(206a) A Decision Point On Public Policy Regarding HFCs: We Are Close to Making Poor Choices at the International Level

The United States government declined to sign the Kyoto Protocol in the late 1990s, but announced through the US EPA on April 24, 2009, and several times since then, that six compounds or classes of compounds that contribute to global climate change are human health hazards. While carbon dioxide is the largest gas of concern, hydrofluorocarbons (HFCs) are included due to their long term impacts through extended atmospheric lifetimes. The classes of compounds considered in the legislation do not include hydrofluoroethers (HFEs), the primary class of compounds poised to replace the soon-to-be regulated HFCs.

An interesting question is, what are the impacts of the next broadly applicable alternative chemicals if the world successfully implements a Kyoto-like Protocol? Hydrofluoroethers are an emerging class of compounds that have chemical and physical properties that enable them to be considered for almost the entire range of products and processes where HFCs are currently in use. This class of compounds is poised to be widely implemented but the implications are unknown. The use of HFEs has not been evaluated from a sustainability perspective due to the lack of chemical and physical property data that prevents analysis of environmental impacts. This work brings together physical properties estimated using quantum chemistry to evaluate HFEs compared to HFCs.

The refrigerant GWPs suggest that switching to technologically possible HFEs would be desirable to prevent global climate change by reducing greenhouse gas emissions. However, our results show the drop-in replacement HFEs for replacing R134a are unfavorable from an overall use-to-disposal lifecycle perspective for large scale freezer applications and for window air conditioner units.

Taking into account the US EPA's imminent regulation of HFCs, these results show that consideration of only the direct GWP contribution for refrigerants would lead to an incorrect prediction that global climate change would be curtailed if HFEs are used as the wide-spread replacement refrigerants on a worldwide basis depending on the use. HFEs are specifically excluded from the current US EPA considerations because their total global radiative forcings are unknown. However, the results here show that the total CO₂ equivalents released per year increases for some uses but not others when the HFEs are used versus the HFC. In contrast, the Montreal Protocol had a significant positive environmental impact by eliminating the ozone depleting R12 from use over time, even though the CO₂ emissions increased moderately as the HFC replacement was introduced.