Oops… substitute refrigerants convert to long-lived greenhouse gases, too

Now Dupont can get to work on its third replacement line of rentseeking substitutes for CFCs.

UV radiation breaks HFCs and HCFCs into carbon tetrafluoride, which is “a potent greenhouse gas that lasts for up to 50,000 years.”

The media release is below.


Some chemicals less damaging to ozone can degrade to long-lived greenhouse gas

WASHINGTON, DC — Some substitutes for ozone-damaging chemicals being phased out worldwide under international agreements are themselves potent greenhouse gases and contribute to warming. Now, a new study published Nov. 2 in Geophysical Research Letters, a publication of the American Geophysical Union, shows for the first time how some of those replacement chemicals can break down in the atmosphere to form a greenhouse gas that can persist for millennia, much longer than the substitute chemicals themselves.

Specifically, when some chemicals widely used as refrigerants break down in the stratosphere — a layer in the middle atmosphere — under some conditions, they can form a potent greenhouse gas that lasts for up to 50,000 years, according to scientists from the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder and the NOAA Earth System Research Laboratory (ESRL) in Boulder.

“This compound, carbon tetrafluoride or CF4, essentially lasts forever because there aren’t any known removal mechanisms in the atmosphere,” said James Burkholder, a research chemist at NOAA ESRL and lead author of the study.

Burkholder’s colleague Aaron Jubb, a CIRES scientist working at NOAA ESRL and now at Oak Ridge National Laboratory, did the laboratory work showing how CF4 can be made from some halocarbons, chemicals that include hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) and are substitutes for the more ozone-damaging chemicals that have largely been phased out. Jubb started with trifluoroacetyl fluoride — a compound produced in the atmosphere when some halocarbons breaks down — exposed it to short-wavelength UV radiation, and looked at the reaction products that formed. CF4 was one of those breakdown products.

The amount of CF4 produced by this photochemical process was shown to be a small fraction of atmospheric CF4; industrial sources are much larger emitters of CF4. Still, identifying this particular source of such a potent and lasting greenhouse gas is important, particularly since its production could continue to grow depending on which “parent” products are used by industry.

“We really need to understand the chemistry of the compounds we use,” Jubb said. “Even as we move towards shorter-lived halocarbons for industrial use, during atmospheric degradation they can produce a long-lived atmospheric effect.”

This work was supported in part by NOAA’s Atmospheric Chemistry, Carbon Cycle, and Climate (AC4) Program and NASA’s Atmospheric Composition Program.


Authors of “An atmospheric photochemical source of the persistent greenhouse gas CF4” are Aaron Jubb (Cooperative Institute for Research in Environmental Sciences and NOAA Earth System Research Laboratory (ESRL) Chemical Sciences Division, now at Oak Ridge National Laboratory), Max McGillen (Cooperative Institute for Research in Environmental Sciences and NOAA ESRL Chemical Sciences Division), Robert W. Portmann (NOAA ESRL Chemical Sciences Division), John S. Daniel (NOAA ESRL Chemical Sciences Division), and James B. Burkholder (NOAA ESRL Chemical Sciences Division).

CIRES is a partnership of NOAA and CU-Boulder.

4 thoughts on “Oops… substitute refrigerants convert to long-lived greenhouse gases, too”

  1. Commenting on tadchems observations:
    This is just the sound of the orchestra tuning up as Dupont starts the process of public hysteria and political mind-bending necessary to maintain their hold on the worldwide refrigerant market as the patent sunset looms for their second generation refrigerants.
    The third generation refrigerants will be even less efficient than the second generation refrigerants, whose efficiency has been documented to be measurably lower than the first generation of fluorocarbon based refrigerants. All of this loss in efficiency translates into increased “greenhouse gas” production from the generation of the additional energy required to run the refrigeration systems longer in order to achieve the same level of cooling output.
    The “laboratory conditions”, unlike the real world, are capable of being manipulated to produce a close approximation of a pre-determined desired result. This is something that the semi-literates who are the output of our public education system are incapable of understanding. All they know is “science” = “the truth”, Those of us with even a modest education and posses “common sense” [something that is increasingly viewed as a Super-Power at the University level] recognize that this is only true for a given value of “science” and a given value of “truth”, both of which are very malleable in the hands of corporate propagandists.
    Research project for inquiring minds; find out how much effect on the atmosphere the residual products from Dupont first generation refrigerants can be measured in the atmosphere, at any level, anyplace in the world.

  2. The “laboratory work showing how CF4 can be made from some halocarbons” reminds me of the ‘work’ that allegedly showed that halocarbons were destroying the ozone layer (never mind the fact that the ozone layer mysteriously recovered every year). The work done in the laboratory did NOT duplicate conditions in the mid and upper atmosphere.
    Ozone is replenished by the absorption of ultraviolet light by oxygen – a process becoming increasingly popular for water purification.
    Similarly, the very property that makes a gas a ‘greenhouse gas’, the ability to absorb invisible radiations and become thermally agitated, also allows the UV light to break down the gas molecule – a process called ‘photoionization’.
    This somehow never figures in to the ‘laboratory work’, which is admittedly directed towards seeing how long these molecules CAN last in the atmosphere.
    The lab bench experiments NEVER include all the possible contributing factors, because that would make analysis of the results very difficult. However failure to include all the factors makes the entire experiment pointless.
    Ionized molecules of CF4 (a trace gas at best) are far more likely to encounter water molecules in the atmosphere, which will convert the ionized fluorides into hydrogen fluoride and other substances readily washed out of the air.

  3. All refrigeration systems could use LPG [or a blend of propane/butane] to avoid the halocarbon problem……..
    The fire risk for domestic-scale installations is minor and large-scale setups often use NH3…..

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