Chapter 19 Topics:  Our energy sources  Coal  Natural gas  Crude oil  Alternative fossil fuels  Environmental impacts of fossil fuels  Political, social, and economic aspects  Conserving energy and enhancing efficiency

Our energy has several sources  Energy powers modern human society  Most of our energy comes from the sun  Solar, wind, hydropower, biomass  Fossil fuels = combustible substances composed of the remains of organisms from past geologic ages  We also use thermal energy from Earth’s core (geothermal energy) and the energy contained in the nuclei of radioactive elements (nuclear energy)  We use many of these sources to produce a “secondary” energy – electricity

Fossil fuels lead the way  Oil, coal, and natural gas have replaced biomass as our dominant sources of energy  The high-energy content of fossil fuels makes them efficient to burn, ship, and store  Consumption is at its highest level

Our energy flow

Renewable vs. non-renewable  Renewable energy = our use does not reduce the amount available in the future  Sunlight, wind, hydropower  Biomass (conditional)  Geothermal energy, and tidal energy  Non-renewable energy = our use will deplete Earth’s accessible store in decades to centuries  Oil, coal, natural gas, nuclear energy  To replenish the fossil fuels we have depleted so far would take millions of yea rs

Formation of fossil fuels  Fossil fuels were formed from organisms that lived 100–500 million years ago  Fossil fuels are formed by anaerobic decomposition; organic material is broken down with little or no O 2  Aerobic decomposition (in the presence of O 2 ) produces carbon dioxide

Global resource distribution  Some regions have substantial reserves whereas others have very few  How long a nation’s reserves will last depends on how much the nation extracts, uses, exports, and imports  Nearly 67% of the world’s proven reserves of crude oil lie in the Middle East  Russia has the largest natural gas reserves  The U.S. has the largest coal reserves

Global consumption distribution  People in developed regions consume far more energy than those in developing nations, using 100 times more energy per person  Energy use in industrialized nations is evenly divided between transportation, industry, and other uses  Developing nations use energy for subsistence activities  Agriculture, food preparation, and home heating  They use manual or animal energy, not fossil fuels

Global consumption – visually

Energy economics  We don’t get energy for free  To find, extract, process, and deliver energy requires substantial inputs of energy  Net energy = the difference between energy returned and energy invested  Energy “return on investment” (EROI) = energy returned/energy invested; higher ratios mean we receive more energy than we invest  EROI ratios can change  When we extract the easiest deposits first, we have to work harder to extract the remaining reserves  The EROI ratio for U.S. has gone from 100:1 to 5:1

Coal  Coal = plant material compressed under high pressure to form dense, solid carbon structures  The world’s most abundant fossil fuel; most known reserves were created 300–400 million years ago  The Earth has enough coal to last a few hundred years  Coal fueled the Industrial Revolution  Now used primarily to generate electricity; provides half the U.S. electrical generating capacity  The U.S. and China are the primary producers and consumers of coal

Coal varies in quality  Coal varies in its potential energy due to variation in its water content and carbon content (density)  Time, heat, and pressure decrease moisture and increase carbon content (density) and potential energy  Peat = near-surface, moist, “dirt-like”  Lignite = lowest grade  Sub-bituminous and bituminous  Anthracite = contains the most energy

A typical coal-fired power plant

Environmental considerations  Coal mining methods are either highly dangerous (subsurface mining) or extremely destructive (strip mining and mountain-top removal)  Coal contain impurities – sulfur, mercury, arsenic, other metals – that are emitted when coal is burned  Sulfur content depends on whether the coal formed in salt water (high) or freshwater (low); eastern coal is high in sulfur, western coal is low in sulfur

Natural gas  Natural gas = methane (CH 4 ), other hydrocarbons  The fastest growing fossil fuel in use today at 25% of global energy consumption  It is versatile (residential, electricity, transportation)  It is cleaner-burning, emitting ½ the CO 2 of coal  World supplies projected to last about 60 years  Russia leads the world in production; the U.S. leads the world in use

Natural gas origins  Biogenic gas = pure methane created at shallow depths by bacterial anaerobic decomposition of organic matter  Thermogenic gas = methane and other gases arise from compression and heat deep underground  Most of the gas that is extracted commercially is thermogenic gas; generally occurs with crude oil  Kerogen = organic matter that results when carbon bonds begin breaking; source material for natural gas and crude oil

Natural gas extraction  Natural gas is extracted through wells drilled into the rock formations in which it has collected  The easily accessible reserves were often free- flowing, but most wells now require pumping  Hydraulic fracturing (“fracking”) = a new method to extract natural gas from shale (a tight, fine-grained rock)  Significantly expanded U.S. reserves  Has its own set of environmental issues

Petroleum (crude oil)  Petroleum (crude oil) = a mixture of hundreds of different types of hydrocarbon molecules; also forms from kerogen  Petroleum is the world’s most used fuel, accounting for 35% of global energy use  Used primarily for transportation fuels, but also provides feedstocks for the chemical industry  Russia and Saudi Arabia are the leading producers; the U.S. is the leading consumer

Exploration and extraction  Geologists use a variety of tools to predict where petroleum deposits occur; eventually exploratory drilling must be done to “prove the reserve”  Petroleum is extracted through production wells  Primary extraction = the initial drilling and pumping of available oil, can be free-flowing initially  Secondary extraction = solvents, water, or steam is used to remove additional oil, but it is expensive  We lack the technology to remove every bit of oil, but as prices rise, it can be economical to reopen wells

Extraction illustrated

Limitations to extraction  Technology limits what can be extracted, but economics determines how much will be extracted  As prices rise, economically recoverable amounts approach technically recoverable amounts  Proven recoverable reserve = the amount of oil that is technically and economically feasible to remove under current conditions  Of the 11.6–31.5 billion barrels of oil in the Arctic National Wildlife Refuge, only 4.3–11.8 billion barrels are currently “technologically recoverable”

Petroleum – how long will it last?  We have about 1 trillion barrels of oil reserves  At current levels of production (30 billion barrels/year), these reserves will last about 40 years  We will begin having problems when the rate of production begins to decline – before we run out  Peak oil = rate of production peaks and declines  Discoveries of new oil fields peaked 30 years ago, and we are using more oil than we are discovering

U.S. peak oil  In 1956, petroleum geologist M. King Hubbard predicted – accurately as it turns out – that oil production would peak around 1970

Global peak oil

And then what?  We won’t recognize that we have passed peak production until several years after it happens  Geologists disagree about reserves; companies and governments do not fully disclose their oil reserves  “Reserves” depend on technology and the economy  Peak production will occur – it’s impact is unclear  The pessimistic “long emergency” – a spiraling collapse of economies based on cheap transportation  The optimistic view – a recognition of the need for improved efficiencies and conservation coupled with a transition to alternative energy sources

Oil sands  Oil sands (tar sands) = sand deposits with bitumen  A form of petroleum rich in carbon, poor in hydrogen  Degraded and chemically altered crude oil deposits  Removed by strip mining  Requires special extraction and refining processes  Most is in Venezuela and Alberta

Oil shale  Oil shale = sedimentary rock filled with kerogen, can be burned like coal or baked in the presence of hydrogen to extract liquid petroleum  World’s supplies may equal 600 billion barrels, 40% is in the U.S., mostly on federally owned land in Colorado, Wyoming, and Utah  Low prices for crude oil have kept investors away, but as oil prices increase, oil shale is attracting interest

Methane hydrates  Methane hydrate (methane ice) = molecules of methane in a crystal lattice of ice molecules  Occurs in Arctic locations and under the seafloor  Immense amounts could be present, from 2 to 20 times the known amounts of natural gas  We do not know how to extract it safely  Stable at cold temperatures and high pressures  A sudden phase change during extraction could cause landslides and tsunamis

Issues with alternative fossil fuels  Net energy values are low because they are expensive to extract and process (EROI = 2:1)  Have the same environmental issues as traditional fossil fuels  Extraction causes significant disruption of landscapes; pollution of land, water, and air; and destruction of ecosystems (with attendant loss of ecosystem services)  Burning these fuels releases CO 2 and has the potential to release other criteria air pollutants with their attendant human health impacts

Externalized costs and subsidies  Costs of alleviating environmental impacts are not internalized in the market price of fossil fuels  External costs are paid for in medical expenses, environmental cleanup, and decreased quality of life  Gas prices and utility bills don’t cover production costs  Government subsidies keep fossil fuel prices cheap  Fossil fuel industries get more than renewable ones

“Clean coal”?  Clean coal technologies = technologies, equipment, and approaches to remove chemical contaminants while generating electricity from coal  Scrubbers chemically convert or remove pollutants  Gasification = coal is converted into synthetic gas  Fluidized bed combustion = allows hotter combustion temperatures for complete combustion  These technologies have reduced pollution, but clean coal is still a dirty way to generate power

Carbon capture/sequestration  Even very clean coal still releases greenhouse gases  Carbon capture and carbon storage (sequestration) captures CO2 emissions, converts it to a liquid, and then stores it underground or in the ocean  The $1.5 billion FutureGen project will design, construct, and operate a coal-burning power plant for electricity while capturing and storing carbon underground  This technology is too unproven to depend on and it prolongs our dependence on fossil fuels

Energy dependence  Due to the uneven global distribution of fossil fuels resources (especially petroleum), many nations are somewhat or fully dependent on foreign energy  Vulnerable to supplies becoming unavailable or costly  Seller nations manipulate prices, causing panics and inflation  The U.S. imports 67% of its crude oil

Dependence affects policy  The politically volatile Middle East has the majority of oil reserves, causing constant concern for the U.S.  The U.S. has a close relationship with Saudi Arabia  Despite Saudi Arabia’s lack of democracy  Because it owns 22% of the world’s oil reserves  Iraq has 10% of the world’s oil, many believe this is why the U.S. invaded it in 2003

Our reliance on fossil fuels

The future of fossil fuels  There are good reasons for our use of fossil fuels  But by definition, their supplies are limited and their use has increasingly unacceptable consequences  We can extend our ability to use fossil fuels and reduce their impacts by improving our conservation and efficiency  Energy conservation = reducing overall energy use, through behavioral choices  Energy efficiency = getting the same energy output from less energy input, through technology improvements

Lessons from the past?  The OPEC embargo of 1973 caused increased conservation, but it didn’t last  Without high prices and shortages, there was no incentive to conserve  Government-supported research into alternative energy decreased  Speed limits increased

CAFE Standards  Corporate average fuel efficiency (CAFE) standards mandate higher fuel efficiency in cars  Fuel efficiency rose quickly prior 1984, but actually decreased during the next 20 years as standards remained unchanged  When the standards were again raised in 2007, fuel efficiencies again quickly responded  European and Japanese cars are twice as efficient as U.S. cars

Summary  Fossil fuels have helped build our complex industrialized societies  We are now approaching a turning point in history – fossil fuel production will begin to decline  We can encourage conservation, improve the efficiency of our use, and develop alternative energy sources  Renewable energy sources are becoming feasible and economical