Nonrenewable Energy

1. Nonrenewable Energy

2. Introduction: Non- Renewable Energy • Nonrenewable energy is energy that comes from the ground and is not replaced in a relatively short amount of time. • Fossil fuels are the main category of nonrenewable energy. • Fossil fuels include; coal, oil and natural gas. • These resources come from animals and plants that have died millions of years ago and then decomposed to create a useable source of energy for humans.

4. 15-1 Basic Science: Net Energy Is the Only Energy That Really Counts • Net energy is the amount of high- quality energy available from an energy resource minus the amount of energy needed to make it available. • Because of the first law of thermodynamics, it takes high- quality energy to get high-quality energy. • For example, before oil becomes useful to us, it must be found, pumped up from beneath the ground, transferred to a refinery, converted to useful fuels, and delivered to us. • Each of these steps uses high-quality energy, mostly obtained by burning fossil fuels such as oil and coal.

5. 15-1 Energy Resources With Low or Negative Net Energy Yields Need Help to Compete in the Marketplace • Any energy resource with a low or negative net energy yield cannot compete in the open marketplace with other energy alternatives with higher net energy. • For example, electricity produced by nuclear power has a low net energy yield because large amounts of energy are needed for each step in the nuclear power cycle.

6. 15-1 Reducing Energy Waste Improves Net Energy Yields and Can Save Money • One component of a net energy ration is the amount of energy resource that is wasted because of the energy lost due to the second law of thermodynamics. • We have no control over this factor except try to use energy resources with net energy yields. • Another component of any net energy ratio is the energy that is unnecessarily wasted in making useful energy available for use. • We can control this factor by reducing unnecessary waste and thus raising the net energy yield of a resource.

7. 15-2 We Depend Heavily on Oil • Oil supplies about one-third of the world’s commercial energy and 40% of that used in the United States. • Petroleum, or crude oil( oil as it comes out of the ground), is a black, gooey liquid consisting of hundreds of different combustible hydrocarbons. Crude oil (a non-renewable resource) is usually found in underground areas called reservoirs. • This conventional oil, makes up about 30% of the world’s estimated supply of oil. • The other 70% is unconventional heavy oil with the consistency of molasses.

8. 15-2 How Long Might Supplies of Conventional Crude Oil Last? • Conventional oil is currently abundant , has a high net energy yield, and is relatively inexpensive. • However, using the oil causes air and water pollution and releases greenhouse gases to the atmosphere..

9. 15-2 OPEC Controls Most of the World’s Crude Oil Supplies • The 13 countries that make up the Organization of Petroleum Exporting Countries (OPEC) have about 60% of the world’s proven crude oil reserves. • A serious problem for oil supplies worldwide is that since 1984, production of conventional crude oil has exceeded new oil discoveries. • Some analysts say that there is a lot of oil still to be found. • But they are talking mostly about small, dispersed, and harder-to-extract deposits of conventional crude oil.

10. 15-2 The United States Uses Much More Oil Than It Produces • The United States gets about 85% of its commercial energy from fossil fuels, with 40% coming from crude oil. • The United States produces about 9% of the world’s crude oil, but it uses 23% of the world’s production. • The basic problem is that the United States has only about 1.5% of the world’s proven crude oil reserves. • The United States cannot even come close to meeting its huge and growing demand for crude oil and gasoline by increasing domestic supplies

11. 15-2 Using Crude Oil Has Advantages and Disadvantages • To keep using conventional oil at the projected increasing rate of consumption, we must discover proven reserves of conventional oil equivalent to the current Saudi Arabian supply every 5 years. • The extraction, processing, and burning of nonrenewable oil and other fossil fuels have severe environmental impacts, including land disruption, greenhouse gas emissions and other forms of pollution, water pollution, and loss of biodiversity. • Advantages of crude oil is that it bountiful, has a high net energy yield (but is decreasing) and had efficient distribution system. • Producing crude oil from tar sands uses large quantities of water.

12. 15-2 Advantages of Oil Shale • Low sulfur content and therefore less air pollution • Has large potential supplies • Easily transported within and between countries

13. 15-2 Disadvantages of Oil Shale • Low net energy yield • Releases CO2 and other air pollutants when produced and burned • Severe land disruption and high water use Oil shale extraction

14. 15-2 Will Heavy Oil from Oil Shale Be a Useful Resource? • Oily rocks are another potential supply of heavy oil. • Such rocks, called oil shales, contain a solid combustible mixture of hydrocarbons) called kerogen. • Kerogens are extracted from crush oil shales after they are heated in a large container. • About 72% of the world’s estimated oil shale reserves are buried deep in rock formations located primarily in Colorado, Wyoming, and Utah.

15. 15-2 Will Heavy Oil from Oil Shale Be a Useful Resource? (Cont.) • The problem is that most of these oil shale deposits are locked up in rock and ore, that it takes a lot of energy and money to mine and convert the kerogen to shale oil. • Its net energy is low, even lower that that of heavy oil produced from tar sands. • Disadvantages of shale oil as an energy source include all of the following except potentially recoverable U.S. deposits are only enough to meet the country's crude oil demand for five years.

16. 15-3 Natural Gas Is a Useful and Clean-Burning Fossil Fuel • Natural Gas is colorless, shapeless, and odorless in its pure form. • Unlike other fossil fuels, natural gas is clean burning and emits lower levels of potentially harmful byproducts into the air. It is therefore called "Clean Gas'. • The main ingredient in natural gas is methane, a gas (or compound) composed of one carbon atom and four hydrogen atoms. • Natural gas supplies about 23.8 percent of the world's energy. Natural Gas Stove Burner

17. 15-3 Natural Gas Is a Useful and Clean-Burning Fossil Fuel • Burning natural gas releases the greenhouse gas carbon dioxide and several other air pollutants into the atmosphere. • However, it releases much less CO2 per unit of energy than do coal, crude oil, tar sands and oil shales, and the nuclear power fuel cycle.

18. 15-3 Is Unconventional Natural Gas the Answer? • There is several sources of unconventional natural gas. • One is coal bed methane gas, which is found in coal beds near the earth’s surface across parts of the USA and Canada. • Another unconventional source is methane hydrate which is methane trapped in icy, cage-like structures of water molecules. • It costs too much to get natural gas from methane hydrates, and release of methane to the atmosphere during removal.

19. 15-4 Coal Is a Plentiful but Dirty Fuel • Coal is formed from fossilised plants and consisting of carbon with various organic and some inorganic compounds. • It is obtained from mining and is the most difficult resource to get. • Coal has been widely used to provide heat and electricity. • The problem is that coal is by far the dirtiest of all fossil fuels. Before it is even burned, the processes of making it available severely degrade land and pollute water and air.

20. 15-4 The Clean Coal and Anti-Coal Campaigns • The U.S. coal industry along with many coal-burning electric utility companies, funded a $40 million publicity campaign to promote the misleading idea of clean coal. • However, critics point out that there is no such thing as clean coal. • Mining coal usually involves disrupting the land and polluting water and air. • Even with stricter air pollution controls, burning coal will always involve some emissions of CO2 and other air pollutants, and it will always create toxic coal ash removed from smokestack emissions. CO2 emissions and the Carbon Cycle

21. 15-4 We Can Convert Coal into Gaseous and Liquid Fuels • We can convert solid coal into synthetic natural gas (SNG) by a process called coal gasification, which removes sulfur and most other impurities from coal. • We can also convert coal into liquid fuels such as methanol and synthetic gasoline through a process called coal liquefaction. • Such fuels are called synfuels, which have a lower net energy yield and cost more to produce than conventional coal. • Greatly increased used of these synfuels would worsen two of the world’s major environmental problems: projected climate change and increasing water shortages

23. 15-5 How Does a Nuclear Fission Reactor Work? • A nuclear power plant is a complex and costly system • It is designed to perform a simple task: to boil water and produce steam that spins a turbine and generates electricity. • The fuel for a reactor is made from uranium ore mined from the earth’s crust . • After it is mined, the ore must be enriched to increase the concentration of its fissionable uranium-235 by 1% to 5%.

24. 15-5 What Is the Nuclear Fuel Cycle? • A nuclear power plant is only one part of the nuclear fuel cycle • The nuclear fuel cycle is the series of industrial processes which involve the production of electricity from uranium in nuclear power reactors. • Uranium is mined in a number of countries and must be processed before it can be used as fuel for a nuclear reactor. • Fuel removed from a reactor, after it has reached the end of its useful life, can be reprocessed to produce new fuel.

25. 15-5 What Happened to Nuclear Power? • In 2010, 436 commercial nuclear reactors in 31 countries produced only 6% of the world’s commercial energy and 14% of its electricity. • Nuclear power is now the world’s slowest-growing form of commercial energy. • Because of the multiple built-in safety features, the risk of exposure to radioactivity from nuclear power plants is extremely low.

26. 15-5 The Conventional Nuclear Power Fuel Cycle Has Advantages and Disadvantages Advantages • Low environmental impact (w/o accidents) • Emits 1/6 as much CO2 as coal Disadvantages • Very low net energy yield and high overall cost • Produces long-lived, harmful radioactive wastes

28. 15-5 Storing Spent Radioactive Fuel Rods Presents Risks • After about 3 or 4 years, the high-grade uranium fuel in a nuclear reactor becomes spent, useless, and must be replaced. • This involves replacing about a third of the reactor’s fuel rods that contain the spent fuel. • After several years of cooling, they can be transferred to dry casks made of metal alloys and concrete. • A 2005 study by the U.S. National Academy of Sciences warned that the intensely radioactive waste storage pools and dry casks are vulnerable to sabotage or terrorist attack.

29. Case Study: A Brief History of Human Energy Use • Some sources of energy, such as oil, coal, and natural gas-also called fossil fuels- are used to fuel nuclear power plants. • Human use of energy has grown dramatically throughout history. • Wood harvested forests was burned to provide energy used for heating buildings and running steam engines. • By 1850, Europeans were harvesting firewood faster than nature could replace it, and thus they depleted many of the forests.

30. Case Study: Heavy oil from Tar Sand • Tar sand, or oil sand, is a mixture of clay, sand, water, and a combustible organic material called bitumen. • Developing this resource has major harmful impacts on the land, air, water, wildlife, and climate. • The process of extracting tar sand, consist of using large amounts of water and creates toxic sludge and wastewater. • The method of producing this heavy oil takes a great deal of energy-mostly through burning natural gas- and therefore has a low net energy yield.

31. Case Study: The Problem of Coal Ash • Burning coal and removing pollutants from it produces an ash that contains highly toxic chemicals such as arsenic, cadmium, lead, and mercury. • One type of ash is what is left over after the coal is burned. • Another form of ash containing toxic chemicals is created because of U.S. government regulations that require the removal of harmful air pollutants from the smokestack • In the U.S., about 57% of the ash is either buried or made into a wet slurry that is stored in holding ponds.

32. Case Study: High- Level Radioactive Wastes in the United States • In 1987, the DOE announced plans to build a repository for underground storage of high- level radioactive wastes on to federal land in the Yucca Mountain desert region in Las Vegas. • Some scientists argued that the site should never be allowed to open, because rock fractures and tiny cracks are likely to allow water to flow through. • The build up of hydrogen gas produced from the breakdown of this water would likely cause an explosion. • Meanwhile, large amounts of U.S. nuclear waste sit in pools and dry casks and these volume of waste continue to grow