Urban Air Pollution - Air Pollution and Global Warming: History, Science, and Solutions - page 96

Although alcohols were used in later prototype engines,
they became relatively expensive in the United States
due to a federal tax placed on alcohol following the
Civil War of 1860 to 1865.
On August 27, 1859, Edwin Laurentine Drake
(1819-1880) discovered oil after using a steam engine
to power a drill through 21 m of rock in Titusville, Penn-
sylvania. This discovery is considered the beginning of
the oil industry. Oil was soon refined to produce gaso-
line. The lower cost of gasoline in comparison with
that of ethanol resulted in the comparatively greater
use of gasoline than ethanol in early U.S. and Euro-
pean automobiles. The first practical gasoline-powered
engine, which ran on illuminating gas, was constructed
by Etienne Lenoir (1822-1900) of France in 1860. In
1862, he built an automobile powered by this engine.
In 1876, German Nikolaus Otto (1832-1891) devel-
oped the first four-stroke internal combustion engine.
In 1885, Karl Benz (1844-1929) of Germany designed
and built the first practical automobile powered by an
internal combustion engine. The same year, Gottlieb
Daimler (1834-1900) of Germany patented the first
successful high-speed internal combustion engine and
developed a carburetor that allowed the use of gasoline
as a fuel. In 1893, J. Frank Duryea (1869-1967) and
Charles E. Duryea (1861-1938) produced the first suc-
cessful gasoline-powered vehicle in the United States.
In 1896, Henry Ford (1863-1947) completed his first
successful automobile in Detroit, Michigan.
Whereas the United States had large oil reserves to
draw on, France and Germany had few oil reserves
and thus used ethanol as a fuel in automobiles to a
greater extent. In 1906, 10 percent of engines at Otto
Gas Engine Works in Germany ran on ethanol (Kovarik,
1998). The same year, the United States repealed the
federal tax on ethanol, making it more competitive with
gasoline. Soon after, however, oil fields in Texas were
discovered, leading to a reduction in gasoline prices and
the near death of the alcohol fuel industry.
Ye t, the alcohol fuel industry managed to survive.
From the 1920s to the 2000s, every industrialized coun-
try, except the United States, marketed blends of ethyl
alcohol with gasoline in greater than nontrivial quanti-
ties. In the 1920s, I. G. Farben, a German firm, discov-
ered a process to make synthetic methanol [CH 3 OH(g)]
from coal. As Hitler prepared for war in 1937, produc-
tion of alcohol as a fuel in Germany increased to about
52 million gallons per year (Egloff, 1940). Neverthe-
less, alcohol may never have represented more than 5
percent of the total fuel use in Europe in the 1930s
(Egloff, 1940).

When methanol is burned as a fuel, its major by-
products are unburned methanol and the carcinogen
formaldehyde. In the atmosphere, unburned methanol
oxidizes to formaldehyde and ozone. Table 4.3 indi-
cates that the only important chemical loss process of
alcohols in the air is through reaction with the hydroxyl
radical. The reaction of methanol with OH(g) is

+ O 2 (g)

85%

CH 2 OH(g) HCHO(g)

+ OH(g)

Formaldehyde

CH 3 OH(g) HO 2 (g)

Methanol

H 2 O(g) CH 3 O(g)

15%

Methoxy radical

(4.57)

Methanol lost from these reactions has an e -folding life-
time of 71 days when [OH] 10 6 molec cm − 3 ;

thus, the reaction is not rapid. The organic product of
the first reaction is formaldehyde, and that of the sec-
ond reaction is the methoxy radical, which produces
formaldehyde by Reaction 4.21. Formaldehyde is an
ozone precursor.
In the 1970s, Brazil began a national effort to ensure
that all gasoline sold contained ethanol (Section 8.2.14).
In the United States, gasoline prices have always been
much lower than alcohol fuel prices, inhibiting the pop-
ularity of alcohol as an alternative to gasoline. When
ethanol is burned as a fuel, its major by-products
are unburned ethanol and acetaldehyde, a carcinogen.
Atmospheric oxidation of unburned ethanol results in
more acetaldehyde (a precursor to PAN) and ozone
through

= 5.0 ×

5% CH 2 CH 2 OH(g)

+ O 2 (g)

+ OH(g)

90% CH 3 CHOH(g) CH 3 CHO(g)

C 2 H 5 OH(g)

Acetaldehyde

Ethanol HO 2 (g)

H 2 O(g)

5%

CH 3 CH 2 O(g)

Ethoxy radical

(4.58)

Ethanol lost from the most probable (middle) reaction
has an e -folding lifetime of about 19 hours when [OH] =

10 6 molec cm − 3 .Acetaldehyde, formed from the
middle reaction, produces PAN and ozone. The rela-
tively long lifetime of ethanol oxidation to acetaldehyde
suggests that unburned ethanol from ethanol-fueled
vehicles may be a free-tropospheric and urban source
of near-surface ozone (Jacobson, 2007).

5.0 ×