Advancing Sustainable Cooling: Novel Eco-Friendly Technology to Replace Harmful Refrigerants

As global heatwaves become more frequent, the demand for air conditioning escalates, leading to increased energy use and environmental challenges. Scientists at the University of Maryland’s Center for Environmental Energy Engineering (CEEE) are pioneering cutting-edge methods to enhance cooling efficiency while minimizing ecological impact. Supported by the Department of Energy, their efforts aim to find greener alternatives to conventional cooling technologies that rely on damaging chemicals.

Environmental Concerns of Conventional Cooling

Air conditioners have commonly utilized hydrofluorocarbons (HFCs) as refrigerants, which are effective for cooling but carry a high global warming potential due to their potent greenhouse gas properties. Following the 2020 enactment of the AIM Act and the 2022 ratification of the Kigali Amendment, there is an urgent international push to phase out HFCs.

One innovative approach gaining momentum is elastocaloric cooling, developed through a collaboration between Dr. Reinhard Radermacher, head of CEEE, and Dr. Ichiro Takeuchi, interim chair of UMD’s Department of Materials Science and Engineering.

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Originally investigating nickel-titanium alloys for biomedical stents, Takeuchi and his team stumbled upon these materials’ capability to generate cooling through mechanical stretching and releasing, inspiring its potential application in cooling systems.

With funding from ARPA-E, Radermacher and Takeuchi combined their expertise to enhance elastocaloric cooling. This method exploits the mechanical stress applied to superelastic shape memory alloys like nickel-titanium, which discharge heat upon compression and absorb heat upon release, producing a cooling effect.

percentage-of-households-equiped-with-ac-in-selected-countries-2018-3f58eed1841e2bd6e389bd86dd0e64d7.png — Proportion of homes with air conditioning in various countries, 2018.

While these alloys currently offer less cooling power than traditional HFCs, they stand out as an eco-friendly alternative because they are crafted from naturally sourced metals with no harmful emissions.

Since its establishment in 1991, CEEE has led the way in environmentally conscious energy technology research, particularly in heat pump innovations. The center involves faculties and graduate students in diverse projects and has significantly influenced air conditioning design worldwide with its software tools.

Thanks to a recent $5 million grant from the Department of Energy, the center is accelerating its work on elastocaloric cooling and related innovations. Radermacher emphasizes the importance of such support, noting that their groundbreaking research demands inventive strategies to effectively manage the heating and cooling properties of materials like nickel-titanium.

Looking Ahead: Broader Uses and International Acclaim

Elastocaloric cooling is attracting worldwide interest and was featured among the World Economic Forum’s top 10 emerging technologies for 2024. The CEEE team aims to create cooling solutions free from harmful fluid emissions. Their initial focus is on compact devices like refrigerators and wine storage coolers utilizing elastocaloric materials.

Takeuchi expresses optimism about the technology’s progress, stating that it has reached an energy density plateau, signaling readiness for scale-up. “We are plateauing in the energy density,” he explained, “which suggests the technology is sufficiently mature. The next step is scaling, allowing us to bring practical applications to market.”