exergy

http://en.wikipedia.org/wiki/Exergy

The company Exergy LLC manufactures heat exchangers. Heat exchangers are items such as parts for boilers, engines and furnaces. Some of their products are used by Shell.

Exergy and Energy. When the sign of potential energy is negative this is called exergy and indicates that energy comes out, thus exergy. This is the case when opposite charges are involved, the potential energy is negative and this configuration emits energy. When the charges are the same the sign is positive and energy is absorbed in this configuration.

Newton discovered that gravity is exergy, emits energy as the masses attract each other. Taking the center at one of the masses, this accounts for the center seeking behavior of gravity.

Energy denotes work in (en-ergy). Work can be energy or exergy ( work out).