Oil shale
 —  Sedimentary Rock  —
Oil shale Image
Combustion of oil shale
Composition
Primary Kerogen, Quartz, Feldspar, Clay, Carbonate, Pyrite
Secondary Uranium, Iron, Vanadium, Nickel, Molybdenum

Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons called shale oil can be produced. Shale oil is a substitute for conventional crude oil; however, extracting shale oil from oil shale is more costly than the production of conventional crude oil both financially and in terms of its environmental impact.[1][2] Deposits of oil shale occur around the world, including major deposits in the United States of America. Estimates of global deposits range from 2.8 trillion to 3.3 trillion barrels (450×109 to 520×109 m3) of recoverable oil.[2][3][4][5]

Heating oil shale to a sufficiently high temperature causes the chemical process of pyrolysis to yield a vapor. Upon cooling the vapor, the liquid shale oil—an unconventional oil—is separated from combustible oil-shale gas (the term shale gas can also refer to gas occurring naturally in shales). Oil shale can also be burnt directly in furnaces as a low-grade fuel for power generation and district heating or used as a raw material in chemical and construction-materials processing.[2][6]

Oil shale gains attention as a potential abundant domestic source of oil whenever the price of crude oil rises.[7][8] At the same time, oil-shale mining and processing raise a number of environmental concerns, such as land use, waste disposal, water use, waste-water management, greenhouse-gas emissions and air pollution.[9][10] Estonia and China have well-established oil shale industries, and Brazil, Germany, Israel and Russia also utilize oil shale.[2]

Geology

File:OilShaleEstonia.jpg
Outcrop of Ordovician oil shale (kukersite), northern Estonia

Oil shale, an organic-rich sedimentary rock, belongs to the group of sapropel fuels.[11] It does not have a definite geological definition nor a specific chemical formula, and its seams do not always have discrete boundaries. Oil shales vary considerably in their mineral content, chemical composition, age, type of kerogen, and depositional history and not all oil shales would necessarily be classified as shales in the strict sense.[12] Oil shale differs from bitumen-impregnated rocks (oil sands and petroleum reservoir rocks), humic coals and carbonaceous shale. While oil sands originate from the biodegradation of oil, heat and pressure have not (yet) transformed the kerogen in oil shale into petroleum.[2][13][14]

Oil shale contains a lower percentage of organic matter than coal. In commercial grades of oil shale the ratio of organic matter to mineral matter lies approximately between 0.75:5 and 1.5:5. At the same time, the organic matter in oil shale has an atomic ratio of hydrogen to carbon (H/C) approximately 1.2 to 1.8 times lower than for crude oil and about 1.5 to 3 times higher than for coals.[2][11][15] The organic components of oil shale derive from a variety of organisms, such as the remains of algae, spores, pollen, plant cuticles and corky fragments of herbaceous and woody plants, and cellular debris from other aquatic and land plants.[2][16] Some deposits contain significant fossils; Germany's Messel Pit has the status of a Unesco World Heritage Site. The mineral matter in oil shale includes various fine-grained silicates and carbonates.[6][11]

Geologists can classify oil shales on the basis of their composition as carbonate-rich shales, siliceous shales, or cannel shales.[17] Another classification, known as the van Krevelen diagram, assigns kerogen types, depending on the hydrogen, carbon, and oxygen content of oil shales' original organic matter.[12] The most commonly used classification of oil shales, developed between 1987 and 1991 by Adrian C. Hutton of the University of Wollongong, adapts petrographic terms from coal terminology. This classification designates oil shales as terrestrial, lacustrine (lake-bottom-deposited), or marine (ocean bottom-deposited), based on the environment of the initial biomass deposit.[6][18] Hutton's classification scheme has proven useful in estimating the yield and composition of the extracted oil.[2]

Reserves

File:OilShaleFossilsEstonia.jpg
Fossils in Ordovician oil shale (kukersite), northern Estonia

As with all oil and gas resources, analysts distinguish between oil shale resources and oil shale reserves. "Resources" refers to all oil shale deposits, while "reserves", represents those deposits from which producers can extract oil shale economically using existing technology. Since extraction technologies develop continuously, planners can only estimate the amount of recoverable kerogen.[1][6] Although resources of oil shale occur in many countries, only 33 countries possess known deposits of possible economic value.[19][20] Well-explored deposits, potentially classifiable as reserves, include the Green River deposits in the western United States, the Tertiary deposits in Queensland, Australia, deposits in Sweden and Estonia, the El-Lajjun deposit in Jordan, and deposits in France, Germany, Brazil, China, southern Mongolia and Russia. These deposits have given rise to expectations of yielding at least 40 liters of shale oil per tonne of oil shale, using the Fischer Assay.[6][12]

A 2005 estimate set the total world resources of oil shale at 411 gigatons — enough to yield 2.8 to 3.3 trillion barrels (520 km3) of shale oil.[2][3][4][5] This exceeds the world's proven conventional oil reserves, estimated at 1.317 trillion barrels (209.4×10^9 m3), as of 1 January 2007.[21] The largest deposits in the world occur in the United States in the Green River Formation, which covers portions of Colorado, Utah, and Wyoming; about 70% of this resource lies on land owned or managed by the United States federal government.[22] Deposits in the United States constitute 62% of world resources; together, the United States, Russia and Brazil account for 86% of the world's resources in terms of shale-oil content.[19] These figures remain tentative, with exploration or analysis of several deposits still outstanding.[2][6] Professor Alan R. Carroll of University of Wisconsin–Madison regards the Upper Permian lacustrine oil-shale deposits of northwest China, absent from previous global oil shale assessments, as comparable in size to the Green River Formation.[23]

History

File:Production of oil shale.svg
Production of oil shale (megatons) in Estonia (Estonia deposit), Russia (Leningrad and Kashpir deposits), United Kingdom (Scotland, Lothians), Brazil (Irati Formation), China (Maoming and Fushun deposits), and Germany (Dotternhausen) from 1880 to 2000[6]

Humans have used oil shale as a fuel since prehistoric times, since it generally burns without any processing.[24] Britons of the Iron Age also used to polish it and form it into ornaments.[25] Modern industrial mining of oil shale began in 1837 in Autun, France, followed by exploitation in Scotland, Germany, and several other countries.[2][26] Operations during the 19th century focused on the production of kerosene, lamp oil, and paraffin; these products helped supply the growing demand for lighting that arose during the Industrial Revolution.[27] Fuel oil, lubricating oil and grease, and ammonium sulfate were also produced.[28] The European oil-shale industry expanded immediately before World War I due to limited access to conventional petroleum resources and to the mass production of automobiles and trucks, which accompanied an increase in gasoline consumption.

Although the Estonian and Chinese oil-shale industries continued to grow after World War II, most other countries abandoned their projects due to high processing costs and the availability of cheaper petroleum.[2][6][26][29] Following the 1973 oil crisis, world production of oil shale reached a peak of 46 million tonnes in 1980 before falling to about 16 million tonnes in 2000, due to competition from cheap conventional petroleum in the 1980s.[9][19] On 2 May 1982, known in some circles as "Black Sunday", Exxon canceled its US$5 billion Colony Shale Oil Project near Parachute, Colorado because of low oil-prices and increased expenses, laying off more than 2,000 workers and leaving a trail of home-foreclosures and small-business bankruptcies.[30] In 1986, President Ronald Reagan signed into law the Consolidated Omnibus Budget Reconciliation Act of 1985 which among other things abolished the United States' Synthetic Liquid Fuels Program.[4]

The global oil-shale industry began to revive at the beginning of the 21st century. In 2003, an oil-shale development program restarted in the United States. Authorities introduced a commercial leasing program permitting the extraction of oil shale and oil sands on federal lands in 2005, in accordance with the Energy Policy Act of 2005.[31][32]

Industry

A photograph of Shell Oil's experimental in situ shale oil extraction facility in the Piceance Basin of northwestern Colorado. In the center of the photo, a number of oil recovery pipes lie on the ground. Several oil pumps are visible in the background.
Shell's experimental in-situ oil-shale facility, Piceance Basin, Colorado, USA

As of 2008, industry uses oil shale in Brazil, China, Estonia and to some extent in Germany, Israel, and Russia. Several additional countries started assessing their reserves or had built experimental production plants, while others had phased out their oil shale industry.[2] Oil shale serves for oil production in Estonia, Brazil, and China; for power generation in Estonia, China, Israel, and Germany; for cement production in Estonia, Germany, and China; and for use in chemical industries in China, Estonia, and Russia.[2][29][33][34] As of 2009, 80% of oil shale used globally is extracted in Estonia.[33][35]

Romania and Russia have in the past run power plants fired by oil shale, but have shut them down or switched to other fuel sources such as natural gas. Jordan and Egypt plan to construct power plants fired by oil shale, while Canada and Turkey plan to burn oil shale along with coal for power generation.[2][19][36] Oil shale serves as the main fuel for power generation only in Estonia, where the oil-shale-fired Narva Power Plants accounted for 95% of electrical generation in 2005.[37]

Extraction and processing

A vertical flowchart begins with an oil shale deposit and follows two major branches. Conventional ex situ processes, shown on the right, proceed through mining, crushing, and retorting. Spent shale output is noted. In situ process flows are shown in the left branch of the flowchart. The deposit may or may not be fractured; in either case, the deposit is retorted and the oil is recovered. The two major branches converge at the bottom of the chart, indicating that extraction is followed by refining, which involves thermal and chemical treatment and hydrogenation, yielding liquid fuels and useful byproducts.
Overview of shale oil extraction.

Most exploitation of oil shale involves mining followed by shipping elsewhere, after which one can burn the shale directly to generate electricity, or undertake further processing. The most common methods of surface mining involve open pit mining and strip mining. These procedures remove most of the overlying material to expose the deposits of oil shale, and become practical when the deposits occur near the surface. Underground mining of oil shale, which removes less of the overlying material, employs the room-and-pillar method.[38]

The extraction of the useful components of oil shale usually takes place above ground (ex-situ processing), although several newer technologies perform this underground (on-site or in-situ processing).[39] In either case, the chemical process of pyrolysis converts the kerogen in the oil shale to shale oil (synthetic crude oil) and oil shale gas. Most conversion technologies involve heating shale in the absence of oxygen to a temperature at which kerogen decomposes (pyrolyses) into gas, condensable oil, and a solid residue. This usually takes place between 450 °C (842 °F) and 500 °C (932 °F).[1] The process of decomposition begins at relatively low temperatures (300 °C / 570 °F), but proceeds more rapidly and more completely at higher temperatures.[40]

In-situ processing involves heating the oil shale underground. Such technologies can potentially extract more oil from a given area of land than ex-situ processes, since they can access the material at greater depths than surface mines can.[41]

Several companies have patented methods for in-situ retorting. However, most of these methods remain in the experimental phase. One can distinguish true in-situ processes (TIS) and modified in-situ processes (MIS). True in-situ processes do not involve mining the oil shale. Modified in-situ processes involve removing part of the oil shale and bringing it to the surface for modified in-situ retorting in order to create permeability for gas flow in a rubble chimney. Explosives rubblize the oil-shale deposit.[42]

Hundreds of patents for oil shale retorting technologies exist;[43] however, only a few dozen have undergone testing. As of 2006, only four technologies remained in commercial use: Kiviter, Galoter, Fushun, and Petrosix.[44]

Applications and products

Industry can use oil shale as a fuel for thermal power-plants, burning it (like coal) to drive steam turbines; some of these plants employ the resulting heat for district heating of homes and businesses. Sizable oil-shale-fired power plants occur in Estonia, which has an installed capacity of 2,967 megawatts (MW), Israel (12.5 MW), China (12 MW), and Germany (9.9 MW).[19][45]

In addition to its use as a fuel, oil shale may also serve in the production of specialty carbon fibers, adsorbent carbons, carbon black, phenols, resins, glues, tanning agents, mastic, road bitumen, cement, bricks, construction and decorative blocks, soil-additives, fertilizers, rock-wool insulation, glass, and pharmaceutical products.[33] However, oil shale use for production of these items remains small or only in its experimental stages.[2][6] Some oil shales yield sulfur, ammonia, alumina, soda ash, uranium, and nahcolite as shale-oil extraction byproducts. Between 1946 and 1952, a marine type of Dictyonema shale served for uranium production in Sillamäe, Estonia, and between 1950 and 1989 Sweden used alum shale for the same purposes.[6] Oil shale gas has served as a substitute for natural gas, but as of 2009, producing oil shale gas as a natural-gas substitute remained economically infeasible.[46][47]

The shale oil derived from oil shale does not directly substitute for crude oil in all applications. It may contain higher concentrations of olefins, oxygen, and nitrogen than conventional crude oil.[4] Some shale oils may have higher sulfur or arsenic content. By comparison with West Texas Intermediate, the benchmark standard for crude oil in the futures-contract market, the Green River shale oil sulfur content ranges from near 0% to 4.9% (in average 0.76%), where West Texas Intermediate's sulfur content has a maximum of 0.42%.[48] The sulfur content in shale oil from Jordan's oil shales may rise even up to 9.5%.[49] The arsenic content, for example, becomes an issue for Green River formation oil shale. The higher concentrations of these materials means that the oil must undergo considerable upgrading (hydrotreating) before serving as oil-refinery feedstock.[17] Above-ground retorting processes tended to yield a lower API gravity shale oil than the in situ processes. Shale oil serves best for producing middle-distillates such as kerosene, jet fuel, and diesel fuel. Worldwide demand for these middle distillates, particularly for diesel fuels, increased rapidly in the 1990s and 2000s.[4][50] However, appropriate refining processes equivalent to hydrocracking can transform shale oil into a lighter-range hydrocarbon (gasoline).[4]

Economics

File:WTI price 96 09.PNG
NYMEX light-sweet crude oil prices 1996–2009 (not adjusted for inflation)

During the early 20th century, the crude-oil industry expanded. Since then, the various attempts to develop oil shale deposits have succeeded only when the cost of shale-oil production in a given region comes in below the price of crude oil or its other substitutes. According to a survey conducted by the RAND Corporation, the cost of producing a barrel of oil at a surface retorting complex in the United States (comprising a mine, retorting plant, upgrading plant, supporting utilities, and spent shale reclamation), would range between US$70–95 ($440–600/m3, adjusted to 2005 values). This estimate considers varying levels of kerogen quality and extraction efficiency. In order to run a profitable operation, the price of crude oil would need to remain above these levels. The analysis also discusses the expectation that processing costs would drop after the establishment of the complex. The hypothetical unit would see a cost reduction of 35–70% after producing its first 500 million barrels (79×10^6 m3). Assuming an increase in output of 25 thousand barrels per day (4.0×10^3 m3/d) during each year after the start of commercial production, RAND predicts the costs would decline to $35–48 per barrel ($220–300/m3) within 12 years. After achieving the milestone of 1 billion barrels (160×10^6 m3), its costs would decline further to $30–40 per barrel ($190–250/m3).[33][38] Some commentators compare the proposed American oil-shale industry to the Athabasca oil-sands industry (the latter enterprise generated over one million barrels of oil per day in late 2007), stating that "the first-generation facility is the hardest, both technically and economically".[51][52]

Royal Dutch Shell has announced that its in situ extraction technology in Colorado could become competitive at prices over $30 per barrel ($190/m3), while other technologies at full-scale production assert profitability at oil prices even lower than $20 per barrel ($130/m3).[42][53][54] To increase efficiency when retorting oil shale, researchers have proposed and tested several co-pyrolysis processes.[55][56][57][58][59]

A 1972 publication in the journal Pétrole Informations (ISSN 0755-561X) compared shale-based oil production unfavorably with the coal liquefaction. The article portrayed coal liquefaction as less expensive, generating more oil, and creating fewer environmental impacts than extraction from oil shale. It cited a conversion ration of 650 litres (170 U.S. gal; 140 imp gal) of oil per one ton of coal, as against 150 litres (40 U.S. gal; 33 imp gal) of shale oil per one ton of oil shale.[26]

A critical measure of the viability of oil shale as an energy source lies in the ratio of the energy produced by the shale to the energy used in its mining and processing, a ratio known as "Energy Returned on Energy Invested" (EROEI). A 1984 study estimated the EROEI of the various known oil-shale deposits as varying between 0.7–13.3[60] although known oil-shale extraction development projects assert an EROEI between 3 to 10. Royal Dutch Shell has reported an EROEI of three to four on its in situ development, Mahogany Research Project.[53][61][62] The water needed in the oil shale retorting process offers an additional economic consideration: this may pose a problem in areas with water scarcity.

Environmental considerations

Mining oil shale involves a number of environmental impacts, more pronounced in surface mining than in underground mining. They include acid drainage induced by the sudden rapid exposure and subsequent oxidation of formerly buried materials, the introduction of metals including mercury[63] into surface-water and groundwater, increased erosion, sulfur-gas emissions, and air pollution caused by the production of particulates during processing, transport, and support activities.[9][10] In 2002, about 97% of air pollution, 86% of total waste and 23% of water pollution in Estonia came from the power industry, which uses oil shale as the main resource for its power production.[64]

Oil-shale extraction can damage the biological and recreational value of land and the ecosystem in the mining area. Combustion and thermal processing generate waste material. In addition, the atmospheric emissions from oil shale processing and combustion include carbon dioxide, a greenhouse gas. Environmentalists oppose production and usage of oil shale, as it creates even more greenhouse gases than conventional fossil fuels.[65] Section 526 of the Energy Independence And Security Act prohibits United States government agencies from buying oil produced by processes that produce more greenhouse gas emissions than would traditional petroleum.[66][67] Experimental in situ conversion processes and carbon capture and storage technologies may reduce some of these concerns in the future, but at the same time they may cause other problems, including groundwater pollution.[68] Among the water contaminants commonly associated with oil shale processing are oxygen and nitrogen heterocyclic hydrocarbons. Commonly detected examples include quinoline derivatives, pyridine, and various alkyl homologues of pyridine (picoline, lutidine).[69]

Some commentators have expressed concerns over the oil shale industry's use of water. In 2002, the oil shale-fired power industry used 91% of the water consumed in Estonia.[64] Depending on technology, above-ground retorting uses between one and five barrels of water per barrel of produced shale-oil.[38][70][71][72] A 2008 programmatic environmental impact statement issued by the US Bureau of Land Management stated that surface mining and retort operations produce 2 to 10 U.S. gallons (7.6 to 38 l; 1.7 to 8.3 imp gal) of waste water per 1 short ton (0.91 t) of processed oil shale.[70] In situ processing, according to one estimate, uses about one-tenth as much water.[73]

Water concerns become particularly sensitive issues in arid regions, such as the western US and Israel's Negev Desert, where plans exist to expand oil-shale extraction despite a water shortage.[74]

Environmental activists, including members of Greenpeace, have organized strong protests against the oil shale industry. In one result, Queensland Energy Resources put the proposed Stuart Oil Shale Project in Australia on hold in 2004.[9][75][76][77]

See also

References

  1. 1.0 1.1 1.2 Script error
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 Script error
  3. 3.0 3.1 Script error
  4. 4.0 4.1 4.2 4.3 4.4 4.5 Script error
  5. 5.0 5.1 Script error
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 Script error
  7. Script error
  8. "Oil Shale and Other Unconventional Fuels Activities". United States Department of Energy. http://www.fossil.energy.gov/programs/reserves/npr/npr_oil_shale_program.html. Retrieved 2007-10-20.
  9. 9.0 9.1 9.2 9.3 Script error
  10. 10.0 10.1 Script error
  11. 11.0 11.1 11.2 Script error
  12. 12.0 12.1 12.2 Script error
  13. Nield, Ted (2007-02-17). "Shale of the Century". Geological Society of London. http://www.geolsoc.org.uk/gsl/null/pid/874;jsessionid=5179DA9427746BC25090419C952A71A1. Retrieved 2011-05-06.
  14. Script error
  15. Script error
  16. Alali, Jamal (2006-11-07). "Jordan Oil Shale, Availability, Distribution, And Investment Opportunity" (PDF). International Oil Shale Conference. Amman, Jordan. http://www.sdnp.jo/International_Oil_Conference/rtos-A117.pdf. Retrieved 2008-03-04.
  17. 17.0 17.1 Script error
  18. Script error
  19. 19.0 19.1 19.2 19.3 19.4 Script error
  20. Script error
  21. "Chapter 3 - Petroleum and Other Liquids Fuels. International Energy Outlook 2007". Energy Information Administration. May 2007. DOE/EIA-0484(2007). http://www.eia.doe.gov/oiaf/ieo/oil.html. Retrieved 2008-04-20.
  22. "About Oil Shale". Argonne National Laboratory. http://ostseis.anl.gov/guide/oilshale/index.cfm. Retrieved 2007-10-20.
  23. Carroll, Alan R. (2007-10-17). "Upper Permian Oil Shale Deposits of Northwest China:World's Largest?" (PDF). 27th Oil Shale Symposium. Golden, Colorado. http://www.ceri-mines.org/documents/27symposium/presentations/av13-4carroll.pdf. Retrieved 2011-05-06.
  24. "Bibliographic Citation: Non-synfuel uses of oil shale". United States Department of Energy. http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6567632. Retrieved 2008-03-20.
  25. West, Ian (2008-01-06). "Kimmeridge - The Blackstone - Oil Shale". University of Southampton. http://www.soton.ac.uk/~imw/Kimmeridge-Oil-Shale.htm. Retrieved 2010-08-07.
  26. 26.0 26.1 26.2 Script error
  27. Doscher, Todd M.. "Petroleum". MSN Encarta. Archived from the original on 2008-05-12. http://web.archive.org/web/20080512122018re_/encarta.msn.com/encyclopedia_761576221/petroleum.html. Retrieved 2008-04-22.
  28. "Oil Shale". American Association of Petroleum Geologists. http://emd.aapg.org/technical_areas/oil_shale.cfm. Retrieved 2008-03-31.
  29. 29.0 29.1 Yin, Liang (2006-11-07). "Current status of oil shale industry in Fushun, China" (PDF). International Oil Shale Conference. Amman, Jordan. http://www.sdnp.jo/International_Oil_Conference/rtos-A106.pdf. Retrieved 2007-06-29.
  30. Collier, Robert (2006-09-04). "Coaxing oil from huge U.S. shale deposits". San Francisco Chronicle. http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/09/04/MNGIEKV0D41.DTL. Retrieved 2008-05-14.
  31. "Nominations for Oil Shale Research Leases Demonstrate Significant Interest in Advancing Energy Technology" (Press release). Bureau of Land Management. 2005-09-20. http://www.blm.gov/wo/st/en/info/newsroom/2005/september/NR_050920.html. Retrieved 2007-07-10.
  32. "What's in the Oil Shale and Tar Sands Leasing Programmatic EIS". Oil Shale and Tar Sands Leasing Programmatic EIS Information Center. http://ostseis.anl.gov/eis/what/index.cfm. Retrieved 2007-07-10.
  33. 33.0 33.1 33.2 33.3 Script error
  34. Script error
  35. "Importance of Future Oil Shale Industry Plans for Estonia". Estonian Ministry of Economic Affairs and Communications. 2009-06-08. http://www.mkm.ee/june-8th-2009-oil-shale-conference-in-tallinn-univer/. Retrieved 2009-09-02.
  36. Script error
  37. Script error
  38. 38.0 38.1 38.2 Script error
  39. Burnham, Alan K.; McConaghy, James R. (2006-10-16). "Comparison of the Acceptability of Various Oil Shale Processes" (PDF). 26th Oil Shale Symposium. Golden, Colorado: Lawrence Livermore National Laboratory. UCRL-CONF-226717. https://e-reports-ext.llnl.gov/pdf/341283.pdf. Retrieved 2007-06-23.
  40. Script error
  41. Script error
  42. 42.0 42.1 Script error
  43. "Process for the recovery of hydrocarbons from oil shale". FreePatentsOnline. http://www.freepatentsonline.com/4449586.html. Retrieved 2007-11-03.
  44. Script error
  45. Qian, Jialin; Wang, Jianqiu; Li, Shuyuan (2007-10-15). "One Year's Progress in the Chinese Oil Shale Business" (PDF). 27th Oil Shale Symposium. Golden, Colorado: China University of Petroleum. http://www.ceri-mines.org/documents/27symposium/presentations/av02-1qian.pdf. Retrieved 2011-05-06.
  46. Script error
  47. Valgma, Ingo. "Map of oil shale mining history in Estonia". Mining Institute of Tallinn Technical University. http://www.ene.ttu.ee/maeinstituut/mgis/mapofhistory.htm. Retrieved 2007-07-21.
  48. Script error
  49. Script error
  50. Script error
  51. Kolbert, Elizabeth (2007-11-12). "A Reporter at Large:Unconventional Crude". The New Yorker. http://www.newyorker.com/reporting/2007/11/12/071112fa_fact_kolbert. Retrieved 2008-03-31.
  52. Script error
  53. 53.0 53.1 Seebach, Linda (2005-09-02). "Shell's ingenious approach to oil shale is pretty slick". Rocky Mountain News. Archived from the original on 2008-04-20. http://web.archive.org/web/20080420145917/http://www.rockymountainnews.com/drmn/news_columnists/article/0,1299,DRMN_86_4051709,00.html. Retrieved 2007-06-02.
  54. Script error
  55. Script error
  56. Script error
  57. Script error
  58. Script error
  59. Script error
  60. Script error
  61. Script error
  62. Reiss, Spencer (2005-12-13). "Tapping the Rock Field". WIRED Magazine. http://www.wired.com/wired/archive/13.12/oilshale.html. Retrieved 2007-08-27.
  63. Western Oil Shale Has a High Mercury Content http://www.westernresearch.org/uploadedFiles/Energy_and_Environmental_Technology/Unconventional_Fuels/Oil_Shale/MercuryinOilShale.pdf
  64. 64.0 64.1 Script error
  65. Script error
  66. Kosich, Dorothy (2008-04-11). "Repeal sought for ban on U.S. Govt. use of CTL, oil shale, tar sands-generated fuel". Mine Web. http://www.mineweb.com/mineweb/view/mineweb/en/page38?oid=50551&sn=Detail. Retrieved 2008-05-27.
  67. Bloom, David I.; Waldron, Roger; Layton, Duane W.; Patrick, Roger W. (2008-03-04). "Energy Independence and Security Act Provision Poses Major Problems for Synthetic and Alternative Fuels" (PDF). Mayer Brown. http://www.mayerbrown.com/publications/article.asp?id=4313&nid=6. Retrieved 2008-05-27.
  68. Bartis, Jim (2006-10-26). "Unconventional Liquid Fuels Overview" (PDF). World Oil Conference. Association for the Study of Peak Oil & Gas - USA. http://www.aspo-usa.com/fall2006/presentations/pdf/Bartis_J_Boston_2006.pdf. Retrieved 2007-06-28.
  69. Sims, G. K. and E.J. O'Loughlin. 1989. Degradation of pyridines in the environment. CRC Critical Reviews in Environmental Control. 19(4): 309-340.
  70. 70.0 70.1 Script error
  71. "Critics charge energy, water needs of oil shale could harm environment". U.S. Water News Online. July 2007. Archived from the original on 2008-06-18. http://web.archive.org/web/20080618074850/http://www.uswaternews.com/archives/arcsupply/7critchar7.html. Retrieved 2008-04-01.
  72. Al-Ayed, Omar (2008). "Jordan Oil Shale Project". Al-Balqa` Applied University. Archived from the original on 2008-06-03. http://web.archive.org/web/20080603231353/http://www.jordanoilshale.net/page4.aspx. Retrieved 2008-08-15.
  73. Script error
  74. Speckman, Stephen (2008-03-22). "Oil-shale 'rush' is sparking concern". Deseret Morning News. http://www.deseretnews.com/article/695263708/Oil-shale-rush-is-sparking-concern.html. Retrieved 2011-05-06.
  75. "Climate-changing shale oil industry stopped". Greenpeace Australia Pacific. 2005-03-03. http://www.greenpeace.org/australia/news-and-events/media/releases/climate-change/climate-changing-shale-oil-ind. Retrieved 2007-06-28.
  76. "Greenpeace happy with part closure of shale oil plant". Australian Broadcasting Corporation. 2004-07-22. http://www.abc.net.au/news/newsitems/200407/s1159133.htm. Retrieved 2008-05-19.
  77. Anderson, Campbell (2002-05-02). "Greenpeace vs the future of Australian oil shale" (PDF). The 53rd Sydney Mining Club. Sydney. http://www.smedg.org.au/miningc/SMCMay02text.pdf. Retrieved 2009-04-10.

External links

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