Non Renewable Resources of Energy

INTRODUCTION

Sufficient, reliable sources of energy are a necessity for industrialized nations. Energy is used for heating, cooking, transportation and manufacturing. Energy can be generally classified as non-renewable and renewable. Over 85% of the energy used in the world is from non-renewable supplies. Most developed nations are dependent on non-renewable energy sources such as fossil fuels (coal and oil) and nuclear power. These sources are called non-renewable because they cannot be renewed or regenerated quickly enough to keep pace with their use. Some sources of energy are renewable or potentially renewable. Examples of renewable energy sources are: solar, geothermal, hydroelectric, biomass, and wind. Renewable energy sources are more commonly by used in developing nations.

Industrialized societies depend on non-renewable energy sources. Fossil fuels are the most commonly used types of non-renewable energy. They were formed when incompletely decomposed plant and animal matter was buried in the earth's crust and converted into carbon-rich material that is useable as fuel. This process occurred over millions of years. The three main types of fossil fuels are coal, oil, and natural gas. Two other less-used sources of fossil fuels are oil shales and tar sands.

FOSSIL FUELS

Non-renewable fossil fuels (crude oil, natural gas, coal, oil shales and tar sands) currently supply Australia with more than 95 percent of our electrical energy needs. Non-renewable energy is energy produced by burning fossil fuels such as coal. They are non-renewable because there are finite resources of fossil fuels on the planet. If they are continually used, one day they will run out.

SOURCE OF FOSSIL FUELS

Just as plants do today, those living millions of years ago converted the sun's light energy into food (chemical) energy through the process of photosynthesis. That 'solar' energy was and is transferred down the food chain in animals. This energy provides living things with the energy to grow and live. When living organisms die the energy contained within them as chemical energy is trapped.

It is estimated that the total amount of energy gained from fossil fuels since the start of civilization is equivalent to the same amount of energy we receive every 30 days from the sun.

Fossil fuels are formed by the burying, and subsequent pressure and heating, of dead plant and animal matter or biomass (organic matter), over millions of years. This is how coal, oil and natural gas are formed. The trapped energy can be released and utilized when the fuels are burnt.

COAL

Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon and hydrocarbons. It is the most abundant fossil fuel produced in the United States.

Coal is a nonrenewable energy source because it takes millions of years to create. The energy in coal comes from the energy stored by plants that lived hundreds of millions of years ago, when the earth was partly covered with swampy forests. For millions of years, a layer of dead plants at the bottom of the swamps was covered by layers of water and dirt, trapping the energy of the dead plants. The heat and pressure from the top layers helped the plant remains turn into what we today call coal.

TYPES OF COAL

Coal is classified into four main types, or ranks (lignite, subbituminous, bituminous, anthracite), depending on the amounts and types of carbon it contains and on the amount of heat energy it can produce. The rank of a deposit of coal depends on the pressure and heat acting on the plant debris as it sank deeper and deeper over millions of years. For the most part, the higher ranks of coal contain more heat-producing energy.

Lignite is the lowest rank of coal with the lowest energy content. Lignite coal deposits tend to be relatively young coal deposits that were not subjected to extreme heat or pressure. Lignite is crumbly and has high moisture content. There are 20 lignite mines in the United States, producing about seven percent of U.S. coal. Most lignite is mined in Texas and North Dakota. Lignite is mainly burned at power plants to generate electricity.

Subbituminous coal has a higher heating value than lignite. Subbituminous coal typically contains 35-45 percent carbon, compared to 25-35 percent for lignite. Most subbituminous coal in the U.S. is at least 100 million years old. About 44 percent of the coal produced in the United States is subbituminous. Wyoming is the leading source of subbituminous coal.

Bituminous coal contains 45-86 percent carbon, and has two to three times the heating value of lignite. Bituminous coal was formed under high heat and pressure. Bituminous coal in the United States is between 100 to 300 million years old. It is the most abundant rank of coal found in the United States, accounting for about half of U.S. coal production. Bituminous coal is used to generate electricity and is an important fuel and raw material for the steel and iron industries. West Virginia, Kentucky, and Pennsylvania are the largest producers of bituminous coal.

Anthracite contains 86-97 percent carbon, and has a heating value slightly lower than bituminous coal. It is very rare in the United States, accounting for less than one-half of a percent of the coal mined in the U.S. All of the anthracite mines in the United States are located in northeastern Pennsylvania.

ADVANTAGES

The biggest advantage of coal is that it is far more abundant than oil and gas. There are about 200 years of coal left (but only 100 years if it was used to replace oil and gas). Neither does coal peak like oil although it does have the problem that, as it is used up, the remaining reserves will be harder to mine.

Like oil, large amounts of coal tends to be found within relatively few countries although, generally and fortunately, these are countries which have little oil or gas themselves. This will help to lessen the effects of resource wars (see chart below).

The six countries with the largest coal reserves are the USA (27.1% of the world), Russia (17.3%), China (12.6%), India (10.2%), Australia (8.6%), and South Africa (5.4%).

Coal can also be converted into oil at a rate of about 3 units of coal to 1 unit of oil.

DISADVANTAGES

Coal is one of the dirtiest of fuels. Burning it produces enormous amounts of ash, and flue gasses containing pollutants such as sulphur dioxide, nitrogen oxides, sulphuric acids and arsenic. It also produces almost twice as much carbon dioxide as gas (for the same heat).

These pollutants can be cleaned out of the system before they are released although this obviously adds an extra expense to the cost. There is also the danger that poorer or less conscientious countries will skimp on these controls.

There is also the environmental, human and energy costs of extracting the coal: subsidence, spoil heaps, miners' death and illnesses. It should be noted that something like 50% of the energy used to mine coal comes from oil.

FUTURE OF COAL

Concerns about global warming will likely restrict expansion of coal until the oil decline becomes severe. Then it is likely that many countries will turn to coal in desperation, particularly those who cannot get hold of oil/gas or who have large reserves of coal themselves. Countries like China and India, with little oil of their own, are most likely to step up coal usage to feed their increasing economies and populations. There is a great danger that they may put the environment in second place.

The increase in global warming though may be tempered by the fall of world population and decline of technological society. The increase in pollution, especially locally, may be the greatest problem.

OIL

Crude oil or liquid petroleum, is a fossil fuel that is refined into many different energy products (e.g., gasoline, diesel fuel, jet fuel, heating oil). Oil forms underground in rock such as shale, which is rich in organic materials. After the oil forms, it migrates upward into porous reservoir rock such as sandstone or limestone, where it can become trapped by an overlying impermeable cap rock. Wells are drilled into these oil reservoirs to remove the gas and oil. Over 70 percent of oil fields are found near tectonic plate boundaries, because the conditions there are conducive to oil formation.

Oil recovery can involve more than one stage. The primary stage involves pumping oil from reservoirs under the normal reservoir pressure. About 25 percent of the oil in a reservoir can be removed during this stage. The secondary recovery stage involves injecting hot water into the reservoir around the well. This water forces the remaining oil toward the area of the well from which it can be recovered. Sometimes a tertiary method of recovery is used in order to remove as much oil as possible. This involves pumping steam, carbon dioxide gas or nitrogen gas into the reservoir to force the remaining oil toward the well. Tertiary recovery is very expensive and can cost up to half of the value of oil removed. Carbon dioxide used in this method remains sequestered in the deep reservoir, thus mitigating its potential greenhouse effect on the atmosphere. The refining process required to convert crude oil into useable hydrocarbon compounds involves boiling the crude and separating the gases in a process known as fractional distillation. Besides its use as a source of energy, oil also provides base material for plastics, provides asphalt for roads and is a source of industrial chemicals.

Over 50 percent of the world's oil is found in the Middle East; sizeable additional reserves occur in North America. Most known oil reserves are already being exploited, and oil is being used at a rate that exceeds the rate of discovery of new sources. If the consumption rate continues to increase and no significant new sources are found, oil supplies may be exhausted in another 30 years or so.

Despite its limited supply, oil is a relatively inexpensive fuel source. It is a preferred fuel source over coal. An equivalent amount of oil produces more kilowatts of energy than coal. It also burns cleaner, producing about 50 percent less sulfur dioxide.

Oil, however, does cause environmental problems. The burning of oil releases atmospheric pollutants such as sulfur dioxide, nitrogen oxides, carbon dioxide and carbon monoxide. These gases are smog-precursors that pollute the air and greenhouse gases that contribute to global warming. Another environmental issue associated with the use of oil is the impact of oil drilling. Substantial oil reserves lie under the ocean. Oil spill accidents involving drilling platforms kill marine organisms and birds. Some reserves such as those in northern Alaska occur in wilderness areas.

ADVANTAGES

Oil is one of the most abundant energy resources

Liquid form of oil makes it easy to transport and use

Oil has high heating value

Relatively inexpensive

No new technology needed to use

DISADVANTAGES

Oil burning leads to carbon emissions

Finite resources (some disagree)

Oil recovery processes not efficient enough—technology needs to be developed to provide better yields

Oil drilling endangers the environment and ecosystem

Oil transportation (by ship) can lead to spills, causing environmental and ecological damage (major oil spill near Spain in late Fall 2002).

NATURAL GAS

Natural gas production is often a by-product of oil recovery, as the two commonly share underground reservoirs. Natural gas is a mixture of gases, the most common being methane (CH4). It also contains some ethane (C2H5), propane (C3H8), and butane (C4H10). Natural gas is usually not contaminated with sulfur and is therefore the cleanest burning fossil fuel. After recovery, propane and butane are removed from the natural gas and made into liquefied petroleum gas (LPG). LPG is shipped in special pressurized tanks as a fuel source for areas not directly served by natural gas pipelines (e.g., rural communities). The remaining natural gas is further refined to remove impurities and water vapor, and then transported in pressurized pipelines. The United States has over 300,000 miles of natural gas pipelines. Natural gas is highly flammable and is odorless. The characteristic smell associated with natural gas is actually that of minute quantities of a smelly sulfur compound (ethyl mercaptan) which is added during refining to warn consumers of gas leaks.

The use of natural gas is growing rapidly. Besides being a clean burning fuel source, natural gas is easy and inexpensive to transport once pipelines are in place. In developed countries, natural gas is used primarily for heating, cooking, and powering vehicles. It is also used in a process for making ammonia fertilizer. The current estimate of natural gas reserves is about 100 million metric tons. At current usage levels, this supply will last an estimated 100 years. Most of the world's natural gas reserves are found in Eastern Europe and the Middle East.

ADVANTAGES

Natural gas' largest advantage is it chemical composition; it is basically methane (CH4). Because methane only has one carbon in its composition, it produces very low carbon emissions. With the other hydrocarbons only have the number of carbon molecules ranging from 1-4, when they burn; the same holds true. In addition, the blue flame that results from burning the flame is from the molecules completing a perfect combustion, because of their chemical structure.

Natural gas' second largest advantage is conveniency. The gas is pumped directly into the consumer home with a network that is as efficient as delivering electricity. This network cannot be easily damaged by weather or conditions. Secondly, natural gas is in abundance in the US, thus the need to import from foreign countries is minimal. Because of this abundance, natural gas is cheaper than oil to burn.

DISADVANTAGES

Because of its composition, natural gas is readily combustible and thus explosions are not unheard of . As a precaution a substance, like ethyl mercaptan, is added to the gas to give it an odor when it leaks. However, when gas leaks and does build up in buildings or other structures, the structure can suffer light to moderate damage if ignited. Natural gas can be toxic, if the fields in which it is extracted are not treated. Lastly, the extraction of the gas can be harmful to the environment, if subsidence is created when it is extracted.

NUCLEAR FUEL

Nuclear fuel makes use of the radioactivity of some elements. The nucleus in the atom may spontaneously break down to release energy and produce fast-moving particles, atoms of other elements. The fast-moving particles that are ejected can also strike other atoms, causing them to break down.

Placing the atoms close together in a fuel rod means that atoms are more likely to be struck by these particles, and so produce more nuclear reactions. As the reactions proceed heat is produced. The task of a nuclear reactor is to control the reaction so that a steady flow of heat is produced.

Nuclear fuel is made from naturally occurring radioactive materials, such as uranium, found in rocks. These materials are extracted and concentrated. They are formed into 'fuel rods'.
When placed close together, the fuel rods set off nuclear reactions that generate heat. This heat is used to turn water into steam and generate electricity. This fuel is classed as non-renewable, although concentrating the fuel further can recycle some of the 'spent fuel'.

There are deposits of the raw material uranium in Africa, Russia and North America.

ADVANTAGES

Nuclear fuel does not produce greenhouse gases, so will not contribute to global warming. There is a relatively long-lasting supply of raw material.

DISADVANTAGES

The waste remains radioactive for a long time (100+ years). If the reaction is not contained and controlled well, then the nuclear reduction could go out of control, as at Chernobyl in 1986. Radioactive material could then escape into the environment.

ENVIRONMENTAL EFFECTS OF FOSSIL FUELS

If fossil fuels are continually used and CO2 emissions are not heavily reduced the environment is going to suffer tremendously. Scientists have predicted that if the greenhouse gases remain the same, three main outcomes while occur. The temperatures will rise. They are expected to rise by 1.0 – 3.5°C by the year 2100. This may not seem much, but the historic Great Ice Age, which covered the earth with ice over 2 km thick, was caused by only a change of a few degrees. The sea levels will rise due to global warming. And finally, the climate will change. There will be changes in rainfall, storms, wind, frost and snow may occur. These could vary between regions, with some areas expecting to receive more or less rain than others. These weather conditions will lead to many changes in agriculture, forestry and marine resources.

The chemicals released from oil, coal and natural gas when burnt are carbon dioxide, sulfur dioxide, nitrogen oxides and other air pollutants. All of these chemicals are harmful to the environment when released into the atmosphere. All three of the fossil fuels contribute to the global warming although coal is known more for contributing to acid rain.

CONCLUSION


Non-renewable energy sources may have originally been wonderful energy sources. It can now be seen that although they are able to produce energy that is needed they are also significantly harming the environment in irreversible fashions. In this day and age there are many new and renewable energy sources that can be used instead of the original fossil fuels that damage the environment.

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