In physics, energy economics and ecological energetics, energy returned on energy invested (EROEI or ERoEI); or energy return on investment (EROI), is the ratio of the amount of usable energy acquired from a particular energy resource to the amount of energy expended to obtain that energy resource. When the EROEI of a resource is less than or equal to one, that energy source becomes an "energy sink", and can no longer be used as a primary source of energy.
Read more about Energy Returned On Energy Invested: Non-manmade Energy Inputs, Relationship To Net Energy Gain, Economic Influence of EROEI, Criticism of EROEI, EROEI Under Rapid Growth
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