N2O, HFC, PFC, SF6: Ce’s nos. 3, 4, 5, 6, respectively

No, I’m not writing in code. Nor is this a bunch of meaningless mumbo jumbo or nonsensical gibberish. What I’m talking about here are the greenhouse gases (GHG) of nitrous oxide (N2O), hydrofluorocarbons (HFC), perfluorocarbons (PFC) and sulfur hexafluoride (SF6). Aside from (N2O) which is the third most prevalent GHG behind carbon dioxide (CO2) and methane (CH4), I’ve ordered the fluorinated gases this way based on both their survivability in the atmosphere and their global warming potentials (GWP) – that is, effectively from shortest- to longest-lived and from lowest to highest GWP. Add in CO2 and CH4 and the greenhouse-gases picture is complete.

The_Earth_seen_from_Apollo_17[1]Interestingly, with the exception of N2O, the fluorinated gases (HFC, PFC and SF6), according to the U.S. Environmental Protection Agency (EPA) from the “Overview of Greenhouse Gases” page on its Web site in particular, are synthetic – not naturally occurring gases – and result in the air from various industrial-related manufacturing processes.

Nitrous oxide emissions, on the other hand, are formed mainly through agriculturally- and industrially-related activities, according to EPA.

Nitrous oxide emissions (at 6%) and fluorinated gases (at 3%) combined with methane (at 9%) and carbon dioxide (at 82%), accounts for total (100%) U.S. GHG concentration amount.

So, let’s talk more about nitrous oxide emissions. Nitrous oxide is not to be confused with oxides of nitrogen (NOx), the two, which people, can and do, get confused. NOx, although a gas, is not a greenhouse gas.

The good news is that N2O, as a pollutant emission, has remained relatively steady since 1990, holding constant at around 400 million metric tons carbon dioxide equivalent (MMTCO2e). Also, according to EPA, a five percent rise is projected from 2005 to 2020, attributed mainly to increased emissions from the agricultural sector. The bulk (75%) of non-naturally-occurring N2O is produced from agricultural activities with lesser percentages from industry/chemical production (6%), five percent each from stationary combustion sources, manure management and other, and from transportation (4%).

And, as for the fluorinated gases, they see heavy use in the manufacture of semi-conductors (semi-conductors are used extensively in the electronics field) and in refrigeration. Hydrofluorocarbons (HFC) replaced hydrochlorofluorocarbons (HCFC) and chlorofluorocarbons (CFC), both of which were damaging to the stratospheric ozone layer.

No matter the greenhouse gas, except for what occurs naturally and is outside the control of humans, excess GHG entering air or water or both, for example, should be reduced if not stopped completely. Essentially, the excess GHG we’re talking about is leftover or waste GHG. As long as any of or all six greenhouse gases – alone, in any combination involving two or more up to five in all, or all six collectively – can be found in the atmosphere other than that which is naturally occurring, and irrespective of whether there’s been a shift in climate or not, said shift (if there is one) being on account of the presence of GHG emissions in the air, I believe what is warranted most definitely, is cause for concern – what this three-part, climate-enemy (what “ce” in the title refers to) discussion, when you get right down to it, is about.

Whatever one’s view of any of the above, minimizing or completely eliminating waste or excess GHG in the air, that’s key which, incidentally, can be achieved in a variety of ways; such as, through better control (management) procedures and techniques and through technological means and improved technology.

Image above: NASA

– Alan Kandel

2 thoughts on “N2O, HFC, PFC, SF6: Ce’s nos. 3, 4, 5, 6, respectively”

  1. I have a couple of comments on chemical nomenclature.

    Nitrous oxide (N2O) – also known as “laughing gas”, the dental anesthetic – is a single species of gas. Using it in the plural form – nitrous oxides – may confuse readers into thinking that it refers to a family of gas species. “Nitrous oxides” should not be used to refer to this single species any more than “carbon dioxides” should be used to refer to this single species of gas.

    NOx is referred to in the air pollution profession as “oxides of nitrogen”, and typically includes the species “nitric oxide” (NO) and “nitrogen dioxide” (NO2). In combustion processes, small quantities of both NO and NO2 are formed in temperature zones exceeding about 1600 oF. Upon release to the atmosphere in exhaust gases, the NO reacts with oxidants (gases harboring surplus oxygen atoms, such as O3 – ozone) to form NO2, the more stable member of the family. Because the two species are almost always found together in combustion exhaust gases, we use the family name – NOx or “oxides of nitrogen” – when referring to these pollutants.

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