December 3, 2024

 

In its report “The Top 10 Emerging Technologies of 2024”, the World Economic Forum (WEF) highlighted that elastocaloric technology is a rapidly advancing field, noting that “heat pumps using elastocaloric materials such as nickel and titanium are proving to be more energy-efficient than traditional heating and cooling systems.”

The same report warns that as global temperatures rise, the demand for cooling solutions will surge. “The International Energy Agency estimates that global energy demand for space cooling will more than triple over the next 30 years, accounting for around 37% of the increase in global electricity demand by 2050.” Thus, the possibility that elastocaloric systems could drastically reduce the energy needed for heating and cooling is highly significant.

A SUSTAINABLE ALTERNATIVE

This technology is based on a phenomenon known as the “elastocaloric effect”, which is the ability of certain materials to emit heat when mechanical stress is applied and to cool when the stress is released, similar to how muscles function. The most well-known and studied material for this purpose is nitinol, a combination of nickel and titanium with shape-memory properties, making the process reversible. “Thus, every time it changes phase or state due to compression or tension, a temperature change occurs,” explains Rodrigo Barraza, an academic and researcher at the Solar Energy Research Center (SERC Chile) and the Energy Transition Center (Centra) at Adolfo Ibáñez University.

While heat pumps are a technology already present in daily life—”they heat millions of homes, serve as car air conditioners, refrigeration systems for our refrigerators, and air conditioning for our homes and sometimes offices”—the vast majority do not rely on elastocaloric technology but on vapor-compression technology, notes Hicham Johra, a research scientist at the Sintef Institute (Norway) and an associate professor at the Department of the Built Environment at Aalborg University (Denmark).

In vapor-compression systems, a refrigerant gas is compressed into a liquid state and then expanded back into a gas. “This is a very mature, safe, reliable, energy-efficient, and cost-effective technology that has greatly benefited humanity,” the researcher adds. However, it has one drawback: the refrigerant used can harm the environment, contributing to the greenhouse effect if released into the atmosphere, which can occur due to system leaks or improper operation, Johra explains.

In contrast, this issue does not arise with elastocaloric heat pumps, as the global warming potential of heating or cooling systems that do not use a refrigerant fluid is effectively zero, says Barraza.

Furthermore, elastocaloric technology offers advantages in terms of energy demand. This is because the materials used have good cooling capacity and a significant temperature difference between the fluid’s cooling temperature and its entry temperature. “Conditions that make them relevant for replacing air conditioning systems,” the Chilean researcher asserts.

The WEF report highlights that, thanks to its energy efficiency, “from a social standpoint, this technology can improve access to cooling in regions with limited or nonexistent electrical grids, thereby improving quality of life and addressing a key aspect of climate change impact.”

PROGRESS AND CHALLENGES

Although a 2014 study by the U.S. Department of Energy already classified this technology as the most promising alternative to current systems, it remains relatively unknown to the general public and professionals in the field.

“It should be noted that developments are still in the prototype stage, and a technology typically requires at least 20 years to become commercially viable,” says Barraza. Due to its novelty, challenges remain in terms of cost, reliability, and the need to improve material lifespan, explains the Adolfo Ibáñez University academic, who believes its adoption will depend on how much is invested in overcoming these technical and economic barriers.

Some universities have already started working on this. A few months ago, researchers from the School of Engineering at the Hong Kong University of Science and Technology developed a cooling device that they claim is 48% more efficient than conventional air conditioning systems and does not require refrigerant gases.

Research scientist Hicham Johra sees great potential in this technology and believes it is worth investing time and money. Above all, “to develop a new generation of sustainable heating and cooling systems that may not completely replace vapor-compression technology but could fulfill a significant portion of the heating and cooling demand for buildings and vehicles,” he concludes.