Return on Investment (Fracking)

"EROI is the net value of an energy source – the surplus that remains after the energy used to acquire the energy is accounted for.  EROI is an important concept – it is not a measure of the financial viability of a project, but rather of the long term societal viability.  Modern economies depend on large energy surpluses in order to grow.  Fossil fuels have strong EROIs, although they decline over time (for example, a new oil strike can be a “gusher,” requiring little additional energy to produce the oil, but as the field ages it will require more and more effort to pump the remaining oil out).  EROI is a measure fo the quality of energy, and the quality of an economy is directly related to the quality and quantity of energy available to run it"

http://energeopolitics.com/2013/06/25/eroi-projections-for-marcellus-shale-gas/