Nonrenewable Energy Resources Chapter 12 Nonrenewable Energy Resources

Nonrenewable Energy Nonrenewable energy resources- fossil fuels (coal, oil, natural gas) and nuclear fuels. Figure 12.1 shows annual energy consumption worldwide. The graph depicts that nonrenewable fossil fuels make up 81% of the annual consumption.

Worldwide patterns Figure 12.2 shows the global variation in total annual energy consumption and per capita energy consumption for several countries. The 10 countries shown are among the largest and the smallest energy users in the world.

Energy Use Commercial energy sources- those that are bought and sold, such as coal, oil and natural gas. Subsistence energy sources- those gathered by individuals for their own use such as wood, charcoal and animal waste.

Patterns of Energy Use in the United States Figure 12.3 shows energy consumption in the U.S. since 1850. The graphs depicts wood and then coal used to dominate our energy supply.

Energy Types and Quality Figure 12.4 (a) shows energy flowchart of the U.S. The types of fuels are shown on the left, and their end uses are shown on the right.

Energy Types and Quality Figure 12.5 outlines the process of energy use from extraction of a resource to electricity generation and disposal of waste products from the power point. This diagram uses energy generation from coal as an example and shows how energy is lost in each stage of the process.

Efficiency & Transportation Nearly 30% of energy use in the United States is for transportation, This is an area in which efficiency is particularly important. Transportation is achieved primarily through the use of vehicles fueled by petroleum products, such as gasoline and diesel.

Efficiency & Transportation Table 12.1 shows the efficiencies of different modes of transportation. Train and motorcycle are the most energy-efficient modes of transportation. Transportation efficiency calculations do not take into account convenience, comfort, or style.

Efficiency & Transportation Figure 12.6 shows the overall fuel efficiency of U.S. automobiles. As more buyers moved from cars to light trucks, SUVs, and minivans, the fuel economy of total U.S. fleet declined.

Electricity Generation Steps for using Coal to produce electricity: The burning fuel from coal transfers energy to water, which becomes steam. The kinetic energy contained within the steam is transferred to the blades of a turbine, a large device that resembles a fan. As the energy in the steam turns the turbine, the shaft in the center of the turbine turns the generator. This mechanical motion generates electricity.

Electricity Generation Figure 12.7 shows a diagram of a coal-fired electricity generation plant. Energy from coal combustion converts water into steam, which turns a turbine. The turbine turns, a generator, which produces electricity.

Energy Efficiency Most coal burning power plants are about 35% efficient. Figure 12.8 shows fuels used for electricity generation in the U.S. Combined cycle technology uses natural gas-fired power plant, which has two turbines and generators. Natural gas is combusted, and the combustion products turn a gas turbine. The waste heat is also collected and boils water to make steam.

Cogeneration Cogeneration- using a fuel to generate electricity and to produce heat. Example- If steam is used for industrial purposes or to heat buildings it is diverted to turn a turbine first. This improves the efficiency to as high as 90%.

Coal Coal- a 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 ranked from lesser to greater age, exposure to pressure, and energy content. lignite, sub-bituminous, bituminous, and anthracite. The largest coal reserves are in the United States, Russia, China, and India.

Coal Figure 12.9 The coal formation process. Peat is the raw material from which coal is formed. Over time and under increasing pressure, various types of coal are formed.

Advantages and Disadvantages of Coal Energy-dense Contains impurities (Sulfur) Plentiful, coal reserves will last a long time. Release impurities into air when burned (leads to acid deposition) Easy to exploit by surface mining Trace metals like mercury, lead, and arsenic are found in coal Technological demands are small, coal needs little refining. Combustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere. Economic costs are low Ash is left behind, leads to possible runoff into local stream and rivers. Easy to handle and transport by train. Carbon is released into the atmosphere which contributes to climate change

Petroleum Petroleum- a mixture of hydrocarbons, water, and sulfur that occurs in underground deposits. The fluid nature of oil and gasoline make this ideal for mobile combustion, such as vehicles for transportation. 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 Liquid petroleum that is removed from the ground is known as crude oil. Figure 12.11 shows how petroleum accumulates underground and how it migrates to the highest point in a formation of porous rock. Such accumulations of petroleum can be removed by drilling a well.

Advantages and Disadvantages of Petroleum Convenient to transport and use through refining process. Releases carbon dioxide into atmosphere Relatively energy-dense Possibility of leaks when extracted and transported, Exxon Valdez and BP Deepwater Horizon Cleaner-burning than coal 85% of the oil entering marine waterways cam from runoff from land and rivers, airplanes, and small boats. Oil is used in my other applications such as plastics Releases sulfur, mercury, lead, and arsenic into the atmosphere when burned

Natural Gas Natural gas- exists as a component of petroleum in the ground as well as in gaseous deposits separate from petroleum. Contains 80 to 95 percent methane and 5 to 20 percent ethane, propane, and butane. Two largest uses of natural gas in the United States are electricity generation and industrial processes. Natural gas is also used to manufacture nitrogen fertilizers and in residences for heating homes and cooking.

Natural Gas LPG – Liquefied petroleum gas is similar to natural gas, but in a liquid form – is a slightly less energy-dense substitute. Figure 12.14 shows natural gas field in Wyoming.

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

Arctic National Wildlife Refuge (ANWR) Debates continue over the trade-off between extracting oil domestically and the consequences for habitat and species living near oil wells or pipelines. Proponents of exploration suggest that ANWR might yield 25 million gallons to 378 billion gallons of oil and substantial quantities of natural gas.

Arctic National Wildlife Refuge (ANWR) Figure 12.13 (b) shows a map of ANWR and adjacent areas on the North Slope of Alaska. The area in orange is under consideration for petroleum exploration and extraction.

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, where bacteria metabolize some of the light hydrocarbons and others evaporate. CTL, “coal-to-liquid”- converting solid coal into a liquid fuel.

Fossil Fuels are a finite resource Figure 12.15 shows U.S. energy use per capita has been level while our energy use per dollar of GDP, has been decreasing in recent years. However, because of our increasing population, our overall energy use continues to increase.

The Hubbert Curve Figure 12.16 shows the Hubbert curve a graph that shows the point at which world oil production would reach a maximum and the point at which we would run out of oil.

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 Figure 12.17 shows a fission reaction, a nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts. Energy in the form a heat is used to create steam.

Nuclear Reactors Figure 12.18 shows a diagram of a nuclear reactor. This schematic shows the basic features of the light-water reactor, the type commonly found in the U.S.

Nuclear Reactors Fuel rods- the cylindrical tubes that house the nuclear fuel used in a nuclear power plant. Nuclear power plants work by using heat from nuclear fission to boil water. This water produces the steam to turn the turbine, which turns a generator. Control rods- cylindrical devices that can be inserted between the fuel rods to absorb excess neutrons, thus slowing or stopping the fission reaction.

Advantages & Disadvantages of Nuclear Energy No air pollution is produced Possibility of accidents, Three Mile Island and Chernobyl Countries can limit their need for imported oil Disposal of the radioactive waste, low and high level. Small amount of Uranium can produce large amounts of energy Poor public opinion

Radioactive Waste Radioactive waste- created once the nuclear fuel cannot produce enough heat to be used in a power plant but it continues to emit radioactivity. Figure 12.19 shows storage of nuclear waste. This waste must be stored in special, highly secure locations because of the danger to living organisms.

Radioactive Waste High-level radioactive waste- the form used in fuel rods. Low-level radioactive waste- the protective clothing, tools, rags, and other items used in routine plant maintenance. Uranium mine tailings- the residue left after uranium ore is mined and enriched.

Radioactive Waste Half-life- the time it takes for one-half of a radioactive isotope’s radioactive atoms to decay. Radiation is measured with a variety of units: Becquerel (Bq) measures the rate at which a sample of radioactive material decays. A curie is 37 billion decays per second.

Fusion Nuclear fusion- the reaction that powers 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 in the future, but so far scientists have had difficulty containing the heat that is produced.