What is exergy and how does it differ from energy?

[monty37]

what exactly is exergy,my book says there is something called exergy like energy?

 

[maverick_starstrider]

Straight from wikipedia: "In thermodynamics, the exergy of a system is the maximum work possible during a process that brings the system into equilibrium with a heat reservoir."

 

[monty37]

so is the term used only with respect tom thermodynamics?
please elaborate equilibrium with heat reservoir