Geoscience Reference
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competing economically with WWS technologies. As a
result, no mechanism currently exists to encourage the
large-scale conversion to WWS. Wisely implemented
policy mechanisms can promote such a conversion;
however, such mechanisms can be implemented only if
policy makers are willing to make changes. Policy mak-
ers in democratic countries are elected, whereas those
in autocratic countries make decisions dictated by one
or a few leaders. Thus, in democratic countries, a large
number of people need to be convinced that changes
are beneficial; in autocratic countries, only a few need
to be convinced. In both cases, those who need to be
convinced require a social evolution in their thought.
Such an evolution comes from a better understanding
of global warming and air pollution science, conse-
quences, and solutions. If the public and policy makers
can become confident in understanding the problems
and the large-scale solution needed to solve them, such
as that outlined in this chapter, they will gravitate toward
the solution. When the solution is finally implemented,
the air pollution and climate problems outlined in this
book will be relegated to the annals of history.
the electrolyzer, compressor, and fuel cell. Assume
the efficiency of the fuel cell converting hydrogen to
energy and water is
f
=
0.5, the lower heating value
33.3 kWh kg
−
1
-H
2
(g), the hydro-
gen leakage rate is
l
h
=
of hydrogen is
L
h
=
0.03 (fraction), the electrolyzer
53.4 kWh kg
−
1
-H
2
(g), and
the compressor energy required is
L
c
energy required is
L
z
=
=
5.64 kWh
kg
−
1
-H
2
(g).
Energy required to move all U.S. vehicles as HFCVs:
E
f
(kWh yr
−
1
)
E
v
/
f
H
2
(g) mass to power all vehicles, accounting for
leaks:
M
h
[kg-H
2
(g) yr
−
1
]
=
[
L
h
(1 -
l
h
)]
Energy needed to power a U.S. HFCV fleet:
E
h
(kWh
yr
−
1
)
=
E
f
/
M
h
Number of wind turbines needed to power a U.S.
HFCV fleet
=
(
L
z
+
L
c
)
×
=
E
h
/
E
t
13.4. Calculate the number of solar PV panels and the
fractional area of the United States required to power a
100 percent BEV fleet with PV from PV power plants.
Assume that the end-use energy required to run a BEV
fleet after the plug-to-wheel efficiency of each vehicle
is accounted for is
E
v
=
13.12. Problems
13.1. How many 5-MW wind turbines with a rotor
diameter of 126 m operating in a mean annual wind
speed of 7.5 m s
−
1
are needed to power the U.S. on-
road vehicle fleet consisting of BEVs if the end-use
energy required to run such a fleet is
E
v
=
10
12
kWh yr
−
1
(2007).
Also, make the following assumptions: the plug-to-
wheel efficiency of an electric vehicle is
1.12
×
e
=
0.85, a
solar panel's rated power is
P
s
=
0.232 kW, the footprint
and spacing area of a solar panel are both
A
s
=
2m
2
,the
10
12
kWh yr
−
1
(2007) and the plug-to-wheel efficiency of
an electric vehicle is
×
panel's capacity factor is
CF
s
=
1.12
0.21, the transmission
plus distribution efficiency of energy from a PV power
plant is
0.85? Assume the system
efficiency of each wind turbine is
e
=
s
=
0.95, and the area of the United States is
0.9.
Hint
:First
determine the total electrical energy required to run the
fleet by dividing the end-use energy required to run
vehicles by the plug-to-wheel efficiency.
t
=
9.162
10
6
km
2
.
Hint
:The single-panel annual energy
output (kWh yr
−
1
)is
E
s
=
×
s
.
13.5. Explain the difference between footprint and
spacing for an energy facility. What are some of the
uses of the spacing?
P
s
×
CF
s
×
H
/
13.2. If each wind turbine in Problem 13.1 has a tubular
tower plus concrete footing base circular diameter of
5m(footprint diameter), and if each turbine in a wind
farm occupies a spacing of
A
t
=
13.6. From Figures 13.12 and 13.13, identify three gen-
eral regions of fast winds (7 m s
−
1
or higher) and three
regions of high solar radiation (150 W m
−
2
or higher)
worldwide over land or near shore. Among these, iden-
tify one area where both wind and solar resources are
good.
7
D
,where
D
is
the turbine rotor diameter, calculate the footprint and
spacing required for all turbines needed to power a U.S.
electric vehicle fleet in 2007. What percent of the fifty-
state U.S. land area (9.162
4
D
×
10
6
km
2
) does this area
×
represent?
13.7. Explain why the conversion from an internal com-
bustion engine gasoline vehicle to an electric vehicle
should reduce overall power demand?
13.3. Using the information obtained from Problem
13.1 and the following equations, calculate the num-
ber of wind turbines required to power a 100 percent
U.S. HFCV fleet, where the hydrogen is produced by
wind electrolysis. Account for energy requirements of
13.8. Identify four policy measures that could be imple-
mented to encourage the expansion of WWS energy
systems.
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