OZONE HOLE: Efforts to mend the ozone hole, pictured here on October 31, could end up further changing the climate if the right replacement chemicals are not encouraged.
Image: NASA
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Carbon dioxide is the primary greenhouse culprit in human-generated global warming, most scientists agree, but CO2 itself, and a handful of other substances, are now being promoted as good alternatives to commonly used refrigerants that threaten Earth's atmosphere and climate.
To understand this paradoxical turn of events, it helps to recall the 1980s, when the world's governments banded together to fix the Antarctic ozone hole, a continent-size gap in the atmospheric layer that protects human beings, among other living things, from the sun's damaging ultraviolet radiation. Via the international treaty that entered into force in 1989 known as the Montreal Protocol, participants agreed to phase out the chemicals that harmed ozone. Closing the hole became one of the globe's greatest and most successful environmental restoration projects. But today, there is a glitch: The touted solution for the ozone predicament could in fact exacerbate our greatest environmental challenge—climate change.
The problem is that under the Montreal Protocol, which the U.S. has signed, hydrofluorocarbons (HFCs) were promoted as the environmental alternative to ozone-depleting hydrochlorofluorocarbons (HCFCs), which had become the standard working coolant in refrigerators, air conditioners and aerosol cans. HCFCs, for their part, originally replaced the even more potent ozone-depleting chlorofluorocarbons (CFCs) that were used liberally until the early 1990s. Whereas HFCs do not destroy the ozone layer, they can be thousands of times more harmful to Earth's climate than carbon dioxide, posing a significant threat should they become HCFCs' main replacement.
"HCFCs and HFCs are two chemicals designed by chemists to trap heat; the fluorinated part of the compound turns what would be a normal hydrocarbon into something that is much more durable," explains Kert Davies, director of research for Greenpeace USA. "When you combine those two properties—heat trapping and durability—in the atmosphere, it creates a greenhouse gas. We created another problem by replacing the ozone depleters with chemicals that cause global warming, and now we need to replace these because they are going to be banned."
Starting January 1, under the Montreal Protocol, the world's developed nations must cut HCFC consumption and production by 75 percent. It will then become illegal to import, produce or sell Freon (HCFC-22) and HCFC-142b, the ubiquitous refrigerants, for use in new equipment. At the same time, Europe is implementing a ban on HFC-134a (a common car air-conditioning refrigerant that can trap 3,400 times more heat in the atmosphere than CO2), beginning in 2011.
The alternatives? Natural refrigerants and a new group of fluorochemicals called hydrofluoro-olefins (HFOs).
Naturally occurring refrigerants, such as hydrocarbons (propane, isobutane and cyclopentane), ammonia and even that climate culprit carbon dioxide, can be used as cooling agents in refrigerators and air conditioners. They all have relatively low or lower global warming potentials, exist in large quantities, and do not have unknown side effects.
Ironically, CO2 seems to rise above the rest. "CO2 is an excellent refrigerant with superior thermodynamic and transport properties, compared to the HFCs in use today," says
David Hinde, manager of research and development for Conyers, Ga.–based Hill Phoenix, which recently became the first company to receive EPA approval to replace HCFCs with CO2 in supermarkets. "By using CO2, refrigeration systems will be able to reduce HFC leaks as well as dramatically reduce the HFC charge (the amount used in a system)."
Like most refrigerants, CO2 can remove heat from the air. The process starts when a refrigerator's compressor condenses CO2, raising its pressure and temperature. The gas is then transferred to a gas cooler where the heat is released cooling the refrigerant, which casts off the heat from a radiator on the back or bottom of the fridge. The CO2 (now between the liquid and vapor phases) then travels through an expansion valve, instantly reducing the liquid's pressure and causing it to rapidly expand into vapor. As the CO2 evaporates it absorbs heat, thereby cooling the air inside the refrigerator compartment. CO2 must be used at a much higher pressure than HFC refrigerants, and therefore requires stronger piping.
Already, companies such as Coca-Cola have begun using CO2 as a refrigerant in vending machines and other retail refrigerators outside of the U.S., as in China during the Olympics. And PepsiCo is now testing these vending machines in Washington, D.C., including in the Capitol.
Another potential alternative is hydrocarbon-based refrigerants, such as isobutane, which has been used in household refrigerators throughout Europe and in parts of Asia for a number of years. General Electric is currently seeking U.S. Environmental Protection Agency approval for its use in the U.S. Ben & Jerry's, a division of Unilever, has applied to the EPA to use propane as a refrigerant in ice-cream freezers. Both requests are pending approval due to fears over combustibility.
Then there are the synthetic refrigerants. In response to the ban on HFC-134a in Europe, chemical industry giants DuPont and Honeywell combined their years of fluorochemical expertise to find an alternative. HFO-1234yf was their answer. It doesn't cause ozone depletion, has an extremely low global warming potential, and is predicted to be ready for commercial use midway through 2011.
Concerns have been raised, however, over possible toxic side effects to the employees working around these chemicals as well as for automobile owners should it ignite. DuPont acknowledges that though HFO-1234yf is flammable, it is no more hazardous than the chemical it is replacing.
As most of these alternatives await approval, the possibility of HFC proliferation hangs in the air. But, not if Deputy Assistant Secretary of State for Environment Dan Reifsnyder has a say in the matter. Reifsnyder, as head of the U.S. delegation to the Montreal Protocol, along with Canada and Mexico, has proposed an amendment to the treaty, calling for an HFC phasedown.
"HFCs today are not yet in wide use and embedded in the world, but if you look out to 2050 without any action being taken, they will be where people go when they leave HCFCs," Reifsnyder says. "The value of this proposal is it will send a signal to the private sector for the need for alternatives that are benign in the ozone and climate sense, and give the private sector time to work on new compounds."
The amendment to the protocol will be negotiated this week in Port Ghalib, Egypt, by the United Nations. If passed, it would mark the first time that language on a greenhouse gas is incorporated into the ozone treaty. It would also mean the EPA could expand its mandate to regulate ozone-depleting substances to include a greenhouse gas, because it is the agency that implements the Montreal Protocol in the U.S.
"Before we end up with a big problem, let's avoid a big problem," Reifsnyder says.
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12 Comments
Add Commentread greenpeace
Reply | Report Abuse | Link to thisFor more information on HFCs and alternatives, read Greenpeace's new report here:
Reply | Report Abuse | Link to thishttp://www.greenpeace.org/raw/content/international/press/reports/hfcs-a-growing-threat-to-the-climate.pdf
Here comes another government edict to make things worse.
Reply | Report Abuse | Link to this50 years ago cheap natural refrigerants in use were outlawed to make a market in patented refrigerants. Freon 12 was an exact replacement for isobutane. Propane was replaced by F-22.
As for the Ozone hole, it is caused by the nature of a south magnetic pole and the location of the antartic continent. Wake up people you are being conned to spend money in a government mandated equipment and material replacement program.
Here comes another government edict to make things worse.
Reply | Report Abuse | Link to this50 years ago cheap natural refrigerants in use were outlawed to make a market in patented refrigerants. Freon 12 was an exact replacement for isobutane. Propane was replaced by F-22.
As for the Ozone hole, it is caused by the nature of a south magnetic pole and the location of the antartic continent. Wake up people you are being conned to spend money in a government mandated equipment and material replacement program.
pgtruspace you're kidding right?
Reply | Report Abuse | Link to thisRead this whole journal article and come back to tell us if it is natural or not.
http://rstb.royalsocietypublishing.org/content/361/1469/769.full
Here, I'll start you off with the abstract.
Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50
km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO2, NO, NO2, Cl and ClO. The NOX and ClOX chains involve the emission at Earth's surface of stable molecules in very low concentration (N2O, CCl2F2, CCl3F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290320
nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtimethe Antarctic ozone hole. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules.
do a little research before hand and look at the science. Not the media's conspiracy theorists.
I am well aware of the chemistry of ozone and chlorines that have been used in this argument. Just as the amount of CO2 in the atmosphere is far to small to cause Global Warming. the amount of human caused chlorinated hydrocarbons is far to small to cause the amount of ozone depleation cited.
Reply | Report Abuse | Link to thisThe Antartic ozone hole was discovered, not created,and was explained in several different manners, one of which was chlorine destruction of the O3.
The "hole" is caused by the high altitude winds, super cold air temperatures and the polar magnetic fields.
As to the refrigerant business I was in that line of work in the 1960-80s and I have considerable knowlage in that field.
I wish to emphasize the super cold air temperatures over the South Pole. Satellite temp measurements have been refusing to cooperate with the blame humans for global warming movement. Even when adjusted by fiat in the 1990's to make them warmer, the readings from satellites and balloon instruments still seem to be too cold to support global warming.
Reply | Report Abuse | Link to thisThe argument over coolants reflects the earlier argument over PCB's, which were used to cool electrical transformers and were non-flammable. Since they were banned for allegedly causing a highly debatable number of cancers when improperly stored, the number of transformer fires has soared because the replacement for PCB's were flammable mineral oils. When isobutane and propane are used more as refrigerants for economic reasons in the developing world, there will be a significant death toll by fire involved.
I believe that the Antarctic ozone hole is an ancient phenomenon that was discovered, as was more recently the extent of global warming fluctuations in the global record that had nothing to do with the CO2 level in the atmosphere, apparently.
pgtruspace, you really must be driven to ignore so much science. I suppose its pointless to argue someone who is motivated to push an agenda, but why did the hole shrink when chlorofluorocarbons were banned? Why do you come to scientific American forums to attack long established and proven science? What agenda do you have?
Reply | Report Abuse | Link to thisYea, I'm calling bullshit on this post. You don't have any idea what you're talking about, pgtruspace. Where did you get your info, anyway? I want to see paper citations.
Reply | Report Abuse | Link to thisAlthough we already know that won't happen because your claims are completely unsubstantiated.
I wish to emphasize the super cold air temperatures over the "South Pole. Satellite temp measurements have been refusing to cooperate with the blame humans for global warming movement. Even when adjusted by fiat in the 1990's to make them warmer, the readings from satellites and balloon instruments still seem to be too cold to support global warming. "
Reply | Report Abuse | Link to thisDo you have peer reviewed evidence for this assertion? Take a look at the evidence I can present:
"Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year"
Here we show that significant warming extends well beyond the Antarctic Peninsula to cover most of West Antarctica, an area of warming much larger than previously reported. West Antarctic warming exceeds 0.1 �C per decade over the past 50 years, and is strongest in winter and spring. Although this is partly offset by autumn cooling in East Antarctica, the continent-wide average near-surface temperature trend is positive."
http://www.nature.com/nature/journal/v457/n7228/abs/nature07669.html
Nature 457, 459-462 (22 January 2009) | doi:10.1038/nature07669; Received 14 January 2008; Accepted 1 December 2008
Reality it exists.
The global warming effects of these gases that exist in ppb as opposed to the ppm of CO2 are important. The older CFCs were even worse. Quoting from the discoverer of ozone depletion, Sherwood Rowland:
Reply | Report Abuse | Link to this"In 1975, ...Ramanathan pointed out that there would be a global warming effect from the CFCs. That's been one of the fallouts about the Montreal Protocol, it is that in fact, that the banning of the CFCs under the Montreal Protocol has had more effect on global warming than any of the efforts so far under the Kyoto Protocol...."
Australian Broadcasting Corp "Science Show", podcast, 2009-09-05
Pgtruspace : Admittedly the quantity of these refrigerant chemicals in the air is small, but unlike other greenhouse gases they are catalysts. So once they have destroyed an ozone molecule, they are free to destroy another, and so on, and so on, and so forth...
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