traffic this latter approach has certain technical advantages. Another method of ensuring that the ELECAT
remains competitive with the individual IC engined car would be to introduce a lower speed limit on highways
equivalent to the maximum safe speed of an articulated vehicle (possibly around 100kph). This would have the
advantage of saving further fuel or energy for cars travelling individually and limiting traffic congestion which
is improved at lower speeds.
5.4.3
Environmental Benefits of the ELECAT
Since initially the ELECAT would carry predominantly standard IC engined cars, it is worth calculating if this
provides any net environmental advantage. An estimate of the CO2 emissions produced per car carried relative
to that if the cars were driven individually is calculated in ‘spreadsheet 2’ ELECAT worksheet, and is
illustrated in figure 18.
46
Since the precise design and aerodynamic characteristics of the ELECAT is difficult to
predict, the CO2 ratio is calculated for a variety of drag coefficients and car loadings. It is assumed a 50:50 mix
of Diesel and Petrol cars are used and a direct injection Diesel engine is used to power the ELECAT at a
constant 100kph.
The CO2 emissions are reduced to around 60% that of driving the cars individually, assuming the drag
coefficient of the ELECAT could be reduced to 0.4 and it transports 8 conventional cars, whilst using a drag
coefficient of 0.7 and transporting 6 cars emits around the same CO2 as driving the cars individually. This
suggests that useful reductions in CO2 and fuel consumption are possible when using this type of ferrying
system even when BEVs are not used. However, as the BEVs become more widespread, the largest CO2
reductions will result from increasing the practicality and popularity of BEVs by effectively extending
their range and encouraging their use in preference to IC engined vehicles on urban roads. It may also be
feasible to power the ELECAT using genuinely renewable biodiesel fuel to reduce the CO2 emissions further.
Ultimately the goal would be to ensure the ELECAT and cars they carry, emit virtually no net carbon or other
emissions.
Extending the maximum permissible lengths of ELECATs on highways would enable them to carry still more
cars with associated environmental benefits, although the safety aspects of this policy would have to be
considered. Another option would be to incorporate low profile vehicles into the ELECAT design as illustrated
in figure 19.
0.5
0.6
0.7
0.8
0.9
1
1.1
0.7
0.6
0.5
0.4
Drag Coefficient
6 cars
7 cars
8 cars
Figure 18 Relative CO2 emissions for a Diesel powered ELECAT
A range of ELECAT drag coefficients and car loadings are used to illustrate the sensitivity of relative CO2 to
these variables.
46 ‘spreadsheet 2’ “CO2 and fuel for various vehicle configurations’
