Noteworthy, efficiency is not an issue in the use of perennial primary energies
(SWGH) (see Chap. 5) for the simple reason that “fuels” like wind and sunlight do
not emit CO 2 and the environmental impact on climate change of their use is not a
real issue. Moreover, they are free and easily available.
Limiting the analysis of the efficiency only to the production of electricity from
fossil-C does not tell the whole story. In fact, the first negative impact is the poor
heat to steam conversion (ca. 41–46% depending on the technology) while the
electricity production by alternators ranges around 98–99%. The overall efficiency
is lowered to 32–35% with the various necessary cleaning technologies linked to
electricity production (abatement of SOx or NOy). This amount of electric energy is
not yet what consumers use, for example, in houses. In fact, transmission of the
electrical energy over the distribution grid between the power station and the
consumer results in a distribution loss of ca. 10% mainly due to the resistance and
dispersion of the electrical cables. Further energy is lost in voltage conversion at the
end user’s appliance. Additionally, incandescent lighting is particularly inefficient
so that finally only 5–10% of the electrical energy is converted into light when
using old tungsten lamps, which are now out of use. Efficiency can be increased
along the entire production–utilization chain. For example, modern lamps are six to
seven times more efficient than the old tungsten ones [4b], but new tungsten bulbs
are coming back with excellent performances.
4.3 Efficiency in the Transport Sector
Considering the transport sector, in an average car only 20–22% of the original
chemical energy of the fuel is used for moving the vehicle, the rest is lost in the
engine itself (61–63%), standing idle (16–17%), drive train (5–7%), and various
parts (1–2%). Diesel cars are more performant than gasoline cars due to the use of
direct injection in the former category. But such difference is going to disappear in
coming years. Turbocharged direct injection engines in the European market are
estimated to attain 18% reduced fuel consumption, part of which is due to intake
valve control and other engine technologies. Other important technologies include
cylinder shutoff during low load conditions and improved valve timing and lift
control [5].
Great efforts are made for improving the efficiency of energy conversion
worldwide in the various sectors of transport. Good results are obtained under the
push of legislation in EU and USA and other countries. Most advanced truck
engines can reach an efficiency of 45% today.
The EU legislation has put strict limitations to emissions by cars in terms of NOx
and CO 2 per km with the various Euro 4, 5, 6 standards. The latter tends to limit the
CO 2 emission to less than 100 g/km. Today, in many cities, the Euro 4 cars are not
admitted. The introduction of “hybrid cars” is further improving the efficiency of
fuels as such cars can save energy in various ways, such as:
50
4 Reduction of the CO 2 Production
(SWGH) (see Chap. 5) for the simple reason that “fuels” like wind and sunlight do
not emit CO 2 and the environmental impact on climate change of their use is not a
real issue. Moreover, they are free and easily available.
Limiting the analysis of the efficiency only to the production of electricity from
fossil-C does not tell the whole story. In fact, the first negative impact is the poor
heat to steam conversion (ca. 41–46% depending on the technology) while the
electricity production by alternators ranges around 98–99%. The overall efficiency
is lowered to 32–35% with the various necessary cleaning technologies linked to
electricity production (abatement of SOx or NOy). This amount of electric energy is
not yet what consumers use, for example, in houses. In fact, transmission of the
electrical energy over the distribution grid between the power station and the
consumer results in a distribution loss of ca. 10% mainly due to the resistance and
dispersion of the electrical cables. Further energy is lost in voltage conversion at the
end user’s appliance. Additionally, incandescent lighting is particularly inefficient
so that finally only 5–10% of the electrical energy is converted into light when
using old tungsten lamps, which are now out of use. Efficiency can be increased
along the entire production–utilization chain. For example, modern lamps are six to
seven times more efficient than the old tungsten ones [4b], but new tungsten bulbs
are coming back with excellent performances.
4.3 Efficiency in the Transport Sector
Considering the transport sector, in an average car only 20–22% of the original
chemical energy of the fuel is used for moving the vehicle, the rest is lost in the
engine itself (61–63%), standing idle (16–17%), drive train (5–7%), and various
parts (1–2%). Diesel cars are more performant than gasoline cars due to the use of
direct injection in the former category. But such difference is going to disappear in
coming years. Turbocharged direct injection engines in the European market are
estimated to attain 18% reduced fuel consumption, part of which is due to intake
valve control and other engine technologies. Other important technologies include
cylinder shutoff during low load conditions and improved valve timing and lift
control [5].
Great efforts are made for improving the efficiency of energy conversion
worldwide in the various sectors of transport. Good results are obtained under the
push of legislation in EU and USA and other countries. Most advanced truck
engines can reach an efficiency of 45% today.
The EU legislation has put strict limitations to emissions by cars in terms of NOx
and CO 2 per km with the various Euro 4, 5, 6 standards. The latter tends to limit the
CO 2 emission to less than 100 g/km. Today, in many cities, the Euro 4 cars are not
admitted. The introduction of “hybrid cars” is further improving the efficiency of
fuels as such cars can save energy in various ways, such as:
50
4 Reduction of the CO 2 Production