energy: renewable and nonrenewable. energy resources and fossil fuels a fossil fuel is a...
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Energy: Renewable and Nonrenewable
Energy Resources and Fossil Fuels
• A fossil fuel is a nonrenewable energy resource formed from the remains of organisms that lived long ago; examples include oil, coal, and natural gas.
• Most of the energy we use comes from this group of natural resources called fossil fuels.
• We use fossil fuels to run cars, ships, planes, and factories and to produce electricity.
Energy Resources and Fossil Fuels
• Fossil fuels are central to life in modern societies, but there are two main problems with fossil fuels.• The supply of fossil fuels is limited.• Obtaining and using them has environmental
consequences.
• In the 21st century, societies will continue to explore alternatives to fossil fuels but will also focus o developing more-efficient ways to use these fuels.
Fuels for Different Uses• Fuel is used for four main purposes:
• Transportation
• Manufacturing
• Heating and cooling buildings
• Generating electricity to run machines and appliances
• Different fuels are used for different purposes.o The suitability of a fuel for each application
depends on the fuel’s energy content, cost, availability, safety, and byproducts.
Electricity-Power on Demand
• Because electricity is more convenient to use, the energy in fuel is often converted before used.
• Electricity can be transported quickly across great distances.
• This makes it a good source of power for computers, light switches, and more.
• Two disadvantages of electricity are that it is difficult to store and other energy sources have to be used to generate it.
How Is Electricity Generated?• An electric generator is a device that
converts mechanical energy into electrical energy.
• Generators produce electrical energy by moving an electrically conductive material within a magnetic field.
• Most commercial electric generators convert the movement of a turbine into electrical energy. A turbine is a wheel that changes the force of a moving gas or a liquid into energy that can do work.
• The turbine spins a generator to produce electricity.
How Is Electricity Generated?
• The turbine spins because of the steam released from boiling water.
• The water is heated using a coal-fired or gas-fired plant, or is heated from the fission of uranium in nuclear plants.
How Is Electricity Generated
World Energy Use• Everything you do, from the food you eat
to the clothes you wear requires energy.• There are dramatic differences in fuel use
and efficiency throughout the world.• People in developed societies use more
energy than people in developing countries do.
• And within developed societies, there are differences in energy consumption.
World Energy Use• The difference in energy use among
developed countries depends on how energy is generated and used in those countries.
Energy Use in the United States
• The United States uses more energy per person than any other country except Canada and the United Arab Emirates.
• The U.S. uses more than 25% of its energy to transport goods and people.
Energy Use in the United States
• Other countries, such as Japan and Switzerland, depend on extensive rail systems and are smaller, compact countries
• Residents of the United States and Canada enjoy some of the lowest gasoline taxes in the world. There is little incentive to conserve gasoline when its cost is so low.
• Countries with limited fossil-fuel resources supplement a greater percentage of their energy needs with other energy sources, such as hydroelectric or nuclear.
• Fossil fuel deposits are not distributed evenly.
• There is an abundance of oil in Texas and Alaska, but very little in Maine.
• The eastern United States produces more coal than other areas.
• The reason for this difference lies in the geologic history of the areas.
How Fossil-Fuel Deposits Form
Oil and Gas Deposits in the United States
Coal Formation• Coal forms from the remains of plants that lived in
swamps hundreds of millions of years ago.• As ocean levels rose and fell, swamps were
repeatedly covered with sediment.• Layers of sediment compressed the plant remains,
and heat and pressure within the Earth’s crust caused coal to form.
• Much of the coal in the United States formed about 300 to 250 million years ago. Deposits in western states, however, formed between 100 and 40 million years ago.
Oil and Natural Gas Formation
• Oil and natural gas result from the decay of tiny marine organisms that accumulated on the bottom of the ocean millions of years ago.
• These remains were buried by sediments and then heated until they became complex energy-rich carbon molecules.
• These molecules, over time, migrated into the porous rock formations that now contain them.
Coal
• Most of the world’s fossil-fuel reserves are made up of coal.
• Coal is relatively inexpensive and it needs little refining after being mined.
• Asia and North America are particularly rich in coal deposits.
Coal
Coal
• Over half the electricity generated in the United States comes from coal-fired power plants.
Coal Mining and the Environment
• The environmental effects of coal mining vary.• Underground mining may have minimal effect
on the environment at the surface, but surface coal-mining operations sometimes remove the top of an entire mountain to reach the coal deposit.
• A lot of research focuses on locating the most productive, clean-burning coal deposits and finding less damaging methods of mining coal.
Air Pollution• The quality of coal varies. Higher-grade coals,
such as bituminous coal, produce more heat and less pollution than lower-grade coal, such as lignite.
• Sulfur, found in all grades of coal, can be a major source of pollution when coal is burned.
• The air pollution and acid precipitation that result from burning high-sulfur coal without adequate pollution controls are serious problems in countries such as China.
• However, clean-burning coal technology has dramatically reduced air pollution in countries such as the United States.
Petroleum
• Petroleum is a liquid mixture of complex hydrocarbon compounds that is used widely as a fuel source.
• Petroleum, also known as crude oil. • Anything that is made from crude oil,
such as fuels, chemicals, and plastics, is called a petroleum product.
• Petroleum accounts for 45% of the world’s commercial energy use.
Locating Oil Deposits• Oil is found in and around major geologic
features, such as folds, faults, and salt domes, that tend to trap oil as it moves in the Earth’s crust.
• Most of the world’s oil reserves are in the Middle East. Large deposits also exist in the United States, Venezuela, the North Sea, Siberia, and Nigeria.
• Geologists use many different methods to locate the rock formations that could contain oil.
Locating Oil Deposits• When geologists have gathered all of the
data that they can from the Earth’s surface, exploration wells are drilled to determine the volume and availability of the oil deposit.
• If oil can be extracted at a profitable rate, wells are drilled and oil is pumped or flows to the surface.
• After petroleum is removed from a well, it is transported to a refinery to be converted into fuels and other petroleum products.
The Environmental Effects of Using Oil
• Petroleum fuel releases pollutants when burned.
• These pollutants contribute to smog and cause health problems.
• Many scientists think that the carbon dioxide released from burning petroleum fuels contributes to global warming.
The Environmental Effects of Using Oil
• Oil spills from tanker ships are another potential environmental problem of oil use .
• While oil spills are dramatic, much more oil pollution comes from everyday sources, like leaking cars.
The Environmental Effects of Using Oil
• Emissions regulations and technologies have helped reduce the air pollution in many areas.
• New measures have recently been taken to prevent oils spills from tankers.
• Unfortunately, measures to reduce everyday contamination of our waterways from oil lag far behind the efforts to prevent large spills.
Natural Gas
• About 20% of the world’s nonrenewable energy comes from natural gas.
• Natural gas, or methane (CH4), produces fewer pollutants than other fossil fuels when burned.
• Vehicles that run on natural gas require fewer pollution controls.
• Electric power plants can also use this clean-burning fuel.
Fossil Fuels and the Future• Fossil fuels supply about 90% of the energy
used in developed countries.• As the demand for energy resources increases,
the cost of fossil fuels will likely increase.• This will make other energy sources more
attractive.• Planning for the energy we will use in the
future is important because it takes many years for a new source of energy to make a significant contribution to our energy supply.
Predicting Oil Prediction• Oil production is still increasing, but
it is increasing much more slowly than it has in the past.
Predicting Oil Production• Many different factors must be considered
when predicting oil production.• Oil reserves are oil deposits that are
discovered and are in commercial production.
• Oil reserves can be extracted profitably at current prices using current technologies.
• In contrast, some oil deposits are yet to be discovered or to become commercial.
Predicting Oil Production• Prediction must also take into account the
changes in technology that will allow more oil to be extracted in the future.
• All predictions of future oil production are guided by an important principle: the relative cost of obtaining fuels influences the amount of fossil fuels we extract from the Earth.
• As supplies decrease, oil may be used more selectively.
• Also, we may begin to rely on other energy sources to power items like cars and power plants.
Future Oil Reserves• No large oil reserves have been discovered in
the past decade.• Geologists predict that oil production from fields
accessible from land will peak in about 2010.• Additional oil reserves exist under the ocean,
but it is expensive to drill for oil in the deep ocean.
• Currently, oil platforms can be built to drill for oil in the ocean, but much of the oil in the deep ocean is currently inaccessible.
Nuclear Energy• In the 1950s and 1960s, nuclear power
plants were seen as the power source of the future because the fuel they use is clean and plentiful.
• In the 1970s and 1980s, however, many planned nuclear power plants were cancelled and others under construction were abandoned.
• Today, nuclear power accounts for 17% of the world’s electricity.
Fission: Splitting Atoms• Nuclear power plants get their power from
nuclear energy. • Nuclear energy is the energy released by a
fission or fusion reaction. It represents the binding energy of the atomic nucleus.
• The forces that hold together a nucleus of an atom are more than 1 million times stronger than the chemical bonds between atoms.
• In nuclear power plants, atoms of the element uranium are used as the fuel.
Fission: Splitting Atoms• The nuclei of uranium atoms are bombarded
with atomic particles called neutrons. These collisions cause the nuclei to split in a process called nuclear fission.
• Nuclear fission is is the splitting of the nucleus of a large atom into two or more fragments.
• Nuclear fission releases a tremendous amount of energy and more neutrons, which in turn collide with more uranium nuclei.
Fission: Splitting Atoms
How Nuclear Energy Works
• The heat released during nuclear reactions is used to generate electricity in the same way that power plants burn fossil fuels to generate electricity.
• The energy released from the fission reactions heats a closed loop of water that heats another body of water.
• As the water boils, it produces steam that drives a turbine, which is used to generate electricity.
How Nuclear Energy Works
The Advantages of Nuclear Energy
• Nuclear fuel is a very concentrated energy source.
• Nuclear power plants do not produce air-polluting gases.
• Nuclear power plants release less radioactivity than coal-fired power plants do, when operated properly.
• Countries will limited fossil-fuel resources rely heavily on nuclear plants to supply electricity.
• Building and maintaining a safe reactor is very expensive.
• This makes nuclear plants no longer competitive with other energy sources in many countries.
• The actual cost of new nuclear power plants is uncertain, so it is difficult to predict whether investors will build new plants in the United States.
Why Aren’t We Using More Nuclear Energy?
Storing Waste• The greatest disadvantage of nuclear power is
the difficulty in finding a safe place to store nuclear waste.
• The fission products produced can remain dangerously radioactive for thousands of years.
• Storage sites for nuclear wastes must be located in areas that are geologically stable for tens of thousands of years.
• Scientists are researching a process called transmutation, that would recycle the radioactive elements in nuclear fuel.
Safety Concerns• In a poorly designed nuclear plant, the fission
process can potentially get out of control.• The Chernobyl reactor was destroyed in 1986
when an unauthorized test caused explosions and blasted radioactive materials into the air.
• Hundreds of people in the Ukraine died from radioactive exposure from this explosion.
• Even today, parts of northern Europe and the Ukraine remain contaminated from this disaster.
Safety Concerns• The most serious nuclear accident in the United
States occurred in 1979 at the Three Mile Island nuclear power plant in Pennsylvania.
• Human error, along with blocked valves and broken pumps, was responsible for this accident.
• Fortunately, only a small amount of radioactive gas escaped.
• Since that accident, the U.S. Nuclear Regulatory Commission has required more than 300 safety improvements to nuclear plants.
The Future of Nuclear Power
• One possible future energy source is nuclear fusion.
• Nuclear fusion is the combination of the nuclei of small atoms to form a larger nucleus. Fusion releases tremendous amounts of energy.
• It is potentially a safer energy source than nuclear fission is because it creates less dangerous radioactive byproducts.
The Future of Nuclear Power
The Future of Nuclear Power
• Although the potential for nuclear fusion is great, so is the technical difficulty of achieving that potential.
• For fusion to occur, three things must occur simultaneously:• Atomic nuclei must be heated to extremely high
temperatures (about 100,000,000ºC or 180,000,000ºF).• The nuclei must be maintained at very high conditions.• The nuclei must be properly confined.
• The technical problems are so complex that building a nuclear fusion plant may take decades or may never happen.
Alternative Energy Sources
Renewable Energy• Renewable energy is energy from
sources that are constantly being formed. • Types of renewable energy includes:
• solar energy• wind energy• the power of moving water• Earth’s heat
• Remember, all sources of energy, including renewable sources, affect the environment.
Solar Energy-Power from the Sun
• Nearly all renewable energy comes directly or indirectly from the sun.
• Direct solar energy is used every day, like when the sun shines on a window and heats the room.
• Solar energy can also be used indirectly to generate electricity in solar cells.
Passive Solar Heating
• Passive solar heating is the use of sunlight to heat buildings directly.
• In the Northern Hemisphere, south facing windows receive the most solar energy.
• Therefore, passive solar buildings have large windows that face south.
• An average household could reduce its energy bills by using any of the passive solar features shown on the next slide.
Passive Solar Heating
Active Solar Heating
• Active solar heating is the gathering of solar energy by collectors that are used to heat water or heat a building.
• More than 1 million homes in the United States use active solar energy to heat water.
• Solar collectors, usually mounted on a roof, capture the sun’s energy.
Active Solar Heating
Active Solar Heating
• A liquid is heated by the sun as it flows through solar collectors.
• The hot liquid is then pumped through heat exchangers, which heats water for the building.
• About 8% of the energy used in the United States is used to heat water; therefore, active solar technology could save a lot of energy.
Photovoltaic Cells• Photovoltaic cells are solar cells that
convert the sun’s energy into electricity.• Solar cells have no moving parts, and they
run on nonpolluting power from the sun.• However, they produce a very small
electrical current. Meeting the electricity needs of a small city would require covering hundreds of acres with solar panels.
Photovoltaic CellsSunlight falls on a semiconductor, causing it to release electrons. The electrons flow through a circuit that is complete when another semiconductor in the solar cell absorbs electrons and passes them on to the first semiconductor.
Photovoltaic Cells
• Solar cells require extended periods of sunshine to produce electricity. This energy is stored in batteries, which supplies electricity when the sun is not shining.
• Currently, solar cells provide energy for more than 1 million households in developing countries, where energy consumption is minimal and electricity distribution networks are limited.
Wind Power
• Energy from the sun warms the Earth’s surface unevenly, which causes air masses to flow in the atmosphere.
• We experience the movement of these air masses as wind.
• Wind power, which converts the movement of wind into electric energy, is the fastest growing energy source in the world.
Wind Farms• Wind turbines are used to capture the energy
from the wind.• Large arrays of wind turbines are called wind
farms. Large wind farms supply electricity to thousands of homes.
• In windy rural areas, small wind farms with 20 or fewer turbines are also becoming common.
• Because wind turbines take up little space, some farmers can add wind turbines to their land and still use the land for other purposes.
Wind Farms
• The cost of wind power has been steadily falling as wind turbines have become more efficient.
An Underdeveloped Resource
• Scientists estimate that the windiest spots on Earth could generate more than ten times the energy used worldwide.
• In the future, the electricity may be used on the wind farm to produce hydrogen from water.
• Today, all of the large energy companies are developing plans to use more wind power.
Biomass-Power from Living Things
• Biomass fuel consists of plant material, manure, or any other organic matter that is used as an energy source.
• Fossil fuels can be thought of as biomass energy sources, although they are nonrenewable.
• Renewable biomass fuels, such as wood and dung, are major sources of energy in developing countries.
• More than half of all wood cut in the world is used as fuel for heating and cooking.
Biomass-Power from Living Things
Biomass-Power from Living Things
• Although materials like wood are a renewable resource, if trees are cut down faster than they grow, the resulting habitat loss, deforestation, and soil erosion can be severe.
• In addition, harmful air pollution may result from burning wood and dung.
Methane• When bacteria decompose organic wastes,
one byproduct is methane gas.• Methane can be burned to generate heat or
electricity.• In China, more than 6 million households use
biogas digesters to ferment manure and produce gas for heating and cooking.
• Some landfills in the United States generate electricity by using the methane from the decomposition of trash.
Alcohol• Liquid fuels can also be derived from biomass.• For example, ethanol, an alcohol, can be made
by fermenting fruit or agricultural waste. In the United States, corn is a major source of ethanol.
• Cars and trucks can run on ethanol or gasohol, a blend of gasoline and ethanol. Gasohol produces less air pollution than fossil fuels.
• Some states require the use of gasohol in vehicles as a way to reduce air pollution.
Hydroelectricity-Power from Moving Water
• Hydroelectric energy is electrical energy produced by falling water.
• Hydroelectric energy accounts for 20% of the world’s electricity.
• Large hydroelectric power plants have a dam that is built across a river to hold back a reservoir of water.
• The water in the reservoir is released to turn a turbine, which generates electricity.
Hydroelectricity-Power from Moving Water
The Benefits of Hydroelectric Energy
• Hydroelectric dams are expensive to build, but relatively inexpensive to operate.
• Unlike fossil fuel plants, hydroelectric dams do not release air pollutants that cause acid precipitation.
• Hydroelectric dams also tend to last much longer than fossil fuel-powered plants.
• Dams also provide other benefits such as flood control and water for drinking, agriculture, industry, and recreation.
Disadvantages of Hydroelectric Energy
• A dam changes a river’s flow, which can have far-reaching consequences.
• A reservoir floods large areas of habitat above the dam. Water flow below the dam is reduced, which disrupts ecosystems downstream.
• For example, many salmon fisheries of the northwestern United States have been destroyed by dams that prevent salmon from swimming upriver to spawn.
Disadvantages of Hydroelectric Energy
• When the land behind a dam is flooded, people are often displaced. If a dam bursts, people living in areas below the dam can be killed.
• River sediments build up behind the dam instead of enriching land farther down the river, making farmland below the dam less productive.
• Recent research has also shown that the decay of plant matter trapped in reservoirs can release large amounts of greenhouse gases-sometimes more than a fossil-fuel powered plant.
Modern Trends• While in developing countries the construction of
large dams continues, in the United States, the era of large dam construction is probably over.
• One modern trend is micro-hydropower, which is electricity produced in a small stream without having to build a big dam. The turbine may even float in the water, not blocking the river at all.
• Micro-hydropower is much cheaper than large hydroelectric dam projects, and it permits energy to be generated from small streams in remote areas.
Geothermal Energy-Power from the Earth
• In some areas, deposits of water in the Earth’s crust are heated by geothermal energy.
• Geothermal energy is the energy produced by heat within the Earth.
• The United States is the world’s largest producer of geothermal energy.
• Although geothermal energy is considered a renewable resource, the water that is used must be managed carefully so that it is not depleted.
Geothermal Energy-Power from the Earth
• Geothermal power plants generate electricity using the following steps• Steam rises through a well• Steam drives turbines, which generate
electricity• Leftover liquid is pumped back into the hot rock
• The leftover liquid, water, is returned to Earth’s crust because it can be reheated by geothermal energy and used again.
Geothermal Energy-Power from the Earth
Geothermal Heat Pumps: Energy for Homes
• More than 600,000 homes in the United States are heated and cooled using geothermal heat pumps.
• A geothermal heat pump uses stable underground temperatures to warm and cool homes because the temperature of the ground is nearly constant year-round.
• A heat pump is simply a loop of piping that circulates a fluid underground.
Geothermal Heat Pumps: Energy for Homes
Geothermal Heat Pumps: Energy for Homes
• In the summer, the ground is cooler than air and the fluid cools the home.
• In the winter, the ground is warmer than air, and the fluid warms the home.
Alternative Energy
• To achieve a future where energy use is sustainable, we must make the most of the energy sources we already have and develop new sources of energy.
• Alternative energy describes energy that does not come from fossil fuels and that is still in development.
Alternative Energy
• For an alternative energy source to become a viable option for the future, the source must be proven to be cost effective.
• Also, the environmental effects of using the energy source must be acceptable.
Tidal Power
• A tidal power plant works much like a hydroelectric dam.
• As the tide rises, water enters a bay behind a dam. The gate then closes at high tide.
• At low tide, the gate opens and the water in the bay rushes through, spinning a turbine that generates electricity.
Tidal Power
Tidal Power
• Although tidal energy is renewable and nonpolluting, it will not become a major energy source in the future.
• The cost of building and maintaining tidal power plants is high, and there are few suitable locations.
Ocean Thermal Energy Conservation
• In the tropics, the temperature difference between the surface of the ocean and the deep ocean waters can be as much as 24ºC (43ºF).
• Ocean thermal energy conservation (OTEC) is the use of temperature differences in ocean water to produce electricity.
Ocean Thermal Energy Conservation
• An OTEC plant produces energy using the following steps• Warm surface water is boiled in a vacuum
chamber.• This produces a steam that drives a turbine
to generate electricity.• Cold deep-ocean water will condense the
steam.• The steam turns into water that can be used
again.
Ocean Thermal Energy Conservation
Ocean Thermal Energy Conservation
• The United States and Japan have experimented with OTEC power, but so far, no project has been able to generate cost effective electricity.
• OTEC plants are inefficient because about one-third of the electricity the plant produces is used to pump cold water up from the deep ocean.
• The environmental effects of pumping large amounts of cold water to the surface are also unknown.
Hydrogen-A Future Fuel Source?
• Hydrogen, the most abundant element in the universe, can be burned as a fuel.
• Hydrogen does not contain carbon, so it does not release pollutants associated with burning fossil fuels and biomass.
• When hydrogen is burned in the atmosphere, it combines with oxygen to produce water vapor, a harmless byproduct, and small amounts of nitrogen oxides.
Hydrogen-A Future Fuel Source?
• Hydrogen gas (H2) can be produced by using electricity to split molecules of water (H2O).
• Hydrogen fuel can be made from any material that contains a lot of hydrogen.
• In the future, we may also be able to grow plants to produce hydrogen cost effectively.
The Challenge of Hydrogen Fuel
• One difficulty of using hydrogen as a fuel today is that hydrogen takes a lot of energy to produce.
• If this energy came from burning fossil fuels, generating hydrogen would be expensive and polluting.
The Challenge of Hydrogen Fuel
• One alternative is to use electricity from solar cells or wind power to split water molecules to produce hydrogen.
• Hydrogen could then be stored in pressurized tanks and transported in gas pipelines.
• Or hydrogen might not be stored at all-it might be used as it is produced, in fuel cells.
Fuel Cells
• A fuel cell is a device that produces electricity chemically by combining hydrogen fuel with oxygen from the air.
• When hydrogen and oxygen are combined, electrical energy is produced and water is the only byproduct.
• Fuel cells can be fueled by anything that contains plenty of hydrogen, including natural gas, alcohol, or even gasoline.
Fuel Cells
Energy Efficiency• There are two main ways to reduce energy use:
• lifestyle changes• increases in energy efficiency
• Energy efficiency is the percentage of energy put into a system that does useful work.
• Energy efficiency can be determined by this equation: energy efficiency (in %) = energy out/energy in
100
Energy Efficiency
• Most of our devices are fairly inefficient. More than 40 percent of all commercial energy used in the United States is wasted.
• Increasing efficiency may involve sacrifices or investments in new technology.
Efficient Transportation
• Developing efficient engines to power vehicles and increasing the use of public transportation systems would help increase energy efficiency of American life.
• The internal combustion engines that power most vehicles do so inefficiently and produce air pollution.
• In the next 50 years, the design of these engines may change radically to meet the need for more efficient transportation.
Hybrid Cars
• Hybrid cars are examples of energy-efficient vehicles.
• Hybrid cars use small, efficient gasoline engines most of the time, but they also use electric motors when extra power is needed, such as while accelerating.
• Hybrid cars do not cost much more than conventional vehicles, they cost less to refuel, and they produce less harmful emissions.
Hybrid Cars
Hybrid Cars
• Hybrid cars feature many efficient technologies. • They convert some energy of braking into
electricity and store this energy in the battery.
• The gasoline engine is sometimes shut off to save fuel, such as when the car is stopped at a red light.
• They are aerodynamic in design and need less energy to accelerate.
Cogeneration
• Cogeneration is the production of two useful forms of energy from the same fuel source.
• For example, the waste heat from an industrial furnace can power a steam turbine that produces electricity.
• Small cogeneration systems have been used for years to supply heat and electricity to multiple buildings at specific sites.
Energy Conservation
• Energy conservation is the process of saving energy by reducing energy use and waste.
• This can occur in many ways, including using energy-efficient devices and wasting less energy.
• Between 1975 and 1985, conservation made more energy available in the United States than all alternative energy sources combined did.
Cities and Towns Saving Energy
• The town of Osage, Iowa, numbers 3,600 people.
• This town saved more than $1 million each year in energy because they found ways to conserve energy.
• In addition to saving energy, the town has greatly improved its economy through energy conservation.
• Businesses have relocated to the area to take advantage of low energy costs. Unemployment rates have also declined.
Conservation Around the Home
• The average household in the U.S. spends more than $1,200 on energy bills each year.
• Unfortunately, much of the energy from homes is lost through poorly insulated windows, doors, walls, and the roof.
• There are dozens of ways to reduce energy use around the home.
Conservation in Daily Life
• There are many simple lifestyle changes that can help save energy.
• Using less of any resource usually translates into saving energy.
Conservation Around the Home
WASTE
The Generation of Waste
• Solid waste is any discarded solid material, such as garbage, refuse, or sludges.
• Solid waste includes everything from junk mail to coffee grounds to cars.
• Every year, the United States generates more than 10 billion metric tons of solid waste.
• Many products we buy today are used once and then thrown away.
• As a result, the amount of solid waste each American produces each year has more than doubled since the 1960s
The Generation of Waste
Space and Waste• Many towns are running out of space to
dispose of the amounts of waste that people create.
• In 1987, a barge was loaded with 3,200 tons of garbage and left the town of Islip, New York, in search of a place to unload its waste.
• The barge sailed for more than five months but no one would accept the garbage.
Space and Waste
• The garbage was finally burned in New York, and the 430 tons of ash sent to Islip to be buried.
Population and Waste
• It is getting harder to dispose of the waste we create because the human population continues to grow, while available land decreases.
• Today, the average person living in the United States produces 4.4 pounds of solid waste per day.
Population and Waste
Not All Wastes Are Equal
• Wastes are made from two basic materials:• biodegradable materials• nonbiodegradable materials.
• A biodegradable material is a material that can be broken down by biological processes.
• Nonbiodegradable material cannot be broken down by biological processes.
Not All Wastes Are Equal• Plant and animal matter are biodegradable. • Products made from natural materials,
including newspapers, paper bags, cotton fibers, and leather, are usually biodegradable.
• Synthetic compounds are not biodegradable.
• Materials like polyester, nylon, and plastic are nonbiodegradable.
Plastic Problems• Plastics are made from petroleum or natural
gas, which consist mostly of carbon and hydrogen.
• Plastics combine these elements in molecular chains that are not found in nature.
• Microorganisms have not developed ways to break down the molecular structures of most plastics.
• Therefore, some plastics that we throw away may accumulate and last for hundreds of years.
Municipal Solid Waste
• Municipal solid waste is the waste produced by households and businesses.
• Most of what we throw out on a day-to-day basis is called municipal solid waste.
• The amount of municipal solid waste is growing much faster than the amount of mining or agricultural waste.
Municipal Solid Waste
• Municipal solid waste creates more than 210 million metric tons each year of solid waste. And this is only 2 percent of the total solid waste in the United States.
Solid Waste from Manufacturing, Mining,
and Agriculture• Consumers indirectly create manufacturing waste by purchasing products that have been manufactured.
• Mining wastes include rock and minerals that are left exposed in large heaps, dumped in oceans and rivers, or disposed by refilling and landscaping abandoned mines.
Solid Waste from Manufacturing, Mining,
and Agriculture• Agricultural waste makes up 9% of the total solid waste but is biodegradable.
• The increased use of fertilizers and pesticides may cause agricultural waste to become more difficult to dispose of because the waste may be harmful if returned to the soil.
Landfills• A landfill is an area of
land or an excavation where wastes are placed for permanent disposal.
• More than 50% of the municipal and manufacturing solid waste in the United States ends up in landfills.
Landfills
• Landfills must contain the waste that is buried inside and keep it from causing problems with the environment.
• Waste inside a landfill must not come into contact with the soil and groundwater surrounding the landfill.
• Landfills are maintained by covering wastes each day with a layer of soil, plastic, or both.
Problems with Landfills• Leachate is a liquid that has passed through
solid waste and has extracted dissolved or suspended materials from waste, such as pesticides in the soil.
• Leachate is a problem for landfills because it may contain chemicals from paints, pesticides, cleansers, cans, batteries, and appliances.
• If landfills are not monitored properly, leachate can flow into groundwater supplies and make nearby wells unsafe to drink.
Problems with Landfills• Methane, a highly flammable gas, presents
another problem for landfills. • Methane forms as organic wastes decompose
deep in the landfill where there is no oxygen.• Methane gas can be pumped out of landfills
and burned to generate electricity. • If methane gas production is not monitored
safely, it may seep through the ground and into basements of nearby homes and cause explosions.
Parts of a Modern Landfill
Safeguarding Landfills• The Resource Conservation and Recovery Act,
passed in 1976 and updated in 1984, requires that new landfills be built with safeguards to reduce pollution problems.
• New landfills must be lined with clay and a plastic liner and must have systems for collecting and treating leachate, as well as vents to carry methane out of the landfill.
• Adding safeguards to landfills, however, increases the cost of building them. Also, finding acceptable places to build landfills is difficult.
Building More Landfills• We are currently running out of space that we
are willing to develop for new landfills.• The materials we bury in landfills are not
decomposing as fast as we can fill landfills. Even biodegradable materials, like newspapers, take several years to decompose.
• The total number of active landfills in the United States in 1988 was 8,000. By 1999, the total number of active landfills decreased to 2,300 because many of the landfills had been filled to capacity.
Building More Landfills
The EPA estimates that active landfills in 20 states will be filled to capacity within 20 years.
Incinerators
• In 1999, the U.S. had 102 operational incinerators that were capable of burning up to 94,000 metric tons of municipal solid waste per day.
• Incinerators are one option for reducing the amount of solid waste in landfills.
• Incinerated materials do not disappear, but the weight of solid waste is reduced.
Incinerators• Incinerated materials can be more toxic
than before it was incinerated.• Special air pollution control devices help
control the amount of toxins released into the air.
• However, even incinerators with these special air pollution control devices release small amounts of poisonous gases and particles of toxic heavy metals into the air.
Incinerators
Reducing Solid Waste• Source reduction is any change in the
design, manufacture, purchase, or use of materials or products to reduce their amount of toxicity before they become municipal solid waste.
• Source reduction also includes the reuse of products or materials.
• If we produce less waste, we will reduce the expense and difficulty of collecting and disposing of it.
Buying Less and Lasting Longer
• Consumers can influence manufacturers to reduce solid waste by buying products that have less packaging or that can be used more than once.
• For example, you could purchase dish towels instead of paper towels.
• Manufacturers could also reduce waste and conserve resources by redesigning products to use less material and to last longer.
Recycling• Recycling is the process of recovering valuable
or useful materials from waste or scrap. Recycling also refers to the process of reusing some items.
• Making products from recycled materials usually saves energy, water, and other resources. For example, 95% less energy is needed to produce aluminum from recycled aluminum than from ore.
• About 70% less energy is needed to make paper from recycled paper than from trees.
Recycling: A Series of Steps
• The steps of recycling include:• collecting and sorting discarded
materials by type• taking the materials to a recycling facility• cleaning the discarded materials so that
they can be shredded or crushed• reusing the shredded or crushed material
to manufacture new products• selling the new products to consumers
Recycling: A Series of Steps
• If more people purchase products made from recycled materials, there would be an increase in demand for these products.
• Manufacturers would then build more facilities to make recycled products and, in turn, make it easier for communities to recycle.
• Compost is a mixture of decomposing organic matter, such as manure and rotting plants, that is used as fertilizer and soil conditioner.
• Compost provides several benefits.
Composting
• Yard waste often makes up more than 15% of a community’s solid waste.
• Composting can be an effective way of handling biodegradable waste from businesses and homes.
• If all biodegradable wastes were composted, the amount of solid waste going to landfills could be reduced.
Composting
Changing the Materials We Use
• Simply changing the materials we use could eliminate much of the solid waste we produce.
• Recycling other common household products into new, useable products could also help eliminate solid waste.
• For example, plastic beverage containers can be recycled to make nonfood containers, insulation, carpet yarn, textiles, fiberfill, and more.
Degradable Plastics
• Photodegradable plastic, unlike nonbiodegradable plastics, is made to become weak and brittle when left in the sun for many weeks. Eventually, it breaks into pieces.
• Green plastic, is made by blending the sugars in plants with a special chemical agent to make plastics.
Degradable Plastics• The production of green plastics requires 20
to 50% less fossil fuel. • This plastic has also been engineered to
degrade within 45 days of being thrown away.• When green plastic is buried, the bacteria in
the soil eat the sugars and leave the plastic weakened and full of microscopic holes.
• The chemical agent then gradually causes the long plastic molecules to break into shorter molecules.
Problems with Degradable Plastics
• The main problem with degradable plastics is that the plastic parts are only reduced to smaller pieces, not eliminated.
• Degradable plastics can help reduce the harmful effects that plastic litter has on animals in the environment.
• Although this type of plastic can help reduce the harmful effects of plastic litter, the plastic itself will remain just as long as regular plastics.
Types of Hazardous Waste• Hazardous wastes are wastes that are a risk to
the health of humans or other living organisms.• They may be solids, liquids, or gases. They often
contain toxic, corrosive, or explosive materials.• Some examples are
• dyes, • cleansers, • solvents, • plastics, • and pesticides.
Types of Hazardous Waste
Types of Hazardous Waste• The methods used to dispose of hazardous
wastes often are not as carefully planned as the manufacturing processes that produce them.
• An improperly maintained hazardous waste disposal site can leak toxic waste into the air, soil, and ground water.
• Federal laws were passed to clean up old waste sites and regulate future waste disposal.
Resource Conservation and Recovery Act
• The Resource Conservation and Recovery Act (RCRA) requires producers of hazardous waste to keep records of how their wastes are handled.
• The RCRA also requires all hazardous waste treatment and disposal facilities to be built and operated according to standards that are designed to prevent the facilities from polluting the environment.
The Superfund Act
• In 1980, Congress passed the Comprehensive Environmental Response, Compensation, and Liability Act, more commonly known as the Superfund Act.
• This act gives the EPA the right to sue the owners of hazardous waste sites who had illegally dumped waste.
• It also allows the EPA to force the owners to pay for the cleanup.
The Superfund Act
• Cleaning up improperly discard waste is difficult and extremely expensive.
• The act also created a fund of money to pay for cleaning up abandoned hazardous waste sites.
• Cleanup has been completed at only 75 of the roughly 1,200 approved or proposed Superfund sites.
The Superfund Act
Preventing Hazardous Waste
• One way to prevent hazardous waste is to produce less of it.
• For example, manufacturers discovered they can redesign manufacturing methods to produce less or no hazardous waste.
• Such techniques save the manufacturers money by cutting the cost of materials as well as in cutting the cost of waste disposal.
Preventing Hazardous Waste
• Another way to prevent hazardous waste is to find a way to reuse it.
• For example, a company that would usually throw away a cleaning solvent after one use can instead sell it to another company that produces a product that is not harmed by small amounts of contamination in the solvent.
Conversion into Nonhazardous Substances
• Some types of wastes can be treated with chemicals to make them less hazardous.
• For example, cyanides, which are extremely poisonous compounds, can be combined with oxygen to form carbon dioxide and nitrogen.
• Wastes can also be treated biologically. • Sludge from petroleum refineries, for
example, may be converted by soil bacteria into less harmful substances
Land Disposal
• Most of the hazardous waste produced in the United States is disposed of on land.
• Hazardous wastes in concentrated or solid forms are often put in barrels and buried in special landfills.
• These landfills have extra safety precautions to prevent leakage.
Land Disposal• One type of land disposal facility uses deep-
well injection.• Deep-well injection involves deep-well
disposal of hazardous waste. • Deep-well injections pump hazardous wastes
deep into the ground, where they are absorbed into a dry layer of rock below the level of groundwater.
• The wastes are then covered with cement to prevent contamination of the groundwater.
Land Disposal
Land Disposal• A surface impoundment is a natural
depression or a human-made excavation that serves as a disposal facility that holds an accumulation of wastes.
• Surface impoundments are basically ponds with sealed bottoms.
• Wastes accumulate and settle to the bottom of the pond, while water evaporates from the pond and leaves room to add more wastes.
Biologically Treating Hazardous Waste
• Some hazardous wastes can be absorbed, broken down, or their toxicity can be reduced when they are treated with biological and chemical agents.
• Certain bacteria and chemicals can be used to help clean up an area in the environment that has been contaminated with hazardous substances.
• Flowering plants and trees that absorb heavy metals can also be planted in contaminated areas.
Incinerating Hazardous Waste
• Some hazardous wastes are disposed of by burning in specially designed incinerators.
• Incineration can be a safe way, but it is generally the most expensive form of disposing waste.
• Incinerators need pollution-control devices and they need to be monitored for hazardous gases and particles.
• Incinerators produce ash that needs to be buried in a hazardous waste landfill.
Exporting Hazardous Waste
• Until recently, only local laws regulated waste disposal in the United States.
• Until the 1980s, companies would often send hazardous waste to landfills in other, less populated states.
• Hazardous wastes are now exported through international trade agreements to facilities in another countries that specialize in treating, disposing of, or recycling a particular hazardous waste.
Hazardous Wastes at Home
• Household produces can also create hazardous waste.
• Some household products should be disposed of in specially designed hazardous waste landfills, and not down
the drain or put in the trash for a solid-waste landfill.
Disposing of Household Hazardous Waste
• More cities around the country have begun to provide collection for household hazardous waste to make sure they are disposed of properly.
• Trained workers sort the hazardous materials and send some for recycling and pack others into barrels for disposal.
• Used batteries and motor oil, for example, can be recycled.
Motor Oil• It is illegal to pour motor oil on the ground or
throw it in the trash.• However, people in the United States throw
away over 700 million liters (185 million gallons) of used motor oil every year. This does not include the oil disposed of by service stations and automobile repair shops.
• Motor oil can be recycled by taking it to an automobile service station. Some cities have designated oil-collection receptors. These cities recycle the used oil turned in by citizens.