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becomes higher than a certain level, energy is theoretically not needed. The skater
who reaches the goal is smoothly circling the rink while not kicking with his/her
foot.
The skater will eventually stop by being caught by his/her coach, or grabbing the
wall by himself/herself. At this time, kinetic energy turns into heat and is released
into the atmosphere. The energy lost is equal to the energy used in starting to skate.
Therefore, if you can store energy generated at the time of stoppage and use it at the
start, you can continue to exercise forever.
A regenerative brake mounted on a hybrid vehicle (HV), etc. is exactly the application of this principle. The energy released when decelerating by applying the
brake is saved in the battery and is utilized when starting and accelerating.
In the case of vertical motion as well as horizontal transport, the theoretical limit
is zero. Pull the wire of the elevator on a pulley and attach a weight of the same
weight to the other side of the elevator. If a good bearing is attached to the pulley,
and without friction, no energy is needed to move the elevator up and down.
That is, friction is the cause of the energy consumed in transportation. A skater
can continue skating by inertia after reaching a certain speed because the friction is
small. Likewise, a satellite continues to fly and the Earth keeps going around the
Sun because the friction is zero in outer space. However, there is friction in the real
world. The bicycle stops unless the rider keeps rowing, and the skater cannot slide
forever.
How can we reduce friction losses? This is the key to energy efficiency in
transportation.
3.2.2 Energy-Efficient Cars Appear One after Another
Let’s think about the energy efficiency of automobiles powered by gasoline engines
that account for the majority of cars in the domestic market now.
A gasoline engine car burns gasoline in a cylinder, imparts a force to the cylinder
head, rotates the shaft with that force, adjusts the direction and speed with many
gears, etc., rotates the wheel, and runs. The overall picture is that the chemical
energy of gasoline is converted to the work of a cylinder head, and that work is used
to transport the car.
The chemical energy of gasoline is converted into work and heat. Since the law
of conservation of applies here, chemical energy is converted by 100% if heat and
work are combined. In theory, all gasoline may be converted to work, but only about
35% becomes work, and the remaining 65% is wastefully consumed as heat. Energy
is thrown away in heat in various places, such as heat radiation from the exhaust gas
and the engine, friction between the tires and the ground, and friction inside the car
such as gears and transmissions.
Especially, when starting and accelerating, it requires a large amount of work, so
a lot of frictional heat is generated and a considerable amount is released into the
atmosphere. After reaching a certain speed, no energy is theoretically necessary,
3.2 Low Carbon Technologies in the Transportation Sector
becomes higher than a certain level, energy is theoretically not needed. The skater
who reaches the goal is smoothly circling the rink while not kicking with his/her
foot.
The skater will eventually stop by being caught by his/her coach, or grabbing the
wall by himself/herself. At this time, kinetic energy turns into heat and is released
into the atmosphere. The energy lost is equal to the energy used in starting to skate.
Therefore, if you can store energy generated at the time of stoppage and use it at the
start, you can continue to exercise forever.
A regenerative brake mounted on a hybrid vehicle (HV), etc. is exactly the application of this principle. The energy released when decelerating by applying the
brake is saved in the battery and is utilized when starting and accelerating.
In the case of vertical motion as well as horizontal transport, the theoretical limit
is zero. Pull the wire of the elevator on a pulley and attach a weight of the same
weight to the other side of the elevator. If a good bearing is attached to the pulley,
and without friction, no energy is needed to move the elevator up and down.
That is, friction is the cause of the energy consumed in transportation. A skater
can continue skating by inertia after reaching a certain speed because the friction is
small. Likewise, a satellite continues to fly and the Earth keeps going around the
Sun because the friction is zero in outer space. However, there is friction in the real
world. The bicycle stops unless the rider keeps rowing, and the skater cannot slide
forever.
How can we reduce friction losses? This is the key to energy efficiency in
transportation.
3.2.2 Energy-Efficient Cars Appear One after Another
Let’s think about the energy efficiency of automobiles powered by gasoline engines
that account for the majority of cars in the domestic market now.
A gasoline engine car burns gasoline in a cylinder, imparts a force to the cylinder
head, rotates the shaft with that force, adjusts the direction and speed with many
gears, etc., rotates the wheel, and runs. The overall picture is that the chemical
energy of gasoline is converted to the work of a cylinder head, and that work is used
to transport the car.
The chemical energy of gasoline is converted into work and heat. Since the law
of conservation of applies here, chemical energy is converted by 100% if heat and
work are combined. In theory, all gasoline may be converted to work, but only about
35% becomes work, and the remaining 65% is wastefully consumed as heat. Energy
is thrown away in heat in various places, such as heat radiation from the exhaust gas
and the engine, friction between the tires and the ground, and friction inside the car
such as gears and transmissions.
Especially, when starting and accelerating, it requires a large amount of work, so
a lot of frictional heat is generated and a considerable amount is released into the
atmosphere. After reaching a certain speed, no energy is theoretically necessary,
3.2 Low Carbon Technologies in the Transportation Sector