Energy storage/EROI
Overview
EROI = Energy Return On Investment.
It's a concept often used for assessing the 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
energy_invested should include a few things:
- the energy it takes to manufacture or construct the energy storage
(...)( preferably including the energy needed to mine the materials. For any estimate, we must be clear about whether or not this is counted. ) - the energy used during its operation (charging)
- the energy it takes to recycle or dismantle the energy storage at its end-of-life
energy_returned 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 EROI >= 1. But we aim to bring it close to 1, or at least reach EROI >= 0.5.
An EROI = 0.5 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.
Importance: The lower the EROI of energy storage, the more energy we're going to need to replace fossil fuels.
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...