Methane: a ‘clean’ fuel
Among fossil fuels, currently methane seems to be the one that will be exploited more and more in the near future, thanks to its relative abundance and thanks to the fact that it is relatively ‘clean’. Its molecule is made up of 4 atoms of hydrogen and one of carbon (CH4): on burning, it is the hydrocarbon that releases the smallest amount of carbon and it is for this reason that it is less harmful for the environment. Its CO2 emissions are 25% lower than petrol, 16% lower than Liquid Propane Gas, 30% lower than diesel and 75% lower than carbon. Its capacity to form ozone is 80% less than petrol and 50% less than diesel and Liquid Propane Gas. Moreover, the combustion emissions do not contain carbonaceous residues, benzene and microscopic dusts (PM10), contrary to petrol and diesel oil. Among all the fossil fuels, methane is surely the most ‘ecological’. The use of methane is expected to increase greatly in the near future. The natural gas reserves that are of ‘geological’ origin are estimated to be sufficient for 60-70 years and they are mostly concentrated in the areas surrounding the Persian Gulf. (vedi speciali e sezione Energia) Much smaller amounts are currently obtained from waste products of zooculture, with the use of anaerobic digesters that enable the production of methane from animal sewage. Other small quantities can be obtained from self-produced methane in abandoned carbon mines; here, this naturally produced gas is tapped and at the same time is prevented from dispersing in the surroundings.
Methane hydrates could be the energy source of the future. A cubic metre of methane hydrates can contain from 160 to 180 m3 of methane gas. It has been calculated that beneath the ocean floor and in areas of permafrost more than 100,000 million billion cubic metres of methane are present, trapped in the form of hydrates. Some estimates state that the ‘reservoirs’ contained in the permafrost of Alaska and Siberia are 5 x 1013 m3 while those contained beneath the ocean floor are 5-25 x 1015 m3. The amount that can be exploited could be at least two orders of magnitude greater than the amount of methane present on the planet and could supply about twice the amount of energy that can be obtained from all the fossil fuel deposits known to date.
Unconventional gas: shale gas
Natural gas has been the last fossil fuel to assert itself on a global scale...
The melting of the ice cells, not only brings about the release of methane gas, but it also produces another important substance: fresh water