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I would think storing energy using compressed air would be more practical. Excess electricity pumps air into a compressed air tank. When electricity supply is

I would think storing energy using compressed air would be more practical. Excess electricity pumps air into a compressed air tank. When electricity supply is low, the compressed air is released turning a turbine to generate electricity. It's basically the same principle as the pumped hydro mentioned in the article but using compressed air. The advantages are size, cost, and availability. You can put it anywhere and scale when necessary.

JohnJamesRambo 8y ago
The disadvantage is that you have made a huge compressed air bomb in the event of failure. The concrete blocks would fail in a more local way by just falling down.
- crispyambulance 8y ago
  The compressed air would be located in deep inside abandoned mines. The volume and thus energy storage potential of such places is vast. The idea has been around for decades, but no one has been able to really do it yet.
  - cgdcraig 8y ago
    Rock isn't necessarily airtight more so in mines. A fractured host material for the ore is very desirable as it means less explosives and higher ore production numbers.
cgdcraig 8y ago
The compressed air systems anger the thermo gods though
giomasce 8y ago
I do not know much about engineering this sort of things, but it seems to me that working against gravity is easier than working against elastic force (as you propose), because the force of gravity is independent of the amount of energy stored, while the elastic force depends on the amount on energy stored (when the air is already pressurized it is much harder to push in some new one). And in general I believe that it is more difficult to build a motor or a generator that are efficient independently of the force they have to work against/with. Just random thoughts, though...
nabla9 8y ago
There are systems like that: * old empty mine in Germany. They pump air into the mine and then heat it to get extra energy when letting it out. * big underwater bags next to wind turbines. Wind turbine directly pumps air into nearby bags. When there is no wind, the air is used to rotate the same electric generator that the wind turbine uses.
andbberger 8y ago
There are substantial thermodynamic challenges to scaling compressed air energy storage. You either need to perfectly insulate the pressure vessel or perfectly cool/heat the air as you compress/decompress it via passive radiators.
aruggirello 8y ago
It's definitely feasible IMHO: http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-off-the-grid-compressed-air-energy-storage.html http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-o...
dredmorbius 8y ago
Think spent natural gas fields. Proven airtight, vast capacity. This is an area of active and relatively promising research. Adibiatic heating and cooling is a concern.
eeZah7Ux 8y ago
Compressed air has been around for centuries, but: """ While pumped hydropower storage has a charge/discharge efficiency of 70-85%, and chemical batteries reach 65-90%, the CAES plants in operation in Germany and the US have an electric-to-electric efficiency of only 40-42% and 51-54%, respectively """ http://www.lowtechmagazine.com/2018/05/history-and-future-of-the-compressed-air-economy.html http://www.lowtechmagazine.com/2018/05/history-and-future-of...
gammarator 8y ago
Doesn't seem to have worked out so well for Lightsail Energy... http://energystoragesense.com/uncategorized/lightsail-another-setback-for-thermo-mechanical-energy-storage/ http://energystoragesense.com/uncategorized/lightsail-anothe...
_fizz_buzz_ 8y ago
Compressed air storage is less efficient. I think practically they have an efficiency of about 50 %, due to thermal losses (e.g. compressing air creates heat).
- DanBC 8y ago
  Doesn't dropping a weight on a cable cause heat? What's the difference?
  - _fizz_buzz_ 8y ago
    The article says that they can achieve an efficiency of 85 %. Which puts them in the ball park of hydro storage or lithium ion batteries. The problem with compressed air storage is that you are fighting with the fundamentals of thermodynamics i.e. compressing and decompressing air. The laws of thermodynamics try to ruin every good idea.

JohnJamesRambo 8y ago

The disadvantage is that you have made a huge compressed air bomb in the event of failure. The concrete blocks would fail in a more local way by just falling down.

crispyambulance 8y ago
The compressed air would be located in deep inside abandoned mines. The volume and thus energy storage potential of such places is vast. The idea has been around for decades, but no one has been able to really do it yet.
- cgdcraig 8y ago
  Rock isn't necessarily airtight more so in mines. A fractured host material for the ore is very desirable as it means less explosives and higher ore production numbers.

cgdcraig 8y ago

The compressed air systems anger the thermo gods though

giomasce 8y ago

I do not know much about engineering this sort of things, but it seems to me that working against gravity is easier than working against elastic force (as you propose), because the force of gravity is independent of the amount of energy stored, while the elastic force depends on the amount on energy stored (when the air is already pressurized it is much harder to push in some new one). And in general I believe that it is more difficult to build a motor or a generator that are efficient independently of the force they have to work against/with. Just random thoughts, though...

nabla9 8y ago

There are systems like that: * old empty mine in Germany. They pump air into the mine and then heat it to get extra energy when letting it out. * big underwater bags next to wind turbines. Wind turbine directly pumps air into nearby bags. When there is no wind, the air is used to rotate the same electric generator that the wind turbine uses.

andbberger 8y ago

There are substantial thermodynamic challenges to scaling compressed air energy storage. You either need to perfectly insulate the pressure vessel or perfectly cool/heat the air as you compress/decompress it via passive radiators.

aruggirello 8y ago

It's definitely feasible IMHO: http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-off-the-grid-compressed-air-energy-storage.html http://www.lowtechmagazine.com/2018/05/ditch-the-batteries-o...

dredmorbius 8y ago

Think spent natural gas fields. Proven airtight, vast capacity. This is an area of active and relatively promising research. Adibiatic heating and cooling is a concern.

eeZah7Ux 8y ago

Compressed air has been around for centuries, but: """ While pumped hydropower storage has a charge/discharge efficiency of 70-85%, and chemical batteries reach 65-90%, the CAES plants in operation in Germany and the US have an electric-to-electric efficiency of only 40-42% and 51-54%, respectively """ http://www.lowtechmagazine.com/2018/05/history-and-future-of-the-compressed-air-economy.html http://www.lowtechmagazine.com/2018/05/history-and-future-of...

gammarator 8y ago

Doesn't seem to have worked out so well for Lightsail Energy... http://energystoragesense.com/uncategorized/lightsail-another-setback-for-thermo-mechanical-energy-storage/ http://energystoragesense.com/uncategorized/lightsail-anothe...

_fizz_buzz_ 8y ago

Compressed air storage is less efficient. I think practically they have an efficiency of about 50 %, due to thermal losses (e.g. compressing air creates heat).

DanBC 8y ago
Doesn't dropping a weight on a cable cause heat? What's the difference?
- _fizz_buzz_ 8y ago
  The article says that they can achieve an efficiency of 85 %. Which puts them in the ball park of hydro storage or lithium ion batteries. The problem with compressed air storage is that you are fighting with the fundamentals of thermodynamics i.e. compressing and decompressing air. The laws of thermodynamics try to ruin every good idea.