Chapter 18 Fossil Fuels and the Environment Fossil
- Slides: 31
Chapter 18 Fossil Fuels and the Environment
Fossil Fuels Forms of stored solar energy created from incomplete biological decomposition of dead organic matter • Crude Oil • Natural Gas • Coal • Also, Oil Shale & Tarsands
Crude Oil and Natural Gas • Crude Oil – Naturally occurring petroleum, normally pumped from wells in oil fields. – Refinement of crude oil produces most of the petroleum products we use today • Natural Gas – Naturally occurring gaseous hydrocarbon generally produced in association with crude oil or from gas wells – An important efficient and clean burning fuel commonly used in homes and industry
Geology of Oil & Gas • Oil & gas found primarily along geologically young tectonic belts at plate boundaries – Source Rock – source material for oil & gas. Fine grained, organic rich sediment, at least 500 m deep – High pressure and high temperature, initiates the chemical transformation & upward migration of gas & oil (relatively light) to reservoir rock
Geology Cont’d Reservoir Rock: coarser grain, porous sandstone or limestone. Empty spaces store oil &/or gas. Cap Rock: traps oil or gas in a pocket in the reservoir rock. Usually shale – very fine grained sedimentary rock Two types of Traps: Anticline (arch shape) Fault (fracture in rock)
Activity • Draw these next slides
Petroleum Production • Primary Production – simply pumping – Recovery only 25% of reserve • Enhanced Production – steam, water, CO 2 or N 2 are injected into reservoir to push oil toward the well
Natural Gas • Only begun to seriously look for natural gas & its’ potential uses – (powering of cars) • Drawback: transported through pipelines • Worldwide estimate of recoverable nat. gas is 165 trillion m 3 - could last 70 years • Much of it is in the US • Considered a clean fuel – less pollutants, less environmental problems
Drilling and Fracking • Youtube video
Environmental Effects of Oil and Natural Gas • Recovery: – Use of land – Pollution of surface and groundwaters – Air pollutants – Land subsidence ( sinking) – Loss of ecosystems – Release of drilling muds (heavy metals) – Aesthetics (presence of rigs) • Refining: soil, water and air pollution – spills & leaks • Delivery and Use: energy to power automobiles, produce electricity, etc. Possible spills and air pollution form use
Coal • Solid, brittle, carbonaceous rock formed from partially decomposed vegetation buried in a sedimentary environment. • Total recoverable resource = 250 billion Metric tons ( 250 yrs )
Coal Composition • Classified according to energy content and sulfur content – Anthracite high energy – Bituminous – Subbitumious (low sulfur) – Lignite (low sulfur) low energy
Content cont’d • Low sulfur coal emits less SO 2. Therefore more desirable fuel • High sulfur coal can be treated before, during or after combustion to reduce sulfur content – This is done on the East coast of US. It is more expensive, but more economical than transporting low sulfur coal from the West •
Coal Mining and the Environment • Strip Mining – A surface mining process in which the overlying layer of soil and rock is stripped off to reach the coal (Cheap & Easy)
Impacts • Acid mine drainage: acid water from mine site is formed from rainwater coming in contact with spoil banks (rock debris) that contains Fe. S 2 (pyrite – common in sedimentary rock). This forms H 2 SO 4 – sulfuric acid – which infiltrates the surface and groundwater. • Good reclamation practices would help • 1000’s of km of land have been disturbed by strip mining, but only 50% has gone through reclamation processes
Impacts cont’d • Surface Mining Control & Reclamation Act of 1977 – US Gov’t requires that mined land be restored to support its pre-mining use.
• Transport of Coal • The Future of Coal – Scrubbing: removes sulfur dioxides • Allowance Trading – Reduces pollution – EPA grants utility companies tradable allowances for polluting
Underground Mining • 40% of coal is mined this way in the US • Dangers = collapse, fire, explosions, respiratory illness • Environmental Problems: – Acid mine drainage – Land subsidence – Coal fires in mines
Coal & the environment • Coal is used to produce electricity, synthetic oil & synthetic gas • Burning coal accounts for 60% of electricity used in US (25% of all energy consumed) • Coal is 90% of fossil fuel reserves in US – (enough for several hundred yrs for US population) – PROBLEMS: emissions of SO 2, NO & CO 2 Clean Air Act of 1990 – mandated that sulfur dioxide emissions be reduced by 70% - 90% This has forced the birth of new technologies
Allowance Trading • EPA grants utility companies tradable allowances for polluting • 1 allowance = 1 ton of SO 2 emissions • If you don’t use your allowance you can trade or sell them. • Encourages competition for cleaner emissions and reduces pollution.
Oil Shale and Tar Sands • Oil Shale – A fine-grained sedimentary rock that must be heated to extract the oil – One ton of oil shale produces 60 liters of oil – (Colorado, Utah & Wyoming) • Tar Sands – Sedimentary rocks or sands impregnated with tar oil, asphalt or bitumen – Wash the sand with hot water to extract oil – Alberta, Canada
Coal-Bed Methane • In the chemical process that converts decomposed organic matter into coal – methane is formed (in large amounts) • Currently two areas in our nation are recovering coal-bed methane – Utah & Wyoming • Wells are cheap ($100, 000 compared to several million for oil wells) • Problems: – Lg amounts of water are used to extract the methane – water becomes contaminated and disposal is a problem. – Migration of methane into urban areas (colorless, odorless and highly explosive
Methane Hydrates • White ice-like compound made up of molecules of methane gas trapped in “cages” of frozen water in the sediments of the deep seafloor • Formed due to microbial digestion of organic matter in sediments on the seafloor. • Discovered 30 yrs ago • Needs high pressure and low temps. Methane hydrate decomposes rapidly as press. & temp change and releases methane • Potential energy source – difficult to mine, bc found along lower continental slopes at greater than 1 km in depth
- Pros and cons of oil energy
- Similarities between biofuels and fossil fuels
- Fossil fuel deposits
- Fossil fuel energy advantages and disadvantages
- Benefits of using fossil fuels
- Advantages of using fossil fuels
- Is petroleum a fossil fuel
- Fossil fuels include
- Fossil fuels summary
- Fossil fuels include
- Fossil fuels formula
- Fossil fuels
- Advantages and disadvantages of nonrenewable energy
- Benefits of using fossil fuels
- The oldest source of energy
- Resources that can be replaced.
- Minerals and fuels
- Minerals and fuels
- Financial environment of business
- Classification of chemical fuels
- Support nuclear energy
- Classification of resources on the basis of exhaustibility
- Fuels
- What are fissil fuels
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