Scientists Invent a Way to Brew Espresso With Ultrasonic Waves—Using 75% Less Energy

The morning coffee ritual is defined by heat and pressure. For decades, the only way to extract a dense, aromatic shot of espresso was to force near-boiling water through a tightly packed bed of finely ground coffee at nine bars of pressure. But researchers at the University of New South Wales (UNSW) in Sydney have successfully stripped heat out of the equation entirely.[1][7]

Using high-frequency sound waves, the engineering team has developed an "ultrasonic espresso" that brews at room temperature in under three minutes. The resulting beverage matches the concentration, extraction yield, and flavor profile of a traditional hot espresso, but requires only a fraction of the electricity to produce.[2][8]

Instead of relying on a traditional boiler, the experimental system uses a bolt-clamped transducer attached directly to a standard espresso filter basket. This metallic horn blasts ultrasonic waves—sound frequencies far beyond the range of human hearing—through the mixture of room-temperature water and coffee grounds.[4][6]

The sound waves trigger a physical phenomenon known as acoustic cavitation. As the ultrasonic vibrations pass through the liquid, they cause billions of microscopic bubbles to rapidly form and collapse. This violent, microscopic activity generates intense localized forces without raising the overall temperature of the water.[3][8]

When these tiny bubbles collapse near the coffee particles, they generate microscopic jets of liquid. Lead researcher Francisco Trujillo describes these jets as acting like invisible scrubbing brushes. They pit and fracture the surface of the coffee grounds, rapidly extracting flavor compounds, emulsified lipids, and caffeine that would normally require near-boiling water to release.[1][3]

The primary benefit of this room-temperature extraction is a massive reduction in energy use. Traditional commercial espresso machines require constant, heavy power draws to maintain a stable boiler temperature of around 90 to 95 degrees Celsius—making them one of the most energy-intensive appliances in any cafe or restaurant.[5][7]

The energy math is stark. The UNSW team measured their ultrasonic setup consuming just 0.020 kilowatt-hours to produce three espresso-strength beverages. A conventional single-group espresso machine required 0.0823 kilowatt-hours to produce the same output. That translates to a 75 percent reduction in energy consumption, even before accounting for the conventional machine's initial warm-up time.[2][8]

A major hurdle for any new coffee technology is the notoriously picky palate of coffee drinkers. To prove the concept's viability, the researchers conducted a blind sensory analysis with 100 participants, serving them both traditional hot-brewed shots and the new room-temperature ultrasonic versions.[1][5]

The participants could not reliably distinguish between the two methods. The sensory panel found no significant differences in aroma, flavor, bitterness, or overall liking. Chemical analysis backed up the taste test, showing no significant differences in caffeine levels or chlorogenic acid—a key antioxidant—between the two brews.[2][4]

Interestingly, when the team applied the same ultrasonic method to a lighter, filter-style coffee, the participants actually preferred the sound-wave version over a conventional pour-over. Sixty-one percent of the panel favored the ultrasonic filter coffee, rating its bitterness profile as significantly more pleasant.[2][5]

While home baristas might not be swapping their countertop machines for sonic reactors immediately, the technology holds massive potential for industrial scale. The researchers see immediate applications for companies manufacturing ready-to-drink bottled coffees and milk-based beverages, where cutting energy costs by 75 percent translates to massive operational savings.[4][6]

The system also dramatically accelerates cold brew production. A process that typically requires 12 to 24 hours of steeping in cold water can be compressed into just a few minutes using acoustic cavitation, producing a smooth, highly concentrated liquid that can be shipped globally and diluted later.[3][7]

UNSW currently holds a pending patent on the ultrasonic brewing sonoreactor. With the fundamental science now published and peer-reviewed, the research team is looking toward commercial partnerships to scale the technology, hoping to eventually bring low-energy, high-speed extraction to the global coffee industry.[2][8]