Environmental science

Nonrenewable Energy Sources, Their Impacts, and Energy Conservation Upon completing this chapter, you will be able to:

➤ Identify the energy sources that we use ➤ Describe the nature and origin of coal, natural gas, and crude oil, and evaluate their extraction and use ➤ Assess concerns over the future depletion of global oil supplies ➤ Describe the nature and potential of alternative fossil fuels ➤ Outline and assess environmental, political, social, and economic impacts of fossil fuel use, and explore

potential solutions ➤ Specify strategies for conserving energy and enhancing efficiency ➤ Describe nuclear energy and how we harness it ➤ Assess the benefits and drawbacks of nuclear power, and outline the societal debate over this energy source

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The Deepwater Horizon drilling rig on fire, April 2010

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The catastrophe in the Gulf began on April 20, 2010, when a large bubble of natu- ral gas rose through the drill pipe at the Macondo well be- ing drilled by British Petro- leum (BP) a mile underwater. The gas bubble shot past a malfunctioning blowout pre- venter and set off a fiery explosion atop the Deepwater Horizon platform, which sank two days later. The stage had been set by a series of set- backs that put the drilling behind schedule and led BP and its contractors to cut corners while govern- ment regulators looked the other way.

As oil spewed from the seafloor at a rate of 2,000 gallons every minute, response efforts swung into ac- tion. Dozens of ships and boats tried to corral the ris- ing oil at the surface and burn off what they could. Planes and helicopters dumped chemical dispersants from the air. Thousands of people in protective Tyvek suits walked the beaches and spread booms to soak up oil. Teams surveyed marshes for contamination

and captured oiled birds and wildlife to clean and release. The work was hot, dirty, and difficult, and the scale of the job seemed overwhelming.

By the time BP engineers finally got the well sealed 86 days later, roughly 4.9 million barrels (230 million gallons) of crude oil had entered the Gulf, creating the largest ac- cidental oil spill in history. As oil washed ashore, it coated beaches and salt marshes,

killing birds, turtles, crabs, fish, and plants, and spoiling tourism for an entire summer. Thousands of fisher- men were thrown out of work as some of the nation’s most productive fisheries were shut down.

Many Americans who watched news coverage of the spill day after day felt shock and outrage. Indeed, the Gulf oil spill resulted from careless missteps by a corporation and its contractors under weak oversight from the federal government. However, the spill is perhaps best viewed not as a single isolated instance of bad practice or misfortune, but as a by-product of

CENTRAL CASE STUDY

Offshore Drilling and the Deepwater Horizon Blowout

“This oil spill is the worst environmental disaster America has ever faced.” —U.S. President Barack Obama, 2010

“The Deepwater Horizon incident is a direct consequence of our global addiction to oil. . . . If this isn’t a call to green power, I don’t know what is.”

—University of Georgia Researcher Dr. Mandy Joye, 2010

I t began with a spectacular and deadly explosion that killed 11 people far out to sea. It

captivated a horrified nation for three months. And its consequences will stretch on for

years. The collapse of British Petroleum’s Deepwater Horizon drilling rig and the resulting

oil spill from its Macondo well in the Gulf of Mexico polluted water, beaches, and marshes;

shut down fisheries; ruined tourism; and killed countless animals. The oil contaminated over

1,050 km (650 mi) of coastline in Louisiana, Mississippi, Alabama, and Florida (FIGURE 15.1). Ulti-

mately, it raised the question of what costs we are prepared to accept in order to continue

relying on fossil fuel energy.

TEXAS LOUISIANA

MISSISSIPPI

ALABAMA

FLORIDA

Gulf Of Mexico MEXICO

Area of oil spill

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SOURCES OF ENERGY Humanity has devised many ways to harness the renewable and nonrenewable forms of energy available on our planet (TABLE 15.1). We use these energy sources to heat and light our homes; power our machinery; fuel our vehicles; produce plastics, pharmaceuticals, and synthetic fibers; and provide the comforts and conveniences to which we’ve grown accus- tomed in the industrial age.

We use a variety of energy sources Most of Earth’s energy comes from the sun. We can har- ness energy from the sun’s radiation directly by using solar power technologies. Solar radiation also helps drive wind and the water cycle, enabling us to harness wind power and hydroelectric power. And of course, sunlight drives pho- tosynthesis (p. 30) and the growth of plants, from which we take wood and other biomass as a fuel source. Finally, when plants die, some may impart their stored chemical en- ergy to fossil fuels, highly combustible substances formed from the remains of organisms from past geologic ages. The three fossil fuels we use widely today are oil, coal, and natu- ral gas.

Fossil fuels provide most of the energy that our econ- omy buys, sells, and consumes, because their high energy content makes them efficient to ship, store, and burn. We use these fuels for transportation, heating, and cooking, and also to generate electricity, a secondary form of energy that is easier to transfer over long distances and apply to a variety of uses. Global consumption of the three main fossil fuels

Very light oiling

Oil on shoreline

Light oiling

Medium oiling

Heavy oiling

1-10 days

Oil on water surface

10-30 days

More than 30 days

ALABAMA GEORGIA

FLORIDA LOUISIANA

MISSISSIPPI Lake Pontchartrain

Macondo Well (site of Deepwater Horizon blowout)

Tallahassee

TampaNew Orleans

(a) Extent of the oil spill

(b) Workers scrub oil from a Louisiana beach

FIGURE 15.1  Oil from the Macondo well blowout spread over thousands of square miles of the Gulf of Mexico (a) in the spring and summer of 2010. Darker areas indicate more days with signs of oil at the surface. Thousands of volunteers, government officials, and citizens paid by British Petroleum assisted (b) in the vast cleanup effort. Source (a): National Geographic and NOAA.

our society’s insatiable appetite for petroleum, driven largely by our reliance on automobiles. Our thirst for fossil fuels has led the oil industry to drill farther and farther out to sea, in search of larger and more prof- itable untapped deposits. In many cases it has found them, but the farther it moves offshore, the more risks build for major accidents that are hard to control.

Until we reduce our dependence on oil and shift to clean and renewable energy sources, we will suf- fer pollution in the sea and in the air, climate change and health impacts from fossil fuel combustion, and economic uncertainty from reliance on foreign sources of oil. Every once in a while, some drastic event makes these costs painfully apparent. The Deepwater Hori- zon spill was not the first such event, and it will likely not be the last. �

TABLE 15.1 Energy Sources We Use Today Energy source Description Type of energy

Crude oil Fossil fuel extracted from ground (liquid)

Nonrenewable

Natural gas Fossil fuel extracted from ground (gas)

Nonrenewable

Coal Fossil fuel extracted from ground (solid)

Nonrenewable

Nuclear energy Energy from atomic nuclei of uranium

Nonrenewable

Biomass energy Energy stored in plant matter from photosynthesis

Renewable

Hydropower Energy from running water

Renewable

Solar energy Energy from sunlight directly

Renewable

Wind energy Energy from wind Renewable

Geothermal energy

Earth’s internal heat rising from core

Renewable

Tidal and wave energy

Energy from tidal forces and ocean waves

Renewable

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G A R R E T T , M E G A N 1 3 2 4 T S

Higher EROI ratios mean that we receive more energy from each unit of energy that we invest. Fossil fuels are widely used because their EROI ratios have historically been high. How- ever, EROI ratios can change over time. Those for U.S. oil and natural gas have declined from over 100:1 in the 1940s to about 5:1 today. This means that we used to be able to gain 100 units of energy for every unit of energy expended, but now we can gain only five. The EROI ratios for oil and gas declined because we extracted the easiest deposits first and now must work harder and harder to extract the remaining amounts.

Energy and its consumption are unevenly distributed Most energy sources are localized and unevenly distributed over Earth’s surface. This is true of oil, coal, and natural gas, and as a result, some regions have substantial reserves of fos- sil fuels whereas others have very few. Nearly two-thirds of the world’s proven reserves of crude oil lie in the Middle East. The Middle East is also rich in natural gas, but Russia holds more natural gas than any other country. Russia is also rich in coal, as is China, but the United States possesses the most coal of any nation (TABLE 15.2).

has risen steadily for years and is now at its highest level ever (FIGURE 15.2).

Energy sources such as sunlight, geothermal energy, and tidal energy are considered perpetually renewable because they are readily replenished, and so we can keep using them without depleting them (pp. 2–3). In contrast, energy sources such as oil, coal, and natural gas are considered nonrenew- able. These nonrenewable fuels result from ongoing natural processes, but it takes so long for fossil fuels to form that, once depleted, they cannot be replaced within any time span useful to our civilization. It takes a thousand years for the biosphere to generate the amount of organic matter that must be buried to produce a single day’s worth of fossil fuels for our society. At our current rate of consumption, we will use up Earth’s ac- cessible store of fossil fuels in just decades to centuries.

Nuclear power as currently harnessed through the fission of uranium (p. 346) is nonrenewable to the extent that ura- nium ore is in limited supply. However, we can also reprocess some uranium and reuse it.

It takes energy to make energy We do not simply get energy for free. To harness, extract, process, and deliver the energy we use, we need to invest sub- stantial inputs of energy. For instance, drilling for oil offshore in the Gulf of Mexico requires the construction of immense drilling platforms (the Deepwater Horizon cost $560 million) and extensive infrastructure to extract and transport oil— all requiring the use of huge amounts of energy. Thus, when evaluating how much energy a source gives us, it is important to subtract costs in energy invested from benefits in energy received. Net energy expresses the difference between en- ergy returned and energy invested:

Net energy = Energy returned – Energy invested

When assessing energy sources, it is useful to use a ratio often denoted as EROI, which stands for energy returned on investment. EROI ratios are calculated as follows:

EROI = Energy returned / Energy invested

4

3

2

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os si

l f ue

l c on

su m

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n (b

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en t)

1

0 1950 1960 1970 1980

Year

1990

Oil

Coal

Natural gas

2000 2010

FIGURE 15.2  Global consumption of fossil fuels has risen greatly over the past half century. Oil use rose steeply during the 1960s to overtake coal, and today it remains our leading energy source. Data from U.S. Energy Information Administration, International Energy Agency, and BP plc. 2011. Statistical review of world energy 2011.

TABLE 15.2 Nations with the Largest Proven Reserves of Fossil Fuels Oil (% world reserves)

Natural gas (% world reserves)

Coal (% world reserves)

Saudi Arabia, 17.3 Russia, 23.9 United States, 27.6

Venezuela, 13.8* Iran, 15.8 Russia, 18.2

Canada, 11.5* Qatar, 13.5 China, 13.3

Iran, 9.0 Turkmenistan, 4.3 Australia, 8.9

Iraq, 7.5 Saudi Arabia, 4.3 India, 7.0

*Most of Canada’s and Venezuela’s oil reserves occur as oil sands (p. 335), which are included in these figures. Data are for 2010, from BP plc. 2011. Statistical review of world energy 2011.

Consumption rates across the world are also uneven. Citizens of developed regions generally consume far more energy than do those of developing regions. The United States has only 4.5% of the world’s population, but it consumes over 20% of the world’s energy. Nations also differ in how they use energy. Developing nations devote a greater proportion of en- ergy to subsistence activities, such as growing and preparing food and heating homes, whereas industrialized countries use a greater proportion for transportation and industry. Because industrialized nations rely more on mechanized equipment and technology, they use more fossil fuels. In the United States, fossil fuels supply 83% of energy needs.

COAL, NATURAL GAS, AND OIL The three major fossil fuels on which we rely today are coal, natural gas, and oil. We will first consider how these fossil fu- els are formed, how we locate deposits, how we extract these resources, and how our society puts them to use. We will then examine some environmental and social impacts of their use.

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Coal is a hard blackish substance formed from organic matter (generally woody plant material) that was compressed under very high pressure, creating dense, solid carbon struc- tures. Coal typically results when water is squeezed out of the material as pressure and heat increase and time passes, and when little decomposition takes place because the ma- terial cannot be digested or appropriate decomposers are not present. The proliferation 300–400 million years ago of swampy environments where organic material was buried has created coal deposits throughout the world.

Natural gas is a gas consisting primarily of methane (CH4) and including varying amounts of other volatile hydro- carbons. Oil, or crude oil, is a sludge-like liquid containing a mix of various hydrocarbon molecules. Oil is also known as petroleum, although this term is commonly used to refer to oil and natural gas collectively. Both natural gas and oil have formed from organic material (especially dead plankton) that drifted down through coastal marine waters millions of years ago and was buried in sediments on the ocean floor. This or- ganic material was transformed by time, heat, and pressure into today’s natural gas and crude oil.

Two processes give rise to natural gas. Biogenic gas is created at shallow depths by the anaerobic decomposition of organic matter by bacteria. An example is the “swamp gas” you may smell when stepping into the muck of a swamp. One source of biogenic natural gas is the decay process in landfills, and many landfill operators are now capturing this gas to sell as fuel (p. 385). Thermogenic gas results from compression and heat deep underground. Thermogenic gas may form directly, along with coal or crude oil, or from coal or oil that is altered by heating. Most gas that we extract commercially is thermogenic and is found above deposits of crude oil or seams of coal, so it is often extracted along with those fossil fuels. Indeed, the Deepwater Horizon blowout occurred because natural gas ac- companying the oil deposit shot up the well shaft once drilling relieved the pressure, and ignited atop the platform.

Because fossil fuels form only under certain conditions, they occur in isolated deposits. For instance, oil and natural gas tend to rise upward through cracks and fissures in porous rock until meeting a dense impermeable rock layer that traps them. Geologists searching for fossil fuels drill cores and conduct ground, air, and seismic surveys to map underground rock formations and predict where fossil fuel deposits might lie.

We mine coal and use it to generate electricity Coal is the world’s most abundant fossil fuel, and it provides 27% of our global primary energy consumption. Once a coal seam is located, we extract coal from the ground using sev- eral methods. For deposits near the surface, we use strip min- ing, whereas for deposits deep underground, we use subsur- face mining (see Figure 11.14, p. 238). Recently, we have begun mining coal on immense scales in the Appalachian Moun- tains, essentially scraping off entire mountaintops in a proc- ess called mountaintop removal mining (p. 240). (We explored mining practices and their impacts more fully in Chapter 11.)

People have burned coal to cook food, heat homes, and fire pottery for thousands of years. Coal-fired steam engines helped drive the industrial revolution, powering factories,

Fossil fuels are indeed fuels created from “fossils” Fossil fuels form only after organic material is broken down over millions of years in an anaerobic environment, one with little or no oxygen. Such environments include the bottoms of lakes, swamps, and shallow seas. The fossil fuels we burn today in our vehicles, homes, industries, and power plants were formed from the tissues of organisms that lived 100–500 million years ago. When organisms were buried quickly in anaerobic sediments after death, chemical energy in their tissues became concentrated as the tissues decomposed and their hydrocarbon compounds (p. 28) were chemically al- tered amid heat and compression (FIGURE 15.3).

Woody terrestrial vegetation dies and falls into swamp

Organic matter from woody land plants partly decomposed by microbes under accumulating sediments; kerogen forms

Coal formed from kerogen

Phytoplankton, zooplankton, and other marine organisms die and sink to sea floor

Organic matter from soft-bodied sea life partly decomposed by microbes under accumulating sediments; some carbon bonds broken; kerogen forms

Thermogenic natural gas formed from kerogen

Crude oil formed from kerogen

Ancient swamp

Anaerobic conditions

Present day

Heat and pressure deep underground

alter kerogen

Ancient ocean

FIGURE 15.3  Fossil fuels begin to form when organisms die and end up in oxygen-poor conditions, such as when trees fall into lakes and are buried by sediment, or when phytoplankton and zooplankton drift to the seafloor and are buried (top diagram). Or- ganic matter that undergoes slow anaerobic decomposition deep under sediments forms kerogen (middle diagram). Geothermal heating then acts on kerogen to create crude oil and natural gas (bottom diagram). Oil and gas come to reside in porous rock lay- ers beneath dense, impervious layers. Coal is formed when plant matter is compacted so tightly that there is little decomposition.

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coal combustion, along with solutions to these problems, later in this chapter (pp. 336, 341). Reducing pollution from coal is important because society’s demand for this abundant fossil fuel may rise once supplies of oil and natural gas begin to decline. Scientists estimate that Earth holds enough coal to supply our society for perhaps a few hundred years more— far longer than oil or natural gas will remain available.

Natural gas burns cleaner than coal Natural gas today provides over one-fifth of global primary energy consumption. Versatile and clean-burning, natural gas emits just half as much carbon dioxide per unit of energy pro- duced as coal and two-thirds as much as oil. We use natural gas to generate electricity in power plants, to heat and cook in our homes, and for much else. Converted to a liquid at low temperatures (liquefied natural gas, or LNG), it can be shipped long distances in refrigerated tankers. Russia and the United States lead the world in gas production and gas consumption, respectively (TABLE 15.4). World supplies of natural gas are projected to last perhaps 60 more years.

Oil is the world’s most-used fuel Oil today accounts for one-third of the world’s primary ener- gy consumption. Global oil consumption has risen 15% in the past decade, and today our society produces and consumes over 750 L (200 gal) of oil annually for every man, woman, and child. TABLE 15.5 shows the top oil-producing and oil- consuming nations.

agriculture, trains, and ships. Today we burn coal largely to generate electricity. In coal-fired power plants, coal combus- tion converts water to steam, which turns a turbine to create electricity (FIGURE 15.4). Coal provides half the electrical gen- erating capacity of the United States, and it powers China’s surging economy. China and the United States are the prima- ry producers and consumers of coal (TABLE 15.3).

Coal varies from deposit to deposit in its water content, carbon content, and potential energy. Coal deposits also vary in the amount of impurities they contain, including sulfur, mercury, arsenic, and other trace metals. Coal from the east- ern United States tends to be high in sulfur because it was formed in marine sediments, where sulfur from seawater was present. The impurities in coal are emitted during its combus- tion unless pollution control measures are in place. We will examine the many health and environmental impacts from

Boiler

Turbine

Cooling loop

Filter

Furnace

Pulverizing mill

Coal bunker

Stack

Ash disposal

Condenser

Generator

Cooling tower

FIGURE 15.4  At a coal-fired power plant, coal is pulverized and blown into a high-temperature furnace. Heat from the combustion boils water, and the resulting steam turns a turbine, generating electricity by passing mag- nets past copper coils. The steam is then cooled and condensed in a cooling loop and returned to the furnace. “Clean coal” technologies (pp. 336–337) help filter out pollutants from the combustion process, and toxic ash residue is taken to hazardous waste disposal sites.

TABLE 15.3 Top Producers and Consumers of Coal Production (% world production)

Consumption (% world consumption)

China, 43.8 China, 45.9

United States, 14.0 United States, 13.2

India, 8.0 India, 9.0

Australia, 5.7 Germany, 3.3

Indonesia, 4.3 Russia, 2.9 Data are for 2009, from U.S. Energy Information Administration, 2011.

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In the United States, many oil fields did not undergo sec- ondary extraction because the price of oil was too low to make it economical. Once oil prices rose in the 1970s, companies reopened those drilling sites for secondary extraction. More are being reopened today. The amount of a fossil fuel that is technologically and economically feasible to remove under current conditions is termed its proven recoverable reserve.

Some drilling occurs offshore We drill for oil and natural gas not only on land but also be- low the seafloor on the continental shelves (FIGURE 15.6). Offshore drilling has required us to develop technology that can withstand wind, waves, and ocean currents. Some drill- ing rigs are fixed, standing platforms built with unusual strength. Others are resilient floating platforms anchored in

We drill to extract oil and gas Once geologists have identified a promising location for an oil or natural gas deposit, a company will typically conduct explor- atory drilling, drilling small holes that descend to great depths. If enough oil or gas is encountered, extraction begins. Because oil and gas are generally under pressure while in the ground, they will rise to the surface of their own accord when a deposit is tapped. Once pressure is relieved and some oil or gas has risen to the surface, however, the remainder becomes more difficult to extract and may need to be pumped out. As much as two-thirds of a deposit may remain in the ground following primary ex- traction, the initial extraction of available oil or gas. Companies may then begin secondary extraction. In secondary extraction for oil, solvents are used or underground rocks are flushed with water or steam (FIGURE 15.5). For gas, we use “fracturing tech- niques” to break into rock formations and pump gas upward. One such technique is to pump salt water under high pressure into rocks to crack them. Sand or small glass beads are injected to hold the cracks open once the water is withdrawn. Even after secondary extraction, quite a bit of oil or gas can remain; we lack technology to remove the entire amounts.

While technology sets a limit on how much can be ex- tracted, economics determines how much will be extracted. This is because extraction becomes increasingly difficult and costly as oil or gas is removed, so companies will not find it profitable to extract the entire amount. Instead, a company will consider the costs of extraction (and other expenses), and balance them against the current price of the fuel on the world market. Because fuel prices fluctuate, the portion of oil or gas from a given deposit that is “economically recoverable” fluctuates as well. At higher prices, economically recoverable amounts approach technically recoverable amounts.

TABLE 15.4 Top Producers and Consumers of Natural Gas Production (% world production)

Consumption (% world consumption)

United States, 19.7 United States, 21.4

Russia, 19.4 Russia, 14.5

Canada, 5.3 Iran, 4.4

Iran, 4.4 Japan, 3.3

Norway, 3.4 Germany, 3.1 Data are for 2009, from U.S. Energy Information Administration, 2011.

TABLE 15.5 Top Producers and Consumers of Oil Production (% world production)

Consumption (% world consumption)

Russia, 11.8 United States, 22.3

Saudi Arabia, 11.6 China, 9.9

United States, 10.8 Japan, 5.3

Iran, 4.9 India, 3.7

China, 4.7 Russia, 3.2 Data are for 2009, from U.S. Energy Information Administration, 2011.

Ocean �oor

Impermeable rock

Oil in pores of rocks

Oil rig

Gas cap

Gas injection

Seawater injection

PressurePressure

Oil well

FIGURE 15.5  Once pressure on an oil deposit drops, material must be injected to increase the pressure. Secondary extraction involves injecting seawater beneath the oil and/or injecting gases just above the oil to force more oil up and out of the deposit.

FIGURE 15.6  Offshore drilling platforms allow the oil industry to drill for petroleum in the seafloor on the continental shelves.

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place above the drilling site. Roughly 35% of the oil and 10% of the natural gas extracted in the United States today comes from offshore sites, primarily in the Gulf of Mexico and sec- ondarily off southern California. The Gulf today is home to 90 drilling rigs and 3,500 production platforms.

Geologists estimate that most U.S. oil and gas remaining to be extracted occurs offshore, and that deepwater sites in the Gulf of Mexico alone may hold 59 billion barrels of oil. We have been drilling in shallow water for several decades, but as oil and gas are depleted at shallow-water sites and as drilling technology improves, the industry is moving into deeper and deeper water. BP’s Macondo well lay beneath 1,500 m (5,000 ft) of water, but the deepest wells in the Gulf of Mexico are now twice that depth. Globally, recent discoveries off the coasts of Brazil, Angola, Nigeria, and other nations suggest that a great deal of oil and gas could lie well offshore, and companies are racing one another to get there. Unfortunately, our ability to drill in deep water has outpaced our capacity to deal with acci- dents there. The fact that it took 86 days for BP to plug the leak in its Macondo well demonstrates the challenge of addressing

(b) Distillation process

(a) Distillation columns

(c) Typical composition of re�ned oil

Boiling temp.

Distillation column

Product

Less than 5ºC Butane

20-180ºC Naphtha

20-200ºC Gasoline

180-260ºC Kerosene

Crude oil

Boiler Residue

260-340ºC Diesel

300-370ºC Lubricating oil

370-600ºC Fuel oil

Gasoline (48.1%)

Diesel fuel and heating oil (19.4%)

Heavy fuel oil (2.8%) Jet fuel (7.5%)

Lique�ed petroleum gases (10.8%)

Other (11.4%)

FIGURE 15.7  At oil refineries (a), crude oil is boiled, causing its many hydrocarbon constituents to volatilize and proceed upward through a distillation column (b). Constituents that boil at the hottest temperatures and condense readily once the temperature cools will condense at low levels in the column. Constituents that volatilize at cooler temperatures will continue rising through the column and condense at higher levels, where temperatures are cooler. In this way, heavy oils (generally those with hydrocarbon molecules with long carbon chains) are separated from lighter oils (generally those with short-chain hydrocarbon molecules). The refining process produces a range of petroleum products. Shown in (c) are percentages of each major category of product typically generated from a barrel of crude oil. Data for (c) from U.S. Energy Information Administration.

an emergency situation a mile or more beneath the surface of the sea.

In 2008 the U.S. Congress lifted a long-standing morato- rium on offshore drilling along much of the nation’s coastline. The administration of President Barack Obama in 2010 then designated vast areas open for drilling. These included most waters along the Atlantic coast from Delaware south to cen- tral Florida, a region of the eastern Gulf of Mexico, and most waters off Alaska’s North Slope. However, just weeks after this announcement, the Deepwater Horizon spill occurred. Public reaction forced the Obama administration to backtrack, can- celing offshore drilling projects it had approved and putting a hold on further approvals until new safety measures could be devised.

Petroleum products have many uses Once we extract crude oil, we refine it (FIGURE 15.7). Crude oil is a mixture of hundreds of types of hydrocarbon molecules characterized by carbon chains of different lengths (p. 28). A

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levels of production (30 billion barrels globally per year), 1.2 trillion barrels would last about 40 more years.

Unfortunately, this does not mean that we have 40 years to figure out what to do once the oil runs out. A growing number of scientists and analysts insist that we will face a cri- sis as soon as the rate of production comes to a peak and then begins to decline—a point in time nicknamed peak oil. They point out that if demand continues to increase (because of rising global population and consumption) while production declines, an oil shortage will result. Because production tends to decline once reserves are depleted halfway, many of these experts calculate that a peak oil crisis will likely begin in the very near future.

To understand the basis of these concerns, we must turn back the clock to 1956. In that year, Shell Oil geologist M. King Hubbert calculated that U.S. oil production would peak around 1970. His prediction was ridiculed at the time, but it proved to be accurate; U.S. production peaked in that very year and has continued to fall since then (FIGURE 15.9A). The peak in production came to be known as Hubbert’s peak.

In 1974, Hubbert analyzed data on technology, eco- nomics, and geology, predicting that global oil production would peak in 1995. It grew past 1995, but many scientists using newer, better data today predict that at some point in the coming decade, production will begin to decline (FIGURE 15.9B). Discoveries of new oil fields peaked 30 years ago, and since then we have been extracting and consuming more oil than we have been discovering.

chain’s length affects its chemical properties, and these have consequences for human use, such as whether a given fuel burns cleanly in a car engine. Oil refineries sort the various hydrocarbons of crude oil, separating those intended for use in gasoline engines from those, such as tar and asphalt, used for other purposes.

Since the 1920s, refining techniques and chemical man- ufacturing have greatly expanded our uses of petroleum to include a wide array of products and applications, from lubricants to plastics to fabrics to pharmaceuticals. Today, petroleum-based products are all around us in our every- day lives (FIGURE 15.8). Because petroleum products have become so central to our lifestyles, many fossil fuel experts today are voicing concern that oil production may soon de- cline as we continue to deplete the world’s recoverable oil reserves.

We may already have depleted half our oil reserves Some scientists and oil industry analysts calculate that we have already extracted half the world’s oil reserves. So far we have used up about 1.1 trillion barrels of oil, and most esti- mates hold that somewhat more than 1 trillion barrels remain. To estimate how long this remaining oil will last, analysts cal- culate the reserves-to-production ratio, or R/P ratio, by di- viding the amount of total remaining reserves by the annual rate of production (i.e., extraction and processing). At current

Cosmetics, medicines, lotions, and soap

Plastic wastebasket

Detergents, cleaning supplies

Nylon and polyester clothing

Light switch Pesticides and fertilizers

Asphalt

Toilet seat

Shoes with synthetic soles

Plastic storage box

Vinyl and plastic laminate furniture

Polypropylene coat

CDs and DVDs Linoleum flooring

Components in TV and stereo

Home heating oil to heat house

Blender and other small appliances

Components of stove and other large appliances

Toothbrush

Shower curtain

Plastic lampshade

ContainersTires, upholstery, and automobile components

Shower head

Plastic picture frame

Bicycle components Gasoline

Paraffin waxes on fruit, candy, and other food

Plastic cups and dishware

Nonstick coating on cookware

FIGURE 15.8  Petroleum products are everywhere in our daily lives. Besides the fuels we use for transportation and heating, petroleum products include many of the fabrics we wear and the plastics in countless items we use every day.

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without petroleum-based fertilizers and pesticides we could feed only a fraction of the world’s 7 billion people, even if we expand agricultural land. The American suburbs would be hit particularly hard because of their utter dependence on the au- tomobile. Kunstler argues that the suburbs will become the slums of the future, a bleak and crime-ridden landscape lit- tered with the hulls of rusted-out SUVs.

More optimistic observers argue that as oil supplies dwindle, rising prices will create powerful incentives for busi- nesses, governments, and individuals to conserve energy, use the more expensive types of fossil fuels like those described on the next page, and develop alternative energy sources (Chap- ter 16)—and that these developments will save us from major disruptions caused by the coming oil peak.

Indeed, to achieve a sustainable society, we will need to switch to renewable energy sources. Investments in energy ef- ficiency and conservation (pp. 343–345) can extend the time we have to make this transition. However, the research and development needed to construct the infrastructure for a new energy economy depend on having cheap oil, and the time we will have to make this enormous transition will be quite limited.

Predicting an exact date for peak oil is difficult. Because of year-to-year variability in production, we will not be able to recognize that we have passed the peak until several years af- ter the fact. Many companies and governments do not reveal their true data on oil reserves, and estimates differ as to how much oil we can extract secondarily from existing deposits. Indeed, a recent U.S. Geological Survey report estimated 2 tril- lion barrels remaining in the world, rather than 1 trillion, and some estimates predict still greater amounts. A 2007 report by the U.S. General Accounting Office reviewed 21 studies and found that most estimates for the timing of the oil production peak ranged from now through 2040.

Whenever it occurs, the coming divergence of demand and supply will likely have momentous economic, social, and political consequences that will profoundly affect the lives of each and every one of us. One prophet of peak oil, writer James Howard Kunstler, has sketched a frightening scenario of our post-peak world during what he calls “the long emer- gency”: Lacking cheap oil with which to transport goods long distances, today’s globalized economy would collapse, and our economies would become intensely localized. Large cities could no longer be supported without urban agriculture, and

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Hubbert’s prediction assuming a total of 200 billion barrels of discoverable oil (total area under curve)

1950 Year

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(a) Hubbert’s prediction of peak in U.S. oil production, with actual data

(b) Modern prediction of peak in global oil production

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FIGURE 15.9  Because fossil fuels are nonrenewable resources, supplies at some point pass the midway point of their depletion, and annual production begins to decline. U.S. oil production peaked in 1970 (a), just as geologist M. King Hubbert had predicted. Success in Alaska, the Gulf of Mexico, and with sec- ondary extraction increased production above his prediction during the decline. Today many analysts believe global oil production is about to peak. Shown (b) is a recent projection, from a 2009 analysis by scientists at the Association for the Study of Peak Oil. Data for (a) from Hubbert, M.K., 1956. Nuclear energy and the

fossil fuels. Shell Development Co. Publ. No.

95, Houston, TX; and U.S. Energy Information

Administration; and for (b) from Campbell,

C.J., and Association for the Study of Peak Oil.

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Three-quarters of the world’s oil sands occur in Venezue- la and in Alberta, Canada. In Alberta, strip mining began in 1967. Rising crude oil prices have made oil sands more profit- able, and dozens of companies are now angling to begin min- ing projects in the region. Canadian oil sands are now produc- ing well over 1 million barrels of oil per day, contributing half of Canada’s petroleum production.

Oil shale Oil shale is sedimentary rock filled with kerogen (organic matter) and can be processed to produce liquid pe- troleum. Oil shale is formed by the same processes that form crude oil but results when kerogen was not buried deeply enough or subjected to enough heat and pressure to form oil.

We mine oil shale using strip mines or subsurface mines. Once mined, oil shale can be burned directly like coal, or can be baked in the presence of hydrogen and in the absence of air to extract liquid petroleum. The world’s known deposits of oil shale may be able to produce over 600 billion barrels of oil (roughly half as much as the conventional crude oil remaining in the world). About 40% of global oil shale reserves are in the United States, mostly on federally owned land in Colorado, Wyoming, and Utah.

Methane hydrate Another novel potential source of fos- sil fuel energy occurs in sediments on the ocean floor. Meth- ane hydrate (also called methane clathrate or methane ice ) is an ice-like solid consisting of molecules of methane (CH 4 , the main component of natural gas) embedded in a crystal lattice of water molecules. Methane hydrate is stable at tem- perature and pressure conditions found in many sediments on the Arctic seafloor and the continental shelves.

Scientists believe there to be immense amounts of meth- ane hydrate on Earth, holding perhaps twice as much carbon as all known deposits of oil, coal, and natural gas combined. However, we do not yet know how to extract these energy sources safely. Destabilizing a methane hydrate deposit dur- ing extraction could lead to a catastrophic release of gas. This could cause a massive landslide and tsunami and would also release huge amounts of methane, a potent greenhouse gas, into the atmosphere, worsening global climate change.

Other fossil fuels exist As oil production declines, we will rely more on natural gas and coal—yet these in turn will also eventually peak and de- cline. At least three further types of fossil fuels exist in large amounts: oil sands, oil shale, and methane hydrate.

Oil sands Oil sands (also called tar sands ) are deposits of moist sand and clay containing 1–20% bitumen , a thick and heavy form of petroleum that is rich in carbon and poor in hydrogen. Oil sands represent crude oil deposits that have been degraded and chemically altered by water erosion and bacterial decomposition. Bitumen is too thick to extract by conventional oil drilling, so oil sands are generally removed by strip mining ( FIGURE 15.10 ). After extraction, bitumen may be sent to specialized refineries, where chemical reac- tions that add hydrogen or remove carbon can upgrade it into more valuable synthetic crude oil.

FAQ

Q: Why should I worry about “peak oil” if there are still years of oil left in the ground? A: The first thing to bear in mind is that the term “peak oil” doesn’t refer to running out of oil. It refers to

the point at which our production of oil comes to a peak. Once we pass this peak and production begins to decline, the economics of supply and demand take over. Supply will fall, with some estimates putting the decline at 5% per year. Demand, meanwhile, is forecast to continue rising, especially as nations like China and India put millions of new vehicles on the road. The divergence of demand and supply will drive up oil prices, causing substantial economic ripple effects. Although high oil prices will provide financial incentive to develop alternative energy sources, we may be challenged in a depressed economy to find adequate time and resources to develop new renewable sources.

FIGURE 15.10  In Alberta, com- panies strip-mine oil sands with the world’s largest dump trucks and power shovels. On average, 2 met- ric tons of oil sands are required to produce 1 barrel of synthetic crude oil.

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coal in our power plants releases sulfur dioxide and nitrogen oxides, which contribute to smog (pp. 287–289) and acid dep- osition (pp. 291–294). Combustion of coal may emit mercury that can bioaccumulate in organisms’ tissues, poisoning ani- mals as it moves up food chains (pp. 216–217) and presenting health risks to people.

Air pollution from fossil fuel combustion is increasing in developing nations that are industrializing rapidly, but it has been reduced in developed nations as a result of laws such as the U.S. Clean Air Act and government regulations to pro- tect public health (Chapter 13). Technologies such as catalytic converters that cut down on vehicle exhaust pollution have helped a great deal, and their wider adoption in the develop- ing world would reduce pollution further. Regarding pollu- tion from coal-fired power plants, scientists and engineers are seeking ways to cleanse coal of its impurities so that it can continue to be used as an energy source while minimizing im- pacts on health and the environment.

Clean coal technologies aim to reduce pollution from coal Clean coal technologies refer to a wide array of techniques, equipment, and approaches that aim to remove chemical con- taminants during the process of generating electricity from coal. Among these technologies are various types of scrubbers (pp. 285–286), devices that chemically convert or physically remove pollutants. Another approach is to dry coal that has high water content, making it cleaner-burning. We can also gain more power from coal with less pollution through a proc- ess called gasification, in which coal is converted into a cleaner synthesis gas, or syngas, by reacting it with oxygen and steam at a high temperature. Syngas from coal can be used to turn a gas turbine or to heat water to turn a steam turbine.

Alternative fossil fuels have drawbacks Oil sands, oil shale, and methane hydrate are abundant, but they are no panacea for our energy challenges. For one thing, their net energy values are low, because they are expensive to extract and process. Thus the ratio of energy returned on energy invested (EROI) is low. For instance, much of the en- ergy content of oil shale is consumed in its production, and oil shale’s EROI is only about 2:1 or 3:1, compared to a 5:1 or greater ratio for conventional crude oil.

Second, these fuels exert severe environmental impacts. Oil sands and oil shale require extensive strip mining, which devastates landscapes and pollutes waterways. Mining these resources also requires an immense amount of water (which is often scarce in mining regions). At Alberta’s oil sands mines, polluted wastewater is left to sit in gigantic reservoirs where waterfowl can die once they land. Besides impacts from their extraction, our combustion of alternative fossil fuels would emit at least as much carbon dioxide, methane, and other air pollutants as our use of coal, oil, and gas. This would worsen the impacts that fossil fuels are already caus- ing, including air pollution and global climate change.

ADDRESSING IMPACTS OF FOSSIL FUEL USE Our society’s love affair with fossil fuels and the many pet- rochemical products we develop from them has eased con- straints on travel, helped lengthen our life spans, and boosted our material standard of living beyond what our ancestors could have dreamed. However, it also causes harm to the en- vironment and human health, and it can lead to political and economic instability.

Fossil fuel emissions pollute air and drive climate change When we burn fossil fuels, we alter fluxes in Earth’s carbon cycle (pp. 38–39). We essentially take carbon that had been retired into a long-term reservoir underground and release it into the air. This occurs as carbon from the hydrocarbon mol- ecules of fossil fuels unites with oxygen from the atmosphere during combustion, producing carbon dioxide (CO2). Carbon dioxide is a greenhouse gas (p. 300), and CO2 released from fossil fuel combustion warms our planet and drives changes in global climate (Chapter 14). Because climate change may have diverse, severe, and widespread ecological and socioeconomic impacts, carbon dioxide pollution (FIGURE 15.11) is becoming recognized as the greatest environmental impact of fossil fuel use. Moreover, methane is a potent greenhouse gas that drives climate warming. Across the world today, many avenues are being considered to address climate change (pp. 316–323).

Besides modifying our climate, fossil fuel emissions affect human health. Gasoline combustion in automobiles releases pollutants that irritate the nose, throat, and lungs, as well as hydrocarbons (such as benzene and toluene) and impurities (such as lead and arsenic) known to cause cancer or other se- rious health risks. The combustion of oil in our vehicles and

Total

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FIGURE 15.11  Emissions from fossil fuel combustion have risen dramatically as industrialization has proceeded and as population and consumption have grown. Here, global emissions of carbon from carbon dioxide are subdivided by their source (oil, coal, or natural gas). Other minor sources (such as cement production) are also included in the graphed total. Data from Carbon Dioxide Informa- tion Analysis Center, Oak Ridge National Laboratory, U.S. Department of

Energy, Oak Ridge, TN.

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where a Canadian oil company buys it to inject into an oilfield to help it pump out oil.

Currently the U.S. Department of Energy is teaming up with nine energy companies to build a prototype of a near-zero- emissions coal-fired power plant. The $1.5 billion FutureGen project, located in Mattoon, Illinois, aims to design, construct, and operate a power plant that burns coal using gasification and combined cycle generation, produces electricity and hydrogen, then captures its carbon dioxide emissions and sequesters the CO2 underground. If this showcase project succeeds, it could be a model for a new generation of power plants.

Energy experts are not ready to rely on the unproven tech- nology of carbon capture and storage quite yet, however. We do not know how to ensure that CO2 will stay underground once injected there, and we do not know whether these at- tempts might trigger earthquakes. Injection could in some cases contaminate groundwater supplies, and injecting carbon dioxide into the ocean would acidify its waters (pp. 259, 311). Moreover, CCS is energy-intensive and decreases the EROI of coal, adding to its cost and the amount we need to use. Finally, many renewable energy advocates fear the CCS approach takes the burden off emitters and prolongs our dependence on fossil fuels rather than facilitating a shift to renewables.

Clean Coal and Carbon Capture Do you think we should be spending billions of dollars to try to find ways to burn coal cleanly and to sequester carbon emissions from fossil fuels?

Or is our money better spent on developing new clean and renewable energy sources, even though they do not yet have enough infrastructure to produce power at the scale that coal can? What pros and cons do you see in each approach?

The U.S. government and the coal industry have each in- vested billions of dollars in clean coal technologies, and these have helped to reduce air pollution from sulfates, nitrogen oxides, mercury, and particulate matter (p. 285). At the same time, the coal industry spends a great deal of money fighting regulations and mandates on its practices. As a result, many power plants are built with little in the way of clean coal tech- nologies, and these plants will continue polluting our air for decades. Moreover, many energy analysts and environmental advocates emphasize that these technologies will never result in energy production that is completely clean. They argue that coal is an inherently dirty way of generating power and that it should be replaced outright with cleaner energy sources.

Can we capture and store carbon? Even if our clean coal technologies were able to remove every last chemical contaminant from power plant emissions, coal combustion would still pump huge amounts of carbon diox- ide into the air, intensifying the greenhouse effect and wors- ening global climate change. This is why many current efforts focus on carbon capture and carbon storage or sequestra- tion (p. 317). This approach consists of capturing carbon di- oxide emissions, converting the gas to a liquid form, and then sequestering (storing) it in the ocean or underground in a geologically stable rock formation (FIGURE 15.12).

Carbon capture and storage (abbreviated as CCS) is be- ing attempted at a variety of new and retrofitted facilities. The world’s first coal-fired power plant to approach zero emis- sions opened in 2008 in Germany. This plant captures its sulfates and carbon dioxide, compresses the CO2 into liquid form, trucks it 160 km (100 mi) away, and injects it 900 m (3,000 ft) underground into a depleted natural gas field. In North Dakota, the Great Plains Synfuels Plant gasifies its coal and then sends half the CO2 through a pipeline into Canada,

CO2

CO2

CO2

CO2

Deep saline aquifer

Coal-fired power plant (emitting CO2)

Oil refinery

Oil or gas reservoir

Abandoned coal seam

FIGURE 15.12  Carbon capture and storage schemes propose to inject liquefied carbon dioxide emissions underground into depleted fossil fuel deposits, deep saline aquifers, or oil or gas deposits undergoing second- ary extraction.

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An EPA scientist takes samples to as- sess impacts of oil on beaches.

when and where oil might reach shore, thereby helping to direct prevention and cleanup efforts.

Tracking movement of the oil underwater was trickier than monitoring its spread on the surface. University of Georgia biochemist Mandy Joye, who had studied natural seeps in the Gulf for years, documented that the leaking wellhead was creating a plume of oil the size of Manhattan. She also found evi- dence of low oxygen concentrations, or hypoxia (pp. 22, 25, 267), resulting from the fact that some bacteria consume oil and gas, depleting the water of oxygen as they proliferate. Hypoxia can make underwater regions uninhabitable for fish and other creatures.

Joye and others worried about im- pacts on marine life in the open ocean and deep beneath the surface. Some researchers feared that the thinly dis- persed oil could prove devastating to plankton (the base of the marine food chain) and to the tiny larvae of shrimp,

fish, and oysters (the pillars of the fish- ing industry). Scientists taking water samples documented sharp drops in plankton during the spill, but it will take a few years to learn whether so many larvae were lost as to diminish popula- tions of adult fish and shellfish.

Other questions revolve around impacts of the chemical dispersant that BP used to break up the oil, a com- pound called Corexit 9500. Work by biologist Philippe Bodin following the Amoco Cadiz oil spill in France in 1978 had found that Corexit 9500 appeared more toxic to marine life than the oil itself. BP applied an unprecedented amount of the chemical to the Deep- water Horizon spill, injecting a great deal directly into the path of the oil at the wellhead. This caused the oil to dis- sociate into trillions of tiny droplets that dispersed across large regions. Many scientists worried that this expanded the oil’s reach, affecting more plank- ton, larvae, and fish.

Impacts of the oil on birds, sea turtles, and marine mammals were somewhat easier to assess. Officially confirmed deaths numbered 6,104 birds, 605 turtles, and 97 mammals—and hun- dreds of animals were cleaned and saved by wildlife rescue teams—but a much larger, unknown, number succumbed to the oil. What effects this mortality may have on populations in coming years is unclear. Following the Exxon Valdez spill in Alaska in 1989, populations of some species rebounded after several years, but populations of others have never recovered. Researchers are following the movements of some marine animals with radio transmitters to try to learn what effects the oil may have had.

As images of oil-coated marshes saturated the media, researchers wor- ried that widespread death of marsh grass would leave the shoreline vulner- able to severe erosion by waves. Louisi- ana has already lost many of its coastal wetlands to subsidence, dredging, sea

THE SCIENCE BEHIND THE STORY

Discovering the Impacts of the Gulf Oil Spill

Oil spills pollute marine and coastal environments Even if we can clean up air pollution from power plants, fossil fuels pollute water in many ways. What comes most readily to mind is the pollution that occurs when massive oil spills from tanker ships or drilling platforms foul coastal waters and beaches.

The Deepwater Horizon spill proved so difficult to con- trol because we had never had to deal with a spill so deep

underwater. It revealed that offshore drilling presents serious risks of environmental impact that may be difficult to address, even with our best engineering. As the oil spread through the Gulf of Mexico and washed ashore, the region suffered a wide array of impacts (see ENVISIONIT, p. 340). Of the countless animals killed, most conspicuous were birds, which cannot regulate their body temperature once their feathers become coated with oil. However, the underwater nature of the BP spill meant that unknown numbers of fish, shrimp, corals,

President Barack Obama echoed the perceptions of many Americans when he called the Deepwater Horizon oil spill “the worst environmental disas-ter America has ever faced.” But what has scientific research told us about the actual impacts of the Gulf oil spill? We don’t have all the answers, because the deep-water nature of the spill has

made it difficult for scientists to study. A great deal will remain unknown. Yet the intense and focused scientific response to the spill demonstrates the dynamic way in which science can assist society today.

Scientists’ first order of business as the spill proceeded was to determine how much oil was leaking and where it was going. Early estimates of the flow rate from BP and the U.S. government proved to be too low, and researchers eventually de- termined the rate as reaching 62,000 barrels per day. Using underwater imaging, aerial surveys, and shipboard water samples, researchers tracked the movement of oil up through the water column and across the Gulf. These data helped predict

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and other marine animals also died, affecting coastal and ocean ecosystems in complex ways. Marsh plants were also killed, and any resulting erosion of marshes puts New Orle- ans and other coastal cities at greater risk from storm surges and flooding. Gulf Coast fisheries, which supply much of the nation’s seafood, were hit hard by the spill, with thousands of fishermen and shrimpers put out of work. Beach tourism suffered, and economic and social impacts were expected to last for years. Throughout this process, scientists have been

studying aspects of the spill and its impact on the region’s people and natural systems (see THE SCIENCE BEHIND THE STORY, above).

As climate change melts sea ice in the Arctic, new ship- ping lanes are opening and nations are jockeying for position, hoping to stake claim to oil and gas deposits that lie beneath the seafloor in this region. Offshore drilling in Arctic waters, however, would pose severe pollution risks, because if a spill were to occur, icebergs, pack ice, storms, cold temperatures,

level rise, and silt capture by dams on the Mississippi River (p. 249). Fortu- nately, researchers found that oil did not penetrate to the roots of most plants, and that many oiled grasses were sending up new growth. Indeed, Louisiana State University researcher Eugene Turner said that loss of marsh- land in 2010 from the oil “pales in comparison” with marshland already lost each year due to other factors.

The ecological impacts of the spill had measurable impacts on people. The region’s mighty fisheries were shut down, forcing thousands of fishermen out of work. The government tested fish and shellfish for contamination and reopened fishing once they were found to be safe, but consumers did not want to buy Gulf seafood. Beach tourism remained low all summer as visitors avoided the region. Together, the losses in fishing and tour- ism totaled billions of dollars.

Stress and anxiety over economic losses affected people’s health, studies showed. Over one-third of parents told Columbia University researchers in a survey that their children had suffered physical or mental health effects as a result of the spill—and this figure increased to one-half for low-income residents. Other studies found rises in depression, headaches, respiratory problems, and domestic violence.

Scientists expect some impacts from the Gulf spill to be long-lasting. Oil from the similar Ixtoc blowout off Mexico’s coast in 1979 still lies in coast- al mangrove forests and in sediments near dead coral reefs. Fishermen there say it took years for catches to return to normal, and oysters have never come back. After the Amoco Cadiz tanker spill, it took seven years for oysters and other marine species to recover. In Alaska, oil from the Exxon Valdez spill remains embedded in beach sand, and researchers debate whether it is

best to try to remove it or to leave it undisturbed.

However, researchers agree on reasons to be hopeful about the Gulf’s recovery. One is that the Gulf’s warm and sunny climate speeds the natu- ral breakdown of oil. In hot sunlight, volatile components of oil evaporate from the surface and degrade in the water, so that fewer toxic compounds such as benzene, naphthalene, and toluene reach marine life. In addition, bacteria that consume hydrocarbons live in the Gulf’s waters, sediments, and marshes, because some oil seeps naturally from the seafloor, and leakage from platforms, tankers, and pipelines are common. Thus, whereas for other major spills, responders tried to apply

oil-eating bacteria or fertilize beaches to encourage bacterial growth, in the Gulf these microbes are already thriv- ing, giving the region a natural self- cleaning capacity.

Researchers are now conducting a wide range of scientific studies (see figure). New funding should help: BP has promised to provide half a bil- lion dollars for research over the next 10 years, which is 10 times what the federal government had been provid- ing before the spill. Answers to our many questions will come in gradually as long-term impacts become clear. Scientists can only hope that many findings will be happy ones and that the Gulf’s systems will recover more fully than expected.

WATER COLUMN AND SEDIMENTS • Water quality surveys • Sediment sampling • Transect surveys to detect oil • Oil plume modeling

FISH, SHELLFISH, AND CORALS • Population monitoring of adults and larvae • Surveys of food supply (plankton and invertebrates) • Tissue collection and sediment sampling • Testing for contaminants

BIRDS, TURTLES, MARINE MAMMALS • Air, land, and boat surveys • Radiotelemetry, satellite tagging, and acoustic monitoring • Tissue sampling • Habitat assessment

SHORELINES • Air and ground surveys • Habitat assessment • Measurements of subsurface oil

HUMAN USE • Air and ground surveys

AQUATIC VEGETATION • Air and coastal surveys

Wellhead

The effort to assess damage to natural resources from the Deepwater Horizon oil spill is the largest-ever undertaking of its kind. In this multi-pronged en- deavor, thousands of researchers are surveying habitats, collecting samples and testing them in the lab, tracking wildlife, monitoring populations, and more.

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