Nonrenewable Energy Resources Nonrenewable energy accounts for most

Nonrenewable Energy Resources

Nonrenewable energy accounts for most of our energy use.

Nonrenewable Energy Nonrenewable energy resources include: Fossil fuels (coal/peat, oil, natural gas) derived from biological materials Nuclear fuels (radioactive)

Energy Use Commercial energy sources: are bought and sold; e. g. , coal, oil, and natural gas. Subsistence energy sources: gathered by individuals for their own use, e. g. , wood, charcoal, and animal waste.

As suggested by the Second Law of Thermodynamics, there will always be losses incurred when energy is extracted or used. Energy is always needed to obtain additional energy.

Inefficiencies in Energy Extraction and Use

About 30% of energy use in the United States is for transportation. Public transportation is more efficient, but often less convenient.

Fuel efficient vehicles are widely available. But many drivers continue to choose vehicles with low fuel efficiency.

Overall Fuel Efficiency of U. S. Automobiles

Electricity is a convenient form of energy.

About 40% of energy used in the United States is to generate electricity But only 13% of that 40% is available, due to conversion losses.

Electricity Generation

Electricity Generation Burning coal transfers energy to water, creating steam. The kinetic energy of the steam is transferred to the blades of the turbine, a large device that resembles a fan.

Electricity Generation Energy in the steam rotates the turbine, and the central shaft of the turbine turns the generator. This mechanical motion generates energy. Electricity is transmitted into the electrical grid for distribution.

Energy Efficiency Most coal-burning power plants are about 35% efficient. Power plants using other fossil fuels can be more efficient. Combined cycle natural gas–fired plants can achieve 60% efficiency.

Cogeneration: using a fuel to generate electricity and heat. Examples: If steam is used for industrial purposes or to heat buildings, it is diverted to turn a turbine first. This increases the efficiency to as high as 90%.

Fossil fuels provide most of the world’s energy.

Fossil fuels provide most of the energy used in both developed and developing countries. Most coal, oil, and natural gas was formed from the biomass of ancient organisms that died 50– 350 million years ago.

Coal: solid fuel formed primarily from the remains of trees, ferns, and other plant materials that were preserved 280 360 million years ago. Four types of coal exist, and are ranked from lesser to greater age, exposure to pressure, and energy content.

Coal These four types are: Lignite Sub-bituminous Bituminous Anthracite Largest coal reserves are in the United States, Russia, China, and India.

Coal

Advantages and Disadvantages of Coal Advantages Disadvantages Energy-dense Contains impurities Plentiful Release impurities into air when burned Easy to exploit by surface mining Trace metals like mercury, lead, and arsenic are found in coal Technological demands are small Combustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere. Economic costs are low Ash is left behind Easy to handle and transport Carbon is released into the atmosphere, which contributes to climate change Needs little refining

Petroleum: a mixture of hydrocarbons, water, and sulfur that occurs in underground deposits. Oil and gasoline are energy-dense and an ideal fuel for mobile combustion, such as in vehicles.

Petroleum Formed from the remains of ocean -dwelling phytoplankton that died 50 150 million years ago. Countries with the most petroleum are Saudi Arabia, Russia, the United States, Iran, China, Canada, and Mexico.

Petroleum

Advantages and Disadvantages of Petroleum Advantages Disadvantage s Convenient to transport and use Releases carbon dioxide into atmosphere Relatively energy-dense Possibility of leaks when extracted and transported Cleaner-burning than coal Releases sulfur, mercury, lead, and arsenic into the

Natural Gas Natural gas: exists as a component of petroleum in the ground, and also as separate gaseous deposits. Contains 80% 95% methane, and 5% 20% percent ethane, propane, and butane.

Advantages and Disadvantages of Natural Gas Advantages Disadvantag es Contains fewer When unburned, impurities and methane escapes into therefore emits almost the atmosphere no sulfur dioxide or particulates Emits only 60% as much carbon dioxide as coal Exploration of natural gas has the potential of contaminating

Other Fossil Fuels Oil sands: slow-flowing, viscous deposits of bitumen mixed with sand, water, and clay. Bitumen (tar or pitch): a degraded type of petroleum that forms when a petroleum migrates close to the surface. As the surface bacteria metabolize some of the light hydrocarbons and others evaporate. Bitumen won’t flow and must be mined.

Fossil fuels are a finite resource.

Per capita energy use has leveled off in the United States. But because of increasing population and more energydemanding devices, energy use continues to intensify.

The Hubbert Curve The Hubbert curve shows the point at which world oil production would reach a maximum and the point where we will run out of oil.

The Hubbert Curve The Hubbert curve suggests that larger or smaller reserves of oil will not substantially change the date by which petroleum reserves are depleted.

The Future of Fossil Fuel Use If current global use continues, we will run out of conventional oil in less than 40 years. Coal supplies will last for at least 200 years, and probably much longer.

Nuclear energy is getting a second look.

Nuclear Energy Fission: a nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts.

Nuclear Reactor

Nuclear Reactors Nuclear power plants work by using heat from nuclear fission to heat water. This water produces the steam to turn the turbine, which turns a generator.

Nuclear Reactors Fuel rods: the cylindrical tubes that house the radioactive nuclear fuel used in a nuclear power plant. Control rods: cylindrical devices that can be inserted between the fuel rods to absorb excess neutrons, to slow or stop the fission reaction.

Nuclear Reactors A nuclear power plant uses radioactivity to heat the water. Othermal power plants (coal, natural gas) use other sources of heat. Otherwise, electricity is generated in the same manner using a turbine.

Advantages and Disadvantages of Nuclear Energy Advantages Disadvantag es No air pollution is produced Possibility of accidents Countries can limit their need for imported oil Disposal of the radioactive waste

Radioactive Waste Radioactive waste: when the nuclear fuel decays it becomes waste. It can no longer produce enough heat to be used in a power plant. But it continues to emit hazardous levels of radioactivity.

Radioactive Waste Radioactive waste must be stored in special, highly secure locations because of the danger to living organisms. Many forms of this waste will remain hazardous for thousands of years. No permanent, ideal solution to this disposal problem has yet been developed.

Radioactive Waste High-level radioactive waste: comes from the fuel rods. Low-level radioactive waste: the protective clothing, tools, rags, and other items used in routine nuclear plant maintenance. Additional wastes come from industry and hospitals.

Fusion Nuclear fusion: the reaction powering the Sun and other stars. This occurs when lighter nuclei are forced together to produce heavier nuclei and heat is released.

Fusion is a promising, unlimited source of energy for the future. So far scientists have had difficulty containing the heat that is produced.

The Future of Nonrenewable Energy Fossil fuels are a finite resource. Oil production will decline in the next few decades. The transition away from oil will have important environmental consequences.

Review Questions What is a nonrenewable energy source? Name three. Define fossil fuels. What is the difference between commercial and subsistence energy sources?

Review Questions What percentage of the total energy used is employed in transportation in the United States? Is any form of energy conversion 100% efficient? Why not? How much of the energy used in the United States is used to generate electricity?

Review Questions What percentage of that energy is actually available for end uses as electricity? How is a turbine turned to drive a generator in a power plant? What is the electrical grid?

Review Questions What is the source of most of the world’s energy? How is coal formed? Name two forms of coal. What is petroleum? What are some advantages and disadvantages of petroleum?

Review Questions What are some advantages to using natural gas as a source of energy? In the United States, has per capita energy use been increasing, declining, or has it leveled off? What is the Hubbert Curve?

Review Questions When will we likely run out of conventional oil supplies? How long will coal supplies likely last? Do current nuclear reactors run by fission or fusion reactions? What are some drawbacks to nuclear power?

Review Questions How do fuel rods differ from control rods? How does a nuclear power plant differ from an ordinary thermal power plant using coal? What are the two types of nuclear waste?