Energy Solutions to Air Pollution and Global Warming - Air Pollution and Global Warming: History, Science, and Solutions - page 315

biofuels are derived from food sources, increasing food
shortages, food prices, and starvation (Delucchi, 2010;
Jacobson, 2009). Even biofuels used for energy pro-
duction that rely on wood waste that would otherwise
decay require energy for gathering and transporting the
waste and result in air pollution during its combustion.
Because biofuels are not so good as WWS technolo-
gies, and often worse than gasoline or diesel in many
respects, they represent opportunity costs. The key to
eliminating air pollution and global warming is elimi-
nating combustion and carbon .
The issues with liquid biofuels are illustrated by com-
paring the impacts of using ethanol to provide energy for
internal combustion engines with those of using WWS
resources to provide energy for BEVs and hydrogen
fuel cell vehicles (HFCVs). Figure 13.1 compares the
net change in (1) carbon dioxide emissions; (2) air pol-
lution deaths; and (3) water required if all light- and
heavy- duty, on-road vehicles in the United States were
converted from those powered by liquid fossil fuels
to those powered by a different technology. The alter-
nate vehicle options include BEVs powered by electric-
ity from wind, concentrated solar power (CSP), photo-
voltaics (PVs), geothermal, tidal, wave, hydroelectric,
nuclear, or coal-CCS; HFCVs powered by hydrogen
electrolyzed using wind power electricity; and internal
combustion vehicles powered by corn E85 or cellulosic
E85.
In the United States, about 26 percent of all CO 2 (g)
emissions are from vehicle exhaust and 6.7 percent are
from the upstream production of fuel. As such, con-
verting to alternate vehicle technologies could reduce
U.S. CO 2 (g) emissions by, at most, 32.7 percent. Figure
13.1a shows that converting to wind-BEVs reduces U.S.
CO 2 (g) emissions by 32.4 to 32.6 percent, which rep-
resents 99 to 99.7 percent of the 32.7 percent possible
reduction.
Using wind electricity to produce hydrogen for
HFCVs results in about three times more emissions
than using wind electricity to power BEVs directly,
butwind-HFCV emissions are still low (97-98.5 per-
cent of the maximum possible CO 2 (g) reduction vs.
99-99.7 percent for wind-BEVs). Wind-HFCVs result
in greater emissions than do wind-BEVs because an
electric vehicle converts 75 to 86 percent of the wind
electricity to motion, whereas an HFCV converts about
one-third of this percentage due to losses in the electro-
lyzer (used to produce hydrogen from electricity),
compressor (used to compress hydrogen), and fuel cell
(used to convert hydrogen to energy and water). Never-
theless, an HFCV is still more efficient than an internal

combustion engine, which converts about 17 to 20 per-
cent of the fuel in its tank to mechanical motion.
Figure 13.1a indicates that other WWS sources pow-
ering BEVs also result in significant CO 2 (g) reductions.
Nuclear-BEVs and coal-CCS-BEVs are less efficient at
reducing CO 2 (g) than are WWS sources. However, corn
E85 and cellulosic E85 vehicles either increase CO 2 (g)
or cause much less CO 2 (g) reduction than do the WWS
options or nuclear or coal-CCS. Even in the best case for
ethanol, using cellulosic E85, carbon emissions are still
much larger than they are for WWS-BEVs. Figure 13.1b
also shows that the air pollution mortality associated
with either corn or cellulosic ethanol exceeds that asso-
ciated with the WWS-BEV options, and Figure 13.1c
indicates that the water requirements for corn ethanol
in particular amount to about 10 percent of the U.S.
water supply. Because of the significant land required
for either corn or cellulosic ethanol (Figure 13.2), it is
also impractical to expect E85 fuels to provide energy
for any more than 30 percent of the U.S. fleet. Analyses
for other types of liquid biofuels result in similar results
in most areas.
For these reasons, the use of nuclear, coal-CCS, nat-
ural gas, and biofuel represents an opportunity cost
compared with the use of WWS technologies for trans-
portation and electricity .Thus, this analysis focuses on
WWS technologies. WWS is assumed to supply elec-
tric power for transportation, cooking, air and water
heating, air conditioning, high-temperature industrial
processes, and general electricity.

13.1.5. Demand-Side Energy Conservation
Although the analysis focuses on energy supply,
demand-side energy conservation measures are also
important for reducing the requirements and impacts of
energy supply. Demand-side energy conservation mea-
sures include improving the energy-out to energy-in
efficiency of end uses (e.g., with more efficient vehi-
cles and lighting, better insulation in homes, and the use
of heat-exchange and filtration systems), using lower-
energy modes of transportation (e.g., using public
transit or telecommuting instead of driving), improving
large-scale planning to reduce energy demand with-
out compromising economic activity or comfort (e.g.,
designing cities to facilitate greater use of nonmotor-
ized transport and to have better matching of origins
and destinations, thereby reducing the need for travel),
and designing buildings to use solar energy directly
(e.g., using more daylighting, solar hot water heating,
and passive solar heating/cooling in buildings).