428 CHAPTER 17 Nonrenewable Energy Resources
pipelines or on the ocean in tanker ships. Natural gas
leaks, while rare, can lead to massive explosions. Oil spills
create environmental damage, particularly in aquatic
ecosystems, where oil slicks can travel great distances.Major US Oil Spills: Exxon Valdez and Deep-
water Horizon The largest oil spill in the United
States took place over 100 years ago in Kern County,
California, when drillers hit a pressurized pocket of
oil that eventually poured out 9 million barrels of oil
onto the surrounding land. Technology developed
after that event has so far prevented a recurrence of
that magnitude. More recently, two major oil spills
indicate the dangers posed by both transporting oil
on the ocean and drilling. In 1989 the supertanker
Exxon Valdez hit Bligh Reef and spilled 260,000 barrels
(10.9 million gals) of crude oil into Prince William
Sound along the coast of Alaska, the largest oil spill
from a tanker in U.S. history (}ÕÀiʣǰ££>]ÊLÊand
c). More than 30,000 birds and between 3500 and 5500
sea otters died as a result of the spill. The area’s orca
and harbor seal populations declined, salmon migra-
tion was disrupted, and the fishing season in the area
was halted that year.
Although Exxon declared the cleanup “complete” in
late 1989, it left behind contaminated shorelines; contin-
ued damage to some species of birds, fishes, and mam-
mals; and a reduced commercial salmon catch, among
other problems.
One positive outcome of the disaster was passage of
the Oil Pollution Act of 1990. This legislation establishes
liability for damages to natural resources resulting from
a catastrophic oil spill, including a trust fund that pays to
clean up spills when the responsible party cannot, and
it requires, by 2015, double hulls on all oil tankers that
enter U.S. waters.
In April of 2010, the Deepwater Horizon oil drill-
ing platform exploded, spilling over 4 million barrels of
crude oil into the Gulf of Mexico (}ÕÀiʣǰ££`Êand e).
The explosion itself killed 11 workers, and the oil that
spread across the ocean floor and the coast of the south-
ern United States killed wildlife and caused extensive
ecological damage.
The effect on residents of coastal Louisiana, Missis-
sippi, Alabama, and Florida was less direct, but included
both economic and social harm. The immediate impact
was the closing of beaches and fisheries due to contami-
nation. This resulted in lost income, empty hotels, andHydraulic fracturing (often referred to as fracking) of
deep deposits of natural gas has markedly changed both
estimates of natural gas resources
and the environmental impacts of
its extraction. Hydraulic fractur-
ing involves injection of pressur-
ized water and chemicals to break
apart natural gas trapped in deep
layers of shale. The process is
more expensive and environmen-
tally disruptive than is extraction of more shallow depos-
its, typically in more porous sandstone. This technique
generated seven times as much natural gas in 2010 as in
2005, a trend that is expected to continue.
How Long Will Oil and Natural Gas Supplies
Last? We cannot predict how many reserves will be dis-
covered, whether technological breakthroughs will allow
us to extract more fuel from each deposit, or whether
world consumption of oil and natural gas will increase,
remain the same, or decrease. Even with technological
advances, the most optimistic predictions are for global
oil production to peak around 2035. Natural gas is more
plentiful than oil. Experts estimate that, at current rates
of consumption, readily recoverable reserves of natu-
ral gas will keep production rising for at least 10 years
after conventional supplies of petroleum have begun to
decline.
Environmental Impacts of Oil
and Natural Gas
Extracting, transporting, and burning oil and natural gas
create a variety of environmental problems. As with coal,
burning oil and natural gas produces CO 2 that contrib-
utes to global climate change. Every gallon of gasoline
your car or truck burns releases about 9 kg (20 lb) of
CO 2 into the atmosphere. Burning oil also leads to acid
deposition and the formation of photochemical smog.
Gasoline combustion contributes about half the nitrogen
oxides released into the atmosphere by human activities.
(Coal combustion contributes the rest.)
Natural gas, on the other hand, is a relatively clean,
efficient source of energy that contains almost no sulfur
and releases far less CO 2 , fewer hydrocarbons, and al-
most no particulate matter compared to oil and coal.
One risk of oil and natural gas production relates to
their transport, often over long distances over land by
hydraulic
fracturing The use
of pressurized water
and chemicals to
extract natural gas
from deep layers of
shale.