• Shutting the engine down when the vehicle is stopped, leaving on the electric
motor;
• Using the electric motor to brake and using the electricity generated to recharge
the battery;
• Using the electric motor to start or boost power during acceleration;
• Using the electric motor instead of the engine at low speed and load (that saves
emissions in city circuits);
• Allowing the use of a more efficient cycle than the standard Otto cycle (in some
hybrids); and
• Shifting power steering and other accessories to (more efficient) electric
operation.
We do not consider here the “full electric cars” as they do not rely on liquid fuels
as power source, but receive energy from outside and represent a different case.
4.4 Energy Utilization Efficiency
Besides increasing the efficiency in the production of energy, even the utilization of
energy deserves attention. A better utilization of energy at the public, industrial,
collective, and individual levels can provide major benefits in CO 2 emission
reduction.
At the public level, several authorities all around the world have put limits to the
temperature within buildings during the cold and warm seasons, reducing the fossil
fuel consumption and the emission of CO 2 . Overall, industries consume roughly
one-third of the total energy (21% of the heavy industries) with some 50% lost as
waste heat. All over the world, industries are implementing saving measures with heat
recovery from flue gases or fluids and reuse either internally or externally, depending
on the temperature, a fundamental factor in deciding the use of heat. Usually, waste
heat is divided into three segments, according to the temperature, namely, below
200 °C (ca. 35% of the total amount of waste heat, at the EU level), which is often
referred to as low-temperature waste heat; in the range 200–500 °C (ca. 25% of the
total); and above 500 °C (ca. 40%, mostly in the range 500–1000 °C). The temperature of waste heat depends on the specific industrial sector within which heat is
generated [6]. For example, the higher temperature range (500–1000 °C) is typical of
iron, steel, and cement industries. The 200–500 °C range is proper of the pulp and
paper, chemical/petrochemical, and iron-steel industry, and the low range (<200 °C)
is common to most light industrial sectors, including food. Concerning the use,
high-temperature heat (>200 °C) can be used for producing high-temperature and
high-pressure steam for driving turbines and producing electric energy, or for
pre-heating fluids used in industrial processes. Conversely, low-temperature heat
(150–200 °C) can be used for heating water used in turn for heating greenhouses (for
growing vegetables and flowers) or even civil and industrial buildings and houses.
4.3 Efficiency in the Transport Sector
51
motor;
• Using the electric motor to brake and using the electricity generated to recharge
the battery;
• Using the electric motor to start or boost power during acceleration;
• Using the electric motor instead of the engine at low speed and load (that saves
emissions in city circuits);
• Allowing the use of a more efficient cycle than the standard Otto cycle (in some
hybrids); and
• Shifting power steering and other accessories to (more efficient) electric
operation.
We do not consider here the “full electric cars” as they do not rely on liquid fuels
as power source, but receive energy from outside and represent a different case.
4.4 Energy Utilization Efficiency
Besides increasing the efficiency in the production of energy, even the utilization of
energy deserves attention. A better utilization of energy at the public, industrial,
collective, and individual levels can provide major benefits in CO 2 emission
reduction.
At the public level, several authorities all around the world have put limits to the
temperature within buildings during the cold and warm seasons, reducing the fossil
fuel consumption and the emission of CO 2 . Overall, industries consume roughly
one-third of the total energy (21% of the heavy industries) with some 50% lost as
waste heat. All over the world, industries are implementing saving measures with heat
recovery from flue gases or fluids and reuse either internally or externally, depending
on the temperature, a fundamental factor in deciding the use of heat. Usually, waste
heat is divided into three segments, according to the temperature, namely, below
200 °C (ca. 35% of the total amount of waste heat, at the EU level), which is often
referred to as low-temperature waste heat; in the range 200–500 °C (ca. 25% of the
total); and above 500 °C (ca. 40%, mostly in the range 500–1000 °C). The temperature of waste heat depends on the specific industrial sector within which heat is
generated [6]. For example, the higher temperature range (500–1000 °C) is typical of
iron, steel, and cement industries. The 200–500 °C range is proper of the pulp and
paper, chemical/petrochemical, and iron-steel industry, and the low range (<200 °C)
is common to most light industrial sectors, including food. Concerning the use,
high-temperature heat (>200 °C) can be used for producing high-temperature and
high-pressure steam for driving turbines and producing electric energy, or for
pre-heating fluids used in industrial processes. Conversely, low-temperature heat
(150–200 °C) can be used for heating water used in turn for heating greenhouses (for
growing vegetables and flowers) or even civil and industrial buildings and houses.
4.3 Efficiency in the Transport Sector
51