Natural gas is a fossil fuel, but not a petroleum product. Due to its composition, which is essentially methane (CH4), it is a very light gas when it is released, rising into the atmosphere and dissipating, thus eliminating the risk of accumulations at ground level. Natural gas also offers a renewable alternative via biogas/biomethane that is still the same chemical product – methane gas – but is produced from the fermentation of biomass of any type. Valdemingómez in Madrid is home to Europe’s largest biomethane plant from solid urban waste that every year injects into the grid an amount of biomethane gas equal to the consumption of Madrid’s 450 refuse trucks all of which run off compressed natural gas (CNG).
As it is the hydrocarbon with the simplest molecule, it offers very clean combustion with significant environmental advantages. Apart from almost entirely eliminating the emission of particles and NOx, the emission of NO2, which is the NOx component used to measure air quality in cities, completely disappears. It is thus a paradox that the sharp fall in NOx that has taken place in diesel engines from €1 to €5 has resulted in all NOx being NO2, leading to an increase in the specific emission of NO2.
This is one of the reasons for alarm bells ringing in Madrid in January because of NO2 and during the end of July due to high levels of troposphere ozone, a secondary contaminant caused by the effect of the sun on NOx and others elements of the air we breathe. CNG in urban fleets is helping improve the air quality of our cities and this is why it will end up becoming the urban fuel of choice. Read more…
Article published in: FuturENERGY September 2015