Energy Resources

P. Lobosco

Fossil Fuels Fossil fuels formed hundreds of

millions of years ago from the remains of dead plants and animals. The dead plants and animals were buried under layers of sediments. Over millions of years het and pressure changed the sediments into rocks and the plant and animal remains into fossil fuels.

Main Fossil Fuels The main fossil fuels are coal, oil and

natural gas. Fossil fuels are rich in hydrocarbons. In the process of combustion or

burning the hydrocarbons combine with oxygen and heat energy and light energy are released.

Problems with Fossil Fuel Use

Some deposits of coal and oil contain large amounts of sulfur which release large amount of pollutants when burned.

Coal Coal is a solid fossil fuel. There are four stages of coal

development: peat, lignite, bituminous coal and anthracite.

Peat Peat is a soft substance made of

decayed plant fibers. When burned, it gives off a great deal of smoke but little heat energy.

Lignite Pressure from the layers of rocks

above it changes peat into lignite. Lignite is soft and has a woody texture. It is also low in heat energy.

Bituminous Coal Added pressure turns lignite into

bituminous coal. It is also soft coal found deep within the Earth. This is the most abundant type of coal.

Anthracite Tremendous pressure turns

bituminous coal into anthracite. It is extremely hard and brittle and almost pure carbon. Reserves are known deposits that can be developed. The major reserves of anthracite in the United States are located in Pennsylvania and the intersection of Nevada, Utah and Idaho.

Oil and Natural Gas Liquid fossil fuel is called oil or petroleum.

Oil is found in areas that were once covered by oceans. When plants and animals in the oceans died, they sank to the ocean floor and were covered by sediments. The layers changed into rocks such as limestone, sandstone and shale. Pressure from the rocks and bacteria changed the plant and animal remains into oil.

Crude Oil Limestone and sandstone contain tiny

pores. Oil droplets seeped through these pores and through cracks in the rock layers forming underground pools of oil known as crude oil. Most crude oil is obtained by drilling wells into underground deposits.

Other Oil Sources Two sources near the surface are tar

sands and oil shale. Tar sands are layers of sand soaked with thick petroleum. Oil shale is a gray rock containing a tar-like material.When oil shale is heated to a high temperature it releases hydrocarbon vapor that can be changed into crude oil.

Natural Gas Natural gas is usually found

associated with oil deposits. Because natural gas is less dense than oil, it rises above the oil. As a result, natural gas deposits are usually located above oil deposits. The most common natural gas is methane.

Uses of Fossil Fuels Fossil fuels are the main sources of

energy for industry, transportation and homes. Industry is the major consumer followed by transportation. Transportation relies o liquid fuels such as gasoline that are produced from crude oil.

Crude Oil Refining Before crude oil can be used it must

be refined or the impurities must be removed. Then the oil can be used to make heating oil, gasoline, kerosene, asphalt and petrochemicals. Some petrochemicals are used to make plastics, fabrics, medicines and building materials.

Natural Gas Natural gas is less expensive and

cleaner than oil or coal but the reserves are limited.

Fossil Fuel Shortages Since 1900, the population of the

United States has increased from 76 million to over 299 million in 2006. Energy use has increased 10 times. The United States with only 5% of the population uses more than 30% of the energy produced in the world. In one day humans can use an amount of oil that took 1000 years to form.

Energy from the Sun Life on Earth would not be possible

without energy from the sun. To be useful, solar energy must be collected, converted and stored. Solar energy is received in the form of light. It must be converted into other forms of energy, such as heat and electricity before it can be used. It must also be stored for use when it is not shining.

Solar Energy Solar energy is one the most resourceful

sources of energy for the future. One of the reasons for this is that the total energy we receive each year from the sun is around 35,000 times the total energy used by man. However, about 1/3 of this energy is either absorbed by the outer atmosphere or reflected back into space (a proccess called albedo).

Passive Solar Heating In a passive heating system, the

windows of a building are positioned so that sunlight enters directly and heats the building. Shades covering the windows hold in the heat during the night. The problem is that when the sun is not shining, the source of heat is gone and a backup heating system is needed such as a wood stove.

Water Passive solar heating can be used for

water. Between 30 and 50% of the energy used in homes is used to heat water. Solar hot-water systems could save up to 50% of the energy cost of heating water. Solar hot-water systems can be used year round.

Active Solar Heating An active solar heating system involves

collecting the sun’s energy in a solar collector. A black surface absorbs energy from the sun and converts it into heat. The surface is covered with plastic or glass panels to trap the heat. Water is heated by pumping it through pipes on the surface. The heated water then flows though a storage tank. The heated water is pumped throughout the building for heat and hot water. The water returns to the solar collector to be reheated by the sun.

Solar Cells Solar Cells are called photovoltaic

cells. They convert sunlight directly into electricity. Solar cells are used in calculators. A solar cell is made of extremely thin layers of silicon. When sunlight strikes the surface, electrons flow across the layers. This flow of elections is an electric current. Each solar cell produces 1 watt of electricity.

Use of Solar Cells Solar cells were first used on a large

scale in 1958 to generate electricity abroad the Vanguard 1. Almost every area of the United States has sufficient resources for PV systems. A 90 square mile system could produce enough electricity to meet the country’s peak demand.

Power Towers An array of mirrors can be used to

focus sunlight onto a boiler mounted on a tower. The sun’s heat converts water in the boiler into steam, which drives a turbine to generate electricity. The first solar plant was called Solar One.

Problems with PV Systems

Producing PV systems produces some toxic chemicals and small quantities of hazardous wastes.

The major drawback for solar cell use in homes, school and factories has been their cost compared to fossil fuels.

Wind and Water Throughout history people have used

the energy of wind and water. Wind energy has been used to propel sailing ships, turn mill wheels, and pump water from wells. Water mills were once common along small streams and rivers. Today this energy is used to generate electricity.

Wind Energy Winds are caused by the uneven

heating of the Earth’s atmosphere by the sun. Wind energy is an indirect form of solar energy. Small windmills were built in the United States in the 1860’s. Early windmills were used to pump water out of the ground. Later they produced electricity.

Use of Wind Energy Wind energy is one of the fastest

growing energy sources in the United States, its capacity increased 25% from 1990 to 2003. It only increased 6% in 2004 due to the expiration of the Production Tax Credit.

Problems with Wind Energy

There are concerns about the visual impact, noise pollution and the death of birds.

The power is intermittent. Well-situated wind turbines can produce power about 65-80% of the time, although they often run at less than maximum capacity.

Water Energy Water energy is also an indirect form

of solar energy. Energy from the sun causes water to evaporate from lakes and oceans. This water vapor enters the atmosphere and condenses to form cloud. From clouds water falls back to the Earth. Runoff from rain or snow forms rivers which empty into the oceans and the cycle begins again.

Water Mills In the late 1700’s, water mills in the

United States provided energy for machine looms to make cloth or for turning millstones to grind grains. By the 1800’s most water mills had been replaced by steam engines. With the invention of the electric light, demand increased and water mills were used again.

Hydroelectric Power The use of mechanical energy of

running water to generate usable electricity is called hydroelectric power. Dams hold back millions of tons of water in reservoirs. Some of this water is drawn through pipes into the power plant where it flows through turbines. The rushing water turns the blades of the turbines and produces electricity.

Problems with Hydroelectric Power

The places where the large dams can be built is limited. Hydroelectric power plants can be harmful to the environment. Fish migration patterns may be altered. The reservoirs have also flooded surrounding lands. It can also lower oxygen levels in water.

Use of Hydroelectric Power

Only 2 percent of the dams in the United States produce electricity. According to the Department of Energy, by adding hydroelectric projects to those dams where it is financially and environmentally feasible, this country could increase its hydropower capacity by 17,000 MW.

Nuclear Energy The heat and light of the sun are

produced as a result of reactions taking place deep within the nuclei of atoms. Atoms are the basic building blocks of matter. The nucleus is the center of an atom made up of protons and neutrons. Nuclear energy is produced when the nucleus is split.

Nuclear Fission In 1939, nuclear fission was

discovered. Nuclear fission is the splitting of an atomic nucleus into two smaller nuclei, during which nuclear energy is released. The most common type of fission reaction is the splitting of a uranium-235 nucleus.

Uranium-235 To split a uranium-235 nucleus,

scientists must shoot a neutron into the nucleus. When it strikes a uranium-235 nucleus, the nucleus is split into two smaller nuclei. During this process, two or more neutrons are released from the uranium-235 nucleus. Energy is released as well.

Chain Reaction Each neutron released during a fission

reaction is capable of causing another fission reaction by splitting another uranium-235 nucleus. The neutrons released by each of these reactions can then split several more nuclei. This process in which the splitting of one nucleus causes the splitting of another is called a chain reaction.

Explosion If a nuclear chain reaction is

uncontrolled, the nuclear energy that is released will create a huge explosion. If the reaction is carefully controlled, the energy can be used.

Nuclear Power Plants The energy released during nuclear

fission is mostly in the form of hear energy. In a nuclear power plant, this heat energy is used to convert water into steam. The steam then passes through a turbine in an electric generator. The steam spins the blades of the turbine, which produces electricity.

Nuclear Reactors Fission reactions in a nuclear power

plant are produced and controlled in a nuclear reactor. The main parts of a nuclear reactor are the containment building and the reactor vessel, which contains the fuel rods and the control rods.

Reactor Vessel The reactor vessel is the central part of a

nuclear reactor. It is within the reactor vessel that nuclear fission takes place. To begin a fission reaction, nuclear fuel rods are placed in the reactor vessel. The most common nuclear fuel is uranium-235. When neutrons strike the fuel rods containing pellets of uranium-235, nuclear fission begins. It takes many rods.

Control Rods In order for a fission reaction to

produce useful energy, the overall speed of the reaction must be carefully controlled. To control the rate of the reaction, neutron-absorbing control rods, often made of cadmium, are placed between the fuel rods to slow down the reaction. If removed, the reaction speeds up.

Use of Nuclear Power There are now some 440 commercial

nuclear power reactors operating in 31 countries, They produce16% of the world's electricity, as base-load power, and their efficiency is increasing.

56 countries operate a total of 284 research reactors reactors and a further 220 reactors power ships and submarines.

Safety of Nuclear Power There is a possibility of nuclear

radiation leaking into the environment. There is the problem of how to dispose

of radioactive nuclear waste. There is the possibility of nuclear

meltdown resulting from overheating due to loss of cooling water.

There is the problem of security.

Nuclear Fusion Nuclear fusion is the combining of two

atomic nuclei to produce one larger nucleus, with the release of nuclear energy. Nuclear fusion produces far more energy per atom than nuclear fission. Nuclear fusion is the reaction that produces the energy given off by the stars.

Sun The sun is composed mainly of

hydrogen. Within the sun, enormous heat and pressure cause the nuclei of hydrogen atoms to combine or fuse into helium nuclei. During this fusion process, some of the mass of the hydrogen is converted into energy.

Power from Nuclear Fusion

To be able to generate useful energy from nuclear fusion, scientists must be able to produce controlled fusion reactions. There are problems involved in producing and sustaining the extremely high temperatures needed for fusion. If possible, it would inexpensive and less polluting than nuclear fission.

Alternative Energy Sources

Geothermal Tidal Wave Ocean Thermal Biomass Hydrogen

Geothermal Energy Geothermal energy is produced from

the heat energy within the Earth. The interior of the Earth is extremely

hot. Molten rock deep within the Earth has an average temperature of 1800°C. In some places, known as hot spots, the molten rock comes close to the surface.

Hot Spots Water near the Earth’s surface comes

into contact with these hot spots, the water is heated and bursts forth from the Earth in fountains of steam and boiling water known as geysers. Old Faithful, in Yellowstone National park in an example of a geyser. In some parts of the world steam form geysers is used to heat buildings.

Geothermal Wells Wells can be drilled into hot, dry rock.

When the water is pumped into these dry wells, the heat in the hot rock turns the water into steam. The steam is then pumped to the surface and used to generate electricity or heat homes. The largest geothermal development in the world is at the Geysers in CA.

Geothermal Use Geothermal energy is the third largest

source of renewable energy, behind hydropower and biomass. In 2003 it accounted for 7% of the electricity generated from renewable sources.

Tidal Energy In areas where the difference between

high tides and low tides is great, the movement of water can be used as a source of tidal energy. The difference between high and low tides must be more than 16 feet. 40 sites worldwide are suitable including some in the United States.

Tidal Power Plant In a tidal power plant, a low dam is

built across the entrance to a shallow bay. As the rising and falling tides cause water to flow into and out of the bay, the dam holds back the flow. The water then flows past turbines to generate electricity. Tidal power is now used in France, Canada and other countries. This power is limited.

Wave Technologies Surface waves and pressure variations

below the ocean’s surface can generate intermittent power. Submerged devices placed in deep water can generate electricity using the bobbing motion of the ocean’s waves. Wave energy systems have been installed in Norway, Japan, Scotland, Australia and Indonesia.

Ocean Thermal Energy The heat stored in the ocean can be used to

generate electricity. The warm water is used to vaporize a fluid. The expanding vapor drives a low pressure turbine attached to a generator that produces electricity. The vapor is then returned to liquid form by exposure to deep cold ocean water. The difference between surface and floor must be at least 35°.

Combustible Materials Any material that can be burned is

combustible. Combustible materials can be used in a variety of ways to produce energy. They can be burned to produce steam which can then be passed through a turbine to generate electricity. Combustible materials can also be burned to provide heat for homes and factories.

Biomass Any materials that come form living

things are known as biomass. Biomass can be burned directly as a fuel or converted into other types of fuels. According to a study by the USDA, biomass from forest and agricultural lands could supply up to 30% of the nation’s energy by 2030.

Direct Burning Biomass has been burned for cooking

heating purposes for thousands of years. The oldest and still most widely used combustible material is wood.

Other Biomass Sources In addition to wood,the other forms of

biomass are plants and animal wastes. Plants used as biomass fuels include corn husks, sugar cane, sunflowers and seaweed. In many areas of the world, wastes are dried and used as fuel. Some cities burn garbage.

Alcohol Production Another use of biomass is to produce

an alternative fuel to gasoline. Almost all cars in the United States are powered by gasoline. One alternative is gasohol, a mixture of gasoline and alcohol (ethanol).

Ethanol Ethanol is produced by the action of

yeast cells on various grains, such as corn, wheat and barley. The yeast cells convert the sugar in the grain into ethanol and carbon dioxide, a process known as fermentation. The use of gasohol was begun in Brazil, which now has large-scale fermentation plants that use sugar cane.

Problems with Gasohol Gasohol burns more slowly, coolly,

and completely, resulting in reduced emissions of some pollutants, but it also vaporizes more readily, potentially aggravating ozone pollution in warm weather. Ethanol-based gasohol is expensive and energy intensive to produce.

Hydrogen Power With the exception of sunlight,

hydrogen is the only truly unlimited energy source on Earth. Oceans, rivers and lakes contain hydrogen. Hydrogen gas can be burned in place of fossil fuels. The only exhaust from burning hydrogen gas is water.

Problem with Hydrogen Power

The problem with using the hydrogen in water is that it is bound to two oxygen atoms. The process of using electricity to break down water is called electrolysis. Electrolysis uses more energy in the form of electricity to produce hydrogen gas than can be obtained by burning hydrogen gas.

Hydrogen Cell Research Pollution-free hydrogen cell technology is

predicted to be the next wave in emissions-control after the hybrid electric motor, currently used in the automotive industry.

Research into hydrogen power has been pumped with funding in the US in particular.

In 2003, President George Bush announced an $1.7bn investment to turn the US into the world leaders of hydrogen-powered automobiles.