Net energy gain

Net Energy Gain (NEG) is a concept used in energy economics that refers to the difference between the energy expended to harvest an energy source and the amount of energy gained from that harvest. When the NEG of a resource is greater than zero, extraction yields excess energy. If the NEG is below zero, it requires more energy to extract the resource than can be extracted from it. The net energy gain, which can be expressed in joules, differs from the net financial gain that may result from the energy harvesting process, in that various sources of energy (e.g. natural gas, coal, etc.) may be priced differently for the same amount of energy.