Energy storage: Difference between revisions

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In the pursuit of green [[energy]], storage is needed for 2 reasons:
In the pursuit of green [[energy]], storage is needed for 2 reasons:
# To smooth out the intermittency of [[solar]] and [[wind]] power.
# To smooth out the intermittency of [[solar]] and [[wind]] power.
# To store energy in [[electric vehicles|electric vehicles]] without gasoline or diesel.
# To store energy in [[electric vehicles]].


==How much would be needed?==
<small>Note: This page does not include [[thermal energy storage]].</small>
 
==Types / Candidates==
{|class="wikitable"
!Type
!Status
|-
|[[Sodium-ion batteries]]
|Good potential / needs investment.
|-
|[[Sodium-sulfur batteries]]
|Good potential / needs investment.
|-
|[[Hydrogen gas]]
|Okay for some applications, but too lossy & platinum-intensive for others.
|-
|[[Lithium ferro phosphate batteries]]<!--(LiFePo4 or LFP)-->
|Okay if used in moderation. A bit too lithium-intensive to be a general solution.
|-
|[[Lithium-ion batteries]] <small>(NMC/NCA type)</small>
|Not scalable enough: Too [[cobalt]]-intensive.
|-
|[[Lithium-sulfur batteries]]
|Can't handle enough charge cycles.<!--
|-
|Lithium Titanate (Li4Ti5O12 or LTO)
|? -->
|-
|[[Lead-acid batteries]]
|Toxic / hazardous.
|-
!colspan=2|Stationary storage only (power grid, not vehicles)
|-
|[[Iron redox flow batteries]]
|Good potential / needs investment.
|-
|[[Compressed air energy storage|Compressed air]]
|?
|-
|[[Pumped hydro]]
|Only viable in rare geographical locations.
|-
|[[Flywheels]]
|?
|-
|[[Gravity blocks]]
|Not viable: Outrageously high environmental footprint of construction.
|-
|}
<small>For more details, read the wikipage of each energy storage type. Links are in the table.</small>
 
So far, sodium-based batteries seem to have the [[the great battery challenge|most hope]] of being a widespread solution - along with iron-based batteries for stationary energy storage.
 
<!--
==How much energy storage might be needed?==
Some quick estimates:


===Vehicles===
===Vehicles===
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}}
}}
{{dp
{{dp
|timescale
|storage_timescale
|24 hours
|24 hours
|How big the "buffer" of energy storage would have to be to be resiliant against weather fluctuations
|How big the "buffer" of energy storage would have to be to be resiliant against weather fluctuations
Line 45: Line 100:
}}
}}
{{calc
{{calc
|other_energy.tfc * timescale
|other_energy.tfc * storage_timescale
|terajoules
|terajoules
|other_energy_storage_needed
|other_energy_storage_needed
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There are more options for this type of energy storage, because it's stationary (not moving in a vehicle).
There are more options for this type of energy storage, because it's stationary (not moving in a vehicle).


===How much storage is this really?===
These numbers might be reused on other wikipages to assess the large-scale viability of various types of energy storage. Don't worry if you're not familiar with <code>terajoules</code> as an [[energy/units|energy unit]].
Most people aren't familiar with terajoules. Let's express it instead in terms of "gallons of gasoline equivalent energy" per person.
{{dp
|world.population
|7.95 billion
}}
{{calc
|(other_energy_storage_needed + vehicle_energy_storage_needed) / world.population
|gallons gasoline per capita
}}
 
This much energy has to be stored in some other way (not gasoline).
 
==Types==
 
===Hydrogen gas===
[[Hydrogen gas]] does not occur in nature, but can be generated using green [[energy]] (by [[electrolysis]]).
 
====Vehicles====
 
Car engines '''can''' viably be built to burn hydrogen gas instead of [[gasoline]]. However, this isn't as efficient as building an electric car powered by [[hydrogen fuel cells]] (which use chemistry to convert the hydrogen energy back to electricity, which powers electric motors that run the car).
 
But even hydrogen fuel cells might not be quite efficient enough:
{{dp
|<nowiki>electrolysis.efficiency</nowiki>
|<nowiki>80%</nowiki>
|<nowiki>Energy efficiency of producing hydrogen & oxygen gases from water</nowiki>
|<nowiki>Hydrogen made by the electrolysis of water is now cost-competitive ...</nowiki><br /><nowiki>
www.carboncommentary.com › blog › hydrogen-made-by-the-electrolysis... </nowiki>
}}
{{dp
|<nowiki>hydrogen_fuel_cell.efficiency</nowiki>
|<nowiki>50%</nowiki>
|<nowiki>Electric energy efficiency of an average hydrogen fuel cell</nowiki>
|<nowiki>Hydrogen Fuel Cells Fact Sheet</nowiki><br /><nowiki>
www.californiahydrogen.org › uploads › files › doe_fuelcell_factsheet</nowiki>
}}
{{calc
|<nowiki>electrolysis.efficiency * hydrogen_fuel_cell.efficiency</nowiki>
|<nowiki>%</nowiki>
}}
This is only half the charge-discharge efficiency of lithium-ion batteries.
 
Hydrogen fuel cells contain rare minerals.{{qn}}
 
Hydrogen gas requires a [[pressurized fuel tank]], which is significantly heavier than a gasoline tank{{qn}} but probably not as heavy as a lithium-ion battery pack, for the same amount of energy. Safety concerns are similar to other pressurized fuels such as [[natural gas]] or [[propane]].
 
====Heating and cooking====
* Homes could be heated with hydrogen gas instead of natural gas.
* Gas-powered stoves could easily be adapted to burn hydrogen.
 
===Lithium-ion batteries===
 
[[Lithium-ion batteries]] are the current standard for electric cars and most small gadgets (phones, laptops, etc).
 
Is there enough lithium?
{{dp
|<nowiki>li_ion.cell_voltage</nowiki>
|<nowiki>3.6 volts</nowiki>
|<nowiki>Voltage of a single lithium-ion cell.</nowiki>
|<nowiki>https://www.cei.washington.edu/education/science-of-solar/battery-technology/</nowiki><br /><nowiki>
https://www.fluxpower.com/blog/what-is-the-energy-density-of-a-lithium-ion-battery</nowiki><br /><nowiki>
It's 3.6 volts for the "cobalt type" of lithium-ion battery. Other types might have a very slightly different voltage.</nowiki>
}}
{{dp
|<nowiki>li_ion.lithium_by_energy</nowiki>
|<nowiki>0.3 grams per amp hour li_ion.cell_voltage</nowiki>
|<nowiki>To store a given amount of energy in lithium-ion batteries, this is how much lithium would be needed.</nowiki>
|<nowiki>https://batteryguy.com/kb/knowledge-base/how-to-calculate-the-lithium-content-in-a-battery/</nowiki><br /><nowiki>
The article says lithium per amp hour. We convert this to lithium per watt hour (energy), by including the cell voltage.</nowiki>
}}
{{dp
|<nowiki>lithium.reserves</nowiki>
|<nowiki>18425000 tonnes</nowiki>
|<nowiki>Lithium metal: Total global mineral reserves</nowiki>
|<nowiki>https://www.statista.com/statistics/268790/countries-with-the-largest-lithium-reserves-worldwide/</nowiki><br /><nowiki>
Added up all the countries: 9,200,000 + 4,700,000 + 1,900,000 + 1,500,000 + 750,000 + 220,000 + 95,000 + 60,000 = 18,425,000 metric tons</nowiki>
}}
{{dp
|<nowiki>li_ion.cobalt_by_energy</nowiki>
|<nowiki>20 kg per 100 kilowatt hours</nowiki>
|<nowiki>To store a given amount of energy, in lithium-ion batteries (cobalt type), this is how much cobalt would be needed.</nowiki>
|<nowiki>https://www.energy.gov/eere/vehicles/articles/reducing-reliance-cobalt-lithium-ion-batteries</nowiki>
}}
{{dp
|<nowiki>cobalt.reserves</nowiki>
|<nowiki>7.1 million tonnes</nowiki>
|<nowiki>Cobalt metal: Total global mineral reserves</nowiki>
|<nowiki>https://www.statista.com/statistics/264930/global-cobalt-reserves/</nowiki>
}}
{{calc
|vehicle_energy_storage_needed * li_ion.lithium_by_energy
|% lithium.reserves
}}
{{calc
|other_energy_storage_needed * li_ion.lithium_by_energy
|% lithium.reserves
}}
 
Just barely. How about cobalt?
{{calc
|vehicle_energy_storage_needed * li_ion.cobalt_by_energy
|% cobalt.reserves
}}
{{calc
|other_energy_storage_needed * li_ion.cobalt_by_energy
|% cobalt.reserves
}}
 
Not viable.
 
Solutions:
* Using some other version of lithium-ion batteries, which doesn't depend so much on cobalt.
* Marketing cheaper electric vehicles with much smaller battery capacity, for city driving only.
* [[Walkability]].
* Extracting [[lithium from seawater]] (the viability of this may be questionable).
 
Other important stats:
{{dp
|<nowiki>li_ion.charge_discharge_efficiency</nowiki>
|<nowiki>85%</nowiki>
|<nowiki>When you charge a lithium-ion battery, this much of the energy is stored. The rest is lost as heat.</nowiki>
|<nowiki>Range: 80 to 90 %</nowiki><br /><nowiki>
from wikipedia; haven't found original source yet</nowiki>
}}
{{calc
|<nowiki> li_ion.charge_discharge_efficiency </nowiki>
|<nowiki>%</nowiki>
}}
 
===Iron-redox flow batteries===
 
[[Iron-redox flow batteries]] are a type of battery made from mostly [[iron]], an extremely abundant metal.
 
But this battery comes with a few challanges:
* The iron has to be kept ''molten'' at very hot temperatures.
** Hence it's only viable to build a battery the size of a [[shipping container]], not smaller.
** This battery is '''not''' suited for electric vehicles.
 
<!-- TODO: ===Lead-acid batteries=== -->
 
===Flywheels===
[[Flywheels]] store energy mechanically by spinning a heavy rotor at high speeds. This has been implemented before, both inside vehicles {{x|but not necessarily storing enough energy to power the vehicle for more than a few kilometers at best}} ''and'' in stationary electrical systems {{x|with a much higher specific energy}}.
 
If flywheels are made mostly of [[steel]] (which is mostly iron, an extremely abundant metal), we ''would'' have enough metal to build enough of them:
{{dp
|flywheels.practical.energy_by_mass
|5 kWh per (450 kg)
|
|Based on this product as an example: http://www.rosseta.de/texte/pdat-t4.pdf
}}
{{dp
|flywheels.theoretical.energy_by_mass
|500 kJ/kg
|
|https://web.archive.org/web/20100710052927/http://www.pddnet.com/article-next-gen-of-flywheel-energy-storage/
}}
{{dp
|iron.reserves
|85 billion tonnes
|Global iron reserves - iron metal recoverable
|Source: Global iron ore reserves 2010-2021 - Statista
}}
{{calc
|other_energy_storage_needed / flywheels.practical.energy_by_mass
|% iron.reserves
}}
{{calc
|other_energy_storage_needed / flywheels.theoretical.energy_by_mass
|% iron.reserves
}}
 
However, it is unknown how much of other metals might be needed to make the flywheel systems - for example the rare earth magnets involved in the motor/generator components. This page needs more research.
 
How much [[energy]] would it take to refine all that steel?
{{dp
|energy.tfc
|9938 Mtoe/year
|Global total final energy consumption
|Source: Key World Energy Statistics 2020
}}
{{dp
|steel.recycled.production.energy_by_mass
|sqrt(1665*4170) watt hours per kg
|
|<cite>How much energy does it take (on average) to produce 1 kilogram of...</cite>https://www.lowtechmagazine.com/what-is-the-embodied-energy-of-materials.html
}}
{{dp
|steel.new.production.energy_by_mass
|sqrt(5550*13900) watt hours per kg
|
|<cite>How much energy does it take (on average) to produce 1 kilogram of...</cite>https://www.lowtechmagazine.com/what-is-the-embodied-energy-of-materials.html
}}
{{calc
|steel.new.production.energy_by_mass * other_energy_storage_needed / flywheels.practical.energy_by_mass
|months energy.tfc
}}
However, the energy needed to ''manufacture'' the flywheels from the steel, might be vastly more. This page needs more research.
<!-- TODO: labor footprint - could work from (required * steel_industry.workers 40 hours/week / steel.production) idk -->
 
 
Viability of flywheels in vehicles is unknown too. Flywheel-based vehicles have existed for over a century, but they don't store enough energy to last more than a kilometer. Perhaps vacuum-sealed electrical type of flywheel could store more energy {{x|this page needs to clarify this more in previous paragraphs}}, but would the bumps of the road cause energy losses too quickly? This page needs more research.


<!-- TODO: ===Compressed air=== -->


<!-- TODO: ===Gravity blocks=== -->
TODO:
* Improve the above commented-out calculations.
* Put them in templates {{Grid energy storage}} and {{Vehicle energy storage}}
* Use the templates on the wikipage of each energy storage type.
-->
[[Category:Energy storage]]

Latest revision as of 15:57, 26 February 2024

In the pursuit of green energy, storage is needed for 2 reasons:

  1. To smooth out the intermittency of solar and wind power.
  2. To store energy in electric vehicles.

Note: This page does not include thermal energy storage.

Types / Candidates

Type Status
Sodium-ion batteries Good potential / needs investment.
Sodium-sulfur batteries Good potential / needs investment.
Hydrogen gas Okay for some applications, but too lossy & platinum-intensive for others.
Lithium ferro phosphate batteries Okay if used in moderation. A bit too lithium-intensive to be a general solution.
Lithium-ion batteries (NMC/NCA type) Not scalable enough: Too cobalt-intensive.
Lithium-sulfur batteries Can't handle enough charge cycles.
Lead-acid batteries Toxic / hazardous.
Stationary storage only (power grid, not vehicles)
Iron redox flow batteries Good potential / needs investment.
Compressed air ?
Pumped hydro Only viable in rare geographical locations.
Flywheels ?
Gravity blocks Not viable: Outrageously high environmental footprint of construction.

For more details, read the wikipage of each energy storage type. Links are in the table.

So far, sodium-based batteries seem to have the most hope of being a widespread solution - along with iron-based batteries for stationary energy storage.

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