8.03 Renewable and Nonrenewable Resources

Biofuel

Biofuel, or biomass, includes wood, garbage, animal dung, and agricultural waste, such as corncobs and wheat straw. The combustion of wood and waste can replace fossil fuels to produce steam to turn the turbines in conventional power plants. Biofuel currently accounts for about 1 percent of the electricity generated in the United States. Burning biofuel makes use of garbage and agricultural waste while reducing our dependence on fossil fuels. Unfortunately, the combustion of biomass still produces pollutants and carbon dioxide like the burning of fossil fuels. There are other possible uses of biofuel for energy production. When animal and plant waste is broken down by bacteria, it produces a mixture of methane and carbon dioxide known as biogas. The methane gas can be used for heating, cooking, and refrigeration needs of small communities. The fermentation of biomass produces ethanol, which can be burned to produce energy. Ethanol can be added to gasoline to reduce our reliance on petroleum. Biofuels are renewable and readily available. However, to have enough fuel to replace the need for nonrenewable resources, a large amount of land would be needed to grow the agricultural materials.

Coal

Did you know that almost 1/2 of the electricity generated in the United States comes from burning coal? Coal is a solid form of carbon that is mined from the ground. It is a non-renewable resource because it takes a very long time to be formed in the ground. With coal being used to produce almost 1/2 of the electricity used in the United States, its diminishing supply is of great concern. It is still estimated that the world's supply of coal will outlast other fossil fuels such as oil and natural gas. In addition to its limited supply, there are other concerns surrounding the use of coal to produce electricity. When coal is burned as fuel, it gives off carbon dioxide, the main greenhouse gas that is linked with global warming. Burning coal also produces emissions, such as sulfur, nitrogen oxide, and mercury, which can pollute the air and water and contribute to acid rain. There are also safety and environmental concerns with the mining of coal, and the transport of coal requires motor vehicles, trains, or boats instead of the pipelines that can be used for oil and natural gas.

Why Do We Need to Conserve Energy?

Energy exists in many different forms, and some of those forms are more useful to us than others. Our cities and homes run on electricity as the main energy source, while we often use stored chemical energy, like in petroleum, to power our cars, planes, and trains. Most of our daily comforts are powered by energy conversions from nonrenewable and renewable resources. Some of those resources have a limited supply or give off large amounts of pollution, which is why we are encouraged to do what we can to cut down on our energy use.

Geothermal

Geothermal power comes from heat energy buried beneath Earth's surface. In some areas of the country, enough heat rises close to Earth's surface to heat underground water into steam, which can be tapped for use in industry, agriculturally, and at steam-turbine plants. This energy source currently generates less than 1 percent of the electricity in the United States. Geothermal facilities are very expensive to build and can be built only in areas with the correct geology. These power plants operate virtually emission- and pollution-free, if constructed and operated correctly, and they do not require fuel or waste to be shipped to or from the facility. Geothermal energy requires a lot less land than any other major power generation technology because it occupies the same amount of space as a gas power plant but without the miles of buried pipelines.

Hydropower

Hydropower is a process that uses flowing water to turn a turbine connected to a generator. Hydropower can be produced when water falls through openings in a dam, like in the Hoover Dam, or when a river current applies pressure to turbine blades installed within the river itself. Although the initial construction and setup is expensive, the cost of electricity production is low once the equipment is installed. Hydropower currently provides more power in the U.S. than other renewable resources, but it still trails behind fossil fuels and nuclear power. This type of electricity production does not produce any pollution or harmful chemicals, but there are other environmental concerns surrounding the use of hydropower. Large hydropower dams flood a lot of land, displacing wildlife and people. There are also concerns that the turbines kill fish, alter the natural flow of rivers, and interfere with seasonal fish migration.

Oil/Petroleum

Liquid fuel from crude oil is the world's largest energy source. A large part of this consumption is as automobile fuel, but it is also consumed for electricity production, fertilizer, industrial uses, and heating fuel. Petroleum, refined from crude oil, can also be burned to heat water into steam to turn a turbine in a power plant. The burning of petroleum, like other fossil fuels, produced carbon dioxide that is linked to global warming. Along with the pollution that its combustion produces, our dependence on oil is a concern for many because of its diminishing supply (some estimate that we may run out in as little as 50-70 years), the risk of pollution from leaking pipelines or tanker spills, and its uneven distribution around the world.

Natural Gas

Natural gas can be burned, producing hot gases that turn turbines to generate electricity. Gas turbines are commonly used when electricity usage is in high demand. Natural gas is the 2nd most common energy source in the U.S. power plants after coal. Natural gas can also be used in individual buildings for heat and cooking. The burning of natural gas can be harmful to the environment because it produces carbon dioxide, which is linked with global warming. It can also produce other emissions that can pollute the air and water, but it does not contribute to acid rain like coal and oil. Like oil, natural gas can be transported by pipeline or tankers, which is convenient but can lead to additional pollution and health risks when there are leaks or spills. Natural gas also has a very limited life span, with a diminishing supply that may run out in as little as 30-70 years.

Nonrenewable Resources

Nonrenewable resources are natural resources that are used at a faster rate than they can be replaced. This is a concern because as the populations around the world continue to increase, the reserves of nonrenewable resources are decreasing. Today, we get most of our energy from nonrenewable energy sources, including the fossil fuels oil, natural gas, and coal. They are called fossil fuels because they were formed by the heat from Earth's core and pressure from rock and soil on the remains, or fossils, of dead plants and animals during the cataclysmic events surrounding the Genesis flood and over long periods of time. When fossil fuels are burned, they produce pollutants that affect the air, water, and climate. Most of the electricity in the United States is produced in steam turbines powered by coal, nuclear power, or natural gas. When the fossil fuel is burned, the resulting heat is used to boil water and produce large amounts of steam. A turbine converts the kinetic energy of the moving gas particles in steam to the mechanical energy of the turning turbine. The rotating turbine is connected to a generator, converting mechanical energy to electrical energy.

Nuclear Power

Nuclear power is another method in which steam is produced to turn a turbine, converting mechanical energy into electrical energy. Nuclear power does not heat the steam through burning or combustion, like the burning of fossil fuels, but through the release of heat during the nuclear fission of radioactive uranium. When atoms of uranium are hit by neutrons they split into smaller atoms, releasing heat, radiation, and more neutrons that can split other uranium atoms. This chain reaction converts nuclear energy contained in the atoms into heat energy, which heats water into steam that turns the turbines of the power plant. Compared to electricity generated by burning fossil fuels, nuclear energy is clean. Nuclear power plants produce no air pollution or carbon dioxide. However, the radiation and radioactive wastes that are produced by the reactions are an environmental concern. There is also concern about the safety of nuclear power plants, because the powerful nuclear reactions can be dangerous if not monitored and contained properly. Some countries use more nuclear power than others, but none has developed an ideal way to dispose of radioactive wastes.

Renewable Resources

Renewable resources are natural resources that can be replaced at the same rate or even faster than they are used. Energy from the sun, water, and wind are examples of renewable resources. There is also research on using renewable organic matter, like garbage and animal waste, as a fuel. As the demand for energy increases and the amount of available fossil fuels decreases, finding alternative ways to make electricity and fuels becomes even more important. Renewable resources provide less than 10% of the world's energy, but the number is growing every year. More than half of the energy from renewable resources goes to producing electricity. The next largest use is the production of heat and steam for industrial purposes. Renewable fuels, such as ethanol, are also used for transportation and to provide heat for homes and businesses. Renewable energy sources play a growing role in the supply of energy. When renewable energy sources are used, the demand for fossil fuels is reduced. Unlike fossil fuels, most renewable sources of energy do not directly emit greenhouse gases, so they are considered safer and better for the environment. Unfortunately, many of these resources can be expensive to use, have limited locations or availability, or cannot supply enough energy to replace our need for nonrenewable resources at this time. The use of renewable resources has grown more quickly in recent years due to higher prices for oil and natural gas, concern over environmental effects and dwindling supplies of fossil fuels, and a number of government incentives. However, more advances must be made if we are going to limit our dependence on fossil fuels.

Solar Power

Solar power converts energy from the sun to electrical energy. The processes used to produce electricity from the sun's energy have been around for years, but they have been significantly more expensive than using conventional fossil fuels. Only a small amount of the electricity in the world is currently produced by solar power. With technological advances, solar power may become a more affordable alternative to fossil fuels in the future. You may have seen photovoltaic cells in your calculator, or even on the roof of a building. These cells are often made from semiconductors, like silicon or germanium, and when sunlight falls on these cells it produces a flow of electrons, known as the photoelectric effect, which can be harnessed as electricity. These photovoltaic cells work well when they get direct exposure to sunlight, but they have low efficiency (10 percent to 20 percent), are expensive, and require a lot of surface area to produce significant amounts of electricity. To use solar power to produce enough electricity to power more than one building, a much larger setup would be required. Such a setup includes a large plot of land filled with mirrors that are controlled by a computer that tracks the position of the sun. These mirrors are used to focus the sun's rays, which are used to heat up a sample of liquid sodium or oil. The heated liquid is pumped to a heat exchanger where a sample of water is boiled to produce steam. Such a setup is pollutant free and has a limitless energy supply, but there are only certain places where there is space and cloudless skies to make a solar power plant worthwhile and useful. Also, the equipment must be able to withstand extreme temperatures, and must be maintained and cleaned regularly. Currently, one of the biggest solar power plants is found in the Mojave Desert in California, where there was enough land and sunlight to make the cost of construction worthwhile.

Wind Power

Wind power converts the kinetic energy of moving wind into electricity by the mechanical turning of wind turbines. Wind power only supplies a small amount of the current power used in the world, but it is a rapidly growing source of electricity. One of the main disadvantages related to wind power is that the wind turbines require a lot of space, and only certain areas of the world supply enough wind to make the cost of the wind turbines worthwhile. The production of electrical power from wind turbines can be unreliable due to changes in local weather patterns, temperature, and time of year. Also, the equipment is very expensive to build and maintain. Many communities are not as interested in this type of energy because of the negative effects the large wind turbines have on the aesthetics, or view, of the surrounding area.

nonrenewable resources:

natural resources that are used at a faster rate than they can be replaced

renewable resources:

natural resources that can be replaced at the same rate or even faster than they are used