View source for Energy storage/EROI

'''Importance:''' ''The lower the EROI of energy storage, the more [[energy]] we're going to need to replace [[fossil fuels]].''

==Overview==

[[EROI]] = Energy Return On Investment.

It's a concept often used for assessing the [[Term:viable|viability]] of energy sources such as [[solar]], [[nuclear]], etc.

But I believe it also needs to be applied to [[energy storage]].
 EROI = energy_returned / energy_invested

<code>energy_invested</code> should include a few things:
* the energy it takes to manufacture or construct the energy storage{{x|This could ''include'' the energy needed to mine the materials. Or not. It's fine either way - but any estimate should ''specify'' whether or not this is included.}}
* the energy used during its operation ('''charging''')
* the energy it takes to recycle or dismantle the energy storage at its end-of-life

<code>energy_returned</code> should include:
* the energy obtained during its operation ('''discharging''')


For batteries with a lifespan defined by a finite number of charge/discharge cycles:
 energy_invested = capacity*lifespan_cycles/charge_discharge_efficiency + energy_in_manufacturing + energy_in_recycling
 energy_returned = capacity*lifespan_cycles

Unlike energy ''sources'', energy storage can never have an <code>EROI >= 1</code>. But we aim to bring it ''close'' to 1, or at least reach <code>EROI >= 0.5</code>.

An <code>EROI = 0.5</code> represents a grand total efficiency of 50%. Over the course of its lifetime, for all its usable stored energy, "only" 2x as much energy ever went into the thing.

==Table==

We need to analyze all the main energy storage options, and put them in a table to compare their EROI.

''The table should go here...''

==Other metrics==
* [[energy_storage/labor]]

==See also==
* [[Life cycle analysis]]