2.1. Sustainable Energy
According to the Brundtlandt Commission report (1983) that defined sustainable development as a process meeting “the needs of the present without compromising the ability of further generations to meet their own needs”, the importance of “sustainability” become a noteworthy area of concern (Carrera & Mack, 2010).
Although the necessity of any kind of energy resources in order to improve the quality of life is indisputable, the usage of some resources have negative effects on the ecosystems such as the emission of the greenhouse gases and this requires a shift away from the current fossil fuel-based energy paradigm to sustainable energy technologies.
The sustainable development has been the subject of wide- ranging discussion and debate within government, non-government and academic community (Bilgen et al., 2008; Omer, 2008; Hofman & Li, 2009; Pereira et al., 2008; Jovanovic et al., 2009).
Sustainability can be seen as the final goal: a balance of social and economic activities and the environment (Hofman & Li, 2009).
Energy systems of today are largely driven by the combustion of fossil fuels. The emissions of greenhouse gases (GHG), the depletion of natural resources and the risks on the security of energy supply are the major consequences of the demand of fossil fuels (Neves & Leal, 2010). So this situation causes to arise a “selection problem of energy resource”.