Environmental Engineering Reference
In-Depth Information
and responds as the physical vehicle would in developing and delivering torque to
the driven wheels. The model contains transient component behaviour so that
simulation of acceleration and deceleration events is emulated, and integration into
a hardware-in-the-loop environment is seamless.
A comparison of vehicle energy usage, both primary energy and vehicle
energy consumption, is shown in Figure 9.4. The total upstream energy needed to
produce the fuel is listed as the primary energy bar, whereas the vehicle TTW
energy over the US combined cycle (i.e. M-H or metro-highway) is shown as
vehicle energy in kWh/mi.
Total energy consumption, US combined cycle
Primary (kWh/mi)
Vehicle (kWh/mi)
Total (kWh/mi)
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
Figure 9.4 Global energy consumption of various technologies from PSAT
(modified from Reference 5)
What is interesting about the global energy picture shown in Figure 9.4 is that
E85 ethanol has the highest total energy consumption at 1.5 kWh/mi even though
its vehicle consumption parallels that of the gasoline ICE. Ethanol requires twice
the primary energy to produce than gasoline. Diesel has the lowest primary energy
consumption because it requires less total processing from its crude feedstock state,
and a global energy consumption paralleling that of a gaseous hydrogen hybrid
vehicle power plant.
The lithium BEV, liquid hydrogen FCV and the gasoline hybrid vehicle all
consume about the same total energy in a WTW comparison, but the BEV requires
the lowest TTW energy because of its more efficient electric M/G. Energy usage on
the gaseous hydrogen is some 34% lower than that for liquid hydrogen because it
takes about 30% of the hydrogen energy just to liquefy it to 20 K.
Then comes a pair of somewhat surprising results. Figure 9.4 shows that the
gasoline hybrid and its conventional gasoline ICE sister have virtually the same
total energy consumption as well as vehicle energy usage. This close call in overall
