Slovenian scientists develop clean cooling technology, replace toxic refrigerants

Now, scientist Jaka Tušek, assistant professor at University of Ljubljana’s faculty of mechanical engineering in Slovenia, and his team are testing a technology that is aimed at replacing toxic refrigerants with metal tubes. Tušek’s study is in extension to a EU research project titled SUPERCOOL which was conducted at the university from 2019 to 2023.

Outdated cooling systems come with a hidden climate cost

Tušek points out that if just 2.2 pounds of certain refrigerants escape into the atmosphere, the environmental impact is comparable to driving a car for about 18,600 miles. Because of this, hydrofluorocarbons are now being phased out. However, natural alternatives like ammonia and isobutane come with their own set of challenges, including toxicity, flammability, and reduced efficiency in hot climates.

While solid-state cooling technologies are still in the early stages, they offer the potential for safer, quieter, and more efficient cooling without harming the environment.

The researchers are now working on bringing this technology to market as part of the E-CO-HEAT project, which runs until early 2026. They are preparing a patent and developing a strategy for industry adoption. Improving the efficiency and sustainability of temperature controlling technologies is a key focus of the EU’s Heating and Cooling Strategy, an essential part of the European Green Deal.

Cooling currently accounts for 10% of global electricity demand, according to the International Energy Agency (IEA). The need for these technologies is rapidly increasing due to rising temperatures and growing demand in developing countries. As temperatures continue to rise, the pressure to find more energy-efficient and sustainable solutions intensifies.

Nickel-titanium alloy can ensure cooling while remaining solid

Tušek notes that there are currently around two billion air conditioning units worldwide, and the IEA expects this number to nearly triple by 2050. This rapid growth, coupled with the fact that many air conditioning units are environmentally harmful, could contribute to a significant environmental crisis.

Cooling relies on the fundamental chemistry of phase changes, where matter shifts between different states—solid, liquid, or gas. In traditional cooling systems, the process of transforming from liquid to gas and back again drives the cooling cycle. However, certain materials, like the nickel-titanium alloy nitinol, can undergo a phase change while remaining in a solid state.

When mechanical stress is applied to certain materials, they heat up, and when the stress is relieved, they cool down. This process, known as elastocaloric cooling, uses materials that are not harmful to individuals or the environment. Unlike traditional refrigerants, elastocaloric materials like nitinol—commonly used in medicine due to their biocompatibility—offer a safer alternative. In theory, this technology could be significantly more efficient, though it is still in the development phase.

The scientists note that their prototype is currently at 15% of its maximum efficiency, while vapor compression technology typically operates at 20-30% efficiency. However, since their technology has been in development for less than 10 years, researchers believe there is still plenty of room for improvement.

Tušek and his team are collaborating with a tech company from Ireland, as well as universities in Germany and Italy, to develop an advanced air conditioner based on the technology. The partnership has been named SMACool.