More information can be found at wikipedia
Natural gas is one of the fossil fuels. It is produced in the same process that makes crude oil and represents the lighter fraction of the organic products of this process.
Natural gas often is found toghether with natural oil; however, it happens that gas finds a way to separate itself from the oil (that is mucht heavier).
In Europe natural gas is mainly found in and around the North Sea. It may contain up to more than 80% methane, about 3 % higher carbonhydrogens and about 15% of Nitrogen + a bit of Carbondioxyde.
Natural gas can have different constitution at different regions. Sometimes it contains some hydrogensulfide ("acid gas").
In the past natural gas often was treated as a simple waste product in the oil industry and subject to gas flaring.
Even now it can be done when natural gas is found far from the civil world en in the case of great transport problems.
Ecologically this is a great pity; of fossil fuels, natural gas is the cleanest.
Gas flaring is better than simply letting methane escape freely to the atmosphere. The contribution of methane to the greenhouse effect is about 25 times more than that of carbondioxyde.
Even better would be to put the gas back into the earth crust. This is very difficult and costly. Poor countries (as well as the oil companies) refuse to make such investments.
Methane, when burned, produces water and carbondioxyde, where coal only produces carbondioxyde in much larger quantity.
Besides, natural gas does not produce ashes, carbon black or soot, and contains less sulphur.
And still there are coal-fired power plants.
Clean natural gas (without H2S)is a scentless substance. To assure that leaking gas will be noticed, some bad smelling substance is added, like tetrahytdrothiophene, about 20 mg per m3. All this just to be warned in time.
Natural gas is a source of energy, used for cooking and heating.
IIt also is used in energy plants and for central city heating.
Natural gas is also used as natural resource in various chemical production processes, for example the production of ammonia.
Methane from bio-fermentation
The process of methane gas production does not need thousands of years, as in the case of oil / coal.
Always in anaerobic processes of organic material, methane can be made, toghether with other gases like carbondioxyde and hydrogen sulphide.
It occurs in absence of oxygen.
Storage of Hydrogen underground
Underground storage of Hydrogen is possible in underground caves, before filled with salt or gas of whatever.
Thus we can have fine storage places for energy.