ENERGY SUPPLY

Energy supply is the total quantity of usable energy available to people. We use forms of energy to do work, to provide warmth and to move people and goods from place to place. Electrical energy operates vacuum cleaners, washing machines and other appliances. Heat energy cooks food on stoves and heats buildings. Mechanical energy turns the wheels of cars.

About 95 per cent of the world’s commercial energy comes from coal, oil and natural gas. Commercial energy is that produced by businesses and government. Coal, oil and natural gas are called fossil fuels because they developed from the fossilized remain of prehistoric plants and animals.

The earth has only a limited supply of fossil fuels. The amount of fossil fuel burned by people has nearly doubled every 20 years since 1900. Someday, the supply will run out. Scientists are seeking new sources of energy to replace shrinking fossil fuel reserves. Scientists are also actively searching for ways to limit the impact of energy production on the environment. They are increasingly aware that energy production causes environmental problems. The burning of fossil fuels produces carbon dioxide which warms up the earth and nuclear power produces radioactive waste.

Sources of energy

The chief sources of energy throughout the world are, in order of importance, fossil fuels, water power and nuclear energy. In addition, solar energy, wind power, tidal energy and geothermal power provide small amounts of energy. Energy sources in the experimental stage include magnetohydrodynamic (MHD) generators, fuel cells, nuclear fusion, solid wastes and hydrogen.

Fossil fuels include, in order of the amount used worldwide, petroleum, coal and natural gas. Bituminous sands and oil shale form important energy resources for the future.

Petroleum furnishes about 40 percent of the commercial energy used in the world. It provides most of the energy used for transportation and heats millions of homes as well.

Petroleum is easier to get out of the ground than coal is, and pipelines carry it cheaply over long distances. Like coal, oil contains impurities that cause air pollution. But refineries can remove many of these pollutants when they process the petroleum.

Coal provides about 28 per cent of all the commercial energy used in the world. The most important uses of coal include the production of electricity and of steel. Coal also provides heat and power for many other industries. In Europe and Asia, coal heats countless homes.

The mining, transportation and burning of coal all involves serious problems. Miners working deep in the earth face the danger of explosions and falling rock and of black lung disease, caused by breathing coal dust. Strip mining destroys trees and makes huge gashes in the landscape. After coal has been mined, it is expensive to haul. And when burned, it releases sulphur and other impurities that pollute the air and cause acid rain.

Chemists have developed various methods of turning coal into a gas or a liquid. Gasified coal can serve as a substitute for natural gas. Liquefied coal can be used to make artificial petrol. Both gasification and liquefaction convert “dirty” into a clean fuel that has a low sulphur content. Both processes also produce fuels that can flow through pipelines and replace natural fuels. But either type of conversation is expensive and requires huge quantity of coal.

Natural gas accounts for about 20 percent of the commercial energy used in the world. Millions of people use natural gas to heat their homes, cook their meals, and dry their laundry. Many industries use natural gas for heat and power.

Natural gas is the cleanest and most convenient fossil fuel. It can easily be transported through pipelines and it caused almost no air pollution.

Bituminous sands, also known as oil sands or tar sands, someday may become a major source of oil. But the process of removing the oil from these sands is more expensive than the normal production of petroleum.

Oil shale is a type of rock that can be processed to yield petroleum. But oil obtained from shale costs more than that pumped from the earth. In addition, oil-shale mining tears up large areas of the countryside and produces huge piles of waste rock.

Wood once served as the chief fuel. It still furnishes a small percentage of the energy used in the world. But wood’s importance as a source of energy will probably decrease in the future.

Water power furnishes about 7 percent of the world’s commercial energy. Water costs nothing and cannot be used up and it supplies energy without pollution. But most water power projects require a dam or other expensive structure. A water power plant, also called a hydroelectric plant, can operate only where water flows from a higher place to a lower one. In several mountainous countries, such as New Zealand and Switzerland, hydroelectric power plants contribute more than half of the total electricity production.

Nuclear energy provides about 5 percent of the commercial energy used in the world. It comes from fission, the splitting of the atoms of certain elements, especially uranium. Fission reactors (devices in which controlled atomic reactions take place) power several ships and generate electricity.

Eventually, physicists expect to control the power of fusion, the combining of atomic nuclei. Fusion produces the heat and light of the sun and stars – and the explosive force of the hydrogen bomb.

Nuclear fission creates huge amounts of energy from small amounts of fuel. Nuclear plants also produce electricity without the air pollution caused by burning.

But fission has several disadvantages as a source of energy. Experts predict that the supply of high-quality uranium will last only until the end of the country. Also, fission plants produce more waste heat than do plants that burn ordinary fuel. Unless nuclear plants have expensive cooling devices, their waste heat creates thermal (heat) pollution that may damage the environment. They also produce tons of radioactive wastes yearly. In addition, nuclear power plants present the danger of accidental discharges of radioactivity.

A breeder reactor could provide immerse quantities of energy. This special types of reactor produces more fuel than it uses to produce energy. Such surplus fissionable material can be used by other nuclear reactors. A breeder reactor would generate less unused heat than an ordinary reactor.

Nuclear fusion occurs only at very high temperatures. For this reason, such a reaction is also called a thermonuclear reactions. Some scientists believe controlled fusion reactions will be achieved by the year 2000. This accomplishment might solve the world’s energy problems for millions of years, if fusion proves to be an economical energy source.

A fusion reactor would use deuterium, a form of hydrogen for fuel. The oceans contain enough deuterium to provide all the energy people may need. In addition, fusion would create little danger of explosion or radiation. The problem of waste disposal would not arise because most of the products of fusion are not radioactive, unlike those of fission.

Solar energy is used throughout the world to perform various small jobs. For example, simple devices called flat-plate collectors heat buildings and water by absorbing the sun’s heat. Devices called solar cells or photovoltaic cells convert light into electricity.

Solar energy could provide a clean and almost unlimited supply of power. But solar energy is spread so  thinly that large-scale use of the sun’s power would require a huge  land area. In addition, darkness and bad weather interrupt the supply of sunlight.

Wind power turns windmills and propels sailing boats. Aeroplanes use the power of a high-altitude wind  called the jet stream. Wind itself costs nothing and creates no pollution. But wind power is commercially practical only in areas that have strong, steady winds.

Tidal energy can be used wherever there are high tides in a bay that can be closed by a dam. During high tide, the bay fills with water. During low tide, the level of the ocean drops below the level of water stored behind the dam. The stored water is then released. As the water falls, it drives turbines that generate electricity. The chief disadvantage of tidal power is that it can produce electricity only at certain times and for short periods. In addition, there are few suitable sites.

Geothermal power is generated wherever water comes in contact with hot rocks below the earth’s surface. The rocks give off heat that makes the water hot enough to turn into stream. Power companies can drill wells and pump the hot water of steam to the surface, where it can be used to generate energy. In areas where no underground water or steam exists naturally, engineers can pump water into the ground to be heated by hot rocks. The production of geothermal energy can occur only in areas where hot rocks lie near the earth’s surface. Iceland, Italy, Japan, the Philippines, New Zealand and the United States have developed geothermal power plants.

Chemical energy is released during chemical reactions. The most common use of such energy is to generate electrical power in batteries. Some chemical reactions are reversible. As a result, storage batteries such as those found in cars can be recharged.

Magnetohydrodynamic (MHD) generators convert fuel directly into electricity. An MHD generator burns coal or other fuel at high temperatures to produce a hot ionized (electrified) gas. The gas shoots through a duct in a magnetic field, where it produces an electric current that is drawn off by electrodes. After the gas has passed through the generator, it can drive a turbine to produce more electricity. MHD generators could provide an efficient power source, but many technical problems remain to be solved.

Fuel cells are battery like devices in which gas or liquid fuels combine chemically to generate electricity. Fuel cells in the U.S. Apollo spacecraft produced electricity from a reaction of hydrogen and oxygen. Fuel cells can produce twice as much electricity as ordinary generators can from a given amount of fuel. Nothing burns in fuel cells, so they cause little pollution and lose little energy as that heat. But they are expensive to make.

Solid Waste can also provide energy. Various cities throughout the world produce electric power by burning waste. Another process, called bioconversion, uses plant and animal wastes to produce such fuels as methanol, natural gas and oil.

Hydrogen could someday replace both gas and oil as a fuel easily, giving off huge amounts of heat and one harmless by-product water. Chilled to liquid form, hydrogen could flow through pipelines. It might serve as a lightweight, nonpolluting fuel for aircraft and cars. Hydrogen can be extracted from ocean water by running an electric current through the water. But this process, called electrolysis enormous quantities of electricity.

History

Early days. Human being learned to make fire about 1 ½ million years ago. Until then, their only sources of energy had been their own strength and direct sunlight. With the heat energy released by burning wood, people warned themselves, cooked food and hardened pottery. About 3200 B.C., the Egyptians invented sails and used the wind to propel their boats. Water wheels, developed in ancient times, harnessed water power.

Until the late 1700’s, wood ranked as the most important fuel. People used so much timber that it began to grow scarce and coal gradually took its place. The growing demand for coal gradually took its place. The growing demand for coal brought a search for better mining methods, including ways to keep mine shafts from flooding. In 1698, an English Inventor named Thomas Savery patented an improved pump to drain mines. Savery’s pump was powered by the first practical steam engine. People now had a device that could change heat into mechanical energy to do work.

The industrial revolution.

The steam engine became the chief source of power for industry and transportation during the Industrial Revolution. People’s use of energy increased tremendously during this period. People’s use of energy increased tremendously during this period, from the 1700’s to the mid-1800’s.  Power-driven machinery largely replaced hand labour and steamboats replaced sailing ships. New uses of energy  made  work easier and more productive and  increased production brought greater wealth. This prosperity helped bring about a growth in population and so there were more people to consume energy. At the same time, people could afford more energy-consuming conveniences.

During the 1800’s, inventors learned about many new sources of energy – and ways to use it. In 1831, two physicists – Michael Faraday of England and Joseph Hendry of the United States – independently discovered a way turn mechanical energy into electricity. They found that a moving magnet produced electric current in a coil of wire. Operating on this principle called electromagnetic induction, generators could produce electricity from the turning of a water wheel or a steam turbine.

In 1860, Jean Joseph Etienne Lenoir, a French inventor, built one of the first workable internal-combustion engines. These engines produced power from the explosion of a mixture of air and flammable vapours. Petrol proved to be the most convenient fuel because it easily turned into vapour. In 1885, Karl Benz, a German engineer, built one of the first petrol-driven cars came into use.

The 1990’s. Since 1900, the use of energy has almost double every 20 years. Causes of this growth include (1) the population increase, (2) the growth of the labour force, (3) increased wealth, (4) energy-using inventions, (5) products that take large amounts of energy  to be manufactured, and (6) nonfuel uses of fossil fuels.

In most industrialized countries, since World War II (1939-1945), the use of energy has increased much faster than the increase in population. The standard of living improved and people could afford to buy such energy-using conveniences as central heating and cars. At the same time, new appliances, including electric dishwashers and microwave ovens, consume power. People also used more of such materials as aluminum and plastic, which required huge amounts of energy to manufacture.

The growth in energy use declined in several industrialized countries during the early  1980’s. A rise in natural gas and petroleum prices caused people to adopt conservation measures to save energy. These conservation measures included buildings more fuel-efficient cars and insulating ildings to reduce heat loss. But a decrease in fuel prices in the mid-1980’s resulted in less interest in conservation and an increase in energy use.

 A person in a developing country uses only about a fifteenth as much energy as a person in one of the develop countries. Eropah, Japan and the United States consume about 70 percent of world’s energy. But they have about 20 percent of its people.

Developing countries can do little to limit their energy consumption without sacrificing important goals.

They need more factories, farm machinery and transportation facilities, all of which require energy to operate. Their people also want more central heating, electric lighting and other comforts that use energy. Several of these countries rely on world and charcoal for heating and cooking. The use of wood and charcoal causes widespread deforestation and other the land becomes unsuitable for agriculture because of desertification.  

The use of energy creates serious problems. They include (1) depletion of fuel reserves (2) environmental pollution, and (3) political and economic effects.

Depletion of fuel reserves. The people of the world have rapidly used up sources of energy that had accumulated for millions of years. The period of greatest fossil-fuel formation began about 360 million years ago. For about 40 million years huge quantities of lead trees and other plants were buried in the earth through natural processes. Time, heat and pressure slowly changed this buried plant material into coal. Petroleum and natural gas were both formed in much the same way from the remains of ocean people burn fuels thousands of times faster than they form.

The rapid growth of energy use threatens to exhaust the world’s supply. Petroleum may become the first fuel to give out – growing scarce in the early 2000’s. Natural gas is also being used up quickly. In the mid-1980’s, gas  experts predicted that the earth’s reserves would last only about 75years. When people have removed all the oil and natural gas from the earth, they will have used up the “easy energy” supplied by nature. After that, they will have to use such solid fuels as coal and oil shale. These substances are more difficult to remove from the earth. Coal, the most plentiful fossil fuel, will last more   than 200 years. Eventually, people will have to find different sources of energy altogether.

Environmental pollution. The production, transportation and use of fossil fuels all create environmental problems. Deep coal mines endanger workers and strip mining exposes large areas of land to erosion. The drilling of offshore oil fields and the shipment of petroleum by tankers sometimes produce oil spills that pollute the ocean, damage beaches and kill wildlife. Burying oil pipelines requires changes in the environment, such as the clearing of trees along the route. Underground coal mines can cave in and can release dangerous gases. Strip mining has exposed large areas of land to erosion. The burning of coal and oil pollutes the air with nitrogen oxides and sulphur dioxide. These substances can react with moisture in the air and fall to earth as acid rain polluting lakes and rivers. Motor-vehicle fuels rank as a leading source of air pollution.

Even the cleanest fossil fuel produces carbon dioxide when it burns. Carbon dioxide is a harmless gas. But a building-up of this gas in the atmosphere may cause a phenomenon called the greenhouse effect. Carbon dioxide, like glass in a greenhouse, allows  sunlight to warm the earth but prevents heat from escaping back into space. The greenhouse effect could permanently raise temperatures on the earth, partially melting the polar icecaps and causing floods.

All other sources of energy also case some environmental damage. Nuclear power plants create thermal pollution and radioactive wastes. Geothermal plants produce waste heat and sometimes offensive odours. Tidal energy plants change conditions along seacoasts and may disturb marine life. Any use of energy continues to grow, the heat released will alter the environment of many cities.

Political and economic effects. About two-thirds of the world’s oil reserves lie in the Middle East and North Africa. Many industrialized nations rely on oil from Arab countries to fuel their economy. Such countries as France, Germany, Great Britain and Japan import most of their petroleum from the Middle East.

The reliance by industrialized nations on Arab oil gives the Middle Eastern nations considerable power. for example, the Arab governments can exert severe political pressure with an oil embargo. In 1973, a number of Arab nations stopped or reduced oil shipments to many Western nations. The Arab governments imposed the embargoes in protest against Western support of Israel. Nations that have backed Israel in its conflicts with the Arab nations may become more friendly toward the Arabs – because of the question of Arab oil.

In addition, many nations that buy large amount of oil from Arab countries do not sell them anything in return. These oil-buying nations may develop a balance-of-payments deficit-that is, they import more goods, services, and money than they export. A large balance-of-payments deficit can weaken a nation’s economy.

Some people fear that if a nation’s use of energy stops growing a depression will result. They point out that fuel shortages during the mid-1970’s resulted in increased unemployment and decreased production. Other people believe industrialized nations waste so much energy that they could save large amounts of it without damaging their economic growth.

As fuels become scarce, their price goes up. Many people then call for price controls on these sources of energy. But many economists believe raising prices encourage energy producers to broaden their explorations and dig deeper for fuels. Low-grade deposits may become profitable to mine and scientists will investigate new sources of energy. Economists also say that higher fuel prices cause people to use energy more carefully.

Nevertheless, the increasing cost of energy can be a serious handicap to developing nations. If energy costs more, many of these countries cannot afford the energy they need to become more industrialized and so strengthen their economy.

Challenges

Challenges presented by the earth’s diminishing energy supply include (1) developing new sources of energy (2) improving the efficiency of power generation, and (3) energy conservation.

Developing new energy sources. Scientists have many problems to solve before new sources of energy become practical. Nuclear physicists have not yet produced a reliable fast breeder or controlled nuclear fusion. To turn solar energy into a practical power source, scientists must find better ways to gather, concentrate and store it. Fuel cells and solar cells have provided power for space programmes, but they cost too much for individuals to use. Hydrogen could replace fossil fuels if power companies could cheaply produce it.

Improving efficiency. Even if new sources of energy appear quickly, people would have to rely on ordinarily fuels for many years. During this period, engineers could make the shrinking fuel reserves last longer by designing more efficient power plants and engines. A car engine, for example actually uses only 20 percent of the energy available in petrol. The rest goes into wasted heat. Even the most efficiency power plants turn only 40 percent of their fuel into electricity. A new type of plant, the combined gas  and steam plant, may boost consumption efficiency to 60 percent. In an ordinary gas-turbine system, hot gas from burning fuel turns a turbine and then is thrown away. But in a combined plant, this gas drives a turbine and then makes steam to produce additional electricity. Most industrialized countries waste about half the fuel that they burn. Greater efficiency would not only save fuel but also would reduce thermal pollution.

Energy conservation. At the same time, conservation can do much to relieve the strain on the earth’s energy supply. Better insulation of buildings could save up to half the fuel used for heating and air conditioning. Waste heat produced by many industrial processes could be recovered and used for heating. More people could travel by bus and train, rather than by car. Those who must drive could buy smaller cars and form car pools. More families could use fluorescent lights, which produce three times more light per unit of electricity than incandescent lights do. Businesses and families could lower their thermostats in winter and raise them in summer and turn off unnecessary lights.  Such conservation actions could provide the time needed for research that might lead to new sources of energy.

Sources of energy

Fossil fuels

Water power

Nuclear energy

Wind power

Tidal energy

Geothermal power

Magnetohydrodynamic

Fuel cells

Solid wastes

Hydrogen

Problems

Depletion of fuel reserves

Environmental pollution

Political and economic effects

Challenges

Developing new energy sources

Improving efficiency

Energy conservation

Questions

What are fossil fuels?

What was the first source of energy used by human beings other than their own strength?

What regions of the world have more than 60 percent of the world’s oil reserves?

How much of the fuel burned in most industrialized countries is being wasted?

What substance ranked as the most important fuel throughout most of history?

What is the most abundant fossil fuel?

What steps can families take to conserve energy?

What is the greenhouse effect?