246
Alternative Fuels for Transportation
moving objects); and electric energy (to feed purely electric appliances—
computers, consumer electronics, etc.).
This conversion can in principle be made in two ways: concentrated in a
few power plants or in several small devices located near the corresponding
final utilization devices. It is obvious that for the latter option to take place,
the final energy form needs to be easily transportable, which is not often the
case. For technical reasons, potential energy from nuclear reactions cannot
be converted in small distributed systems, it needs large power plants. At
present, indeed, energy from nuclear reactions is converted in large power
plants first into heat. The heat is then converted into mechanical movement,
then into electricity that is fed into the electric transmission and distribution
network. Electricity is a very good means of transferring energy from concentrated plants to their place of final use.
As far as potential energy from fossil fuels is concerned, it can be converted into usable energy either in a concentrated (power plants) or distributed (ICEs for vehicles, boilers for ambient heating, etc.) manner. The
concentrated conversion has the advantage that the environmental pollution
created during the process can be controlled much better in large than in
small plants. Also conversion efficiency can be much higher, just to make
a single example, fuel energy can be converted into electricity by modern
combined-cycle power plants with efficiencies that reach 58% while the best
automotive ICEs barely reach 40%. Moreover, concentrated conversion is
made in places located far from densely populated urban areas and therefore the emissions produced can be distributed over very large areas before
reaching large masses of persons, thus far reducing any public health impact
from the emissions. It can be concluded that if an energy carrier is available
that is able to transport energy into places of final utilization, and able to
generate energy in the final form with negligible pollution, it can bring large
environmental advantages.
9.2.2 role of electricity
Today by far, the most widely used energy carrier is electricity. Electricity is
a very flexible means of transferring energy from concentrated conversion
points into the areas of final utilization. However, electricity has the disadvantage of requiring wiring to be conveyed. This is exploited in railways
using electrified lines and catenary for electricity distribution to trains. A
way to exploit electricity in mobile vehicles not having wiring connecting
them to earth is to store it onboard. This can be done converting chemical
potential energy into onboard-installed reservoirs that are the well known
“batteries.” Indeed, this is not very effective because of two reasons:
• Energy per unit of volume that can be stored in batteries and mass
is much lower than that of a fossil fuel (more than an order of
magnitude).
Alternative Fuels for Transportation
moving objects); and electric energy (to feed purely electric appliances—
computers, consumer electronics, etc.).
This conversion can in principle be made in two ways: concentrated in a
few power plants or in several small devices located near the corresponding
final utilization devices. It is obvious that for the latter option to take place,
the final energy form needs to be easily transportable, which is not often the
case. For technical reasons, potential energy from nuclear reactions cannot
be converted in small distributed systems, it needs large power plants. At
present, indeed, energy from nuclear reactions is converted in large power
plants first into heat. The heat is then converted into mechanical movement,
then into electricity that is fed into the electric transmission and distribution
network. Electricity is a very good means of transferring energy from concentrated plants to their place of final use.
As far as potential energy from fossil fuels is concerned, it can be converted into usable energy either in a concentrated (power plants) or distributed (ICEs for vehicles, boilers for ambient heating, etc.) manner. The
concentrated conversion has the advantage that the environmental pollution
created during the process can be controlled much better in large than in
small plants. Also conversion efficiency can be much higher, just to make
a single example, fuel energy can be converted into electricity by modern
combined-cycle power plants with efficiencies that reach 58% while the best
automotive ICEs barely reach 40%. Moreover, concentrated conversion is
made in places located far from densely populated urban areas and therefore the emissions produced can be distributed over very large areas before
reaching large masses of persons, thus far reducing any public health impact
from the emissions. It can be concluded that if an energy carrier is available
that is able to transport energy into places of final utilization, and able to
generate energy in the final form with negligible pollution, it can bring large
environmental advantages.
9.2.2 role of electricity
Today by far, the most widely used energy carrier is electricity. Electricity is
a very flexible means of transferring energy from concentrated conversion
points into the areas of final utilization. However, electricity has the disadvantage of requiring wiring to be conveyed. This is exploited in railways
using electrified lines and catenary for electricity distribution to trains. A
way to exploit electricity in mobile vehicles not having wiring connecting
them to earth is to store it onboard. This can be done converting chemical
potential energy into onboard-installed reservoirs that are the well known
“batteries.” Indeed, this is not very effective because of two reasons:
• Energy per unit of volume that can be stored in batteries and mass
is much lower than that of a fossil fuel (more than an order of
magnitude).