Environmental Engineering Reference
In-Depth Information
abandon the already available technologies. After the most efficient option
represented by the path natural gas-electricity-BEVs (31%), other two very
convenient possibilities, in terms of well-to-wheels efficiency, are the hybrid
thermal electric vehicles (HTEV, 27%) using Diesel oil or gasoline as energy
carriers, and hydrogen fuel cell vehicles (HFCEVs, 25%) adopting hydrogen
produced from natural gas with commercial processes (see
Sect. 2.1
). While the
first option is already object of some commercial realizations, and permits a not
negligible reduction in pollutant emissions and fuel consumption with respect to
internal combustion vehicles, the second solution has to face the same techno-
logical issues of all fuel cell vehicles, but the utilization of mature and available
processes for hydrogen production would have the advantage to favor its rapid
introduction into the world energy system.
The further development and diffusion of these technologies, coupled to a
convinced policy of governmental incentives for high efficiency vehicles, could
give research makers and car manufacturers enough time to overcome technical
problems of totally carbon-free alternatives, such as HFCEVs and BEVs powered
by energy carriers deriving from nuclear and renewable resources (see
Sect. 2.1.2
and
Sect. 3.4
). In particular, the hydrogen fuel cell vehicles, adopting non-fossil
hydrogen as on board energy carrier and fuel cells to generate electric energy, even
if represent a less efficient solution in terms of well-to-wheels analysis with respect
to BEVs and any other fossil-based technology, could become a proper answer to
the requirements of carbon-free transport systems on mid-term.
The Fig.
1.2
reports the carbon and hydrogen contents for some fuels which
have been adopted by humanity in the last three centuries. Starting from wood
(C/H = 9), which was the main fuel available before the industrial revolution, the
Carbon wt%
Hydrogen wt%
100%
80%
60%
40%
20%
0%
Wood
Coal
Crude oil
Methane
Hydrogen
Fig. 1.2
Carbon and hydrogen contents for different fuels
