1. Introduction
Energy is considered as a essential agent for the economic development and a significant factor of creation and
appreciation as well. On the other hand, the unrestrained use of this resource, mainly these two last decades,
generated a concrete risk of environmental degradation and the prevalent ecological concern. The increasing
obviousness of the environmental problems is due to a combination of several factors, since the environmental
impact of the human activities increased considerably because of the growth of the world population, the energetic
consumption and the industrial activities [1, 2].