Methane - SpeedyLook encyclopedia

Some properties

With the Normal conditions of temperature and pressure, it is a Gaz lighter than the Air, colorless and odorless. It is liquefied with -161,4 °C and is solidified with -182,6 °C.
the density of liquid methane is from 0,415 to -164 °C.
Its solubility in water is of 0,4 ml for 100 ml of water at the temperature of 20 °C, this solubility in alcohol is of 47 ml at the same temperature and 104 ml with 10 °C in ether, always for the same volume of 100 ml.
methane is a fuel. It ignites with 667 °C in the presence of oxygen. The reaction of combustion of methane is written:

CH₄ + 2O₂ → CO₂ + 2:00 ₂O méthane + Dioxygène → Carbon dioxide + Water

1 m ³ of methane with 15 °C (Natural gas) releases an energy of 9,89 kWh (35,6 MJ)
methane (in fact, the natural gas, made up with more than methane 90%) is transported by ships (Méthanier S) at a temperature of -162 °C and a pressure close to the Atmospheric pressure. The tanks are built on the principle of the “Thermos bottle” and their capacity can go up to 40 or 50.000 m ³ of liquid gas by tank. A methane tanker comprising several tanks, its cargo can currently reach 154.000 m ³ GNL, Natural gas Liquefied , composed with more than methane 90%. The future methane tankers will be able to transport up to 260.000 m ³ of GNL. The volume of methane in a gas state is equal to 600 times its volume with the state Liquide, with atmospheric pressure.
methane is regarded as very dangerous, because it explodes easily, in the Raffinerie S. the flares burn it to avoid the problems. This point must be modified to recover methane under correct security conditions. It is an explosion due to the methane which blew the Total refinery of Châteauneuf-the-Martigues in 1992.

History

Alessandro Volta discovers methane in 1776 while being interested in “marsh gas” (the old name of methane).

It is because of the Grisou, person in charge (still nowadays) of too many Catastrophe S mines which were developed, the lamps of safety in the coal mines, and in particular the lamp with Acétylène.

Until the years 1970, the impact of methane on the climate was unknown. In 1976, it was shown that methane was a Gaz with greenhouse effect.

It is only with the space Conquête that one discovered the omnipresence of this body in the Universe.

Use

The fossil layers of Natural gas comprise between 50 and 60% of methane, the rough natural gas are purified before being injected on the distribution network. The proportion of methane present in the Natural gas that we use is higher than 90% in the majority of gases.

Biological methane, or Biogas, which is produced by the Fermentation Anaérobie of organic matter comprises 50 to methane 80%, (60-65% generally)

The Biogaz produces in the discharges could be (well more) recovered and developed in the form of electricity, of heat or like automobile Carburant. For the moment, only some isolated experiments (in farms, déchetteries…) were born, especially in the coldest areas (north of Germany, of France, Scandinavia…), but the economic profitability of these installations is far from being acquired. (see the experiment in Rwandan prison)

Contribution to the greenhouse effect

Methane, gas with greenhouse effect

Methane is a Gaz with greenhouse effect which influences the climate. It absorbs part of the infra-red radiation emitted by the Earth, and thus prevents it from escaping towards space. This phenomenon contributes to the warming of the Earth.

Moreover it contributes also indirectly to the greenhouse effect by decreasing the capacity of the atmosphere to oxidize other gases with greenhouse effect (like the freons). Its use as fuel emits of CO₂ to a total value of 380 Mt/an (industrial emissions border 6000 Mt/an) and of the steam, another gas with important greenhouse effect.

The influence of methane on the climate is less important than that of the Carbon dioxide but it is nevertheless alarming. A methane molecule absorbs on average 23 times more radiation than a molecule of Carbon dioxide over one 100 years period. See: Potential of total warming. Methane is regarded as the 3rd gas responsible for the climatic disordered state , after the CO₂ and the freons).

In the past, the methane rate in the atmosphere varied like the temperature. The methane concentration increased approximately 150% since 1750 and reached today an unequalled rate in the history. This increase is mainly due to the human activities.

It is estimated that without its presence, the average temperature of surface of the Ground would be lower of 1,3°C.

Sources of methane

All in all, one estimates the emissions of CH₄ towards the atmosphere at 500 Mt/an, of which the three quarters come from sources of origin Anthropique.

The independent sources are:

wetlands: 32% of the emissions.

The tropical Marsh, Mangrove S and the Rizière S are prone to the action of bacteria methanogenes in anaerobic medium. The temperature affects the emissions, which reach their maximum value between 37 °C and 48 °C, from where an amplification of the emissions in the event of warming.

the fossil energies: 21% of the emissions

The Natural gas is composed to 90% of methane. The escapes in the atmosphere during its extraction, of its transport, its treatment and its distribution could represent up to 2% of the production of natural gas, the three quarters of these escapes taking place at the customer, after the meter. In the same way, the gas trapped in the seams of coal during its formation is slackened during the extraction of the ore. If one does not want to reduce the use of these fossil energies and without an massive investment in alternative energies, it is thus necessary to seek solutions to limit the escapes.

ruminants: 16% of the emissions.

Methane is a product of incomplete digestion during the gastro-enteric fermentation of the ruminants. Only one Vache can emit 100 to 500 liters of methane per day. To that is added emitted waste who continue their decomposition on the ground. Only one solution: to improve the mode of these animals and to avoid the storage of waste, which cannot be desiccated when they are piled up.

human waste: 12% of the emissions

The stock rooms of waste ferment and emit methane; this gas could be re-used like energy source.

the biomass: 10% of the emissions

Emitted methane comes from the incomplete combustion of the plants, but especially of their natural organic decomposition (like the dead sheets of the underwoods).

sediments and oceans: 4% of the emissions

The hydrates containing of methane (Clathrate S) could emit gas in the event of disturbance of the oceanic temperature and/or the thaw of certain rich grounds of the Toundra Siberian and Canadian, but these emissions are currently limited. However, an increase in temperature involves an increase in the emission of CH₄ by the clathrates. This source could thus constitute a true bomb with climatic delayed-action in the event of warming of the oceanic funds.

The future variations of these emissions remain dubious, one however envisages an increase in the contributions of fossil energy, waste and sources agricultural, because of the development of the world population, the industrialization of certain countries and the increasing demand in energy.

Methane wells

The various mechanisms of elimination of atmospheric methane withdraw approximately 515 Mt/an. The principal well with CH₄ is the radical Hydroxyde OH^- contained in the atmosphere, which contributes to 90% of the disappearance of CH₄. OH, oxidising agent of the principal pollutants of the atmosphere (CH ₄, CO, Nox, made up organics), comes from the photochemical dissociation of O ₃ and H₂O. The content of radical Hydroxyde is thus influenced by the atmospheric concentration of CH₄ but also by that of its products, of which CO. In the same way, various mechanisms affect the content of OH^-:

the increase in urban concentration out of Nox generates more formation of O₃ and thus more dissociation in OH^-;
the fall of the stratospheric concentration of O₃ induced more radiation UV reaching the Troposphere and thus more tropospheric dissociation of O₃;
the increase in the steam resulting from the increase in the average temperature produces more clouds blocking flows of Proton S, effect reducing the formation of OH^-, and more steam, reagent of formation of OH^-.

It was noted that since 1750, the level of OH^- decreased by approximately 20% because of increase out of CO and CH₄, and is stable today. From here 2050, this level should further decrease by 25%, which will have an significant impact on the contents of elements gas traces. The 10% remainders are due to the oxidation of methane in dry ground by bacteria Méthanotrophe S which use it like source of carbon, like by its transfer towards stratosphere.

To reduce the methane emissions

There exist means of decreasing the methane emissions to decrease its action on the Greenhouse effect:

to collect methane, or Biogas, emitted on the level of the discharges of refuse or purification plants and to burn it (combustion forms CO₂ which has a less important greenhouse effect). That would make it possible to partly replace other energies fossible instead of burning it in flare as it is often the case currently.
to collect and use methane, or Biogas, produced on the level of the storage systems of the effluents of breedings.
to recover the methane emitted at the time of mining.
to select methane producing rice species and to use less fertilizers, to drain water regularly.

at the personal level :

to reduce its meat consumption (in particular bovine)
to reduce its rice consumption (see the bond between rice growing and the greenhouse effect)

Methane in the Universe (source ESA)

methane was found with the state of traces in several interstellar clouds.
methane is everywhere on Titan, and even in the form of lakes, of rivers, and seas. Its presence was established by it as of 1944. So much so that the heat released by the Huygens probe, at the time of the impact of the January 14th 2005 caused a notable methane gas release.
Titan presents a uniform atmosphere of nitrogenize-methane. It did not rain when the Huygens probe was posed on Titan, but the ESA does not exclude that methane downpours are frequent there. Simply, the aridity of the ground would absorb these precipitations quickly, with the manner of the terrestrial deserts.
Of the methane traces was also discovered in the atmosphere of Mars.
Some share, in the Universe, is a life containing Methane and either of Eau conceivable if not possible? It is one of the great questions raised by this mission. With Cassini it is thus all our design of the Exoplanète S (and thus of the world) which is to be re-examined.
the atmosphere of methane would allow it the flight of “less heavy than the air” so much so that the planetologists of ESA, dream to send to it Ballon S, Montgolfière S, Robot S mobiles… in order to include/understand this extraterrestrial world from which one comes to explore only one negligible part.
In four billion years, when the sun swells inordinately before exploding and absorbing the Earth, the planetologists having fun to imagine time that it would make on Titan, think that it should make good live there in its atmosphere of methane (during one brief moment only).

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