As nations meet this week to work on an amendment to the Montreal Protocol to reduce hydrofluorocarbons (HFCs) — one of the most potent greenhouse gases – a U.S. program is helping to reduce domestic emissions and demonstrate to other countries that there are practical, climate-friendly alternatives.
Hydrofluorocarbons, chemicals widely used in refrigeration, air conditioning, foam blowing, and other applications, were developed to replace ozone-depleting substances (primarily chlorofluorcarbons and hydrochlorofluorocarbons – CFCs and HCFCs) a few decades ago. But while HFCs don’t deplete the ozone layer, they do contribute to global warming, and, without policy intervention, their use is expected to grow dramatically over time.
Congress created the significant new alternatives program (SNAP) under the 1990 Amendments to the Clean Air Act. Its objective was to require the Environmental Protection Agency (EPA) to review substitutes for ozone-depleting chemicals to avoid having them create new health or environmental problems. EPA has implemented this rule using a comparative risk-based framework (e.g., comparing risks of toxicity, flammability, ozone-depleting potential, and global warming potential).
As new alternatives have been developed, the lists of acceptable and unacceptable substitutes have also changed. The latest two changes in April and July focused on adding to the lists of acceptable alternatives, while also eliminating uses of certain potent HFC gases where more climate-friendly alternatives are now available. For example, for automobile air conditioning, HFC-134a, with a global warming potential of 1430, is being replaced with a new chemical, HFO-1234yf, which has a global warming potential of 4, less than three-tenths of a percent of the HFC it’s replacing. In addition, HFC-152a systems and carbon dioxide-based auto air conditioning systems are allowable under SNAP and are being explored by some in the auto industry.
EPA’s actions to limit certain HFCs are building blocks in achieving the domestic reductions in greenhouse gases called for in President Obama’s Climate Action Plan.
The actions are also important to two major efforts to reduce greenhouse gases globally. As nations work to come to an agreement in November under the Montreal Protocol to phase down HFCs, EPA’s SNAP rules signal to other countries and to industry worldwide that alternatives are commercially available. In addition, the SNAP rules provide credibility to the U.S. commitment to reduce greenhouse gas emissions by 26-28 percent by 2025 and help the U.S. demonstrate its commitment in the effort to reach an international climate agreement in December in Paris.