Comparison between Exergy(Availability) and Energy can be made in the following ways.
|1||Exergy(Availability) doesn’t follow the law of conservation of energy.||Energy follows the law of conservation of energy.|
|2||It is a function of states of the matter under consideration and the ‘environment’.||It is a function of the state of matter under consideration.|
|3||It is estimated with respect to the state of reference imposed by the environment.||It may be calculated based upon the assumed state of reference.|
|4||Exergy always depends upon pressure.||In case of ideal gas, energy does not depend upon pressure.|
|5||Exergy increases with a temperature drop at low temperatures. For constant pressure processes, exergy attains minimum value at the temperature of the environment.||Energy increases with rising of temperature.|
|6||Exergy has positive value for ideal vacuum.||Energy is zero for an ideal vacuum.|