Oil shale

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Oil Shale

Oil shale is a general term applied to a fine-grained sedimentary rock containing enough organic material (called kerogen) to yield oil and combustible gas upon distillation. In addition to the oil shale, the other groups of organic-rich sedimentary rock are bitumen-impregnated rocks (tar sands and petroleum reservoir rocks), and humic coals and carbonaceous shale.

The United States Energy Information Administration estimates the world supply of oil shale at 2.6 trillion barrels of recoverable oil, 1.0-1.2 trillion barrels of which are in the United States.^[1] However, attempts to develop these reserves have been going on for over 100 years with limited success.^[2]

The kerogen in oil shale can be converted to oil through the chemical process of pyrolysis. Oil shale could also burn directly as a low-grade fuel for power generation and heating, and be used as a raw material in the chemical and construction materials industries. Estonia, Russia, Brazil, China, Australia, Israel and Germany currently mine oil shale.^[3]

[edit] Geology

[edit] Classification

Oil shale does not have definite geological definition nor a specific chemical formula. Different type of oil shales vary by the chemical consist, type of kerogen, age, and depositional history, including the organisms from which they were derived.^[4] Based upon environment of deposition, different oil shales could be divide into three groups, which are terrestrial, lacustrine, and marine.

**Classification of oil shales by environment of deposition**^[5]
Terrestrial	Lacustrine	Marine
cannel coal	lamosite; torbanite	kukersite; tasmanite; marinite

[edit] Composition

Organic matter in oil shale consists the remains of algae, spores, pollen, plant cuticle and corky fragments of herbaceous and woody plants, and other cellular remains of lacustrine, marine, and land plants, which form carbon, hydrogen, oxygen, nitrogen, and sulfur. While terrestrial oil shales consists resins spores, waxy cuticles, and corky tissue of roots and stems of vascular terrestrial plants, lacustrine oil shales include lipid-rich organic matter derived from algae, and marine oil shales are composed by marine algae, acritarchs, and marine dinoflagellates. Some oil-shale deposits may also contain different minerals and metals like alum, nahcolite (NaHCO3), dawsonite, sulfur, ammonium sulfate, vanadium, zinc, copper, uranium, and other minerals and metals.^[6]

[edit] Formation

Oil shale is considered to be formed by the deposition of organic matter in lakes, lagoons and restricted estuarine areas such as oxbow lakes and muskegs. Generally, oil shales are considered to be formed by accumulation of algal debris.

When plants die in these peat swamp environments, their biomass is deposited in anaerobic aquatic environments where low oxygen levels prevent their complete decay by bacteria. For masses of undecayed organic matter to be preserved and to form oil shale the environment must remain steady for prolonged periods of time to build up sufficiently thick sequences of algal matter. Unlike coal, oil shale does not necessarily require low mineral and ash content, as it is used mainly for extraction, and mineral waste in oil liquefaction plants is easier to deal with.

Eventually, and usually due to the initial onset of orogeny or other tectonic events, the algal swamp-forming environment is disrupted and oil shale accumulation ceases. Another important control on oil shale preservation and distribution in lacustrine oil shale is lake level and lake salinity.

Burial by sedimentary loading on top of the algal swamp converts the organic matter to kerogen by the following processes;

Compaction, due to loading of the sediments on the coal which flattens the organic matter
Removal of the water held within the peat in between the plant fragments
With ongoing compaction, removal of water from the inter-cellular structure of fossilized plants
With heat and compaction, removal of molecular water
Methanogenesis; similar to treating wood in a pressure cooker, methane is produced, which removes hydrogen and some carbon, and some further oxygen (as water)
Dehydration, which removes hydroxyl groups from the cellulose and other plant molecules, resulting in the production of hydrogen-reduced coals

However the heat and pressure were not as great as in the similar process that forms petroleum. Oil shale is known as 'rock that burns'.

[edit] Reserves

Although oil shale resources occur in many countries, only 33 countries possess deposits worth recording. Total resources of these countries are estimated at 411 billion tonnes of in-place shale oil which is equivalent to 2.9 trillion U.S. barrels of shale oil.^[6] Among those, USA account for 62% of the world resources, and USA, Russia and Brazil together account for 86% in terms of shale oil content.^[3]^[7]

The above mentioned figure of total reserves is very conservative because several deposits have not been explored sufficiently to make accurate estimates and other deposits were not included. Estimating shale oil reserves is complicated by several factors. First, the amount of kerogen contained in oil shale deposits varies considerably. Second, some nations report as reserves the total amount of kerogen in place, which means all kerogen regardless of technical or economic constraints, and not as an estimate of kerogen which may be extracted from identified and assayed oil shale rock using available technology and under current economic conditions. Third, by definition, "reserves" refers only to the amount of resource which is technically exploitable and economically feasible under current economic conditions. Fourth, shale oil recovery technologies are still developing, so the amount of recoverable kerogen can only be estimated.

The table in below reports reserves by amount of shale oil. Shale oil refers to synthetic oil obtained by heating organic material (kerogen) contained in oil shale rock to a temperature which will convert it to oil, combustible gas, and residual carbon that remains in the spent shale.^[3] All figures are presented in barrels and metric tons ("tonnes", equal to 2204 pounds).

**Shale oil: resources and production at end-2002**^[3]
Region	In-place shale oil resources (million barrels)	In-place shale oil resources (million tonnes)	Production in 2002(thousand tonnes (oil))
Africa	159,243	23,317	-
Asia	45,894	6,562	100
Europe	368,156	52,845	275
Middle East	38,172	5,792	-
North America	2,602,469	382,758	-
Oceania	31,748	4,534	46
South America	82,421	11,794	157

[edit] Africa

Major oil shale deposits are located in the Democratic Republic of Congo (14,310 million tonnes of shale oil) and Morocco (12.3 billion tonnes or 8,167 million tonnes of shale oil). There are oil shale reserves also in Egypt, South Africa and Madagascar.

[edit] Asia

Major oil shale deposits are located in China (totally 32 billion tonnes of which technically exploitable and economically feasible 4.4 billion tonnes), Thailand (18.7 billion tonnes), Kazakhstan (several deposits with major deposit of the Kenderlyk Field having 4 billion tonnes) and Turkey (2.2 billion tonnes).^[3]^[4]^[8] Main Chinese oil shale deposits and production lay in Fushun, Liaoning. Other deposits lays in Huadian in Jilin, Heilongjiang and Shandong. In 2002, China produced more than 90,000 tonnes of shale oil per year.^[8] There are oil shale reserves also in Uzbekistan, Turkmenistan, Myanmar, Armenia and Mongolia.

[edit] Europe

The biggest oil shale reserves in Europe are located in Russia (equal to 35,470 million tonnes of shale oil). Other major oil shale deposits are located in Italy (10,446 million tonnes of shale oil), Estonia (2,494 million tonnes of shale oil), France (1,002 million tonnes of shale oil), Belarus (1,000 million tonnes of shale oil), Sweden (875 million tonnes of shale oil), Ukraine (600 million tonnes of shale oil) and the United Kingdom (501 million tonnes of shale oil). There are oil shale reserves also in Germany, Luxembourg, Spain, Bulgaria, Hungary, Poland, Austria, Albania and Romania. Estonia is currently producing shale oil and using oil shale (kukersite) as a fuel for electricity production, while Germany and Russia have some minor production of oil shale.

[edit] Middle East

Major oil shale deposits are located in Jordan (5,242 million tonnes of shale oil or 65 billion tonnes of oil shale) and Israel (550 million tonnes of shale oil or 12 billion tonnes of oil shale). Jordanian oil shales are high quality - comparable to Western US oil shale - with the exception of high sulfur content. Israeli oil shale is a relatively low in heating value and oil yield.

[edit] North America

At 3.3 trillion tonnes, the oil shale deposits in the United States are easily the largest in the world. There are two major deposits: the Eastern US deposits, located in Devonian-Mississippian shales, cover 250,000 square miles (650,000 square kilometers). The Western US deposits, the Green River formation in Colorado, Wyoming and Utah, are among the richest oil shale deposits in the world.

In Canada 19 deposits have been identified. The most explored deposits are in Nova Scotia and New Brunswick.

[edit] Oceania

Australia's oil shale resource is estimated to be around 58 billion tonnes or 4,531 million tonnes of shale oil. Australia is one of the few locations currently producing kerogen from oil shale. The Stuart demonstration project is designed to produce 4,500 barrels per day of shale oil products. There is also oil shale in New Zealand.

[edit] South America

Brazil has the world's second largest known oil shale (the Irati shale and lacustrine deposits) resources and has second largest shale oil production after Estonia. Oil shale resources lay in São Mateus do Sul, Paraná, and in Paraiba's Valley. Brazil developed the world’s largest surface oil shale pyrolysis retort Petrosix, which is 11-m vertical shaft retort. Production in 1999 was about 200,000 tonnes.^[9]^[4] Small resources are also in Argentina and Chile.

[edit] Industry

[edit] History of usage

Oil shale has been used since ancient times and can be used directly as a fuel just like coal. The modern use of oil shale to produce oil dates to Scotland in the 1850s. In 1847 Dr James Young prepared lighting oil, lubricating oil and wax from coal. Then he moved his operations to Edinburgh where oil shale deposits were found. In 1850 he patented the process of "cracking" oil into its constituent parts. Oil from oil shale was produced in that region from 1857 until 1962 when production was cancelled due to the much lower cost of petroleum.

Estonia first used oil shale as a low-grade fuel in 1838 after attempts to distill oil from the material failed. However it was not exploited until fuel shortages during World War I. Mining began in 1918 and has continued since, with the size of operation increasing with demand. After the World War II, Estonian produced oil shale gas was used in Leningrad and the cities in North Estonia as a substitute to the natural gas. Two large oil shale-fired power stations were opened, a 1,400 MW plant in 1965 and a 1,600 MW plant in 1973. Oil shale production peaked in 1980 at 31.35 million tonnes. However, in 1981 the fourth reactor of the Sosnovy Bor nuclear power station opened in the nearby in Leningrad Oblast of Russia, reducing demand for Estonian shale. Production gradually decreased until 1995, since when production has increased again albeit only slightly. In 1999 the country used 11 million tonnes of shale in energy production, and plans to cut oil shale's share of primary energy production from 62% to 47–50% in 2010.

Australia mined 4 million tonnes of oil shale between 1862 and 1952, when government support of mining ceased. More recently, from the 1970s on, oil companies have been exploring possible reserves. Since 1995 Southern Pacific Petroleum N.L. and Central Pacific Minerals N.L. (SPP/CPM) (at one time joined by the Canadian company Suncor) has been studying the Stuart Deposit near Gladstone, Queensland, which has a potential to produce 2.6 billion barrels of oil. From June 2001 through to March 2003, 703,000 barrels of oil, 62,860 barrels of light fuel oil, and 88,040 barrels of ultra-low sulphur naphtha were produced from the Gladstone area. Once heavily processed, the oil produced will be suitable for production of low-emission petrol. Southern Pacific Petroleum was placed in receivership by its majority shareholder — US energy investor Jeff Sandefer — in 2003, and by July 2004, Queensland Energy Resources announced an end to the Stuart Shale Oil Project in Australia.

Brazil has produced oil from oil shales since 1935. Small demonstration oil-production plants were built in the 1970s and 1980s, with small-scale production continuing today. China has been mining oil shale to a limited degree since the 1920s near Fushun, but the low price of crude oil has kept production levels down. Russia has been mining its reserves on a small-scale basis since the 1930s.

The United States has seen some attempts at large-scale exploitation. Oil distilled from shale was first burnt for horticultural purposes in the 19th Century, but it was not until the 1900s that larger investigations were made and the Office of Naval Petroleum and Oil Shale Reserves was established in 1912. The reserves were seen as a possible emergency source of fuel for the military, particularly the Navy.

After World War II, the US Bureau of Mines opened a demonstration mine at Anvils Point, just west of Rifle, Colorado, which operated at a small-scale. In the early sixties TOSCO (The Oil Shale Corporation) opened an underground mine and built an experimental plant near Parachute, Colorado. It closed in the late sixties because the price of production exceeded the cost of imported crude oil. It was not until the oil crisis of the 1970s and the US becoming a net importer of oil that efforts at utilization were increased. Military uses were deemed less important and commercial exploitation came to the fore, with several oil companies investing. Unocal returned to the same area where TOSCO had worked. Several billion dollars were spent until declining oil prices rendered production uneconomical once more and Unocal withdrew in 1991. In late 2005, President Bush authorized discrete mining of federally owned reserves under Colorado's surface. The federal government currently owns 72% of all known oil shale in the US.

[edit] Mining

The oil shale is/can be mined either by traditional underground mining or surface mining. There are several mining methods, however the aim of all of them is the fragmenting of oil shale deposit to enable the transport of shale fragments to a power plant or retorting facility. Main methods of surface mining are open pit mining and strip mining. Main sub-surface mining method is the room-and-pillar method.^[10]

[edit] Power generation

Oil shale could be used as a fuel for thermal power plants, where the shale is burned like coal to drive steam turbines. Currently there are oil shale-fired power plants in Estonia (2967 MW installed capacities), Israel (12.5 MW), Germany (9.9 MW), and China.^[7]^[8] While some countries have closed their oil shale-fired power plants (e.g. Romania) or converted to other fuels (e.g. Russia), some other countries are looking for construction of these power plants(e.g. Jordan and Egypt), or burn oil shale at the power plants together with coal (e.g. Canada and Turkey).^[3]^[7]^[11] The most modern technology of a combustion of oil shale in power plants is a bubbling fluidized bed (BFB) or circulating fluidized bed (CFB) process, which is used in Israel and in two units of Narva Power Plants in Estonia, while the traditional way of burning oil shale is through pulverized firing.^[12]^[7]

[edit] Oil extraction

At present, the major shale oil producers are Estonia, Brazil, China, and Australia, while some other countries as USA, Canada and Jordan have planned to start shale oil production.^[7]^[11]

There are two main methods of extracting oil from shale - ex-situ and in-situ.

**Classification of oil shale processing according to heating method and location**^[13]
Heating Method	Above Ground (ex-situ)	Below Ground (in-situ)
Conduction through a wall (various fuels)	Pumpherston, Fischer assay, Oil-Tech	Shell ICP (primary method)
Externally generated hot gas	PetroSIX, Union B, Paraho Indirect, Superior Indirect	-
Internal combustion	Kiviter, Fushun, Union A, Paraho Direct, Superior Direct	Oxy MIS, LLNL RISE, Geokinetics Horizontal, Rio Blanco
Hot recycled solids (inert or burned shale)	Alberta Taciuk, Galoter, Lurgi, TOSCO II, Chevron STB, LLNL HRS, Shell Spher	-
Reactive fluids	IGT Hytort (high-pressure H2), Donor solvent processes	Shell ICP (some embodiments)
Volumetric heating	-	ITTRI and LLNL radiofrequency

[edit] Ex-situ

In case of the ex-situ method, the oil shale is/can be mined either by traditional underground mining or surface mining from the ground and then transported to a processing facility. At the facility, the shale is usually heated to 450–500 °C (750-950°F). At this temperature, the kerogen in the shale decomposes to gas, oil vapour and char, a process known as retorting. The gas and oil vapours are separated from the spent shale and cooled causing the oil to condense. The oil may be sold as a fuel oil or upgraded to meet refinery feed specifications by adding hydrogen and removing impurities such as sulphur and nitrogen. The non-condensible retort gas and char on the spent shale may be burned and the heat may be recovered for heating the raw shale or generating electricity. Combustion exhaust gases and water condenced with the oil need to be treated prior to emission to the environment. Usually the spent shale is cooled and moistened with water before disposal back to the mine, settling ponds or tailing piles.

There are hundreds of patents for oil shale retorting technologies. However, only a few dozen have been tested in a pilot plant (1 to 10 t/h) and less than 10 technologies have been tested at a demonstration scale (40 to 400 t/h). One method of classifying the different ex-situ technologies is by the method that is used to heat the shale to retorting temperature. The classes are internal combustion technologies, hot recycled solids technologies, conduction through a wall technologies, externally generated hot gas technologies, and reactive fluids technologies.^[13]

[edit] Internal combustion technologies

Internal combustion or directly heated technologies uses heat, which is transferred by flowing gases generated by combustion within the retort. Common characteristics of these technolgies are the feed shale consists of lumps (10-100 mm) and the retort vapours are diluted with the combustion exhaust. The main technologies are Kiviter, Union A, Paraho Direct, Superior Direct, and Fushun processes.^[13]^[14] The Kiviter processing takes place in gravitational shaft retorts and it's possible only using large-particle feed. The process gas combustion products are used as the heat carrier. In the case of kukersite the yield of crude oil accounts 14-17% of shale and the oil consists only small amount of low-boiling fractions. Main problems of Kiviter process are related with environmental concerns like extensive use and pollution of water in the process, as also solid residue continues to leach toxic substances.^[15] The Kiviter process is used by Estonian company VKG Oil, a subsidiary of Viru Keemia Grupp.^[16] The company operates several retorts, the largest processing 40 t/h of oil shale.

Like the Kiviter, the Fushun-type retort processes oil shale lumps in a vertical shaft kiln. The Fushun Mining Group in Liaoning Province, China operates the largest shale oil plant in the world employing 80 Fushun-type retorts.^[17]

The Paraho Direct is an American version of the lump-processing vertical shaft kiln. Shale Technologies LLC owns and operates a pilot plant facility in Rifle Colorado.^[18]

[edit] Hot recycled solids technologies

Hot recycled solids technologies use heat, which is transferred by mixing hot solid particles with the oil shale. These technologies usually process oil shale fines (less than 10 mm). The heat carrier (usually shale ash) is heated by combustion in a separate chamber or vessel, thus the retort vapours are not diluted with combustion exhaust. The main technologies are Alberta Taciuk Process, Galoter, TOSCO II, Lurgi-Ruhrgas, Chevron STB, LLNL HRS, and Shell Spher processes.^[13]^[14] In the Galoter process, retorting takes place in a rotary kiln-type retort and it's possible to use also shale fines. The spent shale is burned in a spouted bed and solid shale ash is used as the heat carrier. In the case of kukersite the yield of crude oil accounts roughly 12% of shale and the oil consists 15-20% of low-boiling fractions. The Galoter process is more environmental-friendly than the Kiviter process, as the water use and pollution is smaller. However, the burning residue causes some environmental problems because of organic carbon and calcium sulphide consistent.^[15] The Galoter process is used for oil production by Eesti Energia, Estonian energy company.^[16] The company has 2 retorts both processing 125 t/h of oil shale and plans to build 2 more.^[19] Another Estonian company, VKG Oil AS, is constructing in 2007/08 a new production line using the Galoter process engineered by Atomenergoproject of St Petersburg^[20]

Like the Galoter process, the Alberta Taciuk processes oil shale fines in a rotary kiln-type retort. The unique feature of the Alberta Taciuk is that drying and pyrolysis of the feed shale and combustion, recycling and cooling of the spent shale all occur in a single multi-chamber horizontal, rotating vessel.^[21] The produced oil consists up to 30% of low-boiling fractions. The water pollution in the process is quite moderate.^[15] Southern Pacific Petroleum NL, an Australian oil company, operated a 250 t/h industrial-scale pilot plant using the Alberta Taciuk Processor. The plant closed in 2004. UMATAC Industrial Processes is designing the 6000-ton-per-day Alberta Taciuk Processor in China, scheduled for operation in 2008.^[22] Estonian VKG Oil is considering construction of new retort using the Alberta Taciuk Processor.^[16] Oil Shale Exploration Company LLC has arranged for an exclusive right to license the ATP for research, development and demonstration near Vernal Utah.^[23]

Like the Galoter and Alberta Taciuk, the TOSCO II also processes oil shale fines that are heated with hot recycled solids in a rotary kiln. However instead of recycling shale ash, the TOSCO II circulates hot ceramic balls between the retort and a heater. The process was tested in a 40 t/h test facility near Parachute Colorado that closed in 1972.

The LLNL HRS (hot-recycled-solid) retorting process is worked out by the Lawrence Livermore National Laboratory. The technology was used in a 4-tonne/day pilot plant from 1990 to 1993. A delayed-fall combustor, which is used in this process, gives greater control over the combustion process compared with a lift pipe combustor. A fluidized-bed mixer is used instead of the screw mixer. which is used in the Lurgi process. The majority of the pyrolysis occurs in a settling-bed unit.^[13]

[edit] Conduction through a wall technologies

Conduction through a wall technologies use heat, which is transferred by conduction through the retort wall. These technologies normally process fines and the retort vapours are not diluted by combustion exhaust. Technologies include Pumpherston, Fischer assay, Hom Tov and Oil-Tech processes.^[13]^[14] Oil-Tech staged electrically heated retort process is developed by Millennium Synfuels, LLC (former Oil Tech Inc.). In this process, the feedstock material is heated to greater degrees as it goes further down the retort. The retort-style prototype was reported to have passed a test.^[24]

In the Hom Tov process (US Patent 5372708), fine oil shale is slurried with waste bitumen and pumped through coils in a heater. Israli promoters claim that the technology enables the shale to be processed at somewhat lower temperatures with the addition of the catalyzing bitumen. The technology has not been tested in a pilot plant yet.

Fischer Assay is a standardized laboratory test that is used to measure the grade of an oil shale sample. A 100-gram sample crushed is heated to minus 8-mesh (2.38 mm mesh) screen in a small aluminum retort to 500 °C at a rate of 12 °C per minute, and held at that temperature for 40 minutes.^[6] The oil yields achieved by other technologies are often reported as a percentage of the Fischer Assay oil yield. The standardized Fischer assay method The distilled vapors of oil, gas, and water are passed through a condenser cooled with ice water into a graduated centrifuge tube.

[edit] Externally generated hot gas technologies

Externally generated hot gas technologies or indirectly heated technologies use heat, which is transferred by gases that are heated outside of the retort vessel. The main technologies are Petrosix, Union B, Paraho Indirect, and Superior Indirect processes.^[13]^[14] Like the internal combustion technologies, most of the externally-generated hot gas technologies process oil shale lumps in vertical shaft kilns, however the retort vapours are not diluted with combustion exhaust. The world’s largest surface oil shale pyrolysis reactor currently operating is the Petrosix in São Mateus do Sul, Paraná, Brazil. The 11-m diameter vertical shaft kiln is owned by Petrobras and has being operating since 1992 with high availlability. The company operates 2 retort, the largest of which processes 260 t/h of oil shale.

The largest retort ever built used the Union B technology, developed by Unocal. The Union B processed 400 t/h 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 and hot gas entered 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.^[16]

[edit] Reactive fluids technologies

Reactive fluids technologies are IGT Hytort (high-pressure H2), and Donor solvent processes.^[13]

[edit] In-situ

The in-situ technologies are usually classified as true in-situ processes (TIS) and modified in-situ processes (MIS). While true in-situ processes do not involve mining the shale, the modified in-situ involves prior to heating mining beneath the target oil shale deposit, and drilling and fracturing the target deposit above the mined area to create void space of 20 to 25 percent to improve the flow of gases and liquid fluids through the rock formation, and by that increasing the volumes and quality of the oil produced.^[16] The in-situ technologies could be also classified similarly to the ex-situ classification by the method of heating.

First in-situ oil shale experiment was conducted by Occidental Petroleum in 1972 at Logan Wash.^[16] In-situ operations could potentially extract more oil from a given area of land than conventional oil shale mining and retorting, as the wells can reach much deeper than surface strip-mines can. With in-situ processing, the shale is fractured and heated underground to release gases and oils. Several companies have patented methods for in-situ retorting. However, most of these methods are still experimental.

[edit] Shell's In-Situ Conversion Process

The Shell Oil Company has been developing a new method under the name the Mahogany Research Project in Colorado, some 200 miles (320 km) west of Denver. This is a true in-situ technology which uses conduction through a wall and reactive fluids (some embodiments) methods for the heating. First a freeze wall is constructed to seal off groundwater by drilling 2000' wells, eight feet apart, around the perimeter of a 10 acre working zone, and then circulating with a super-chilled liquid to freeze the ground to -60^oF. The working zone is then dewatered. Recovery wells are drilled on 40' spacing within the working zone. An electrical heating element is lowered into each well and allowed to heat the kerogen to 650 to 700^oF over a period of approximately four years, slowly converting it into oils and gases, which are then pumped to the surface. An operation producing 100,000 barrels a day would require a dedicated electrical generating capacity of 1.2 gigawatts. To maximize the functionality of the freeze walls, working zones will be developed, in succession, adjacent to each other. This in-situ method requires 100% surface disturbance, greatly increasing the footprint of extraction operations in comparison to conventional oil and gas drilling.

[edit] Volumetric heating by radio waves technologies

The concept of volumetric heating by radio waves (radio frequency processing) of oil shale was developed at IITRI in the late 1970s. The concept was to heat modest volumes of shale over using vertical electrode arrays. Deeper large volumes could be processed at slower heating rates over a period. The technology was developed later by the Lawrence Livermore National Laboratory (LLNL), and by several other inventors. The LLNL concept based on the use of wells spaced at tens of meters to heat cubic kilometers of deep oil shale very slowly. The concept presumed a radio frequency at which the skin depth is many tens of meters, and thereby overcoming the thermal diffusion times needed for conductive heating.^[13]^[25]

[edit] Other uses

Oil shale is or could be used for production of different products like specialty carbon fibers, adsorbent carbons, carbon black, bricks, construction and decorative blocks, soil additives, fertilizers, rock wool insulating material, and glass. However, oil shale usage for production of these products are still small or even in experimental stages only.

Some oil shales could be used for uranium production. In 1946-1952, a marine type of Dictyonema shale was used for uranium production in Sillamäe, Estonia, and in 1950-1989 alum shale was used in Sweden for the same purpose.^[6] Oil shale gas could be used as a substitute for natural gas, however at the current price level this is not economically feasible.

[edit] Economics

If the price of a barrel of oil is under 40 USD, shale oil produced by using standard processing technologies is not competitive with conventional crude oil.^[3] In 2005, Royal Dutch Shell announced that its insitu extraction technology deployed in Colorado could be competitive at prices over 30 USD/barrel.^[26] The Israel's AFSK Hom Tov process, which produces oil from a mixture of oil refinery residue, in the form of bitumen, and oil shale, claims profitable at the price of $16-$17 USD/barrel, however this technology still at the test phase.

Due the low price of oil and other competitive fuels, oil shale production has ceased in Canada, Scotland, Sweden, France, Australia, Romania and South Africa, and has not taken off in the USA, Belarus, Jordan and Morocco.^[7] During the oil crisis of the 1970s, people thought that oil supplies were peaking, expected oil prices to be around seventy dollars a barrel for some time to come, and invested huge amounts of money in refining oil shale — money that they lost. Because of the hugh loses last time around, there is considerable reluctance to invest in shale oil production. Investors are waiting to see if oil prices really will remain in high level and no hurry to develop oil shale. However, Australia restarted oil shale production in 1999, and USA, Canada and Jordan are planning or already started with test projects.^[7]

*US Companies with Oil Shale operations or pilot projects*
Company	Method
Petrobras	Externally generated hot gas (Petrosix process)
Shell Frontier Oil and Gas	In-situ Conversion Process
ExxonMobil
Chevron Shale Oil Company	In-situ Conversion Process
EGL Resources
Millennium Synfuels	Staged electrically heated retort process
Oil Shale Exploration	ATP

A critical measure of the viability of oil shale is the ratio of energy used to produce the oil, compared to the energy returned (Energy Returned on Energy Invested - EROEI). Oil shale typically has a very low EROEI. Generally, the oil shale has to be mined, transported, retorted, and then disposed of, so at least 40% of the energy value is consumed in production. Royal Dutch Shell reported a figure of EROEI about 3:1. That is, energy equivalent to one barrel of oil was used for every three gained, on its recent in-situ development (which uses electric heating of the shale up to 500 degrees fahrenheit (260 °C) while it is still in the ground, while also creating a frost shield around the mining site), Mahogany Research Project. This compares to a figure of typically 5:1 for conventional oil extraction. EROEI may be less important if alternate energy sources are used to fund the process. Coal was the primary power source used by the Shell pilot project.

Water is also needed to add hydrogen to the oil-shale oil before it can be shipped to a conventional oil refinery. The largest deposit of oil shale in the United States is in western Colorado (the Green River Shale deposits), a dry region with no surplus water. The oil shale can be ground into a slurry and transported via pipeline to a more suitable pre-refining location.

[edit] Environmental considerations

Surface-mining of oil shale deposits has all the detrimental environmental effects from open-pit mining. In addition, the pre-refining process to obtain crude oil generates ash, and the waste rock (a known carcinogen^{[citation needed]}) must be disposed of. Oil shale rock needs disposal. Oil shale processing also requires water, which may be in short supply.

The energy demands of blasting, transporting, crushing, heating the material, and then adding hydrogen, together with the safe disposal of huge quantities of waste material, are large. These inefficiencies, plus the cost of environmental restoration, mean that oil shale exploitation will only be economical when oil prices are high (and projected to remain so).

Currently, the in-situ process is the most attractive proposition due to the reduction in standard surface environmental problems. However, in-situ processes do involve possible significant environmental costs to aquifers, especially since current in-situ methods may require ice-capping or some other form of barrier to restrict the flow of the newly gained oil into the groundwater aquifers.

[edit] See also

[edit] References

^ Energy Information Administration, Annual Energy Outlook 2006
^ “Oil Shale Development Imminent”, R-Squared Energy Blog June 15, 2006
^ ^a ^b ^c ^d ^e ^f ^g Survey of energy resources - oil shale, World Energy Council 2004
^ ^a ^b ^c Oil Shales in the world and Turkey; reservs, current situation and future prospects: a review, by N. E. Altun, C. Hiçyilmaz, J.-Y. Hwang, A. Suat Bağci, M. V. Kök. Oil Shale. A Scientific-Technical Journal, 2006, Vol. 23, No. 3 pp.211-227. ISSN 0208-189X
^ Hutton, A.C. 1987. Petrographic classification of oil shales // Intern. J. Coal Geol. 1987. Vol. 8. P. 203–231.
^ ^a ^b ^c ^d Geology and resources of some world oil-shale deposits (Presented at Symposium on Oil Shale in Tallinn, Estonia, November 18-21, 2002), by J. R. Dyni, U.S. Geological Survey. Oil Shale. A Scientific-Technical Journal, 2003, Vol. 20, No. 3 pp.193-252. ISSN 0208-189X
^ ^a ^b ^c ^d ^e ^f ^g Global oil shale issues and perspectives. Synthesis of the Symposium on Oil Shale held in Tallinn (Estonia) on 18 and 19 November 2002, by Dr. K. Brendow, World Energy Council, Geneva
^ ^a ^b ^c Oil Shale Development in China, by J. Qian, J. Wang, S. Li (Petroleum University, Beijing, China). Oil Shale. A Scientific-Technical Journal, 2003, Vol. 20, No. 3 pp.356-359. ISSN 0208-189X
^ Review on oil shale data, by Jean Laherrere, September 2005
^ Oil Shale Development in the United States. Prospects and Policy Issues by James T. Bartis, Tom LaTourrette, Lloyd Dixon, D.J. Peterson, Gary Cecchine, The RAND Corporation. Prepared for the National Energy Technology Laboratory of the U.S. Department of Energy 2005. ISBN 978-0-8330-3848-7
^ ^a ^b Oil Shale Resources Development In Jordan, by Dr. Yousef Hamarneh, 1998; updated by Dr. Jamal Alali and Eng. Suzan Sawaqed, Natural Resources Authority of Jordan, Amman, November 2006
^ Reduction of sulphur dioxide emissions and transboundary effects of oil shale based energy production, by V. Liblik, M. Kaasik, M. Pensa, A. Rätsep, E. Rull, A. Tordik. Oil Shale. A Scientific-Technical Journal, 2006, Vol. 23 No. 1 pp.29-38. ISSN 0208-189X
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Alan K. Burnham, James R. McConaghy. Comparison of the Acceptability of Various Oil Shale Processes. AICHE 2006 Spring National Meeting, Orlando, FL, United States. 14 March 2006
^ ^a ^b ^c ^d An Assessment of Oil Shale Technologies, June 1980. NTIS order #PB80-210115
^ ^a ^b ^c Estonian Oil Shale Retorting Industry at a Crossroads. Oil Shale. A Scientific-Technical Journal, 2004, Vol. 21 No. 2 pp.97-98. ISSN 0208-189X
^ ^a ^b ^c ^d ^e ^f Strategic Significance of America’s Oil Shale Resource. Volume II Oil Shale Resources, Technology and Economics, March 2004
^ Today's rainbow ends in Fushun, by J. Purga. Oil Shale. A Scientific-Technical Journal, 2004, Vol. 21 No. 4 pp 269-272. ISSN 0208-189X
^ Shale Technologies LLC homepage
^ Oil Shale Energetics in Estonia, by Sandor Liive. Oil Shale. A Scientific-Technical Journal, 2007 Vol 24 No 1 pp 1-4. ISSN 0208-189X
^ New shale oil line for VKG Oil AS, Rintekno Newsletter Nov 2006 p.8
^ Technology Details: Alberta Taciuk Process
^ US eyes Alberta as model for developing oil shale. Alberta Oil Volume 2 Issue 4
^ OSEC's Process: A Proven TechnologyOSEC website
^ Hopes for shale oil are revived, by Perry A. Fischer, Editor , WorldOil.com Vol. 226 No. 8 August 2005
^ Slow Radio-Frequency Processing of Large Oil Shale Volumes to Produce Petroleum-like Shale Oil, by Allan K. Burnham. 20 August 2003. UCRL-ID-155045
^ Shell's Ingenious Approach to Oil Shale is Pretty Slick, Rocky Mountain News, September 3, 2005

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