Exergy and Emergy have been developed as two complementary goal functions. Quantitative applications of Exergy for higher organisms were made with traditional thermodynamic considerations. The concept of Emergy originally came from systems ecology. Exergy is a property of a system, measuring the maximum work that can be extracted from a system when it goes towards the thermodynamic equilibrium with a reference state, whereas Emergy is the energy required to make a service or product expressed in energy of o...