Gravity batteries in abandoned mines could power the whole planet, scientists say

Daniel Sims

Posts: 762   +30
Staff
Why it matters: Gravity batteries are a potential candidate for storing excess renewable energy, but finding places to install them is a challenge. Researchers have proposed that abandoned mines across the globe could be a cost-effective solution that may also provide jobs.

A study from the International Institute for Applied Systems Analysis (IIASA) proposes that decommissioned mines could be repurposed to operate gravity batteries. Converting old mines could provide enough energy to match the entire planet's current daily electricity consumption.

Gravity batteries try to solve one of the central problems regarding renewable energy sources like wind and solar – storing excess energy. Wind and solar often generate more energy than a grid can immediately use, so power companies have to store what's left over, usually in batteries.

Methods like the IIASA experiment use that extra energy to lift heavy objects. When the energy is needed again, the weight is dropped which spins a turbine and converts the kinetic energy from gravity.

Theoretically, gravity batteries can be anything with a lot of weight, like water or solid objects. The IIASA study lowered and lifted sand in abandoned mine shafts, moving it back and forth between upper and lower chambers based on energy needs.

Another advantage of the process is that while batteries tend to self-discharge over time, gradually losing their stored energy, the gravity method stores the energy in the sand (or whatever else is lifted to harness gravity) which doesn't self-discharge.

The IIASA proposes using abandoned mines because there are already likely millions of them across the planet that could be relatively cheaply converted for this purpose. Most contain the basic infrastructure for the job and are already connected to the power grid.

The researchers think that, after a roughly $1-10 per kilowatt-hour investment cost and a $2,000 per kilowatt power capacity cost, their method could have a global potential of 7-70 terawatt-hours. According to the International Energy Association, global energy consumption for 2020 – the most recent year on record – totaled 24,901.4 terawatt-hours, which divides into about 68 terawatt-hours per day.

Furthermore, operating gravity batteries in abandoned mines could restore or preserve some of the jobs lost when those mines closed.

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yannus

Posts: 165   +146
We were discussing that concept with friends a few weeks ago at a household level. Surprisingly enough there are gravity light bulbs for black outs and third world countries but they are expensive which doesn't make sense. Still it's a good idea. We were discussing the possible constraints of storing energy lifting a 1 ton concrete block to replace batteries. We didn't reach a conclusion as it would need some calculation we probably are not capable of yet.
 

Endymio

Posts: 2,004   +2,088
We didn't reach a conclusion as it would need some calculation we probably are not capable of yet.
Thanks to the MKS system, it's as simple as it gets. A 1 metric ton block is 1000kg. Lifting it 36 meters stores 36,000g joules ... call it 360 thousand. That's 1/10 of a kilowatt-hour.

As you can see, gravity storage systems require a lot of mass to store significant amounts of energy.
 

AlaskaGuy

Posts: 752   +629
Yet another globalist shill.

The IIASA mission is to provide scientific guidance to policymakers by finding solutions to global problems through applied systems analysis in order to improve human wellbeing and protect the environment.

In 2010, IIASA launched a new strategic plan for the next ten years, which focuses on three general problem areas: Energy and Climate Change, Food and Water, and Poverty and Equity.[9]

There are currently nine IIASA research programs carrying out research into the dynamics of global change. These programs use holistic approaches and effective, interdisciplinary collaborations to identify the multiple solutions needed to bring about a global transformation to true sustainability: Advanced Systems Analysis, Air Quality and Greenhouse Gases, Ecosystem Services and Management, Energy, Evolution and Ecology, Risk and Resilience, Transitions to New Technologies, Water, and World Population.
 

Tantor

Posts: 390   +660
Gravity batteries are old technology. Look at ancient Roman waterwheels. They harnessed the energy of water moving from higher to lower locations.

The main difference is how you recharge the reservoirs. Roman engineers depended on nature (rain and snow) to move water back up to a higher location. Whereas modern engineers build reservoirs to hold the water, and pumps to charge them.

I don't think that systems with mechanical weights and pullys are realistic. What if your giant concrete weight gets stuck in the shaft? Much easier to deal with water.

I'm not convinced that human-charged gravity batteries can be made cost effective. If it was that easy they could have done it back in the late 1800's when they started large scale power distribution systems.
 
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Bullwinkle M

Posts: 858   +773
The IIASA mission is to provide scientific guidance to policymakers by finding solutions to global problems through applied systems analysis in order to improve human wellbeing and protect the environment.

In 2010, IIASA launched a new strategic plan for the next ten years, which focuses on three general problem areas: Energy and Climate Change, Food and Water

Energy and Climate Change, Food and Water are not problems we need to deal with

The problem is Humans breeding like Rats

Get rid of the rat problem and suddenly Energy / Climate Change, food and water are no longer problems

It's the final solution!

 
This is already in use at the old Britannia Mine in Britannia BC Canada. The mine was plugged at the bottom, water builds up during the winter and is release through a turbine that generates electricity for the effluent processing plant.
 

Thanthan

Posts: 111   +232
Thanks to the MKS system, it's as simple as it gets. A 1 metric ton block is 1000kg. Lifting it 36 meters stores 36,000g joules ... call it 360 thousand. That's 1/10 of a kilowatt-hour.

As you can see, gravity storage systems require a lot of mass to store significant amounts of energy.

A ton in most Engineering contexts would be considered very little weight. Working a project currently where we’re shifting 16-20 mio tons of rock. Also the weight requirement is one of the typical reasons for using water in gravity batteries. Easy to find a couple of million tons of the stuff in a lot of places.
 

Endymio

Posts: 2,004   +2,088
the weight requirement is one of the typical reasons for using water in gravity batteries. Easy to find a couple of million tons of the stuff in a lot of places.
A couple million metric tons of water is a couple million cubic meters of volume. And, of course, you can't flood the entire mine, or the water has nowhere to be pumped to. The other problem with using water is that (besides its corrosive properties) it tends to evaporate and/or seep through the surrounding rock. Above-ground gravity batteries like these generally lose about 30% efficiency from this. For this reason, I believe this new proposal uses tamped sand ... about 60% denser than water, and no seepage losses.
 

dangh

Posts: 857   +1,450
Water would be much better option here. all the weights would require a lot of mechanical components like chains/lines, blocks, so wear and tear will be quickly an issue. While water going down requires only a pipes and a turbine, and only effort would be required to pump it back up. As well there is no need to spread the load at the lowest levels, it will simply spread itself there without additional equipment. Sure some coating would be required.
 

Thanthan

Posts: 111   +232
A couple million metric tons of water is a couple million cubic meters of volume. And, of course, you can't flood the entire mine, or the water has nowhere to be pumped to. The other problem with using water is that (besides its corrosive properties) it tends to evaporate and/or seep through the surrounding rock. Above-ground gravity batteries like these generally lose about 30% efficiency from this. For this reason, I believe this new proposal uses tamped sand ... about 60% denser than water, and no seepage losses.
A couple of million cubic metres is also not very much depending on the geometry you’re working with (the ideal case for water would be an open pit mine with layer deep shafts ofc). A million cubic meters is 100x100x100m, or about the volume of a typical stadium. In the context of using abandoned mines, that really isn’t very much, these will often be much, much larger. The largest open pit mine in the world has a volume of roughly 10-12 billion cubic meters (4km circumference, 1.2km deep, considering a roughly pyramidal shape). I think getting right geometry for gravity batteries will be much tougher than finding volume. Here, water is a lot more flexible than solids.
 

Endymio

Posts: 2,004   +2,088
A million cubic meters is 100x100x100m, or about the volume of a typical stadium.
Yes, but to pump the active medium you need two volumes that large, separated vertically from each other by as many meters as possible. If the volumes are closer together or overlap, you store correspondingly less energy.

IThe largest open pit mine in the world has a volume of roughly 10-12 billion cubic meters
But an open-pit mine is entirely unsuitable for such an endeavor; it would be no more than an exposed reservoir. We already have many such used for pumped-storage, but between the surface area they consume, the evaporative losses, the environmental effects, etc, they've never been extremely successful.

A closed mine, however, has the capability to be 95%+ efficient, while consuming nearly no land surface area at all. These, though, tend to be substantially smaller than the open-pit mines.
 

Gastec

Posts: 302   +156
"enough energy to match the entire planet's current daily electricity consumption"
For a mere $1 to $10 per kWh. And "free" electricity from fusion reactors for only $19.99/kWh.
 

Gastec

Posts: 302   +156
Yet another globalist shill.

The IIASA mission is to provide scientific guidance to policymakers by finding solutions to global problems through applied systems analysis in order to improve human wellbeing and protect the environment.

In 2010, IIASA launched a new strategic plan for the next ten years, which focuses on three general problem areas: Energy and Climate Change, Food and Water, and Poverty and Equity.[9]

There are currently nine IIASA research programs carrying out research into the dynamics of global change. These programs use holistic approaches and effective, interdisciplinary collaborations to identify the multiple solutions needed to bring about a global transformation to true sustainability: Advanced Systems Analysis, Air Quality and Greenhouse Gases, Ecosystem Services and Management, Energy, Evolution and Ecology, Risk and Resilience, Transitions to New Technologies, Water, and World Population.
"effective, interdisciplinary collaborations to identify the multiple solutions needed to bring about a global transformation to true sustainability" Wow, everything is clear now and resolved! All we need is more wooden language and demagogy and solutions will start poping up like pop-corn.
 

Gastec

Posts: 302   +156
Gravity batteries are old technology. Look at ancient Roman waterwheels. They harnessed the energy of water moving from higher to lower locations.

The main difference is how you recharge the reservoirs. Roman engineers depended on nature (rain and snow) to move water back up to a higher location. Whereas modern engineers build reservoirs to hold the water, and pumps to charge them.

I don't think that systems with mechanical weights and pullys are realistic. What if your giant concrete weight gets stuck in the shaft? Much easier to deal with water.

I'm not convinced that human-charged gravity batteries can be made cost effective. If it was that easy they could have done it back in the late 1800's when they started large scale power distribution systems.
We could use slave labour, exploit them with little to no food to produce that electricity. There are billions of potential human-chargers on Earth.
 

yannus

Posts: 165   +146
Thanks to the MKS system, it's as simple as it gets. A 1 metric ton block is 1000kg. Lifting it 36 meters stores 36,000g joules ... call it 360 thousand. That's 1/10 of a kilowatt-hour.

As you can see, gravity storage systems require a lot of mass to store significant amounts of energy.
Thanks, it seemed so low that I took the time to check your calculation.... and you're right ! That's without taking into account the efficiency of the motor and generator.
 

BobHome

Posts: 173   +68
Why not? It would be their own energy they would be storing this way. Is this another tinfoil hat global conspiracy theories like energy companies holding back new battery tech?
Not while there is still coal to mine and oil to pump.
Sadly.
 

alexnode

Posts: 111   +40
Energy companies will never allow this to happen.
Not really, they will still sell the retail power, they can just produce power in a cheaper way. Loads of solar and wind goes to waste at night for example, but ideally it could all be utilised during peak times.
 
I'm not convinced that human-charged gravity batteries can be made cost effective. If it was that easy they could have done it back in the late 1800's when they started large scale power distribution systems.

Gravity batteries weren't needed in the late 1800s when power was primarily generated by burning coal. If they needed more power, they could always throw more coal on the fire, anytime day or night.

Gravity batteries are needed when dealing with power sources that vary throughout the day, and cannot simply be ramped up whenever you need more power. Many renewable resources are like this, like solar and wind. With solar power, you get an abundance of power during the day, and none at night. So, during the day, you use any excess power to lift a weight and store the electrical energy as potential energy. Then, during the night, you lower the weight and convert the potential energy back to electrical energy.