Burning natural gas puts off 50% the CO2 as coal in generation plants, and in transportation it pollutes far less than diesel or gasoline. We know this, and the industry runs adds on TV to drive it home, so the public believes it could help reverse the slide to global warming. In truth it won’t, or if it does, not much and not for a very long time.
The largest use of natural gas is for electricity generation. For a number of years now it's been replacing coal as a fuel, the replacement rate is 2.5% a year. Sounds good so far.
When we burn methane (natural gas) it makes CO2, a greenhouse gas, who’s molecules live for up to 100 years aloft if not absorbed into the biosphere. If there is a methane leak at the well, pipeline or generation plant, the unburned methane rises, also a greenhouse gas and
102 20-25 times more powerful than CO2. 102 20-25 times more powerful than CO2 at trapping heat. Methane molecules life in the upper
atmosphere is about 12 years.
Estimates and early studies vary, but leaks (from well to the turbine's flame) range from 1.5% to 8% of natural gas is lost. So it’s complicated, but like compounding of interest the numbers are rather startling when figuring; the conversion rate, the CO2 savings in burning NG over coal, the leak rates, the life and power of each destructive green house molecule.
The worse case scenario is the 8% leak rate. If this is true the switch to NG makes things worse for 60 years before it achieves an actual improvement. If the rate of conversion to NG doubled to 5% a year it would take 50 years to cross into the plus column. If however, the leak rate is 1.5%, the pay off is immediate, but it’s not much of a gain, we would be only a little better off, and I would take that small advantage. My gut says that 1.5% is not going to stand up, the leak rate, like every ship wreck or oil platform explosion will turn out to be multiples of what the industry wants to claim.
This only looked at one item, power generation fuel substitution. It did not look at fracking and it’s multiple layers of community damage. It did not look at transportation use of NG and the leaks in those tanks, engines, and during refueling. Nor the hissing leaking pipes running below our streets, into our homes. It did not look at oil wells which often (as you may smell if you drive past one) has methane escaping at the wellhead. Refiners often flare off NG rather than capture it during refining of oil. The overall oil and gas industry methane leak rate is unknown but might be over 15% of what we use. The industry however says oh it’s tiny, why would we let an asset escape? Well, maybe because your making so damn much money on it that putting improved seals in the pipeline compressor or capturing rather than flaring just isn’t worth it. We have to remember, they are in the business of ripping resources from the earth, nothing else.