French startup uses Hi-Fi speakers to develop eco-friendly heat pumps


Amidst the climate and energy crisis, heat pumps have emerged on the housing heating market as a technology that can replace gas and oil, while lowering the energy bills. Yet, their air compression systems require refrigerants to work. These refrigerants, also known as hydrofluorocarbons (HFCs), are amongst the most potent greenhouse gasses.

Founded in 2017 and having raised €5 million, French deeptech startup Equium is seeking to provide a more ecological alternative. With this aim, it has developed a novel, acoustic heat pump core that harnesses the energy of sound.

The so-called Acoustic Heat Pump (AHP) can cover a household’s heating needs without the use of refrigerants. Instead, its operation is based on the phenomenon of thermoacoustics — the convergence of thermics, acoustics, and fluid mechanics.

The core works with a high-fidelity (Hi-Fi) speaker powered by electricity, which generates an acoustic wave in tubes filled with helium — a neutral and non-toxic gas that accelerates the propagation of sound. The acoustic wave causes the gas to compress or expand, producing heat or cold, respectively. It remains confined within the system, which allows the machine to be silent.