Thermoacoustic heat pumps on the verge of commercial breakthrough

slwvx

For context: https://en.wikipedia.org/wiki/Thermoacoustic_heat_engine The company cited in the article is [Bluehart]( https://blueheartenergy.com/our-technology ) One disadvantage that Bluehart lists of classic heat pumps is the need for a refrigerant fluid. But Bluehar uses helium internally; I wonder how often the helium would need to be replaced.