ABSTRACT
The human population increase along with the raise of living
standards is about to cause doubling of the global primary energy
consumption in less than 50 years [1]. Such continuous increase of
energy demand will soon become unsustainable when considering
that most of the currently exploited energy comes from fossil fuels
whose resources are, obviously, limited. Moreover, burning of fossil
fuels by the humankind in the past 250 years released such a
quantity of carbon (in the form of CO2-an important greenhouse
gas) that it took our planet about 250 million of years to sequester
[2]. An increasing awareness comes up on the energy demand issue
and new pressing challenges arise to provide people with enough
energy within a sustainable development scenario.
