Aline Leon ´ In the last years, public attention was increasingly
shifted by the media and world governmentsto the conceptsof saving
energy, reducingpollution, protectingthe - vironment, and developing
long-term energy supply solutions. In parallel, research funding
relating to alternative fuels and energy carriers is increasing on
both - tional and international levels. Why has future energy supply
become such a matter of concern? The reasons are the problems created by
the world's current energy supply s- tem which is mainly based on fossil
fuels. In fact, the energystored in hydrocarb- based solid, liquid, and
gaseous fuels was, is, and will be widely consumed for internal
combustion engine-based transportation, for electricity and heat
generation in residential and industrial sectors, and for the production
of fertilizers in agric- ture, as it is convenient, abundant, and cheap.
However, such a widespread use of fossil fuels by a constantly growing
world population (from 2. 3 billion in 1939 to 6. 5 billion in 2006)
gives rise to the two problems of oil supply and environmental
degradation. The problemrelated to oil supply is caused by the fact that
fossil fuels are not - newable primary energy sources: This means that
since the rst barrel of petroleum has been pumped out from the ground,
we have been exhausting a heritage given by nature.