Elastocaloric cooling: heat produces cold

Producing cold without using an electric compressor could become one of the new frontiers of refrigeration . A recent experimental prototype has demonstrated the possibility of using waste heat or solar thermal energy to power a solid-state cooling system , exploiting thin films made of shape-memory alloys.

The principle is based on elastocaloric refrigeration , a technology in which cooling results from the structural transformations of specific materials subjected to mechanical loading and unloading. The innovation lies in replacing the normally required electric actuator with a second material capable of directly converting heat into motion.

How heat-powered elastocaloric cooling works

The prototype uses two very thin metal films with different functions.

The first acts as a thermal actuator : when heated, it contracts thanks to the shape memory effect, converting thermal energy into mechanical work. The movement is transferred to a second elastocaloric film, which is cyclically subjected to deformation and release.

During this process, the material undergoes reversible transformations in its crystalline structure. Releasing the load causes a decrease in temperature, thus generating the refrigeration effect.

The key difference compared to previous elastocaloric configurations is the source of the energy required for movement. Instead of using an electrically powered motor or actuator, the heat itself produces the force needed to initiate the cycle.

The system can therefore be schematized in three steps :

• a heat source heats the actuator material;
• the material converts heat into mechanical motion;
• the second element uses movement to produce cooling.

This is a very different approach from vapor-compression refrigeration, in which a compressor moves and compresses a refrigerant within a circuit.

The first results: up to about 13 °C on the material

The experimental tests provided a first concrete demonstration of the system's feasibility.

With the actuator heated to 86°C, the prototype achieved a temperature difference of approximately 4°C across the device, while a variation of close to 13°C was measured on the film used as the elastocaloric material.

The system was also tested using an external heat source at 130°C, demonstrating that the principle can also work with heat from a real source and not just the electrical heating used in laboratory tests. The scientific study reports a temperature difference across the device of 2.2 K in this configuration.

However, these values ​​should not be interpreted as performance comparable to that of commercial refrigeration systems. The prototype was created as a proof of concept and is still far from having refrigeration capacities suitable for large-scale applications. Research is focusing specifically on the possibility of connecting multiple films in parallel to increase available power.

Waste heat and data centers among the possible applications

One of the most interesting aspects concerns the usable energy source .

Because the system can be powered by heat, it could theoretically harness thermal energy that is currently simply wasted in the future, converting some of it into useful cooling.

Among the applications envisioned are, in particular, compact systems for cooling electronics . A processor, for example, already generates heat during operation: part of this energy could be used to help cool the device itself. A similar principle could be applied to power electronics or components in vehicles.

The topic is also particularly interesting for data centers , where the growth of artificial intelligence is rapidly increasing the thermal density of servers and the need for cooling.

In this context, a future heat-driven elastocaloric technology could complement the solutions currently under development, especially for local and high-density applications. However, before considering data center-scale deployment, cooling capacity will need to be increased by several orders of magnitude and long-term reliability demonstrated.

Solid-state refrigeration: a still experimental technology

Elastocaloric cooling belongs to a larger family of solid-state technologies, studied as a possible alternative to traditional vapor compression systems.

The main theoretical advantage is the absence of a gaseous refrigerant that must be compressed, evaporated, and condensed. The refrigeration effect is generated directly through the transformation of the material.

Research is also making progress on the durability front. For example, in 2026, an experimental elastocaloric device was presented, capable of maintaining its cooling capacity after over a million cycles, one of the most historically significant challenges for these technologies.

However, several obstacles remain before commercial diffusion:

• increase in cooling power;
• durability of alloys subjected to repeated cycles;
• overall system efficiency;
• speed of implementation;
• heat transfer to and from the material;
• costs and production scalability.

The value of the new research lies primarily in having demonstrated that heat can replace the electric actuator in the elastocaloric cycle. This opens up a new perspective for refrigeration: using a waste heat source not simply to generate electricity, but directly to generate cold.

For now, this is an experimental technology. But the ability to combine solid-state cooling, heat recovery, and the absence of a compressor makes this approach particularly attractive for next-generation refrigeration applications.