Natural gas is a fossil fuel formed by the decomposition of organic substances. It is a mixture of various gases, comprising mostly methane or CH4 (up to 99%). Also present are ethane, propane, butane, particles of heavy hydrocarbons, nitrogen and carbon dioxide. Natural gas is extracted from underground deposits and then transmitted to users via underground gas transmission networks.
Natural gas is the cleanest fossil fuel, with the lowest CO2 emissions when burned. It serves multiple purposes and is energy efficient. Natural gas is non-toxic. It is lighter than air, odourless and is explosive in the right combination with air. Thus, for safety reasons an odorant is added to natural gas in the distribution process in order to detect its presence.
CO2 and H2O are generated when methane is burned and chemical energy is converted to heat.
The abbreviation NG is used to designate natural gas.
Basic technical information about natural gas:
- Gross calorific value: (kJ/Sm3) → From 36,000 to 40,000
- Wobbe number (MJ/Sm3) → From 48 to 52
- Density (kg/Sm3) → From 0,6 to 0,8
- Relative density (air = 1) → From 0,54 to 0,59
Sm3 = standard cubic meter (15ºC and 1.01325 bar)
Shale
According to data from the Energy Information Administration (EIA), the extraction of natural gas from shale could increase potential global stocks by some 47%. These calculations are quite uncertain, as additional research will be required for more precise data. Nevertheless, the production of this unconventional form of natural gas is growing sharply. Currently the aforementioned extraction technology is only used for commercial purposes in the US, Canada and China. In the US, such production already accounts for 39% of total natural gas production, compared with 15% in Canada and just 1% in China. According to some figures, the production of shale gas is expected to account for one half of all production in North America by 2020. Elsewhere around the world, shale gas is not yet used commercially, primarily due to the technology used, which in North America is the most advanced. That technology is based on hydraulic fracturing or “fracking”, which is a process in which a mixture of water, chemicals and sand is injected into layers of rock deep below the surface. This creates fractures in these layers, which releases the natural gas trapped in the rock to the surface. According to the EIA’s latest figures, there is an estimated 206,000 billion m3 in gas stocks from 137 deposits in 41 countries. That number is rising every year, as this new technology facilitates the search for natural gas at depths that were previously unachievable. According to some estimates and unofficial numbers, stocks of shale gas could be at least three times higher than stated above. According to currently available data, the largest reserves of this form of natural gas can be found in China, the US, Argentina and Mexico.
*Data from 2013
Source: http://www.eia.gov/analysis/studies/worldshalegas/
