Chapter 11 Fossil Fuels

Transcription

1 Chapter 11 Fossil Fuels

2 I. Energy Sources and Consumption A. Energy sources that were used were obtained locally and now they are worldwide Fossil fuels Nuclear energy Electricity B. Energy consumption is different between developing and developed nations 20% of world s population use 60% of the world s energy sources

3 C. Energy density Amount of energy contained in a given volume or mass of an energy source D. Energy efficiency A measure of the fraction of energy used relative to the total energy available in a given source

4 E. Per capita energy consumption of selected developed and developing countries

5 Energy Consumption in the US YOU NEED TO KNOW TABLE 11.1 on page 229!

6 II. US Energy Policy A. Objective 1: Increase Energy Efficiency and Conservation Requires many unpopular decisions Examples Decrease speed limit to conserve fuel Eliminate government subsidies B. Objective 2: Secure Future Fossil Fuel Energy Supplies 2 oppositions: environmental and economic

7 C. Objective 3: Develop Alternative Energy Sources Who should pay for this? Gas taxes? D. Objective 4: Meet the First Three Objectives Without Further Damage to the Environment Example 5 cent tax on each barrel of domestically produced oil or ton of domestically produced coal to establish a reclamation fund for some of the environmental damage caused by drilling or mining, production, and refining

8 III. Fossil Fuels A. Combustible deposits in the Earth s crust Composed of the remnants (fossils) of prehistoric organisms that existed millions of years ago Includes coal, oil (petroleum) and natural gas B. Non-renewable resource Fossil fuels are created too slowly to replace the reserves we use

9 IV. How Are Fossil Fuels Formed? A. 300 million years ago Climate was mild Vast swamps covered much of the land Dead plant material decayed slowly in the swamp environment

10 B. Coal Heat, pressure and time turned the plant material into carbon-rich rock (coal) C. Oil Sediment deposited over microscopic plants Heat pressure and time turned them into hydrocarbons (oil) D. Natural Gas Formed the same way as oil, but at temperatures higher than 100 C

11 V. Coal A. Most, if not all, coal deposits have been identified B. Occurs in different grades - based on variations in heat and pressure during burial

12 C. US has 25% of world s coal supplies D. Known coal deposits could last 200 years At present rate of consumption

13 E. Two Types of Coal Mining 1. Surface mining (right) Chosen if coal is within 30m of surface 60% 2. Subsurface mining Extraction of mineral and energy resources from deep underground deposits 40%

14 F. Environmental Impacts of Mining Coal 1. Surface Mining Control and Reclamation Act (SMCRA) (1977) Requires filling (reclaiming) of surface mines after mining Reduces Acid Mine Drainage Requires permits and inspections of active coal mining sights Prohibits coal mining in sensitive areas

15 Mountain Top Removal

16 G. Environmental Impacts of Burning Coal 1. Releases large quantities of CO 2 into atmosphere Greenhouse gas 2. Releases other pollutants into atmosphere Mercury Sulfur oxides Nitrogen oxides 3. Can cause acid precipitation

17 H. Making Coal Cleaner 1. Scrubbers 2. Fluidized Bed Combustion (below) mixes crushed coal with particles of limestone in a strong air current during combustion Lower temp. and fewer nitrogen oxides are produced sulfur reacts with the calcium in the limestone so scrubbers are not needed

18 VI. Oil and Natural Gas A. Oil and gas provide 60% of world s energy They provide 62% of US s energy

19 B. Petroleum Refining 1. Numerous hydrocarbons present in crude oil (petroleum) are separated Based on boiling point 2. Natural gas contains far fewer hydrocarbons than crude oil Methane, ethane, propane and butane

20 C. Oil and Natural Gas Exploration 1. Oil and natural gas migrate upwards until they hit impermeable rock 2. Usually located in structural traps

21 D. Oil Reserves 1. Uneven distribution globally 2. More than half is located in the Middle East

22 E. Natural Gas Reserves 1. Uneven distribution globally 2. More than half is located in Russia and Iran

23 F. How long will supplies last? 1. Difficult to determine and estimates vary 2. Depends on: Locating more deposits Future extraction technologies Changes in global consumption rates 3. Experts indicate there may be shortages in 21 st century

24 G. Environmental Impacts of Oil and Natural Gas 1. Combustion Increase carbon dioxide and pollutant emissions Natural gas is far cleaner burning than oil 2. Production Disturbance to land and habitat 3. Transport Spills - especially in aquatic systems Ex: Alaskan Oil Spill (1989)

25 1989 Alaskan Oil Spill

26 1989 Alaskan Oil Spill H Alaskan Oil Spill Exxon Valdez hit a reef and spilled 260,000 barrels of crude oil into sound Second largest oil spill in US history Led to Oil Pollution Act of 1990

27 I. Gulf Oil Spill April 22, 2010 Worst spill in US History and worst accidental oil spill in the world s history 206 million gallons were released Deepwater Horizon rig had a gas explosion 11 people were killed Oil gushed for 85 days before a cap could be placed on the well - oil covered 572 miles of Gulf shoreline 1.82 million gallons of dispersant were used unknown effects on humans

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31 13 worst oils spills in history

32 J. Case Study ANWR A national wildlife refuge in Alaska

33 Congress declared a section of northeastern Alaska protected because of its distinctive wildlife Congress expanded this wilderness area to form the Arctic National Wildlife Refuge (ANWR) 3. the Department of the Interior was given permission to determine the potential for oil discoveries in this area, but exploration and development could proceed only with congressional approval s pressure to open the refuge to oil development 1994 the US imported more than 50% of their oil concluded that oil drilling would harm the ecosystem but the Senate and House of Representatives passed measures to allow it but President Clinton vetoed the bill

34 President George W. Bush announced his support for opening the refuge to drilling but after many debates, the Senate voted against doing so 6. still continues to be a debate that plays heavily in Presidential elections 7. Pros and Cons Pros economic Cons habitat damage

35 K. Fracking Hydraulic Fracturing 1. Process - After a well is drilled, the casing is perforated, typically with explosive charges. A pad of fluids is then injected, at a sufficient pressure and rate, to fracture the formation surrounding the perforations. The fractured formations are typically located thousands are feet below the water table. Next, producers inject a slurry, which consists of fracking fluids and sand, to extend and develop the fracture.

36 Fracking Process

37 2. Economic Benefits to Fracking a. Development of a domestic energy resource (reducing foreign influences on price). b. Creation of jobs. c. Financial gains to individuals who lease their property to the natural gas companies.

38 3. Environmental Drawbacks of Fracking a. Habitat fragmentation/destruction can occur from setting up the drilling site or from building roads. b. Earthquakes can result from the drilling/fracking process. c. Methane can leak (into the atmosphere) during the process, resulting in an increase of greenhouse gases. d. Subsidence of the land can occur once fracking fluids are removed. e. Trucks and drilling equipment consume a nonrenewable fuel and release CO2 (greenhouse gases) and, potentially, SOx (which produce acid rain) and NOx (which produce acid rain and photochemical smog). f. Noise pollution is caused by the drilling rigs and by increased truck traffic. g. Soil salinization or heavy metal contamination can result from the spraying of wastewater. h. The drilling site increases the amount of particulate matter in the air.

39 4. Water Related Environmental Problems of Fracking a. Ground water contamination (1) Fracking liquids or chemicals can contaminate drinking water or groundwater. (2) Liquid waste stored in waste lagoons can leach into groundwater (aquifer). (3) Drilling can allow methane (or natural gas) to seep into groundwater. (4) Leaks from the well casings can contaminate the water with either fracking liquids or flowback liquids. (5) Radioactive isotopes used as tracers in fracking fluids can contaminate groundwater.

40 b. Surface water contamination (1) Brine (or wastewater) sprayed on roadways can run off and contaminate rivers, streams, and lakes. (2) Spills of brine (or wastewater) can contaminate rivers, streams, and lakes. (3) Wastewater disposed of in streams and rivers may contain salts, heavy metals, benzene, and/or other components of fracking liquid.

41 c. Excessive water use or consumption (1) Considerable amounts of water are used in the fracking process. This can result in overdrafts of aquifers. (2) Water demands for the fracking process compete with water demands for drinking or irrigation (agriculture).

42 VI. Synfuel and Other Fossil Fuel A. Synfuel Resources Synthesized fuel from coal and other naturally occurring sources Used in place of oil or natural gas B. Include: Tar sands Oil shales Gas hydrates Liquefied coal Coal gas (right)