Emergy: concept, necessity and applications

In this paper, first, the history of emergy concept formation is described and then, tried to be the superficies of subjects more than their depth with knowing approach of different sections of emergy. Therefore, the principles of emergy are discussed, briefly and then, the language of energy systems is expressed and the method of ecology energy calculations also mentioned. In addition, decision making procedure based on emergy assessment is introduced and its indices are defined. Eventually, the emergy concept is described as a function of exergy in order to two different study solutions.