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January 10, 2023
In October 2022, the United States Senate ratified the Kigali Amendment to the Montreal Protocol, an 1987 international treaty to protect the ozone layer, a critical shield protecting life on earth from the sun’s ultraviolet radiation. The Kigali Amendment, agreed to in 2016 by more than 170 countries, phases down the production and use of hydrofluorocarbons (HFCs), potent greenhouse gases. HFCs were originally introduced as an alternative to chlorofluorocarbons (CFCs), which had been widely used in aerosols and as refrigerants until they were found to erode the ozone layer and phased out by the Montreal Protocol.
The Kigali Amendment represents a big step towards confronting the climate crisis; however, HFCs are just one of four main types of fluorinated gases, which also include perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3). This article will explain what fluorinated gases are, how their harmful effects on the climate can be mitigated, and summarize what actions policymakers are currently taking in the United States and abroad.
In the 1970s, manufacturers and governments were faced with a problem. CFCs had been widely used as refrigerants, but posed a significant threat to the ozone layer. Without the ozone, the earth and humanity would be exposed to harmful ultraviolet radiation that can damage crops and cause skin cancers and cataracts. In 1987, the international community acted by signing the Montreal Protocol, which committed countries to begin a “step-based” phasedown of ozone-depleting substances, including chlorofluorocarbons. The protocol was ratified by the United States the following year. As countries began their phasedowns, a new refrigerant was needed to replace CFCs. This is where fluorinated gases come into the picture.
Fluorinated gases, or F-gases, are man-made substances typically classified into four main categories: hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3). HFCs—the most common F-gas—were developed to replace ozone-depleting CFCs as a refrigerant. They are used in air-conditioning, insulating foams, aerosol propellants, and in fire protection. The other F-gases are primarily used or emitted as part of manufacturing processes. SF6 is used in power grids to transfer electricity and is emitted as a byproduct of producing magnesium. PFCs are emitted when manufacturing aluminum. All four F-gases are considered essential for creating complex microchips. It is clear that F-gases are an integral part of the manufacturing process in a wide array of industrial sectors. However, while F-gases pose less of a threat to the ozone layer than CFCs, they present problems of their own.
According to the U.S. Environmental Protection Agency (EPA), “fluorinated greenhouse gases include the most potent and longest-lasting greenhouse gases emitted by human activity.” They can be thousands of times more powerful at warming the atmosphere than carbon dioxide (CO2) and can stay in the atmosphere for hundreds or even thousands of years. For example, HFCs stay in the atmosphere for up to 270 years. PFCs, which are commonly released during the manufacturing of chemical solutions used in electronic parts, stay in the atmosphere for anywhere between 2,600 to 50,000 years. Below are a few key strategies to reduce F-gas emissions.
HFCs are often released when refrigerant canisters in air conditioning units leak. Research spanning back to the early 2000s suggests that leakage is even more of a concern for refrigerants used in a commercial setting. The Kigali Amendment and subsequent global phasedown of HFCs pushed companies such as Bacharach and Emerson to develop more sophisticated leak detection systems for commercial buyers. In Bacharach’s case, these detection systems can even monitor for phasedown compliance. The EPA, in partnership with Green Proving Ground, a program of the U.S. General Services Administration, has developed its own emission-monitoring tools and a bank of new methods to reduce HFC leaks.
Nearly 90 percent of greenhouse gas emissions from refrigerants are caused by end-of-life leaking. Mitigating leaks will mitigate emissions. One way to reduce the risk of leaks is by bringing old units to destruction facilities that can dispose of refrigerants safely. The nonprofit Project Drawdown argues that weak regulations surrounding refrigerant leakage and end-of-life disposal, as well as a lack of economic incentives for recovery and destruction, keep emission management efforts from reaching their potential. More robust tracking systems for existing refrigerants may also help predict the level of support needed for end-of-life management. Supporting destruction facilities and promoting their expansion is crucial.
A 2016 rule by the Department of Defense, General Services Administration, and National Aeronautics and Space Administration also encourages the use of reclaimed, non-virgin HFCs as “sustainable procurement” under the Federal Acquisition Regulation. A potential model for facilitating the recovery and re-use of F-gases can be found in Retradeables, an EU-funded online marketplace for used F-gas.
However, the American Innovation and Manufacturing Act (AIM Act) and Kigali Amendment may prove more effective as they seek to phase down the use of HFCs. Passed in 2020 as part of the Consolidated Appropriations Act of 2021 (P.L. 116-260), the AIM Act dictates that HFCs are to be reduced by 85 percent from their current use before 2036.
As the Kigali Amendment begins a nearly global phasedown of HFCs, manufacturers and policymakers are looking for sustainable replacements. The immediate goal is to replace HFCs with gases relatively benign to the ozone layer that also have lower global warming potentials. In some products where HFCs serve as a refrigerant, they can be replaced by natural refrigerants such as ammonia gas and hydrocarbons. Moreover, in a variety of applications, ammonia and hydrocarbons (e.g., propane or butane) seem to be competitive with HFCs in terms of both energy efficiency and economic cost. Questions remain, however, over the safety of some of these natural refrigerants and whether we can harness ammonia and hydrocarbons in all applications.
While it may seem surprising, CO2 is a natural refrigerant that can serve as a less harmful option in commercial refrigeration and air conditioning units because it has little effect on the ozone and a relatively low global warming potential next to HFCs. When CO2 is used as a refrigerant in closed cycles, it causes negligible emissions in comparison with CO2 emissions from transportation and other sectors. Yet many parties still support finding an even greener alternative. For its part, the EPA is using its Significant New Alternatives Policy (SNAP) program to aid private companies in the development of substitutes for HFCs.
The Senate’s ratification of the Kigali Amendment formalized the United States’ commitment to phasing down HFCs, but efforts to scale them back had already been set in motion by the AIM Act. The EPA has been tasked with implementing this phasedown. In the coming years, manufacturers will receive yearly HFC usage allowances. The EPA recently released its methodology for allocating these allowances. It plans to enforce the phasedown through a system of inspections and by tracking remaining HFC containers. The phasedown will help manufacturers reduce their HFC levels while spurring the use of cleaner alternatives.
Kigali and the AIM Act will likely have economic implications. American manufacturers will have a chance to stay competitive in the global market since they can now continue selling their products in countries that have already ratified the Kigali Amendment. It is unclear how the EPA will regulate imported products containing HFCs. One way the EPA could address this issue is by following the European Environment Agency's policy of imposing the same restrictions on imports as on domestic production.
Navigating the regulation of imports is not the only area where the United States could learn from other countries. Many governments did not only implement Kigali earlier (and are now well on their way to reaching their phasedown goals), but they have also further regulated F-gases. Since 2015, the use of F-gases by EU manufacturers in many new products has been banned. In 2022, the European Union Commission proposed a regulation on fluorinated gases that would reduce the EU market HFC quota, update best practices for fluorinated gas management, ban the use of F-gases in specific applications, and work to align EU legislation with the Montreal Protocol.
Though not as commonly used as HFCs, PFCs have the highest capacity of any F-gas to trap massive amounts of heat for long periods of time. This has encouraged governments to begin enacting PFC regulations. PFCs were listed as a Canadian Environmental Protection Act Schedule One toxic substance, which indicates a significant danger to the environment and justifies potential government action.
In the grand scheme of things, the dialogue surrounding F-gases illustrates our ever-improving understanding of and our relationship with the environment. Once considered a solution for phasing out ozone-depleting substances, decision-makers are finally recognizing and responding to the harm F-gases can cause with their high global warming potential. However, there is still work to be done to refine regulations and find the best alternatives. More extensive federal regulatory policies or further amendments to the Montreal Protocol are needed in order to transition away from our reliance on F-gases, especially as rising global temperatures make cooling, and thus refrigerants, even more essential to human health and safety.
By Nick Solis and Molly Brind’Amour
Read the other articles in our Non-CO2 Greenhouse Gases series on Methane and Nitrous Oxide.
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