Energy Efficiency: Evaluation Methods and Methodological analyses

In the debate on fossil fuels versus renewables/alternative sources, the search for more efficiency in the conversion processes has become absolutely necessary. In this paper, we start from a brief exposition of the global energy system and pass through a recall of the basic concept of thermodynamics, with the aim to propose a methodological approach to the Energy system problems. The margins of improvement in the use and conversion of energy are, yet today, absolutely wide and regard transversely any different kind of energy source. Themodynamical analysis should accompany any single decisional process in energy policy.