Now, a team from China has shattered that temperature limit. Using a revolutionary heat pump with no moving parts, they achieved an output of 270 degrees with a 145-degree heat source to drive the cycle.

Developed by a team led by Luo Ercang at the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences (CAS), the technology could generate high-grade heat from modest sources, such as solar collectors or industrial exhausts, for applications in ceramics, petrochemicals and metallurgy.

This could lead to solar farms directly producing the intense heat needed to smelt iron ore or refine aluminium, and chemical factories recycling their own waste warmth for splitting or combining molecules.

The breakthrough comes at a pivotal moment in the global energy race. Nearly half the world’s final energy consumption is devoted to heating and cooling, and industry accounts for almost half of that usage.

Much of this energy is generated by burning coal, oil or natural gas. In China alone, between 10 per cent and 27 per cent of total energy is lost as waste heat.

Capturing and upgrading even a fraction of this dissipated energy could transform China’s industrial efficiency, slash carbon emissions and drastically reduce manufacturing costs.

Luo’s team envisions that, by 2040, ultra-high-temperature heat pumps could deliver zero-carbon heat of up to 1,300 degrees, ushering in a green industrial revolution powered by sunlight, nuclear reactors and waste heat.

At the heart of this breakthrough lies a novel heat-driven thermoacoustic heat pump.

Unlike conventional pumps limited to heating homes or powering refrigerators, this system leverages the physics of sound and heat resonance, also known as thermoacoustic Stirling principles, to amplify low-grade thermal energy into ultra-high-temperature output.

Converting heat into powerful acoustic waves to drive a closed-loop thermal upgrade could bypass the mechanical and material limitations that have long plagued compressors and turbines, according to the researchers.

The innovation was quickly published in top international journals, including Nature Energy, Applied Physics Letters, and Energy.

A December 3 article in China Science Daily quoted Luo as saying that the development of ultra-high-temperature industrial heat pumps for efficient energy use would be “a key pathway towards achieving carbon neutrality goals”.

Accordingly, the CAS research team developed a prototype of a new Stirling thermoacoustic ultra-high-temperature heat pump.

This device combines the principles of the Stirling cycle, patented by Scottish inventor Robert Stirling in 1816, with thermoacoustics. The heat pump operates by using acoustic energy – intense standing sound waves – to pump heat from a lower-temperature source to a higher-temperature sink, making it an efficient, acoustically driven heat pump.

The prototype can absorb heat from a source as low as 49 degrees. When the heat source temperature is 67 degrees, the system provides heating at 214 degrees.

The thermoacoustic heat pump has no moving parts, making it inherently reliable for long-term operation and capable of achieving a high temperature lift with the potential for high efficiency.

Currently, advanced absorption heat pumps provide heating at about 100 degrees with a temperature lift of about 50 degrees. Absorption heat transformers can achieve temperatures below 200 degrees, also with a 50-degree lift.

In industrial processes, sectors like papermaking, dyeing, brewing and pharmaceuticals require heat of between 100 degrees and 200 degrees, while ceramics, metallurgy and petrochemicals need high-temperature heat from 200 degrees to over 1,000 degrees.

In a December 5 article in Nature Energy, Luo summarised various research fronts, including his team’s thermoacoustic Stirling heat pump, as promising pathways towards the realisation of ultra-high-temperature heat pumps.

He also suggested development directions for materials and technologies needed for future ultra-high-temperature heat pumps operating from 600K to 1,600K, or 327 degrees to 1,327 degrees, saying these could be achieved by 2040.

Luo said his team would next “focus on heat pumps for processes like petrochemicals, metallurgy and ceramics that require even higher temperatures”.

He explained that a heat-driven pump could use a thermal source, such as a nuclear pressurised water reactor (about 300 degrees) or a solar trough collector (400 degrees to 500 degrees), as the energy input.

“Using ultra-high-temperature thermoacoustic heat pumps, this could be raised to 500 degrees to 800 degrees, offering a new technological pathway for zero-carbon high-temperature heat in heavy industry,” Luo added.