Oil shale gas
Encyclopedia
Oil shale gas is a synthetic gas mixture (syngas
) produced by oil shale
pyrolysis
. Although often referred to as shale gas, it differs from the natural gas produced from shale
, which is also known as shale gas.
decomposes
into vapor
s of a petroleum
-like condensable
shale oil
, non-condensible combustible
oil shale gas, and spent shale—a solid residue. The process is a same as the shale oil extraction and oil shale gas usually occurs as a byproduct of shale oil production. The ratio of oil shale gas to shale oil
depends of retorting temperature and as a rule increases by the rise of temperature.
, hydrogen
, carbon monoxide
, carbon dioxide
, nitrogen
, and different hydrocarbons like ethylene
. It may also consist of hydrogen sulfide
and other impurities.
. In the 19th century and in the beginning of the 20th century oil shale gas was used as illuminating gas. In 1920s, gas plants in Tallinn
and Tartu
produced oil shale gas as a town gas. Since 1948, Estonian-produced oil shale gas was used in Leningrad
and the cities in North Estonia. For this purpose, 276 gas generators were operational in Kohtla-Järve
until 1987.
As oil shale gas occurs often as a byproduct of shale oil extraction, depending the processing technology it may be used for heating the pyrolysis process.
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...
) produced by oil shale
Oil shale
Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen from which liquid hydrocarbons called shale oil can be produced...
pyrolysis
Pyrolysis
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...
. Although often referred to as shale gas, it differs from the natural gas produced from shale
Shale gas
Shale gas is natural gas produced from shale. Shale gas has become an increasingly important source of natural gas in the United States over the past decade, and interest has spread to potential gas shales in the rest of the world...
, which is also known as shale gas.
Process
Oil shale gas is produced by retorting (pyrolysis) of oil shale. In the pyrolysis process, oil shale is heated until its kerogenKerogen
Kerogen is a mixture of organic chemical compounds that make up a portion of the organic matter in sedimentary rocks. It is insoluble in normal organic solvents because of the huge molecular weight of its component compounds. The soluble portion is known as bitumen. When heated to the right...
decomposes
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
into vapor
Vapor
A vapor or vapour is a substance in the gas phase at a temperature lower than its critical point....
s of a petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
-like condensable
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....
shale oil
Shale oil
Shale oil, known also as kerogen oil or oil-shale oil, is an unconventional oil produced from oil shale by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock into synthetic oil and gas...
, non-condensible combustible
Combustibility
Combustibility is a measure of how easily a substance will set on fire, through fire or combustion. This is an important property to consider when a substance is used for construction or is being stored. Special precautions are usually required for substances that are easily combustible...
oil shale gas, and spent shale—a solid residue. The process is a same as the shale oil extraction and oil shale gas usually occurs as a byproduct of shale oil production. The ratio of oil shale gas to shale oil
Shale oil
Shale oil, known also as kerogen oil or oil-shale oil, is an unconventional oil produced from oil shale by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock into synthetic oil and gas...
depends of retorting temperature and as a rule increases by the rise of temperature.
Composition
There is no exact formula of oil shale gas. Compositions of oil shale gas depends of retorted oil shale and exploited technology. Typical components of oil shale gas are usually methaneMethane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
, hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
, carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, and different hydrocarbons like ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...
. It may also consist of hydrogen sulfide
Hydrogen sulfide
Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
and other impurities.
Usage
Oil shale gas has served as a substitute for natural gasNatural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
. In the 19th century and in the beginning of the 20th century oil shale gas was used as illuminating gas. In 1920s, gas plants in Tallinn
Tallinn
Tallinn is the capital and largest city of Estonia. It occupies an area of with a population of 414,940. It is situated on the northern coast of the country, on the banks of the Gulf of Finland, south of Helsinki, east of Stockholm and west of Saint Petersburg. Tallinn's Old Town is in the list...
and Tartu
Tartu
Tartu is the second largest city of Estonia. In contrast to Estonia's political and financial capital Tallinn, Tartu is often considered the intellectual and cultural hub, especially since it is home to Estonia's oldest and most renowned university. Situated 186 km southeast of Tallinn, the...
produced oil shale gas as a town gas. Since 1948, Estonian-produced oil shale gas was used in Leningrad
Leningrad
Leningrad is the former name of Saint Petersburg, Russia.Leningrad may also refer to:- Places :* Leningrad Oblast, a federal subject of Russia, around Saint Petersburg* Leningrad, Tajikistan, capital of Muminobod district in Khatlon Province...
and the cities in North Estonia. For this purpose, 276 gas generators were operational in Kohtla-Järve
Kohtla-Järve
Kohtla-Järve is a city and municipality in north-eastern Estonia, founded in 1924 and incorporated as a town in 1946. The city is highly industrial, and is both a processor of oil shales and is a large producer of various petroleum products. The city is also very diverse ethnically: it contains...
until 1987.
As oil shale gas occurs often as a byproduct of shale oil extraction, depending the processing technology it may be used for heating the pyrolysis process.