Electric Cars
Historical aspects
Electric
Cars were developed in the late 1800's but batteries were weak
and electricity was not available everywhere yet. Besides, fuel was quite
cheap (only 10 Cents per Gallon in US)! At that time, people were even
hesitant to replace kerosene lamps as electric lights became available.
Until the beginning of 900's the electric vehicle represented a valid
competitor of the internal combustion engine: the first vehicle to break
the limit of 100 Km/h, in 1899, the "Jamais Contente" of Camille
Jenatzy, was an electric vehicle!
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The "Jamais Contente",
of Camille Jenatzy: the first vehicle to break the limit of 100
Km/h, in 1899.
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The research on electric vehicles continues also after the internal combustion
engine established as the almost exclusive solution for cars.
The 35-Year old Mars II pictured above (still in operation!) was
manufactured by Electric Fuel Propulsion Corporation (EFP) in 1968. These
cars had a driving range of 146 miles and were equipped with Lead Cobalt
Batteries (Source: http://www.electricauto.com/_newsArch/news004.html).
An example of high performace electric car is the Eliica concept
car, developed at the Keio University in Japan, with 370 km/h top speed
and 200 km range.
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The Mars II, manufactured by Electric
Fuel Propulsion Corporation (EFP) in 1968.
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Eliica Electric Car, developed at
the Keio University in Japan, http://www.eliica.com
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Within the years of the nuclear energy as a solution for
all the problems, the electric car, because of its very low emission,
represented an interesting attraction for the future. But very soon it
showed its limit compared with the traditional powered engines and could
be considered only as city car. The main problem was a difficult storage
of the energy. Batteries with a higher energy density and power, either
in the charging process or in the discharging one, were expected for the
future. The main characteristics had to be:
- low cost
- environmental compatible
- minimum lack in the autodischarging process
- long life
Electric motor versus thermal engine
The conversion from thermal to mechanical energy in a thermal engine
is subject to the limitation posed by the Second
Law of Thermodynamics, apart the further losses due to friction
and difference from the actual thermodynamic cycle from the perfect one
(the Carnot cycle). Electric motors efficiency is limited by Joule effect
and friction, but may attain values significantly higher with respect
to thermal engines ones.
Electric
cars could therefore achieve greater on-board conversion efficiencies
to mechanical energy, and without the emissions associated to the combustion
process (and with low noise too). It should be noted, however, that the
use of electrical cars, while improving air quality and noise emissions
in urban areas, does not necessarily contribute to the CO2 mitigation,
since in many countries most of electrical energy is still obtained starting
from fossil fuels.
The major limitation of electrical cars is due to the lower energy density
associated to the use of batteries (with lead acid batteries, traditionally
used for automotive application, this density is almost 20 times lower
than a gasoline tank). In other words, the weight associated to the batteries
should be almost 20 times greater than the weight of a gasoline tank,
for the same range. The recourse to the hybrid electric
vehicle concept allows to maintain some of these advantages (lower
noise and pollution in urban areas), without range restriction but, of
course, with higher complexity and costs.
Links
http://www.electriccars.com/
http://www.electricauto.com/
http://americanhistory.si.edu/edison/ed_d22.htm
http://www.eliica.com/
http://www.aae.it/indice.htm
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