PhD Thesis - Energy Systems Research Unit - University of Strathclyde

vehicles if they are increased by 10% [2]. To give the fuel consumption figure
in litres/km, this figure is divided by 100.
The use of fuel cell vehicles is less established than the other types of vehicle
being considered here, so there is a limited amount of information available
from manufacturers. The fuel consumption for these vehicles is input in
kWh/100km, using a measure of the energy content to eliminate the problems
associated with the different storage mediums. This fuel consumption unit has
been chosen, as this is easy to convert to from the various ways in which fuel
consumption is being quoted for this type of vehicle. To give the fuel
consumption figure in kWh/km, this figure is divided by 100.
Fuel consumption figures for electric vehicles are quoted in kWh/100km, which
is divided by 100 to give the fuel consumption in kWh/km. The overall amount
of energy available from a battery depends on its rate of discharge [3], however,
when considering vehicles, no information is given about the effects of rate of
discharge on the delivered energy. As the vehicle ‘fuel consumption’, or more
correctly for a battery, discharge rate, is quoted for typical use, and there are a
limited range of discharge rates at which the vehicle would require to draw
energy, the quoted discharge rate (kWh/100km) is used, and not varied with the
energy drawn. This is the same simplification as using average fuel
consumption rates for the other types of vehicle, as the fuel consumption of
these vehicles would vary with the speed and type of driving. Also, as general
transport demands are being modelled over half hourly time periods, and the use
of onboard storage is being taken into consideration, these are reasonable
assumptions.
Batteries also suffer from self-discharge if left unused for months. As these
vehicles would generally be in almost constant use, and as information about
self-discharge rates for vehicles are not easily available, this has not been taken
into consideration here. Therefore, the energy use (discharging) of electric
vehicles is treated in a similar way to the other types of vehicle being considered
here. Recharging, however, must be treated slightly differently, and this is
discussed later.
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