Oil shale industry
Oil shale industry is an industry of mining and processing of oil shale—a fine-grained sedimentary rock, containing significant amounts of kerogen (a solid mixture of organic chemical compounds), from which liquid hydrocarbons can be manufactured. The industry has developed in Brazil, China, Estonia and to some extent in Germany and Russia. Several other countries are currently conducting research on their oil shale reserves and production methods to improve efficiency and recovery. However, Australia has halted their pilot projects due to environmental concerns. Estonia accounts for about 70% of the world's oil shale production.
Oil shale has been used for industrial purposes since the early 17th century, when it was mined for its minerals. Since the late 19th century, shale oil has also been used for its oil content and as a low grade fuel for power generation. However, barring countries having significant oil shale deposits, its use for power generation is not particularly widespread. Similarly, oil shale is a source for production of synthetic crude oil and it is seen as a solution towards increasing domestic production of oil in countries that are reliant on imports.
Oil shale has been used since ancient times. Modern industrial oil shale mining began in 1837 at the Autun mines in France, followed by Britain, Germany and several other countries. The oil shale industry started growing just before World War I because of the mass production of automobiles and trucks and the supposed shortage of gasoline for transportation needs. In 1924, the Tallinn Power Plant was the first power plant in the world to switch to oil shale firing.
Following the end of World War II, the oil shale industry declined due to the discovery of large supplies of easily accessible and cheaper crude oil. Oil shale production however, continued to grow in Estonia, Russia and China.
Following the 1973 oil crisis, the oil shale industry was restarted in several countries, but in the 1980s, when oil prices fell, many industries faced closure. The global oil shale industry has grown again from the mid-1990s. In 2003, the oil shale development program was initiated in the United States, and in 2005, the commercial leasing program for oil shale and tar sands was introduced.
As of May 2007, Estonia is actively engaged in exploitation of oil shale on a significant scale and accounts for 70% of the world's processed oil shale. Estonia is unique in that its oil shale deposit account for just 17% of total deposits in European Union but it generates 90% of its power from oil shale. Oil shale industry in Estonia employs 7,500 people, which is about 1% of national employment, accounting for 4% of its gross domestic product.
Oil shale is mined either by traditional underground mining or surface mining techniques. There are several mining methods available, but the common aim of all these methods is to fragment the oil shale deposits in order to enable the transport of shale fragments to a power plant or retorting facility. The main methods of surface mining are open pit mining and strip mining. An important method of sub-surface mining is the room-and-pillar method. In this method, the material is extracted across a horizontal plane while leaving "pillars" of untouched material to support the roof. These pillars reduce the likelihood of a collapse. Oil shale can also be obtained as a by-product of coal mining.
The largest oil shale mine in the world is the Estonia Mine, operated by Eesti Energia Kaevandused. In 2005, Estonia mined 14.8 million tonnes of oil shale. During the same period, mining permits were issued for almost 24 million tonnes, with applications being received for mining an additional 26 million tonnes. In 2008, the Estonian Parliament approved the "National Development Plan for the Use of Oil Shale 2008-2015", which limits the annual extraction of oil shale to 20 million tonnes.
Oil shale can be used as a fuel in thermal power plants, wherein oil shale is burnt like coal to drive the steam turbines. As of 2012, there are oil shale-fired power plants in Estonia with a generating capacity of 2,967 megawatts (MW), China, and Germany. Also Israel, Romania and Russia have run oil shale-fired power plants, but have shut them down or switched to other fuels like natural gas. Jordan and Egypt have announced their plans to construct oil shale-fired power plants, while Canada and Turkey plan to burn oil shale at the power plants along with coal.
Thermal power plants which use oil shale as a fuel mostly employ two types of combustion methods. The traditional method is Pulverized combustion (PC) which is used in the older units of oil shale-fired power plants in Estonia, while the more advanced method is Fluidized bed combustion (FBC), which is used in the Holcim cement factory in Dotternhausen, Germany, and was used in the Mishor Rotem power plant in Israel. The main FBC technologies are Bubbling fluidized bed combustion (BFBC) and Circulating fluidized bed combustion (CFBC).
There are more than 60 power plants around the world, which are using CFBC technology for combustion of coal and lignite, but only two new units at Narva Power Plants in Estonia, and one at Huadian Power Plant in China use CFBC technology for combustion of oil shale. The most advanced and efficient oil shale combustion technology is Pressurized fluidized-bed combustion (PFBC). However, this technology is still premature and is in its nascent stage.
As of 2008[update], the major shale oil producers are Estonia, Brazil and China, while Australia, USA, Canada and Jordan have planned to set up or restart shale oil production. According to the World Energy Council, in 2008 the total production of shale oil from oil shale was 930,000 tonnes, equal to 17,700 barrels per day (2,810 m3/d), of which China produced 375,000 tonnes, Estonia 355,000 tonnes, and Brazil 200 tonnes. In comparison, production of the conventional oil and natural gas liquids in 2008 amounted 3.95 billion tonnes or 82.12 million barrels per day (13.056×106 m3/d).
Although there are several oil shale retorting technologies, only four technologies are currently in commercial use. These are Kiviter, Galoter, Fushun, and Petrosix. The two main methods of extracting oil from shale are ex-situ and in-situ. In ex-situ method, the oil shale is mined and transported to the retort facility in order to extract the oil. The in-situ method converts the kerogen while it is still in the form of an oil shale deposit, and then extracts it via a well, where it rises up as normal petroleum.
|Aqaba Petroleum||Al Attarat, Jordan||Hot recycled solids (Galoter process)||Memorandum of understanding|
|Ambre Energy||Utah, USA||Conduction through a wall (Oil-Tech process)||Pilot project|
|American Shale Oil
(parent: Genie Oil & Gas and Total S.A.)
|Colorado, USA||True in-situ process (Conduction, Convection, Reflux Conversion Process)||Pilot project|
|Beipiao Coal Mining Company||Beipiao, Liaoning, China||Internal combustion (Fushun process)||Operational|
|Daqing Oil Company
|Mudanjiang, Heilongjiang, China||Hot recycled solids||Under construction|
|Eesti Energia||Narva, Estonia||Hot recycled solids (Galoter process)
Hot recycled solids (Enefit process)
|1.2 million barrels
|Enefit American Oil
(parent: Eesti Energia)
|Utah, USA||Hot recycled solids (Enefit process)||Testing|
|EnShale||Utah, USA||Externally generated hot gas||Testing|
|ExxonMobil||Colorado, USA||Modified in-situ process; reactive fluids (ExxonMobil Electrofrac)||Testing|
|Fushun Mining Group||Fushun, China||Internal combustion (Fushun process)
Hot solids recycle (Alberta Taciuk Process)
|2.2 million barrels
|Hong Sheng Energy Company||Huadian, Jilin, China||Internal combustion (Modified Fushun process)||Operational|
|Independent Energy Partners||Colorado, USA||True in-situ process (fuel cell process)||Testing|
|Inter RAO||Al Attarat, Jordan||Hot recycled solids (Galoter process)||Memorandum of understanding|
|Israel Energy Initiatives
(parent: Genie Oil & Gas)
|Shfela region, Israel||True in-situ process||Testing|
|Jordan Oil Shale Energy Company
(parent: Eesti Energia)
|Attarat Umm Ghudran, Jordan||Hot recycled solids (Enefit process)||Testing|
|Jordan Oil Shale Company
(parent: Royal Dutch Shell)
|Azraq and Al-Jafr blocks, Jordan||True in-situ process (ICP)||Testing|
|Karak International Oil
(parent: Jordan Energy and Mining)
|El Lajjun, Jordan||Hot recycled solids (Alberta Taciuk process)||Concession agreement signed|
|Kiviõli Keemiatööstus||Kiviõli, Estonia||Internal combustion (Kiviter process)||Operational||0.3 million barrels|
|Liaoning Chengda||Jimsar County, Xinjiang, China||Internal combustion (Modified Fushun process)||Under construction|
|Longhua Harbin Coal Chemical Industry Company
(parent: China National Coal Corporation)
|Yilan, Heilongjiang, China||Hot recycled solids||Demonstration project|
|Longkou Mining Group
(parent: Shandong Energy)
|Longkou, China||Internal combustion (Fushun process)||Operational||0.7 million barrels (2011)|
|Mountain West Energy||Utah, USA||True in-situ process (IGE process)||Testing|
|Northwood Exploration Israel||Mishor Rotem, Israel||Hot recycled solids (Galoter process)||Feasibility study|
|Petrobras||São Mateus do Sul, Paraná, Brazil||Externally generated hot gas (Petrosix process)||Operational||2.2 million barrels
|Attarat Umm Ghudran, Jordan||Externally generated hot gas (Petrosix process)||memorandum of understanding|
|Timahdit, Morocco||Externally generated hot gas (Petrosix process)||memorandum of understanding|
|Queensland Energy Resources||Stuart Deposit, Queensland, Australia||Externally generated hot gas (Paraho Indirect process)||Completed two-year technology demonstration program producing ultra-low sulphur diesel and aviation fuel|
|Red Leaf Resources||Utah, USA||Conduction through a wall (EcoShale In-Capsule Process)||Testing|
|TomCo Energy||Utah, USA||Conduction through a wall (EcoShale In-Capsule Process)||Planning and permitting|
|San Leon Energy||Tarfaya, Morocco||True in-situ process (IGE process)
Hot recycled solids (Enefit process)
|Memorandum of understanding|
|Saudi Arabian International Corporation for Oil Shale Investment||El Lajjun and Attarat Umm Ghudran, Jordan||Hot recycled solids (Galoter process)||Memorandum of understanding|
|Shale Technologies LLC||Rifle, Colorado, USA||Internal combustion (Paraho Direct process)||Pilot project|
|Shell Frontier Oil and Gas||Colorado, USA||True in-situ process (ICP)||Pilot project|
|Uzbekneftegaz||Sangruntau, Uzbekistan||Hot recycled solids (Galoter process)||Construction started|
|VKG Oil||Kohtla-Järve, Estonia||Internal combustion (Kiviter process)
Hot solids recycle (Petroter process)
|Operational||2.2 million barrels
|Wangqing County Longteng Energy Development Co.||Wangqing, Jilin, China||Internal combustion (Fushun process)||Operational|
|Yaojie Coal Electricity Group||Gansu, China||Internal combustion (Gas combustion retort)||Operational|
Other industrial uses
Oil shale is used for cement production by Kunda Nordic Cement in Estonia, by Holcim in Germany, and by Fushun cement factory in China. Oil shale can also be used for production of different chemical products, construction materials, and pharmaceutical products, e.g. ammonium bituminosulfonate. However, use of oil shale for production of these products is still very rare and in experimental stages only.
Some oil shales are suitable source for sulfur, ammonia, alumina, soda ash, and nahcolite which occur as shale oil extraction byproducts. Some oil shales can also be used for uranium and other rare chemical element production. During 1946–1952, a marine variety of Dictyonema shale was used for uranium production in Sillamäe, Estonia, and during 1950–1989 alum shale was used in Sweden for the same purpose. Oil shale gas can also be used as a substitute for natural gas. After World War II, Estonian-produced oil shale gas was used in Leningrad and the cities in North Estonia. However, at the current price level of natural gas, this is not economically feasible.
The amount of economically recoverable oil shale is unknown. 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 shale oil at a hypothetical 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. Assuming a gradual increase in output after the start of commercial production, the analysis projects a gradual reduction in processing costs to $30–40 per barrel ($190–250/m3) after achieving the milestone of 1 billion barrels (160×106 m3). Royal Dutch Shell has announced that its Shell ICP technology would realize a profit when crude oil prices are higher than $30 per barrel ($190/m3), while some technologies at full-scale production assert profitability at oil prices even lower than $20 per barrel ($130/m3).
To increase the efficiency of oil shale retorting and by this the viability of the shale oil production, researchers have proposed and tested several co-pyrolysis processes, in which other materials such as biomass, peat, waste bitumen, or rubber and plastic wastes are retorted along with the oil shale. Some modified technologies propose combining a fluidized bed retort with a circulated fluidized bed furnace for burning the by-products of pyrolysis (char and oil shale gas) and thereby improving oil yield, increasing throughput, and decreasing retorting time.
In a 1972 publication by the journal Pétrole Informations (ISSN 0755-561X), shale oil production was unfavorably compared to the coal liquefaction. The article stated that coal liquefaction was less expensive, generated more oil, and created fewer environmental impacts than oil shale extraction. It cited a conversion ration of 650 litres (170 U.S. gal; 140 imp gal) of oil per one tonne of coal, as against 150 litres (40 U.S. gal; 33 imp gal) of shale oil per one tonne of oil shale.
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 although known oil-shale extraction development projects assert an EROEI between 3 to 10. According to the World Energy Outlook 2010, the EROEI of ex-situ processing is typically 4 to 5 while of in-situ processing it may be even as low as 2. However, according to the IEA most of used energy can be provided by burning the spent shale or oil-shale gas.
The water needed in the oil shale retorting process offers an additional economic consideration: this may pose a problem in areas with water scarcity.
Oil shale mining 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 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. 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.
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. 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. 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.
Concerns have been prominently raised over the oil shale industry's use of water, particularly in arid regions where water consumption is a sensitive issue. In some cases, oil shale mining requires the lowering of groundwater levels below the level of the oil shale strata, which may affect the surrounding arable land and forest. Above-ground retorting typically consumes between one and five barrels of water per barrel of produced shale oil, depending on technology. Water is usually used for spent shale cooling and oil shale ash disposal. In situ processing, according to one estimate, uses about one-tenth as much water.
A 2008 programmatic environmental impact statement issued by the United States Bureau of Land Management stated that surface mining and retort operations produce 2 to 10 U.S. gallons (7.6 to 37.9 l; 1.7 to 8.3 imp gal) of waste water per 1 short ton (0.91 t) of processed oil shale.
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.
- Dyni, John R. (2010). "Oil Shale" (PDF). In Clarke, Alan W.; Trinnaman, Judy A. Survey of energy resources (22 ed.). WEC. pp. 93–123. ISBN 978-0-946121-02-1. Retrieved 2012-04-22.
- Greenpeace Australia Pacific (2005-03-03). "Climate-changing shale oil industry stopped". Retrieved 2007-06-28.
- "Non-Nuclear Energy Research in Europe – A comparative study. Country Reports A – I. Volume 2" (PDF). European Commission. Directorate-General for Research. 2005. EUR 21614/2. Retrieved 2007-06-29.
- Allix, Pierre; Burnham, Alan K. (2010-12-01). "Coaxing Oil from Shale" (PDF). Oilfield Review (Schlumberger) 22 (4): 6. Retrieved 2012-04-18.
- Laherrère, Jean (2005). "Review on oil shale data" (PDF). Hubbert Peak. Retrieved 2007-06-17.
- Ots, Arvo (2007-02-12). "Estonian oil shale properties and utilization in power plants" (PDF). Energetika (Lithuanian Academy of Sciences Publishers) 53 (2): 8–18. Retrieved 2011-05-06.
- Dyni, John R. (2006). Geology and resources of some world oil-shale deposits. Scientific Investigations Report 2005–5294 (PDF). United States Geological Survey. Retrieved 2011-11-15.
- Yin, Liang (2006-11-07). "Current status of oil shale industry in Fushun, China" (PDF). Amman, Jordan: International Oil Shale Conference. Retrieved 2007-06-29.
- "Nominations for Oil Shale Research Leases Demonstrate Significant Interest in Advancing Energy Technology. Press release" (Press release). Bureau of Land Management. 2005-09-20. Retrieved 2007-07-10.
- "What's in the Oil Shale and Tar Sands Leasing Programmatic EIS". Oil Shale and Tar Sands Leasing Programmatic EIS Information Center. Retrieved 2007-07-10.
- "Tiny Estonia could go nuclear, sees oil shale hope". BBJ. 2008-03-06. Retrieved 2010-10-09.
- Francu, Juraj; Harvie, Barbra; Laenen, Ben; Siirde, Andres; Veiderma, Mihkel (May 2007). "A study on the EU oil shale industry viewed in the light of the Estonian experience. A report by EASAC to the Committee on Industry, Research and Energy of the European Parliament" (PDF). European Academies Science Advisory Council. pp. 12–13; 18–19; 23–24; 28. Retrieved 2010-06-21.
- Bartis, James T.; LaTourrette, Tom; Dixon, Lloyd; Peterson, D.J.; Cecchine, Gary (2005). "Oil Shale Development in the United States. Prospects and Policy Issues. Prepared for the National Energy Technology Laboratory of the U.S. Department of Energy" (PDF). The RAND Corporation. ISBN 978-0-8330-3848-7. Retrieved 2007-06-29.
- "Minister of Social Affairs Jaak Aab acquainted himself with the working conditions of the miners" (Press release). Eesti Põlevkivi. 2006-01-25. Archived from the original on 2007-08-14. Retrieved 2007-07-29.
- "Mining and use of oil shale to be based on interests of state". Ministry of the Environment of Estonia. 2008. Retrieved 2008-03-06.
- "Riigikogu approves development plan for use of oil shale". Ministry of the Environment of Estonia. 2008. Retrieved 2008-11-02.
- Brendow, K. (2003). "Global oil shale issues and perspectives. Synthesis of the Symposium on Oil Shale. 18–19 November, Tallinn" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 20 (1): 81–92. ISSN 0208-189X. Retrieved 2007-07-21.
- 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. Retrieved 2011-05-08.
- Azulai, Yuval (2011-03-22). "We are not drying up the Dead Sea". Globes. Retrieved 2012-03-15.
- Alali, Jamal (2006-11-07). "Jordan Oil Shale, Availability, Distribution, And Investment Opportunity" (PDF). Amman, Jordan: International Oil Shale Conference. Retrieved 2008-03-04.
- Alali, Jamal; Abu Salah, Abdelfattah; Yasin, Suha M.; Al Omari, Wasfi (2006). "Oil Shale in Jordan" (PDF). Natural Resources Authority of Jordan. Retrieved 2007-06-29.
- Liive, Sandor (2007). "Oil Shale Energetics in Estonia" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 24 (1): 1–4. ISSN 0208-189X. Retrieved 2007-10-23.
- Liblik, V.; Kaasik, M.; Pensa, M.; Rätsep, A.; Rull, E.; Tordik, A. (2006). "Reduction of sulphur dioxide emissions and transboundary effects of oil shale based energy production" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 23 (1): 29–38. ISSN 0208-189X. Retrieved 2007-06-16.
- Agabus, H.; Landsberg, M.; Tammoja, H. (2007). "Reduction of CO2 emissions in Estonia during 2000–2030" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 24 (2 Special): 209–224. ISSN 0208-189X. Retrieved 2007-09-02.
- Qian, Jialin; Wang Jianqiu (2006-11-07). "World oil shale retorting technologies" (PDF). International Oil Shale Conference. Amman, Jordan: Jordanian Natural Resources Authority. Retrieved 2007-06-29.
- 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. Retrieved 2007-05-27.
- Secure Fuels from Domestic Resources: The Continuing Evolution of America's Oil Shale and Tar Sands Industries (PDF) (5th ed.). United States Department of Energy. 2010. Retrieved 2012-03-15.
- Li, Shuyuan (2012). "The developments of Chinese oil shale activities" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 29 (2): 101–102. doi:10.3176/oil.2012.2.01. ISSN 0208-189X. Retrieved 2012-05-31.
- "Eesti Energia Annual Report 2010/2011" (PDF). Eesti Energia. 2011. Retrieved 2012-05-16.
- "Atomenergoproekt have completed a conceptual design for 8 x UTT-3000 complex in Uzbekistan (Sangruntau)". TTU Ltd. 2012-11-20. Retrieved 2013-03-31.
- Jafarova, Aynur (2013-05-13). "Oil-shale processing plant to be commissioned in Uzbekistan by 2016". AzerNews. Retrieved 2014-03-10.
- "Yearbook 2011" (PDF). Viru Keemia Grupp AS. 2011. Retrieved 2012-05-16.
- Koel, Mihkel (1999). "Estonian oil shale". Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) (Extra). ISSN 0208-189X. Retrieved 2007-07-21.
- Ingo Valgma. "Map of oil shale mining history in Estonia". Mining Institute of Tallinn University of Technology. Retrieved 2007-07-21.
- Schora, F. C.; Tarman, P. B.; Feldkirchner, H. L.; Weil, S. A. (1976). "Hydrocarbon fuels from oil shale". Proceedings (American Institute of Chemical Engineers) 1: 325–330. A77-12662 02-44.
- IEA (2010). World Energy Outlook 2010. Paris: OECD. pp. 165–169. ISBN 978-92-64-08624-1.
- Rapier, Robert (2006-06-12). "Oil Shale Development Imminent". R-Squared Energy Blog. Retrieved 2007-06-22.
- Schmidt, S. J. (2003). "New directions for shale oil:path to a secure new oil supply well into this century: on the example of Australia" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 20 (3): 333–346. ISSN 0208-189X. Retrieved 2007-06-02.
- Seebach, Linda (2005-09-02). "Shell's ingenious approach to oil shale is pretty slick". Rocky Mountain News. Archived from the original on 2007-04-30. Retrieved 2007-06-02.
- Johnson, Harry R.; Crawford, Peter M.; Bunger, James W. (March 2004). "Strategic Significance of America's Oil Shale Resource. Volume II Oil Shale Resources, Technology and Economics" (PDF). United States Department of Energy. Retrieved 2014-02-09.
- Tiikma, Laine; Johannes, Ille; Pryadka, Natalja (2002). "Co-pyrolysis of waste plastics with oil shale". Proceedings. Symposium on Oil Shale 2002, Tallinn, Estonia: 76.
- Tiikma, Laine; Johannes, Ille; Luik, Hans (March 2006). "Fixation of chlorine evolved in pyrolysis of PVC waste by Estonian oil shales". Journal of Analytical and Applied Pyrolysis 75 (2): 205–210. doi:10.1016/j.jaap.2005.06.001.
- Veski, R.; Palu, V.; Kruusement, K. (2006). "Co-liquefaction of kukersite oil shale and pine wood in supercritical water" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 23 (3): 236–248. ISSN 0208-189X. Retrieved 2007-06-16.
- Aboulkas, A.; El Harfi, K.; El Bouadili, A.; Benchanaa, M.; Mokhlisse, A.; Outzourit, A. (2007). "Kinetics of co-pyrolysis of Tarfaya (Morocco) oil shale with high-density polyethylene" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 24 (1): 15–33. ISSN 0208-189X. Retrieved 2007-06-16.
- Ozdemir, M.; A. Akar, A. Aydoğan, E. Kalafatoglu; E. Ekinci (2006-11-07). "Copyrolysis of Goynuk oil shale and thermoplastics" (PDF). International Oil Shale Conference. Amman, Jordan: Jordanian Natural Resources Authority. Retrieved 2007-06-29.
- Siirde, Andres; Martins, Ants (2009-06-07). "Oil shale fluidized bed retorting technology with CFB furnace for burning the by-products" (PDF). International Oil Shale Symphosium. Tallinn, Estonia: Tallinn University of Technology. Retrieved 2009-05-22.
- Cleveland, Cutler J.; Costanza, Robert; Hall, Charles A. S.; Kaufmann, Robert (1984-08-31). "Energy and the U.S. Economy: A Biophysical Perspective". Science (American Association for the Advancement of Science) 225 (4665): 890–897. doi:10.1126/science.225.4665.890. ISSN 0036-8075. PMID 17779848.
- Burnham, A. K. (2003-08-20). "Slow Radio-Frequency Processing of Large Oil Shale Volumes to Produce Petroleum-like Shale Oil" (PDF). Lawrence Livermore National Laboratory. UCRL-ID-155045. Retrieved 2007-06-28.
- "Environmental Impacts from Mining" (PDF). US Office of Surface Mining Reclamation and Enforcement. 2006-08-02. Retrieved 2008-03-29.
- Raukas, Anto (2004). "Opening a new decade" (PDF). Oil Shale. A Scientific-Technical Journal (Estonian Academy Publishers) 21 (1): 1–2. ISSN 0208-189X. Retrieved 2008-05-14.
- "Driving It Home. Choosing the Right Path for Fueling North America's Transportation Future" (PDF). Natural Resources Defense Council. June 2007. Retrieved 2008-04-19.
- Kosich, Dorothy (2008-04-11). "Repeal sought for ban on U.S. Govt. use of CTL, oil shale, tar sands-generated fuel". Mine Web. Retrieved 2008-05-27.
- Bloom David I, Waldron Roger, Layton Duane W, Patrick Roger W (2008-03-04). "United States: Energy Independence And Security Act Provision Poses Major Problems For Synthetic And Alternative Fuels". Retrieved 2008-05-27.
- Bartis, Jim, RAND Corporation (2006-10-26). "Unconventional Liquid Fuels Overview. 2006 Boston World Oil Conference" (PDF). Association for the Study of Peak Oil & Gas - USA. Retrieved 2007-06-28.
- Speckman, Stephen (2008-03-22). "Oil-shale 'rush' is sparking concern". Deseret News (Deseret News Publishing Co.). ISSN 0745-4724. Retrieved 2008-08-24.
- "Chapter 4. Effects of Oil Shale Technologies" (PDF). Proposed Oil Shale and Tar Sands Resource Management Plan Amendments to Address Land Use Allocations in Colorado, Utah, and Wyoming and Final Programmatic Environmental Impact Statement. Bureau of Land Management. September 2008. pp. 4‑3. FES 08-32. Retrieved 2010-08-07.
- Fischer, Perry A. (August 2005). "Hopes for shale oil are revived". World Oil Magazine (Gulf Publishing Company). Archived from the original on 2008-06-17. Retrieved 2010-06-21.
- "Climate-changing shale oil industry stopped". Greenpeace Australia Pacific. 2005-03-03. Retrieved 2007-06-28.
- "Greenpeace happy with part closure of shale oil plant". Australian Broadcasting Corporation. 2004-07-22. Retrieved 2008-05-19.