon, gravity batteries

might be installed in skyscrapers.

Energy Vault plans to do just that,

in collaboration with an engineering company.

Gravity energy storage is still in its infancy.

It can't compete with the scale

and low cost of lithium-ion storage.

But it doesn't have to,

since gravity storage is intended

for longer-term storage of six hours or more.

But there are other new technologies

in that energy segment

that are already more cost-effective today.

Like thermal energy,

compressed air,

and gas energy storage.

And according to Bloomberg NEF,

the cost of gravity energy storage

is likely to drop by only 2% per year.

"I would not say we see this becoming mainstream.

I think a big part of the excitement is

because it's novel and so simple

and so different conceptually

to what we think of as a battery."

So gravity batteries might become

one of MANY options

to store energy long-term.

But you probably won't be seeing

many of these popping up near you

any time soon.

If you want to learn more about

other energy storage technologies,

like salt or even the ocean

go check out our channel.

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