The system mechanically deforms ultrathin Ni-Ti wires to absorbs and releases heat Saarland University
A team of researchers at Saarland University and the Center for Mechatronics and Automation Technology (ZeMA) in Germany has unveiled an innovative air conditioning technology that promises significant energy savings and environmental benefits.
The system can cool and heat without using volatile refrigerants or burning fossil fuels by exploiting the “elastocaloric effect” in nickel-titanium (Ni-Ti) shape memory alloys. Dubbed elastocalorics, this breakthrough method is cleaner than conventional systems, as it is only as polluting as the electricity that powers it.
The technology is already receiving international recognition. The EU Commission called it a leading alternative to standard cooling systems. The World Economic Forum also ranked elastocalorics among its “Top Ten Emerging Technologies” in 2024.
Professors Stefan Seelecke and Paul Motzki, pioneers in the field, say their prototypes demonstrate how repeated mechanical deformation of ultrathin Ni-Ti wires or sheets can efficiently move heat from one place to another. The result is an air conditioning system that can serve as both a refrigerator and a heat pump, offering much higher energy efficiency compared to typical setups.
Shape memory alloys in action
Nickel-titanium’s “shape memory” property is the driving force behind elastocaloric cooling. While water switches between solid, liquid, and gas, nitinol transitions between two solid crystallographic phases. When pulled (i.e., placed under tension), the material absorbs heat.
Once the load is released, the alloy reverts to its original phase and releases that heat elsewhere. The air passing over the stressed or unstressed material gains or loses heat in a highly controllable way. Building a functional system around this phenomenon requires sophisticated engineering.
The Saarbrücken researchers have designed prototypes that stretch and relax Ni-Ti wires or sheets in cycles. Heat is transferred to or from a flowing medium—such as air or a water-glycol mix—and runs continuously.
By eliminating standard refrigerants, these prototypes minimize the risk of environmental damage while boosting overall energy efficiency. Government and industry stakeholders, including Volkswagen and the Fraunhofer Institute, are collaborating with the research group to develop applications for electric vehicles, residential buildings, and more.
Moving towards commercialization
With more than €17 million invested in a dedicated project and an additional €3.5 million in government funding, elastocalorics is moving quickly toward commercial viability. The first prototypes under development include a lightweight air-conditioning unit for electric cars and a system that cools EV traction batteries.
For residential buildings, the team is engineering a compact version that can heat or cool rooms via vents in outer walls. Trials suggest that single-stage elastocaloric components can achieve temperature differentials of around 68°F (20°C), and multi-stage solutions can offer even larger deltas.
The researchers’ progress builds on 15 years of work, which yielded the world’s first continuous air-to-air elastocaloric prototype and the first elastocaloric mini fridge. At Hannover Messe, they showcase a rotating cam-track fridge powered by 200-micron-thin Ni-Ti wire bundles that are continuously tensioned and released.
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As the wires move in and out of the cooling chamber, they transfer heat steadily. Self-sensing technology, aided by artificial intelligence, monitors wire deformation to maintain precise control.
By fusing cutting-edge materials science with practical engineering, the Saarland team has laid the groundwork for a future in which climate control is safer, cleaner, and more energy-efficient. Their elastocaloric systems promise to reshape an industry that accounts for a significant portion of global energy use, offering a path toward more sustainable heating and cooling solutions for homes, vehicles, and beyond.
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Kaif Shaikh Kaif Shaikh is a journalist and writer passionate about turning complex information into clear, impactful stories. His writing covers technology, sustainability, geopolitics, and occasionally fiction. Kaif's bylines can be found in Times of India, Techopedia, and Kitaab. Apart from the long list of things he does outside work, he likes to read, breathe, and practice gratitude.
