Answer to question on fluorocarbons and global warming

by Andreas Schuld

August 27, 2001

Question: Last year we studied flourocarbons in school in environmental studies. Nobody ever said anything about the fluoride in there and we never talked about fluoroform. do you know why the US ...

Dear Klara,

Not too surprising... Fluoride is called the "protected pollutant". Hardly anybody is aware of what it does to our health and our environment.

you might find the following interesting:

FROM: The Atmospheric Radiation Measurement Program, U.S. Department of Energy (DOE) "Professor Polar Bear" - Educational Site

ChloroFluoroCarbons [CFCs]

"Unlike some other greenhouse gases [nitrous oxide, methane, and carbon dioxide] CFCs [chlorofluorocarbons] do not occur in nature. They are humanly-created molecules ' used in industry for air conditioning, refrigeration, electronics, packaging, and foams. When these molecules leak into the air, they are very effective at trapping heat.

When they drift up through the atmosphere, they also destroy molecules in part of the upper atmosphere [the ozone layer].

Because CFCs are now known to break down the ozone layer, many countries have agreed to phase out their production. That is the good news. Unfortunately, some of the new substitutes for CFCs still trap heat. Furthermore, they have long lifetimes in the atmosphere. So even though they do not destroy ozone, they still contribute to global warming. That is the bad news. Fortunately, environmentally-safe alternatives to CFCs do exist. Although they are not yet used by many manufacturers, water-and helium-based technologies might some day replace CFCs.

Yet another surprise is in store! Because of the growing concern over the ozone layer and the role played by CFCs, manufacturers of refrigerators, and air-conditioners, in recent years have been persuaded to switch to the use of the more ozone-friendly HCFC-22, a hydrofluorocarbon.

Ironically, only in the early weeks of 1998, following a re-analysis of the archived air samples collected at Cape Grim on the north west coast of Tasmania, was it discovered that the atmosphere probably contains 135 000 ton's of fluoroform, a previously unnoticed greenhouse gas with a global warming potential some 10 000 times greater than that of carbon dioxide, although of course it is present in much smaller quantities.

Nevertheless, scientists in the University of East Anglia in the UK calculate that the current volume of fluoroform in the atmosphere has a global warming potential of 1.6 billion ton's of carbon dioxide, or three times the annual emissions of carbon dioxide in Britain. Fluoroform is said to be increasing at the rate of 5 per cent each year so that it cannot be ignored.

The connection with refrigeration is that fluoroform, HFC-23, unfortunately is a waste byproduct of the manufacture of HCFC-22. It is used for a variety of purposes in its own right in industry including the lubrication of computer disks. Ironically again, the information became available just after the intergovernmental meeting in late 1997 at Kyoto, Japan, so that the agreement on practices to limit the release of greenhouse gases reached at that meeting, of necessity completely ignored this newly-discovered danger. This was Grim news in more ways than one.

So we have found yet another example of the difficulties involved in curing the ills of the environment. Here, as in many other cases we have not cured the problem of CFCs. We have merely shifted the problem into another area."

Out of the six gases specifically targeted by the international community - through the Kyoto protocol - for emission reductions, three are fluoride gases. They are

  1. sulfur hexafluoride (SF6)
  2. hydrofluorocarbons (HFCs)
  3. perfluorocarbons (PFCs)

The other three are carbon dioxide, methane, and nitrous oxide (N2O).

Sulfur hexafluoride (SF6) is about 23,900 times more destructive, pound for pound, than carbon dioxide over the course of 100 years.

The electric power industry apparently accounts for most of the 6,500 to 7,000 metric tons produced worldwide each year.

The EPA estimates that some seven-million metric tons of carbon equivalent (MMTCE) escaped from electric power systems emitting SF6 in 1996 alone.

Perfluorocarbons are compounds composed of carbon and fluorine. PFC emissions are not regulated, although their high GWP (Global Warming Potential) has now been recognized. [ 6,500 for perfluoromethane (CF4) and 9,200 for perfluoroethane (C2F6)]

The principle source of PFCs is from aluminum smelting.

The EPA estimates U.S. emissions in aluminum production at 1,420 metric tons of perfluoromethane and 120 tons of perfluoroethane in 1998. U.S. aluminum production has been increasing since 1994, so figures are expected to go up.

For more on fluoride gases in global warming, please see:

On Dec. 20, 2000 President George W. Bush selected Paul O'Neill, the chairman of aluminum maker Alcoa Inc., to become the U.S. Treasury secretary.

Is there any surprise that in May the U.S. pulled out of the Kyoto protocol discussions?

The United States is the world's leading emitter of greenhouse gases.

Take care, Andreas