  Energy has always been the driving force in the technological and economic
development of societies. The consumption of a significant amount of energy is
required to provide basic living conditions of developed countries (heating,
transportation, lighting, etc.). Today energy supply has a considerable impact
on the environment, since it is fuelled by the burning of fossil fuels. In
addition to this, the fossil fuel reserves are decreasing while the demand for
energy is rapidly rising. Climate change, the depletion and geographical
segregation of fossil fuel resources, health related issues as well as energy
poverty constitute the driving forces towards the pursuit of alternative energy
sources. In addition, countries with no access to oil reserves are being
dependent from other countries for their energy supply, with a strong impact on
politics and financial issues.
