Hydrofluorocarbons
Hydrofluorocarbons (HFCs) are a group of organic compounds composed of hydrogen, fluorine, and carbon, typically found as colorless and odorless gases at room temperature. While HFCs do not damage the ozone layer, they are significant contributors to global warming and are recognized as high global warming potential (HGWP) gases. Developed as alternatives to ozone-depleting substances like chlorofluorocarbons (CFCs), HFCs are commonly used in refrigeration, air conditioning, and various industrial applications. Notable examples include HFC-23, HFC-134a, and HFC-152a, each with varying levels of atmospheric impact and global warming potential.
Despite being preferred over CFCs due to their lack of chlorine, HFC emissions are projected to increase in the coming years, prompting international agreements such as the Kigali Amendment, where over 150 countries committed to phasing out HFCs. The United States also pledged to reduce HFC use significantly by 2036. However, the regulations have led to a black market for HFCs as companies seek cheaper alternatives. Some studies have indicated potential health risks associated with HFC exposure, though these concerns primarily arise at levels much higher than those typically found in the atmosphere.
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Hydrofluorocarbons
Definition
Hydrofluorocarbons (HFCs) are a family of organic chemical compounds composed entirely of hydrogen, fluorine, and carbon. They are generally colorless, odorless, and chemically unreactive gases at room temperature. HFCs fall under the broader classification of haloalkanes. While HFCs do not harm the ozone layer, they contribute to global warming as and are considered one of the major groups of high global warming potential (HGWP) gases.
Significance for Climate Change
Many of the HFCs were developed for use in industrial, commercial, and consumer products as alternatives to ozone-depleting substances such as and hydrochlorofluorocarbons (HCFCs). Common HFCs, in order of atmospheric abundance, include HFC-23 (fluoroform), HFC 134a (1,1,1,2-Tetrafluoroethane, tetrafluoroethane, R-134a, Genetron 134a, or Suva 134a), and HFC-152a (1,1-Difluoroethane, difluoroethane, or R-152a). HFC-23 is used in a wide range of industrial processes and is a by-product of Teflon(TM) production. HFC-134a is primarily used as a refrigerant for domestic refrigeration and automobile air conditioners. HFC-152a is commonly used in refrigeration, electronic cleaning products, and automobile applications as an alternative to HFC-134a.
The global warming potentials (GWPs) of HFCs range from 140 (for HFC-152a) to 11,700 (for HFC-23). These GWPs are significantly lower than those of the gases the HFCs are designed to replace. The atmospheric lifetimes of the same two HFCs are just over 1 year and 260 years, respectively. HFCs are one of two groups of haloalkanes that were targeted in the Kyoto Protocol. HFC emissions are projected to increase in the coming years, as industry continues to strive to decrease CFC and HCFC production.
HFCs are preferred over CFCs and HCFCs, because HFCs lack chlorine. When CFCs are emitted into the atmosphere, chlorine (Cl) atoms contained in those CFCs become disassociated through interaction with ultraviolet light. The resulting free Cl atoms decompose ozone into oxygen, and regenerated Cl atoms go on to degrade more ozone molecules. This reaction continues for the atmospheric lifetime of the Cl atom, which ranges from one to two years. On average, a single Cl atom destroys 100,000 ozone molecules. Thus, the lack of Cl in HFCs makes them a desirable alternative.
Dubbed "super greenhouse gases," in 2016 the Environmental Investigation Agency (EIA) decided to phase out the use of HFCs. More than 150 countries signed the Kigali Amendment, promising to reduce their use gradually and eventually stop using them. The United States and other developed nations pledged to reduce their use of HFCs by 85 percent by 2036, switching to climate friendly alternative.
The 2020 American Innovation and Manufacturing Act gave the Environmental Protection Agency (EPA) the authority to permit some companies, such as those making military products or manufacturing inhalers, to use a limited amount of HFCs. However, the total number is finite, so it was reduced each year after 2020. This created a black market for smugglers who illegally imported HFCs into the country and sold them to companies that could not afford or did not want to purchase new cooling systems that do not use HFCs.
Some studies indicate that excessive exposure to HFCs may affect the brain and heart. However, this has only been established for concentrations higher than those found in the atmosphere.
"EPA Issues Enforcement Alert to Address Illegal Import of Hydrofluorocarbons Into the United States." US Environmental Protection Agency (EPA), 6 Sept. 2024, www.epa.gov/newsreleases/epa-issues-enforcement-alert-address-illegal-import-hydrofluorocarbons-united-states. Accessed 20 Dec. 2024.
"Hydrofluorocarbons." Climate & Clean Air Coalition, 2024, https://www.ccacoalition.org/short-lived-climate-pollutants/hydrofluorocarbons-hfcs. Accessed 20 Dec. 2024.
Tan, Tammy, Lisa Reynolds, and Bryan Parthum. "The Social Costs of Hydrofluorocarbons and the Benefits from Their Expedited Phase-Down." Nature Climate Change, vol. 15, 3 Jan. 2024, pp. 55-60, doi.org/10.1038/s41558-023-01898-9. Accessed 20 Dec. 2024.