ABSTRACT
The second law of thermodynamics is an expression of empirical fact that all forms of energy are not necessarily equivalent in their ability to perform useful work. There are many statements and corollaries of the second law that can be found in the literature on thermodynamics. The Carnot cycle would make for a most efficient engine if it could be utilized as such. The problem is the difficulty of devising heat transfer processes that are constant temperature. The only known system that may be considered equivalent to a Carnot engine is in nature: the hurricane. The available energy for a process that receives heat is the amount of net work that would be obtained from the most efficient engine cycle. Similarly, the unavailable energy for a process is the amount of energy that would be rejected from the most efficient engine cycle.
