Energy returned on energy invested - ESOEI

ESOEI is used when EROEI is below 1.

Reference 1: ESOEI[7].

Reference 2: Lithium ion battery, NaS battery, Lead acid battery, Vanadium redox battery, Zinc bromide battery, CAES and Pumped hydroelectric storage.

Source: http://en.wikipedia.org/wiki/Energy_returned_on_energy_invested