The Automotive Industry 505
Design demands for allelectric vehicles are high. A very high energy
density is needed for the propulsion system, but there are also everpresent pressures to reduce the amount of space occupied by both
the fuel cells and supporting fuel tanks for storing the hydrogen.
Known sensitivities to humidity variations must be addressed.
Durabilily demands are extremely high. Many current fuel cells are
relatively sensitive to mishandling, so high levels of ruggedness are
required (also see Section 9.7).
The hydrogen storage problem is particularly acute for vehicles. Large
quantities of fuel must be able to be stored and replenished safely.
Several options are under exploration. Compressed gas hydrogen
is possible but quite costly due to the need for expensive tanks.
Liquid hydrogen storage has been explored as well, but significant
inefficiencies and energy losses occur because of the necessary conversion processes. Combination gas/liquid systems are also being
explored. Solidstate materials may ultimately prove to be the best
storage medium if needed storage densities and charge and release
rates can be achieved. These are difficult problems. Still, materials
such as hydrogenabsorbing hydrides or others may prove effective
for onboard storage of hydrogen for fuelcell vehicles.
Despite the interest in electric propulsion, the internal combustion engine is by no means out of the picture. Its power and other
advantages will give it a place in vehicle fleets for a long time. The
internal combustion engine has also by no means seen the last
of improvements and efficiency increases made possible through
both design and material advances. Nanocomposites can help meet
their wellidentified role of providing strength, hardness, and wearresistance improvements for many components, ranging from cylinder liners and pistons to a host of other parts, including bearings.
Efficiencies can also be improved by limiting losses in enginegenerated thermal energy—particularly important in diesel engines.
Various nanocrystalline ceramics that have both hardness and heatretention capabilities, such as zirconia, are being explored for use
as cylinder liners. The interesting field of nanotribological studies,
which deals with friction, has obvious applications in the design of
the many mechanisms and linkages present. Even traditional sparkplugs are being rethought to make them more resistant to erosion
or corrosion.
The catalytic characteristics of many nanomaterials that have been
discussed earlier have the potential to further reduce unwanted
emissions. Currently, precious metals such as platinum are used in
catalytic converters. This material is costly and subject to shortages.
Design demands for allelectric vehicles are high. A very high energy
density is needed for the propulsion system, but there are also everpresent pressures to reduce the amount of space occupied by both
the fuel cells and supporting fuel tanks for storing the hydrogen.
Known sensitivities to humidity variations must be addressed.
Durabilily demands are extremely high. Many current fuel cells are
relatively sensitive to mishandling, so high levels of ruggedness are
required (also see Section 9.7).
The hydrogen storage problem is particularly acute for vehicles. Large
quantities of fuel must be able to be stored and replenished safely.
Several options are under exploration. Compressed gas hydrogen
is possible but quite costly due to the need for expensive tanks.
Liquid hydrogen storage has been explored as well, but significant
inefficiencies and energy losses occur because of the necessary conversion processes. Combination gas/liquid systems are also being
explored. Solidstate materials may ultimately prove to be the best
storage medium if needed storage densities and charge and release
rates can be achieved. These are difficult problems. Still, materials
such as hydrogenabsorbing hydrides or others may prove effective
for onboard storage of hydrogen for fuelcell vehicles.
Despite the interest in electric propulsion, the internal combustion engine is by no means out of the picture. Its power and other
advantages will give it a place in vehicle fleets for a long time. The
internal combustion engine has also by no means seen the last
of improvements and efficiency increases made possible through
both design and material advances. Nanocomposites can help meet
their wellidentified role of providing strength, hardness, and wearresistance improvements for many components, ranging from cylinder liners and pistons to a host of other parts, including bearings.
Efficiencies can also be improved by limiting losses in enginegenerated thermal energy—particularly important in diesel engines.
Various nanocrystalline ceramics that have both hardness and heatretention capabilities, such as zirconia, are being explored for use
as cylinder liners. The interesting field of nanotribological studies,
which deals with friction, has obvious applications in the design of
the many mechanisms and linkages present. Even traditional sparkplugs are being rethought to make them more resistant to erosion
or corrosion.
The catalytic characteristics of many nanomaterials that have been
discussed earlier have the potential to further reduce unwanted
emissions. Currently, precious metals such as platinum are used in
catalytic converters. This material is costly and subject to shortages.