Energy Return On Energy Invested

This ratio, abbreviated to EROEI, has become quite a hot topic lately in the movement to replace fossil fuels with forms of energy that will not further contribute to global warming. The energy return of a power technology is the energy output of the system – nuclear, wind, hydro, etc. – over its expected lifetime. That, divided by the energy that must be invested to bring that system on-line and keep it functioning, is the EROEI.

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