Oil shale extraction

Oil shale extraction is an industrial process in which kerogen—a mixture of organic chemical compounds (including hydrocarbons) found in oil shale—is converted into synthetic crude oil through pyrolysis. In pyrolysis, oil shale is heated in the absence of oxygen until its kerogen decomposes into a petroleum-like condensable shale oil—a form of non-conventional oil—and combustible shale gas (shale gas can also refer to the gases that occur naturally in shales). In addition, oil shale extraction produces a solid residue—spent shale. The temperature when perceptible decomposition of oil shale occurs depends on the time-scale of the process; in the above ground retorting process the decomposition begins at convert|300|°C|°F|-1, but proceeds more rapidly and completely at higher temperatures.Cite journal
last=Koel|first=Mihkel
title=Estonian oil shale
journal=Oil Shale. A Scientific-Technical Journal
publisher=Estonian Academy Publishers
issue=Extra
year=1999
url=http://www.kirj.ee/public/oilshale/Est-OS.htm
issn=0208-189X
accessdate=2007-07-21] For the modern "in-situ" (underground) process, which might take several months of heating, decomposition starts as low as convert|250|°C|°F|-1.

Oil shale pyrolysis is commonly performed above ground ("ex-situ" processing), although some newer technologies perform the process underground (on-site or "in-situ" processing). A number of oil shale pyrolysis and retorting technologies have been patented. While a few dozen have been tested in a pilot plant (with a capacity between 1 and 10 tonnes of oil shale per hour), fewer than ten technologies are known to have been tested at a demonstration scale (40 to 400 tonnes per hour). As of 2008, only four technologies are in commercial use: Kiviter, Galoter, Fushun, and Petrosix.Cite conference
last=Qian|first=Jialin
coauthors = Wang Jianqiu
title=World oil shale retorting technologies
publisher = International Oil Shale Conference
date=2006-11-07
location = Amman, Jordan
url=http://www.sdnp.jo/International_Oil_Conference/rtos-A118.pdf
format=PDF
accessdate=2007-06-29]

Pyrolysis is endothermic; it requires an external source of energy. Most technologies use combustion of the shale or other fuels to generate heat, although some experimental extraction methods use electricity, radio frequency and microwaves, and reactive fluids for this purpose. Non-condensible retort shale gas and char—carbonaceous residue formed from kerogen—may be burned as an additional source of energy, and the heat of the spent shale may be reused to pre-heat the raw oil shale. A variety of direct and indirect methods are used for heat transfer. Almost all of the commercial retorts currently in operation or under development are internal heating retorts.

Oil shale has gained attention as an energy resource due to rising prices of conventional hydrocarbons such as petroleum.Cite web
title = Oil Shale Activities
publisher = United States Department of Energy
url = http://www.fossil.energy.gov/programs/reserves/npr/npr_oil_shale_program.html
accessdate =2007-10-20] By 2008, oil shale extraction was being undertaken in Estonia, Brazil and China, while Australia, USA, Canada and Jordan have planned to start or restore shale oil production.Cite journal
last=Brendow |first=K.
title=Global oil shale issues and perspectives. Synthesis of the Symposium on Oil Shale. 18-19 November, Tallinn
journal=Oil Shale. A Scientific-Technical Journal
publisher=Estonian Academy Publishers
volume=20
issue=1
pages=81–92
year=2003
url=http://www.kirj.ee/public/oilshale/9_brendow_1_03.pdf
format=PDF
issn=0208-189X
accessdate=2007-07-21] Cite paper
last=Hamarneh |first=Yousef
title=Oil Shale Resources Development In Jordan
location=Amman
publisher=Natural Resources Authority of Jordan
date=1998; 2006
url = http://www.nra.gov.jo/images/stories/pdf_files/Updated_Report_2006.pdf
format=PDF
accessdate=2007-06-16] The shale oil may be used as a fuel oil or upgraded to meet refinery feedstock specifications by adding hydrogen and removing impurities such as sulfur and nitrogen.

Oil shale processing involves a number of environmental management issues, such as waste disposal, extensive water use and waste water management, and air pollution.

Classifications

Industry analysts have created several classifications of the methods by which hydrocarbons are extracted from oil shale.

By location

A frequently-used distinction considers whether retorting is done above or below ground, and classifies the technologies broadly as "ex situ" (displaced) or "in situ" (in place). In the "ex situ" process, also known as above-ground retorting, the oil shale is mined and transported to a retort facility. In contrast, the "in situ" method converts the kerogen while it is still in the form of an oil shale deposit; it is then extracted via an oil well, where it rises in the same way as conventional petroleum.

By retort style

Based on the materials and techniques used to heat the oil shale to an appropriate temperature, its processing has been classified into internal combustion, hot recycled solids, wall conduction, externally-generated hot gas, reactive fluid, and volumetric heating methods. There are many possible realizations and combinations of these methods; therefore the following table is representative but not complete. Some processes are difficult to classify due to their unique methods of heat input (e.g. ExxonMobil's Electrofrac) or due to limited information.Cite paper
last = Burnham | first = Alan K.
last2 = McConaghy | first2 = James R.
title = Comparison of the acceptability of various oil shale processes
date = 2006-10-16
place =Golden
publisher = 26th Oil shale symposium
url =https://e-reports-ext.llnl.gov/pdf/341283.pdf
format = PDF
id =UCRL-CONF-226717
accessdate =2007-06-23]

The heating methods used to decompose the rock may be classified as direct or indirect. Internal combustion technologies, which burn materials within the retort, are classified as direct - all other heating technologies are described as indirect. Indirect processes are further separated by how the heat is delivered. Distinct heat delivery methods are with a recirculated hot solid, by conduction through a wall separating the heater from the shale, with an externally heated inert gas, with an externally heated reactive gas or liquid, or by way of electromagnetic radiation, which penetrates the rock without the thermal diffusion limitations of all other indirect methods.

The various "ex situ" extraction processes may be differentiated by the size of the oil shale particles that are fed into the retorts. As a rule, oil shale "lumps" varying in diameter from 10 to 100 millimetres (0.4 to 4 in) are used in internal hot gas carrier technologies, while oil shale that has been crushed into particulates less than convert|10|mm|in|1|disp=s in diameter is used in internal hot solid carrier technologies.

"Ex situ" technologies

In "ex situ" methods, the oil shale is mined either underground or at the surface and then transported to a processing facility. At the facility, the oil shale is heated, usually to between 450 °C and 500 °C (840 °F to 930 °F). At these temperatures the kerogen in the oil shale decomposes into gas, oil vapor, and char. This process is known as retorting. The gas and oil vapors are separated from the spent shale and cooled, causing the oil to condense.

Internal combustion

Internal combustion technologies burn materials within the retort to supply heat; the retort vapors mix with the exhaust generated by combustion. Lump oil shale is used as a feed. The principal technologies in this category are the Kiviter, Union A, Paraho Direct, Superior Direct, and Fushun processes.

In the Kiviter process, shale within a vertical shaft retort is brought to temperature by igniting coke residue (char) and non-condensable shale gas. Raw oil shale is fed into the top of the retort, and is heated by the rising combustion gases below it, which pass laterally through the descending oil shale. The shale oil vapors and evolving gases are directed into a collection chamber. After entering the collection chamber, the hot oil vapor is delivered to a condensing system. The shale residue is heated to about convert|900|°C|°F to burn off the char. Recycle gas enters the bottom of the retort and cools the spent shale, which then leaves the retort through a water-sealed discharge system. There are environmental issues associated with the Kiviter process; it uses large amounts of water, which is polluted during processing, and the solid waste residue contains water-soluble toxic substances that leach into the surrounding area.Cite journal
last=Mölder
first=Leevi
title=Estonian Oil Shale Retorting Industry at a Crossroads
journal= Oil Shale. A Scientific-Technical Journal
publisher=Estonian Academy Publishers
volume=21
issue=2
pages =97–98
year=2004
url=http://www.kirj.ee/public/oilshale/1_ed_page_2004_2.pdf
format=PDF
issn=0208-189X
accessdate =2007-06-23] Cite conference
last= Soone|first= Jüri
coauthors = Hella Riisalu, Ljudmilla Kekisheva, Svjatoslav Doilov
title = Environmentally sustainable use of energy and chemical potential of oil shale
publisher = International Oil Shale Conference
date = 2006-11-07
location = Amman, Jordan
url=http://www.sdnp.jo/International_Oil_Conference/rtos-A104.pdf
format=PDF
accessdate = 2007-06-29] The Kiviter process is used by the Estonian Viru Keemia Grupp's subsidiary VKG Oil.Cite paper
title =Strategic significance of America’s oil shale resource. Volume II: Oil shale resources, technology and economics
publisher= Office of Deputy Assistant Secretary for Petroleum Reserves; Office of Naval Petroleum and Oil Shale Reserves; United States Department of Energy
date=2004
url=http://www.fossil.energy.gov/programs/reserves/npr/publications/npr_strategic_significancev2.pdf
format=PDF
accessdate =2007-06-23] The company operates several Kiviter retorts, the largest of them having a processing capacity of 40 tonnes per hour of oil shale feedstock.

The Fushun process uses a vertical shaft retort similar to the Kiviter retort. The Fushun Mining Group in Liaoning Province, China, operates the largest shale oil plant in the world. In 2003, the group operated 80 Fushun retorts; by 2007 it was operating 180. Each retort processes about 4 tonnes of shale per hour.Cite journal
last=Purga |first=Jaanus
title =Today's rainbow ends in Fushun
journal=Oil Shale. A Scientific-Technical Journal
publisher= Estonian Academy Publishers
volume =21
issue =4
pages =269–272
year=2004
url=http://www.kirj.ee/public/oilshale/1_purga_2004_4.pdf
format=PDF
issn=0208-189X
accessdate =2007-06-23]

The Paraho Direct is a US version of a vertical shaft kiln.cite book
publisher = National Academy Press
title = Fuels to drive our future
author = Committee on Production Technologies for Liquid Transportation Fuels, Energy Engineering Board, National Research Council
url= http://books.nap.edu/openbook.php?record_id=1440&page=183
year = 1990
pages = 183
isbn=978-0-309-08645-5
accessdate=2008-05-04] This technology is used by Shale Technologies LLC in a pilot plant facility in Rifle, Colorado.cite web
publisher = Shale Technologies
title = Shale Technologies
url= http://www.shaletechnologies.com/home.html
accessdate=2007-06-24] cite web
publisher = Process Register, Inc.
title = Shale Technologies, LLC
url= http://www.processregister.com/Shale_Technologies_LLC/Supplier/sid28259.htm
accessdate=2008-08-15] cite paper
publisher = Regent Energy Corporation
title = Notes to financial statements to the U.S. Securities and Exchange Commission
url= http://sec.edgar-online.com/2001/02/14/0001078782-01-000002/Section6.asp
date = 2001-02-14
accessdate=2008-08-15
id = 10QSB SEC]

Hot recycled solids

Hot recycled solids technologies use solid particles—usually shale ash—to carry heat in the retorting zone. The principal technologies in this category include the Galoter, Alberta Taciuk, TOSCO II, Lurgi-Ruhrgas, Chevron STB, LLNL HRS, and Shell Spher processes. Typically, these technologies use retorts, fed by fine oil shale particles. While the particles are generally smaller than 10 mm in diameter, some technologies use particles even smaller than 2.5 mm. The particles are heated in a separate chamber or vessel, preventing the dilution of product gas with combustion exhaust. The Galoter (also known as TSK or SHC) process uses rotating kiln-type retort. In this process spent shale is burnt in a separate furnace. The resulting hot (convert|800|°C|°F|-1) ash is mixed with dried oil shale and is used as a heat carrier. The temperature of pyrolyis in the Galoter retort is convert|520|°C|°F|-1. This process creates less pollution than internal combustion technologies, as it uses less water, but it still generates carbon dioxide and the burning residue produces organic carbon disulfide and calcium sulfide. Two Galoter installations are used for oil production by Eesti Energia, an Estonian energy company. Both process 125 tonnes per hour of oil shale.Cite journal
last=Liive|first=Sandor
title=Oil Shale Energetics in Estonia
journal=Oil Shale. A Scientific-Technical Journal
publisher=Estonian Academy Publishers
volume=24
issue=1
pages=1–4
year=2007
url=http://www.kirj.ee/public/oilshale/oil-2007-1-1.pdf
format=PDF
issn=0208-189X
accessdate=2007-06-24] Cite paper
title=Annual Report 2007/2008
publisher=Eesti Energia
date=2008
url= http://www.energia.ee/fileadmin/files/dokumendid/annual_report/annual_report_2007-2008.pdf
format=PDF
accessdate=2008-08-15] cite web
title = Jordan Oil Shale Project
publisher = Omar Al-Ayed, Balqa Applied University
date = 2008
url = http://www.jordanoilshale.net/page4.aspx
accessdate = 2008-08-15]

The Alberta Taciuk is similar to the Galoter process in that heat transfer is performed by fine particles of oil shale in a rotating kiln. Its distinguishing feature is that the drying and pyrolysis of the feed shale and the combustion, recycling, and cooling of spent shale all occur in a single rotating multi-chamber horizontal vessel.Cite patent|US|5366596"Dry thermal processor."] cite web
publisher=AECOM Technology Group
title=UMATAC and the Alberta Taciuk Process
url=http://www.uma.aecom.com/MarketsAndServices/41/64/index.jsp
accessdate=2008-08-13] The water pollution caused by this process is quite limited. Two Australian oil companies, Southern Pacific Petroleum NL and later Queensland Energy Resources, operated a 250 tonnes per hour Alberta Taciuk Processor industrial-scale pilot plant which was shut down in 2004.

As in the Galoter and Alberta Taciuk processes, TOSCO II uses fine particles of oil shale that are heated in a rotating kiln. However, instead of recycling shale ash, TOSCO II circulates hot ceramic balls between the retort and a heater. The process was tested in a 40 tonnes-per-hour test facility near Parachute, Colorado; this facility was, however, shut down in 1972. Lawrence Livermore National Laboratory developed the hot recycled solid (LLNL HRS) retorting process. This technology was used in a 4 tonnes-per-day pilot plant between 1990 and 1993. The delayed-fall combustor used in this process gives greater control over the combustion process as compared to a lift pipe combustor, used in the older Lurgi-Ruhrgas process, originally developed during the 1950s in Germany by Lurgi Corporation. Another difference is that the LLNL HRS process uses a fluidized bed mixer instead of the screw mixer used in the Lurgi-Ruhrgas process. The use of fluidized bed mixer results in better mixture, which in turn increases the mean quantity of oil yield and oil shale throughput.Cite book
last = Lee | first = Sunggyu
title = Oil Shale Technology
publisher = CRC Press
pages = 117−118
year = 1991
url = http://books.google.com/books?id=N0wMCusO6yIC&pg=PA253&lpg=PA253&source=web&ots=RUeSKpiSxN&sig=pvW6H4fqTIb-cHHdVuO57pozdeg#PPP1,M1
isbn = 0849346150
accessdate = 2008-05-11] In the LLNL HRS process, most of the pyrolysis occurs in a settling-bed unit (plug flow).

Conduction through a wall

A variety of technologies, including the Fischer Assay, Pumpherston, Hom Tov, and Oil-Tech processes, transfer heat to the oil shale by conducting it through the retort wall. These technologies generally use fine particles; their advantage lies in the fact that retort vapors are not combined with combustion exhaust.Cite paper
title=An Assessment of Oil Shale Technologies
date=June 1980
url=http://www.princeton.edu/~ota/disk3/1980/8004/8004.PDF
format=PDF
id=NTIS order #PB80-210115
accessdate=2007-11-03] The Fischer Assay is a standardized laboratory test used to measure the grade of an oil shale sample. A 100 gram sample crushed to less than 2.38 mm is heated in a small aluminum retort to convert|500|°C|°F|-1 at a rate of convert|12|°C|°F|0 per minute, and held at that temperature for 40 minutes.Cite paper
last=Dyni|first=John R.
title=Geology and resources of some world oil shale deposits. Scientific Investigations Report 2005–5294
publisher=United States Department of the Interior; United States Geological Survey
year=2006
url=http://pubs.usgs.gov/sir/2005/5294/pdf/sir5294_508.pdf
format=PDF
accessdate=2007-07-09] The distilled vapors of oil, gas, and water are passed through a condenser and cooled with ice water into a graduated centrifuge tube. The oil yields achieved by other technologies are often reported as a percentage of the Fischer Assay oil yield.

In the Hom Tov process, fine particles of oil shale are slurried with waste bitumen and pumped through coils in a heater. The promoters of this process assert that the technology enables the shale to be processed at somewhat lower temperatures, since the bitumen acts as a catalyst. The technology has not yet been demonstrated in a pilot plant.Cite journal
last=Sandler|first=Neal
title=Israel assesses new oil shale technology
publisher=Platts
journal=Energy Economist
issue=297
year=2006
url=http://www.iaee.org/documents/2006/summary2.pdf
format=PDF
accessdate =2007-11-11]

In the Red Leaf Resources EcoShale In-Capsule Process, a hot gas is generated by burning natural gas, coal bed methane or pyrolysis shale gas. It is then circulated through oil shale rubble using a set of parallel pipes. The heat is transferred to the shale through the pipe walls rather than being injected directly into the rubble, thereby avoiding dilution of the product gas with the heating gas. The pile of oil shale rubble is enclosed by a low-cost earthen impoundment structure designed to prevent environmental contamination and to provide easy reclamation. Heat from the spent shale is recovered, enhancing the process's energy efficiency, by passing cool gas through pipes and then using it to preheat adjacent capsules.Cite paper
last=Patten | first=James W.
title= Red-Leaf Resources. Presentation at the Utah Energy Summit
publisher=Utah Energy Summit
year=2007
url=http://utahenergysummit.com/Presentations/April_17_2007/James.Patten.Final%5B1%5DApril%20Energy,%20Little%20America.pdf
format=PDF
accessdate=2007-11-11]

A new process from Combustion Resources, Inc., seeks to eliminate carbon dioxide emissions from the shale oil production process. Pyrolysis occurs in a rotating kiln heated by hot gas flowing through an outer annulus. The hot gas is created by burning hydrogen generated in a separate unit by coal gasification followed by carbon dioxide separation. The geometry of the annulus enables the transfer of heat to the moving shale through a wall.Cite conference
title=A method of reducing CO₂ emissions from oil shale retorting
last=Coates |first=Ralph L.
co-authors=Kent E. Hatfield, L. Douglas Smoot
publisher=27th Oil Shale Symposium
location=Colorado School of Mines
date= October 2007] Cite conference
title=A New Improved Process for Processing Oil Shale Ore into Motor Ready Fuel Products
last=Coates |first=Ralph L.
co-authors=Kent E. Hatfield, L. Douglas Smoot
publisher= American Chemical Society
date= 2008]

The Oil-Tech staged electrically heated retort process was developed by Oil-Tech, Inc. (now part of Ambre Energy). In this process, crushed oil shale is lifted by a conveyor system to the vertical retort, and loaded into the retort from the top. The retort consists of a series of connected individual heating chambers, stacked atop each other. Heating rods extend into the centers of each of these chambers. The feed oil shale is heated to increasingly-higher temperatures as it moves down the retort, attaining a temperature of convert|1000|°F|°C|-1 in the lowest chamber. The gases and vapors are vacuumed into a condensing unit. The spent shale is used for pre-heating feed oil shale.cite paper
url=http://ostseis.anl.gov/documents/dpeis/vol3/OSTS_DPEIS_vol3_App_A.pdf
title=Draft Oil Shale and Tar Sands Resource Management Plan Amendments to Address Land Use Allocations in Colorado, Utah, and Wyoming and Programmatic Environmental Impact Statement. Appendix A: Oil Shale Development Background and Technology Overview
format=PDF
pages= 54 − 55
publisher=Argonne National Laboratory
date= 2007-12-07
accessdate=2008-05-11] The advantages of this technology are its modular design, which enhances its portability and adaptability, its low water requirements, its heating efficiency, and the relatively high quality of the resulting product.

Externally generated hot gas

Externally generated hot gas technologies or indirectly heated technologies use heat, transferred by gases which are heated outside the retort vessel. The main technologies are Petrosix, Union B, Paraho Indirect, and Superior Indirect processes. As with the internal combustion technologies, most of the externally-generated hot gas technologies process oil shale lumps in vertical shaft kilns; however, the retort vapors are not diluted with combustion exhaust. The world’s largest operational surface oil shale pyrolysis reactor is the Petrosix which is located in São Mateus do Sul, Paraná, Brazil. The convert|11|m|ft|0 diameter vertical shaft kiln is owned by Petrobras and has been operating since 1992 with high availability. The company operates two retorts, the largest of which processes 260 tonnes per hour of oil shale.Cite paper
last=Laherrère|first=Jean
title=Review on oil shale data
publisher=Hubbert Peak
date=2005
url=http://www.hubbertpeak.com/laherrere/OilShaleReview200509.pdf
format=PDF
accessdate=2007-06-17]

The largest retort ever built used the Union B technology, developed by Unocal. The Union B processed 400 tonnes per hour of oil shale lumps heated by externally generated hot gas. However, unlike all other vertical shaft kilns, the Union B pumped the oil shale into the bottom of the retort, with the hot gas entering at the top. Unocal operated the retort from 1986 to 1992 near Parachute, Colorado. The Paraho Indirect technology is similar to the Petrosix which is considered a highly reliable technology for use with U.S. oil shale.

Two companies, Syntec Energy and Western Energy Partners, have proposed new hot gas processes based on linking coal gasification with rotating kiln retorts. The hot, hydrogen-rich synthesis gas from the coal gasifier is fed into the rotating kiln in direct contact with the oil shale, thereby heating it to pyrolysis temperature. The effluent synthesis gas is then used to generate electric power or other products typical of synthesis gas processes.Cite journal
last=Parkinson |first=Gerald
title=Oil Shale: The U.S. Takes Another Look at a Huge Domestic Resource
publisher=American Institute of Chemical Engineers
journal = Chemical Engineering Progress
volume = 102
issue = 7
year=2007
url=http://findarticles.com/p/articles/mi_qa5350/is_200607/ai_n21394714
accessdate=2008-08-21]

Reactive fluids

Reactive fluids technologies include the IGT Hytort (high-pressure H₂) process, donor solvent processes, and the Chattanooga fluidized bed reactor. In the IGT Hytort process, developed by the Institute of Gas Technology (IGT), oil shales are processed at controlled heating rates in a high-pressure hydrogen environment.Cite paper
last=Weil |first=S. A.
last2=Feldkirchner |first2=H. L.
last3=Punwani |first3=D. V.
last4=Janka |first4= J. C.
publisher=Institute of Gas Technology,Chicago, IL
title=IGT HYTORT Process for hydrogen retorting of Devonian oil shales
date=1979-01-01
id=CONF-790571-3] Examples of the donor solvent processes are Xtract Energy's Xtract Technology (supercritical solvent extraction) and Blue Ensign Technologies' Rendall Process; both processes to be tested at the Julia Creek oil shale deposits in North West Queensland, Australia.Cite news
title=New technology raises oil shale hopes in Qld
author=Rick Wikinson
publisher=Petroleum News
date=2006-05-29
url=http://www.blueensigntech.com.au/06.05.29%20EnergyReview.net.htm
accessdate=2008-08-18] Cite web
title=Xtract Ltd
publisher=Xtract Energy Plc
year=2007
url=http://www.xtractenergy.co.uk/activities/oil_shale.php
accessdate=2008-05-01] Cite news
title=Xtract Energy plc - Investment Update
publisher=Reuters
date=2008-01-10
url=http://www.reuters.com/article/pressRelease/idUS105283+10-Jan-2008+RNS20080110
accessdate=2008-08-18] Cite paper
title=Investment Profile: Blue Ensign Technology Ltd. Oil Shale production and technology development
publisher=Martin Place Securities Pty Ltd
date=2008-02-18
url=http://www.martinplacesecurities.com.au/Publications/2008/Blue%20Ensign%20Company%20Informational%2020%20Feb%2008.pdf
format=PDF
accessdate=2008-08-18]

Chattanooga Corporation has developed an extraction process that uses a fluidized bed reactor and an associated hydrogen-fired heater. In this process, retorting occurs at relatively low temperatures (convert|1000|°F|°C|-1|disp=s) through thermal cracking and hydrogenation of the shale into hydrocarbon vapors and spent solids. The thermal cracking allows hydrocarbon vapors to be extracted and scrubbed of solids. The vapors are then cooled, inducing the condensate to drop out of the gas. The remaining hydrogen, light hydrocarbons, and acid gases are passed through an amine scrubbing system to remove hydrogen sulfide which is converted to elemental sulfur. The cleaned hydrogen and light hydrocarbon gases are then fed back into the system for compression or into the hydrogen heater to provide heat for the fluidized bed reactor. This system is a nearly-closed loop; almost all of its energy needs are provided by the source material. The demonstration plant in Alberta was able to produce bbl to t|930|API=29 of oil per kilotonne of oil shale with an API gravity ranging between 28 and 30. With hydrotreating (the reaction of oil with high pressure hydrogen), it would be possible to improve this to 38-40 °API. Chattanooga Corporation is considering a design that would implemented in a bbl to t|2500|API=39|per=h|adj=on facility.Cite paper
publisher=United States Department of Energy
title=Secure Fuels from Domestic Resources: The Continuing Evolution of America’s Oil Shale and Tar Sands Industries
pages=1-68
date=2007
url=http://www.nevtahoilsands.com/pdf/Oil-Shale-and-Tar-Sands-Company-Profiles.pdf
format=PDF
accessdate=2007-07-11]

Reactive fluid technologies could be useful for processing oil shales with a low hydrogen content, such as the Eastern US Devonian formations. In these shales, only a third of the organic carbon is typically converted to oil during conventional above-ground retorting. Hydrogen or hydrogen donors (chemicals that donate hydrogen during chemical reactions) react with coke precursors (a chemical structure in the oil shale that is prone to form coke during retorting but has not yet done so). The reaction roughly doubles the yield of oil, depending on the characteristics of the shale and process.Cite book
last=Rex|first=R.
last2=Janka |first2=J. C.
last3=Knowlton |first3=T.
title=Cold Flow Model Testing of the Hytort Process Retort Design. 17th Oil Shale Symposium
publisher=Colorado School of Mines Press
pages=17-36
date=1984]

"In situ" technologies

"In situ" processes heat the oil shale underground. These technologies are potentially able to extract more oil from a given area of land than conventional "ex situ" processing technologies, as the wells can reach greater depths than surface mines.Cite paper
last=Ennis|first=D.L.
title=Oil Shale—An Investment We Can’t Afford
publisher=California Chronicle
url=http://www.californiachronicle.com/articles/12494
date=2006-08-15
accessdate=2008-05-01] They present an opportunity to recover shale oil from low-grade deposits that would not be reachable by ordinary mining techniques.Cite journal
last =Kök | first =M. V.
last2 =Guner | first2 =G.
last3 =Suat Bağci | first3 =A.
title =Application of EOR techniques for oil shale fields (in-situ combustion approach)
journal =Oil Shale. A Scientific-Technical Journal
publisher = Estonian Academy Publishers
volume = 25
issue =2
pages =217–225
year =2008
url=http://www.kirj.ee/public/oilshale_pdf/2008/issue_2/oil-2008-2-217-225.pdf
format = PDF
issn = 0208-189X
accessdate =2008-06-07
doi =10.3176/oil.2008.2.04] Several companies have patented methods for "in situ" retorting. However, most of these methods are still in experimental stages.

These technologies are usually classified as "true in situ" processes (TIS) and "modified in situ" processes (MIS). "True in situ" processes do not involve mining or crushing the oil shale. "Modified in situ" processes involve drilling and fracturing the target deposit to create voids occupying between 20 and 25% of the area. The voids improve the flow of gases and fluids through the rock, thereby increasing the volume and quality of the oil produced.

Early "in situ" processes

One of the earliest "in-situ" processes was the underground gasification by electrical energy—process exploited between 1940 and 1966 for the oil shale extraction at Kvarntorp, Sweden. In this process, electric heater were installed in bore holes and the gas pressure generated by heating pressed oil and gas vapors through conduits to condensors and wash towers, after which these gases were sucked out and treated in the treatment plant.Cite paper
last=Weddige|first=K.
title= The gasification of oil shale underground at Kvarntorp in Central Sweden
publisher=United States Bureau of Mines
date=1955] A variety of "in situ" processes were tried in the United States before oil shale industry crash in the 1980s. Most notable are the Equity Oil process, which injected superheated steam into the permeable leached zone of Colorado's Piceance Basin,Cite book
last=Dougan|first=P.M.
last2=Dockter|first2=L.
title=BX In Situ Oil Shale Project. 14th Oil Shale Symposium
publisher=Colorado School of Mines Press
pages=118-127
date=1981] and the Geokinetics Process. The latter used a horizontal combustion retort; the formation was made more permeable by explosive uplift and the creation of variously-sized fragments (rubblization).Cite book
last=Tyner|first=C.E.
last2=Parrish|first2=R.L.
last3=Major|first3=B.H.
last4=Lekas|first4=J.M.
title=Sandia/Geokinetics Retort 23: A Horizontal In Situ Retorting Experiment. 15th Oil shale Symposium Proceedings
publisher=Colorado School of Mines Press
pages=370-384
date=1982] Cite paper
last=Costimiris|first=E.C.
title=Investigation of the Geokinetics horizontal in-situ oil-shale-retorting process. Annual Report 1981
publisher=Geokinetics, Inc
date=1982] Little is known of the yields from the Equity process, but the Geokinetics process generally recovered 40-50% of the Fischer Assay oil.

Variations of the modified "in situ" (MIS) process have been investigated by the US Bureau of Mines, Lawrence Livermore National Laboratory, Occidental Petroleum, Rio Blanco Corporation, and Multi-Mineral Corporation. A proposal in the 1960s involved the creation of a rubble chimney using a nuclear explosive.Cite journal
last=Lombard|first=D.B.
last2=Carpenter|first2=H.C.
title=Recovering Oil by Retorting a Nuclear Chimney in Oil Shale
journal=Journal of Petroleum Technology
publisher=Society of Petroleum Engineers
pages=727-734
issue=19
date=1967] However, this approach was abandoned for a number of technical reasons. Subsequently, a variety of rubblization approaches were explored. The first MIS oil shale experiment was conducted by Occidental Petroleum in 1972 at Logan Wash, Colorado. The installation's oil yield was adversely affected by non-uniform permeability in the formation, causing an inefficient sweep of the rubblized zone.Cite book
last=Gregg|first=M.L.
last2=Campbell
first2=J.H.
title=Sweep efficiency modeling of modified in situ retorts. 13th Oil shale Symposium Proceedings
publisher=Colorado School of Mines Press
pages=87-100
date=1980] A later series of field experiments aimed at creating a more uniform permeable zone were carried out using different mining and blasting techniques. Depending on the calculation used, Occidental achieved 50-60% Fischer Assay oil yield in Retorts 7 and 8.Cite paper
last=Bickel
first=T.C.
title=Data Acquisition and Analysis of Occidental Vertical Modified In Situ Retorts 7 and 8, Sandia Report SAND83-2649
date=1984] The Rio Blanco Corporation used a mining and blasting approach that created a bed with close to 40% porosity. This enabled them to retort the chimney at a substantially faster rate and achieve higher oil yields (about 70% of the Fischer Assay).Cite book
last=Berry|first=K.L.
last2=Hutson|first2=R.L.
last3=Sterrett|first3=J.S.
last4=Knepper|first4=J.C.
title=Modified In-Situ Retorting Results of Two Field Retorts. 15th Oil shale Symposium Proceedings
publisher=Colorado School of Mines Press
pages=385-396
date=1982] The Multi-Mineral Corporation proposed a more complex MIS process for Saline Zone oil shale; it included recovery of the minerals nahcolite and dawsonite.Cite web
title= Integrated in situ shale oil and mineral recovery process
url=http://www.freepatentsonline.com/4285547.html
publisher=FreePatentsOnline
id=United States Patent 4285547
date=1981-08-25
accessdate=2007-11-11] Cite web
title= Oil Shale Projects
url= http://www.agapito.com/Oil%20Shale%20Projects.htm
publisher=Agapito Associates, Inc.
accessdate=2008-08-13]

Modern "in situ" processes

There has been a recent resurgence of interest in "in situ" recovery processes. The processes either inject hot fluids into the formation (Chevron CRUSH and Petro Probe) or use line or plane heating sources following by thermal conduction and convection to distribute heat through the formation (Shell ICP, EGL Resources, and ExxonMobil Electrofrac). Most of these processes are expected to produce an oil with an API gravity of about 40 containing fewer olefins and polar molecules due to "in situ" oil coking and cracking.

Wall conduction

"In situ" wall conduction technologies include Shell's "In situ" Conversion Process (ICP), the EGL Resources Process, and the IEP Geothermic Fuels Cells Process. Since 2000, the Shell Oil Company has been developing its "in situ" method at the Mahogany Research Project, located convert|200|mi|km|-1 west of Denver on Colorado's Western Slope. Although this method is energy-intensive, it compares well to other heavy oil projects such as tar sands development. Over the project life cycle, Shell estimates that for every unit of energy consumed, three to four units would be produced. A freeze wall is first constructed to isolate the processing area from surrounding groundwater. convert|2000|ft|m|0 wells, eight feet apart, are drilled and filled with a circulating super-chilled liquid to cool the ground to convert|-60|°F|°C|-1. Water is then removed from the working zone. Heating and recovery wells are drilled at convert|40|ft|m|0 intervals within the working zone. Electrical heating elements are lowered into the heating wells and used to heat the kerogen to between convert|650|°F|°C|-1 and convert|700|°F|°C|-1 over a period of approximately four years, slowly converting it into oil and gases, which are then pumped to the surface. Shell believes that it will be possible to recover some 65-70% of the hydrocarbons using this technique. An operation producing 100,000 barrels a day would require a dedicated power generating capacity of 1.2 gigawatts. To maximize the functionality of the freeze walls, adjacent working zones will be developed in succession. This "in situ" method requires 100% disturbance of the surface, greatly increasing the footprint of extraction operations in comparison to conventional oil and gas drilling. The current test sites are expected to produce in the region of bbl to t|600|to|1500|API=29|per=d.cite paper
title=Oil Shale Test Project. Oil Shale Research and Development Project
publisher=Shell Frontier Oil and Gas Inc.
date=2006-02-15
url=http://www.blm.gov/pgdata/etc/medialib/blm/co/field_offices/white_river_field/oil_shale.Par.79837.File.dat/OSTPlanofOperations.pdf
format=PDF
accessdate=2007-06-30] Extensive water use and the risk of groundwater pollution are the technology's greatest challenges.cite paper
author=Jon Birger
title=Oil shale may finally have its moment
publisher=Fortune
date=2007-11-01
url=http://money.cnn.com/2007/10/30/magazines/fortune/Oil_from_stone.fortune/
accessdate=2007-11-17]

The EGL Resources Process combines horizontal wells, through which steam is passed, and vertical wells, which provide both vertical heat transfer through refluxing of generated oil and a means to collect and produce the oil. In contrast to the Equity process, the steam circulates through a closed loop, and no fluids are injected into the formation. Horizontal heat transfer from the vertical wells is similar to that in the Shell ICP, and a similar quality of oil is expected. American Shale Oil Corporation (former EGL Oil Shale, a subsidiary of EGL Resources) is leasing a convert|160|acre|m2|-4 test tract in the Piceance Basin from the United States Bureau of Land Management to test this technology.cite web
title=Innovation in Shale Technology
publisher=EGL Shale.
date=2006-11-16
url=http://www.egloilshale.com/
accessdate=2007-07-06] cite paper
title= Plan of Operation for Oil Shale Research, Development and Demonstration (R,D/D) Tract
publisher= E.G.L. Resources, Inc.
date=2006-02-15
url= http://www.blm.gov/pgdata/etc/medialib/blm/co/field_offices/white_river_field/oil_shale.Par.62160.File.dat/PlanofOperation.pdf
format=PDF
accessdate=2008-05-01]

In Independent Energy Partners' Geothermic Fuels Cells Process (IEP GFC), a high-temperature stack of fuel cells is placed in the formation to heat the ground. During an initial warm-up period, the cells are fueled by an external source of natural gas. Afterwards, the process is able to fuel itself using gases liberated by its own waste heat. The formation is fractured by rising fluid pressure in the heated zone. Alternatively, the formation can be pre-fractured to enhance the flow of hydrocarbons between heating and producing wells. The company asserts a ratio of approximately 18 units of energy produced per unit used, when primary recovery is combined with gasification of the residual char and use of the resulting synthetic gas.

Externally generated hot gas

The "in situ" technologies that use externally-heated gases to decompose oil shale include the Chevron CRUSH process, the Petro Probe process, and Mountain West Energy's "In Situ" Gas Extraction (MWE IGE) technology. Chevron Corporation and Los Alamos National Laboratory formed a joint research project in 2006 to develop the Chevron CRUSH process. The project is investigating whether heated carbon dioxide can be injected into the formation to decompose the rock. The carbon dioxide would be injected via conventionally-drilled wells and then exposed to the formation via a series of horizontal fractures in which it circulates. The shale oil would then be brought up in conventional vertical oil wells. This method is based on research and trials carried out in the 1950s by Sinclair Oil, which developed a processing method using existing and induced fractures between vertical wells. Continental Oil (now ConocoPhillips) and the University of Akron demonstrated the process; patents were issued that demonstrated the usefulness of carbon dioxide as a heat carrier.cite paper
title= Oil Shale Research, Development & Demonstration Project. Plan of Operation
publisher= Chevron USA Inc.
date=2006-02-15
url= http://www.blm.gov/pgdata/etc/medialib/blm/co/field_offices/white_river_field/oil_shale.Par.37256.File.dat/OILSHALEPLANOFOPERATIONS.pdf
format=PDF
accessdate=2008-05-01]

Petro Probe, a subsidiary of Earth Science Search, has described a process which involves injecting super-heated air into wells drilled into the oil shale formation. The super-heated air mixes and melts the shale; its hydrocarbons are transported to the surface in a gaseous state. At the surface, the gas is cooled and the condensate is collected. The remaining gas is re-used to heat the air and is injected back into the formation along with other waste products, thereby minimizing the process's environmental impact. Mountain West Energy's technology (also known as In Situ Vapor Extraction) uses similar principles. A high-temperature gas is injected into the oil shale formation to decompose the oil shale. After it has swept the oil vapors to the surface, where they are condensed and separated, the gas is recirculated.cite web
title= MWE's In-situ Vapor Extraction Technology (IVE)
publisher= Mountain West Energy LLC
url= http://www.mtnwestenergy.com/mwe.html
accessdate=2008-05-02]

ExxonMobil Electrofrac

ExxonMobil, which has been involved in oil shale development since the 1960s, is focusing on its own "in situ" technology. A series of hydraulic fractures is created in the rock and an electrically-conductive heating fluid is injected into the formation. The shale oil is then extracted by separate dedicated production wells. The most likely method involves horizontal wells which have been hydraulically fractured along the vertical axis. These wells are placed in a parallel row with a second horizontal well intersecting them at their toe. This will allow opposing electrical charges to be applied at either end. The Electrofrac method has been tested in laboratories and test sites are being considered for a field trial.

Volumetric heating

The concept of volumetric heating by radio waves (radio frequency processing) of oil shale was developed at the Illinois Institute of Technology during the late 1970s. The concept was to heat modest volumes of oil shale, using vertical electrode arrays. Deeper large volumes could be processed at slower heating rates over time. The technology was developed later by Lawrence Livermore National Laboratory, and by several other inventors. This concept was based on the use of installations spaced at tens of meters that would heat sizeable quantities of deep oil shale very slowly. The concept presumed a radio frequency at which the skin depth is many tens of meters, thereby overcoming the thermal diffusion times needed for conductive heating.cite paper
author=A.K. Burnham
title=Slow Radio-Frequency Processing of Large Oil Shale Volumes to Produce Petroleum-like Shale Oil
publisher=Lawrence Livermore National Laboratory
date=2003-08-20
url = https://e-reports-ext.llnl.gov/pdf/243505.pdf
format=PDF
id=UCRL-ID-155045
accessdate=2007-06-28] Microwave heating technologies are based on the same principles as radio wave heating, although it is believed that radio wave heating is an improvement over microwave heating because the energy can penetrate farther into the formation. Radio frequency processing in conjunction with critical fluids is being developed by Raytheon together with CF Technologies and tested by Schlumberger, while Global Resource Corporation is testing microwave heating.cite paper
url= http://www.raytheon.com/businesses/rids/products/rtnwcm/groups/public/documents/content/rtn_bus_ids_prod_rfcf_pdf.pdf
title= Radio Frequency/Critical Fluid Oil Extraction Technology
publisher=Raytheon
format=PDF
accessdate=2008-08-20] cite news
url= http://updates.spe.org/index.php/2008/02/01/oil-shale-extraction-technology-has-a-new-owner/
title= Oil-shale extraction technology has a new owner
author = Ted Moon
publisher=Society of Petroleum Engineers
date=2008-02-01
accessdate=2008-08-20] cite news
url= http://www.downstreamtoday.com/News/Articles/200703/Global_Resource_Reports_Progress_on_Oil__1943.aspx
title= Global Resource Reports Progress on Oil Shale Conversion Process
publisher=Downstream Today
date=2007-03-09
accessdate=2008-05-31] Electro-Petroleum proposes electrically enhanced oil recovery for heating oil shale and generating shale oil. Direct current is passed between cathodes in producing wells and anodes located either at the surface or at depth in other wells. The passage of the current through the formation results in resistive Joule heating. This process has increased production from heavy oil fields in short-term tests.cite paper
title=Electrically enhanced oil recovery using DC technology
publisher=Electro-Petroleum, Inc
url= http://www.electropetroleum.com/Our%20Technology.htm
accessdate=2008-05-01]

Economics

During the early 20th century, the petroleum 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 is lower than the price of petroleum 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 for the operation to be profitable, the price of petroleum would need to remain above these levels. The analysis discusses the expectation that processing costs would drop after the complex was established. The hypothetical unit would see a cost reduction of 35–70% after its first convert|500|Moilbbl were produced. Assuming an increase in output of convert|25|koilbbl/d during each year after the start of commercial production, the costs would then be expected to decline to $35–48 per barrel ($220–300/m³) within 12 years. After achieving the milestone of convert|1|Goilbbl, its costs would decline further to $30–40 per barrel ($190–250/m³).Cite paper
last = Bartis | first = James T.
last2 =LaTourrette | first2 = Tom
last3 = Dixon | first3 =Lloyd
last4 = Peterson | first4 =D.J.
last5 = Cecchine | first5 = Gary
title = Oil Shale Development in the United States. Prospects and Policy Issues. Prepared for the National Energy Technology Laboratory of the United States Department of Energy
publisher = The RAND Corporation
date = 2005
url = http://www.netl.doe.gov/energy-analyses/pubs/Oil%20Shale%20Development%20in%20the%20United%20States%20-%20RAND%20August%20200.pdf
format=PDF
isbn = 978-0-8330-3848-7
accessdate =2007-06-29] cite journal
publisher = European Academies Science Advisory Council
url = http://www.easac.org/displaypagedoc.asp?id=78
title = 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
format = PDF
date = May 2007
accessdate = 2007-11-25] A comparison of the proposed United States oil shale industry to the Alberta tar-sands industry has been drawn (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". [cite web
url=http://www.newyorker.com/reporting/2007/11/12/071112fa_fact_kolbert
title=A Reporter at Large:Unconventional Crude
publisher=The New Yorker
date=2007-11-12
accessdate=2008-03-31] cite web
url=http://www.fossil.energy.gov/programs/reserves/publications/Pubs-NPR/40010-373.pdf
format=PDF
title=Is Oil Shale The Answer To America's Peak-Oil Challenge?
publisher=United States Department of Energy
date=2008-02-08
accessdate=2008-03-31
format=PDF]

Royal Dutch Shell has announced that its "in situ" extraction technology in Colorado would realize a profit when crude oil prices are higher than $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).cite news
publisher="Rocky Mountain News"
author=Seebach, Linda
url= http://www.rockymountainnews.com/drmn/news_columnists/article/0,1299,DRMN_86_4051709,00.html
title =Shell's ingenious approach to oil shale is pretty slick
date = 2005-09-02
accessdate=2007-06-02] Cite journal
last = Schmidt | first = S. J.
title = New directions for shale oil:path to a secure new oil supply well into this century: on the example of Australia
journal =Oil Shale. A Scientific-Technical Journal
publisher = Estonian Academy Publishers
volume =20
issue =3
pages =333–346
year = 2003
url = http://www.kirj.ee/public/oilshale/7_schmidt_2003_3s.pdf
format = PDF
issn = 0208-189X
accessdate = 2007-06-02] To increase the efficiency of oil shale retorting, researchers have proposed and tested several co-pyrolysis processes, in which other materials such as wood or waste plastics are retorted along with the oil shale.Cite journal
title =Co-pyrolysis of waste plastics with oil shale
last = Tiikma | first=Laine
last2 = Johannes | first2=Ille
last3 = Pryadka | first3=Natalja
year = 2002
journal = Proceedings. Symposium on Oil Shale 2002, Tallinn, Estonia
pages= 76] Cite journal
title =Fixation of chlorine evolved in pyrolysis of PVC waste by Estonian oil shales
last = Tiikma | first=Laine
last2 = Johannes | first2=Ille
last3 = Luik | first3=Hans
journal=Journal of Analytical and Applied Pyrolysis
date = March 2006
volume=75
issue=2
pages=205–210
format=PDF
url=http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6TG7-4GR33JX-1-9&_cdi=5247&_user=10&_orig=search&_coverDate=03%2F31%2F2006&_sk=999249997&view=c&wchp=dGLbVtz-zSkWW&md5=9e583e16281cce35e8d52957730ad3f3&ie=/sdarticle.pdf
accessdate =2007-10-20
doi =10.1016/j.jaap.2005.06.001] Cite journal
last =Veski | first =R.
last2 =Palu | first2 =V.
last3 =Kruusement | first3 =K.
title =Co-liquefaction of kukersite oil shale and pine wood in supercritical water
journal =Oil Shale. A Scientific-Technical Journal
publisher = Estonian Academy Publishers
volume =23
issue =3
pages =236–248
year =2006
url=http://www.kirj.ee/public/oilshale/oil-2006-3-4.pdf
format = PDF
issn = 0208-189X
accessdate =2007-06-16] Cite journal
last = Aboulkas | first =A.
last2 =El Harfi | first2 =K.
last3 =El Bouadili | first3 =A.
last4 =Benchanaa | first4 =M.
last5 =Mokhlisse | first5 =A.
last6 =Outzourit | first6 =A.
title = Kinetics of co-pyrolysis of Tarfaya (Morocco) oil shale with high-density polyethylene
journal = Oil Shale. A Scientific-Technical Journal
publisher = Estonian Academy Publishers
volume =24
issue =1
pages =15–33
year =2007
url=http://www.kirj.ee/public/oilshale/oil-2006-3-4.pdf
format = PDF
issn = 0208-189X
accessdate =2007-06-16] Cite conference
last = Ozdemir | first = M.
last2 = A. Akar, A. Aydoğan, E. Kalafatoglu; E. Ekinci
title = Copyrolysis of Goynuk oil shale and thermoplastics
publisher = International Oil Shale Conference
date = 2006-11-07
location = Amman, Jordan
url = http://www.sdnp.jo/International_Oil_Conference/rtos-A114.pdf
format = PDF
accessdate = 2007-06-29]

In a 1972 publication by the journal "Pétrole Informations" (ISSN 0755-561X), shale oil production was unfavorably compared to the liquefaction of coal. 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 convert|650|L|U.S.gal impgal|lk=on of oil per one ton of coal, as against convert|150|L|U.S.gal impgal per one ton of shale oil.

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;Cite journal
last = Cleveland | first = Cutler J.
last2 = Costanza | first2 = Robert
last3 = Hall | first3 = Charles A. S.
last4 = Kaufmann | first4 = Robert
title =Energy and the U.S. Economy: A Biophysical Perspective
journal = Science
publisher = American Association for the Advancement of Science
volume = 225
issue = 4665
pages =890–897
date = 1984-08-31
year = 1984
url = http://www.eroei.com/pdf/Energy%20and%20the%20U.S.%20Economy-%20A%20Biophysical%20Perspective.pdf
format = PDF
issn = 00368075
accessdate=2007-08-28
doi =10.1126/science.225.4665.890
pmid =17779848] some newer companies and processes assert an EROI between 3 and 10. Royal Dutch Shell has reported an EROEI of three to four on its "in situ" development, the Mahogany Research Project.cite web
publisher=WIRED Magazine
author=Reiss, Spencer
url= http://www.wired.com/wired/archive/13.12/oilshale.html
title =Tapping the Rock Field
date = 2005-12-13
accessdate=2007-08-27] The water needed in the extraction process offers an additional economic consideration: this may pose a problem in areas with water scarcity.

Environmental considerations

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.cite paper
title=Environmental Impacts from Mining
url=http://www.ott.wrcc.osmre.gov/library/hbmanual/epa530c/chapter3.pdf
format=PDF
publisher=US Office of Surface Mining Reclamation and Enforcement
date=2006-08-02
accessdate=2008-03-29]

Oil shale extraction can damage the biological and recreational value of land and the ecosystem. Surface mining for "ex situ" processing as also "in-situ" processing requires extensive land use. "Ex situ" thermal processing generates waste material, which needs to be disposed. Mining, processing and waste disposal require land to be withdrawn from traditional uses, and therefore should avoid high density population areas. The waste material may consist of several pollutants including sulfates, heavy metals, and polycylic aromatic hydrocarbons, some of which are toxic and carcinogenic.Cite journal
last =Tuvikene | first =Arvo
coauthors = Sirpa Huuskonen, Kari Koponen, Ossi Ritola, Ülle Mauer, Pirjo Lindström-Seppä
title =Oil Shale Processing as a Source of Aquatic Pollution: Monitoring of the Biologic Effects in Caged and Feral Freshwater Fish
journal =Environmental Health Perspectives
publisher =United States' National Institute of Environmental Health Sciences
volume =107
issue =9
pages =745—752
date =1999
url=http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1566439&blobtype=pdf
format = PDF
accessdate =2007-06-16
doi =10.2307/3434660]

The atmospheric emissions from oil shale processing include carbon dioxide, a greenhouse gas. Environmentalists oppose production and usage of oil shale, as it generates usually more greenhouse gases than conventional fossil fuels.cite paper
title= Driving It Home. Choosing the Right Path for Fueling North America's Transportation Future
url= http://www.nrdc.org/energy/drivingithome/drivingithome.pdf
format= PDF
publisher= Natural Resources Defense Council
date= June 2007
accessdate= 2008-04-19] 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 traditional petroleum extraction.cite news
title= Repeal sought for ban on U.S. Govt. use of CTL, oil shale, tar sands-generated fuel
url=http://www.mineweb.com/mineweb/view/mineweb/en/page38?oid=50551&sn=Detail
last = Kosich| first = Dorothy
publisher= Moneyweb Holdings
date= 2008-04-11
accessdate= 2008-05-27] [cite news
title=United States: Energy Independence And Security Act Provision Poses Major Problems For Synthetic And Alternative Fuels
author=Bloom David I, Waldron Roger, Layton Duane W, Patrick Roger W
url=http://www.mondaq.com/article.asp?articleid=58310
date=2008-03-04
accessdate=2008-05-27] In addition, depending technology and oil shale composition, the oil shale extraction may create other atmospheric emissions such as sulfur dioxide, hydrogen sulfide, carbonyl sulfide and nitrogen oxides.cite book
publisher = William Andrew Inc
title = Environmental Consequences Of, and Control Processes For, Energy Technologies
author = Argonne National Laboratory
url= http://books.google.com/books?id=qgFtunVE5T8C&pg=PA104&lpg=PA104&dq=oil+shale+extraction+sulfur+emissions&source=web&ots=z0RSwWNDrp&sig=-GcsH5ms-WXqw8CbaKFHWEF4RRQ
year = 1990
pages = 104
isbn=9780815512318
accessdate=2008-08-19]

Experimental "in situ" conversion processes may reduce some of these impacts, but at the same time they may cause other problems, including groundwater pollution. Developing carbon capture and storage technologies may reduce the processes' carbon footprint.cite paper
url=http://www.aspo-usa.com/fall2006/presentations/pdf/Bartis_J_Boston_2006.pdf
format = PDF
title=Unconventional Liquid Fuels Overview. 2006 Boston World Oil Conference
author=Bartis, Jim
publisher=Association for the Study of Peak Oil & Gas - USA
date= 2006-10-26
accessdate=2007-06-28 ]

There are concerns over the oil shale industry's use of water. Depending on technology, above-ground retorting uses between one and five barrels of water per barrel of produced shale-oil.cite web
title = Oil Shale Myths
publisher = Shale Oil Information Center
date = 2005-07-09
url = http://www.shaleoilinfo.org/library/citizens/lukens2005Jul09.php
author = Luken, Larry
accessdate = 2008-04-01] cite web
title = Critics charge energy, water needs of oil shale could harm environment
publisher = U.S. Water News Online
date = July 2007
url = http://www.uswaternews.com/archives/arcsupply/7critchar7.html
accessdate = 2008-04-01] A 2007 programmatic environmental impact statement issued by the United States Bureau of Land Management stated that surface mining and retort operations produce two to ten US gallons nowrap|(1.5–8 imperial gallons or 8–38 L) of wastewater per tonne of processed oil shale.cite web
url=http://ostseis.anl.gov/documents/dpeis/volumes/OSTS_DPEIS_Vol_2.pdf
title=Draft Oil Shale and Tar Sands Resource Management Plan Amendments to Address Land Use Allocations in Colorado, Utah, and Wyoming and Programmatic Environmental Impact Statement. Volume 2
format=PDF
page=36
publisher=Argonne National Laboratory
date= 2007-12-07
accessdate=2008-03-31] "In situ" processing, according to one estimate, uses about one-tenth as much water. [cite web
last = Fischer
first = Perry A.
title=Hopes for shale oil are revived
url=http://www.worldoil.com/magazine/MAGAZINE_DETAIL.asp?ART_ID=2658&MONTH_YEAR=Aug-2005
publisher= World Oil
date = August 2005

accessdate=2008-04-01

] Water consumption is a particularly sensitive issue in arid regions, such as the western US and Israel's Negev Desert, where there are plans to expand the oil shale industry despite water shortages. [cite news
last = Speckman
first = Stephen
url=http://deseretnews.com/article/1,5143,695263708,00.html
title=Oil-shale 'rush' is sparking concern
publisher="Deseret Morning News"
date=2008-03-22
accessdate=2008-08-24]

Environmental organizations, including Greenpeace, have mounted strong protests against the oil shale industry. In one instance, Queensland Energy Resources put the proposed Stuart Oil Shale Project in Australia on hold in 2004.cite web
url=http://www.greenpeace.org/australia/news-and-events/media/releases/climate-change/climate-changing-shale-oil-ind
title=Climate-changing shale oil industry stopped
publisher=Greenpeace Australia Pacific
date=2005-03-03
accessdate=2007-06-28] [cite web
url=http://www.abc.net.au/news/newsitems/200407/s1159133.htm
title=Greenpeace happy with part closure of shale oil plant
publisher=Australian Broadcasting Corporation
date=2004-07-22
accessdate=2008-05-19]

ee also

* Oil shale geology
* Oil shale reserves

References

External links

* [http://www.ostseis.anl.gov/ Oil Shale and Tar Sands Draft Programmatic Environmental Impact Statement (EIS)] Concerning potential leases of Federal oil sands lands in Utah and oil shale lands in Utah, Wyoming, and Colorado