Francisco Trujillo’s espresso doesn’t bubble, hiss, or steam—because it’s brewed in silence, at room temperature, using nothing but sound. In a lab at the University of New South Wales in Sydney, the chemical engineer and his team have reimagined one of the world’s most ritualized drinks: espresso. Their method replaces heat and pressure with ultrasonic vibrations, producing a shot in under three minutes that, in blind tastings, is indistinguishable from the traditional version—yet uses just 25 percent of the energy.
This isn’t a gimmick for gadget lovers. With coffee being one of the most consumed beverages globally, the environmental footprint of brewing adds up fast. Commercial espresso machines rely on heating elements that draw significant power, often running for hours a day in cafes, offices, and hotels. Trujillo’s innovation taps into a phenomenon called acoustic cavitation: a transducer fitted to a standard filter basket sends ultrasonic waves through water and coffee grounds, creating microscopic bubbles that collapse with enough force to extract flavor, caffeine, and oils—just like heat does, but without the energy cost.
Getting the brew right wasn’t simple. The team tested grind sizes, water-to-coffee ratios, and exposure times, eventually landing on a formula that delivers the concentrated punch espresso lovers expect. “The most important [part] was the brew ratio,” Trujillo explained, “because this helps ensure the final drink is concentrated and not too diluted.” His prior work on ultrasonic cold brew laid the groundwork, but espresso posed a greater challenge—its intensity demanded precision.
When 100 coffee drinkers sampled both versions side by side, they couldn’t reliably tell which was made with heat and which with sound. In some cases, the ultrasonic brew even scored higher. “These findings showed that using ultrasound did not harm taste, and in some cases even improved it, despite brewing at room temperature and without the heat normally associated with coffee making,” Trujillo said. That’s a rare win in food tech: a sustainable alternative that doesn’t ask consumers to compromise.
While the technology is still in the research phase, its implications stretch far beyond the lab. If adopted at scale—by cafes, roasters, or commercial beverage producers—the energy savings could be transformative. The study, published in the Journal of Food Engineering, proves that rethinking even the most entrenched processes can yield surprising, delicious results. And for a world seeking ways to cut emissions without sacrificing pleasure, that’s a note worth amplifying.