Environmental Engineering Reference
In-Depth Information
Chapter 2
Hydrogen as Future Energy Carrier
In the view of a desirable and drastic reduction of both world-wide greenhouse gas
emissions and not-renewable resource exploitation, the utilization of sustainable
energy sources, such as solar, wind, hydro, or biomass are a mandatory option as
well as the use of alternative fuels in the transportation field. In the context of new
advanced energy conversion technologies, since 1990s a strong interest of inter-
national scientific and industrial community has been addressed towards the
possible development of a global 'hydrogen economy' based on the hypothesis
that hydrogen could play a basilar role as future energy carrier [
1
-
3
], in particular
as innovative fuel in automotive field, where it could flank or, in a long-term
scenario, replace the traditional oil-derived liquid mixtures in passenger cars.
Hydrogen is the most common element in the universe, and its molecule (H
2
) has
the highest energy content per unit weight of any known fuel, but it never occurs
by itself on earth, as it always combines with other elements such as oxygen
(to form water as molecule) or carbon (to form hydrocarbons and coal). Thus, it
needs to be produced and for this reason it is not a primary source, but only an
energy carrier, which could be used in combination with electricity in an inno-
vative overall energy system.
In this chapter, the state of art on the main technologies for hydrogen pro-
duction, distribution and storage is detailed and analysed evidencing the technical
potentialities of this fuel and the barriers which hinder its massive diffusion in
automotive field. The key factor for a large utilization of hydrogen not only in
transportation sector but also in all the other energy markets is represented by cost
and efficiency of production technologies. In the first paragraph the technical
issues of the main hydrogen production methods are discussed taking into account
that hydrogen can be produced starting from a large variety of primary resources.
Moreover, the application of hydrogen in the transportation sector introduces
additional problems correlated to the creation of a large infrastructure network for
fuel utilization, strictly related to the selected production technologies. The
development of specific on-board storage technologies is necessary to match the
