Coffee is one of the most widely-consumed drinks worldwide. The unfortunate side effect of this huge global appetite is a considerable agricultural footprint—as well as the large amounts of energy required to heat water and percolate beans to brew this beloved drink.
But now researchers have jumped this heating hurdle with an innovative and surprising new brewing method: they’ve made espresso from room-temperature water, using ultrasonic sound waves.
The University of South Wales team had already had success with experiments to reduce the time and resources it takes to make cold-brew coffee. Next, they set their sights on hot coffees. Their tools were simple, if high-tech: a piece of equipment called a horn transducer that emits sound waves, and an espresso maker.
For the experiments, they loaded ground coffee into the basket of a filter handle, the portable spoon-shaped instrument that slots into the machine. Then they attached the custom-built horn transducer onto the loaded filter spoon. This transducer emits ultrasonic sound waves—beyond the range of human hearing—and was designed to touch the coffee-loaded basket that sits inside the spoon.
Then room temperature water was pumped from the espresso machine through the ground beans, while the transducer emitted pulses of ultrasonic waves. Upon contact with the water and the coffee, the sound waves vibrated through the substance, creating a phenomenon where thousands of tiny bubbles are released into the liquid. These rapidly form and collapse in a way that generates high temperatures and helps to break down the materials they come into contact with.
Through this process, the researchers ended up with a quality shot of espresso, yet requiring just 24.3%% of the energy usually used to make it. This cut energy use by 75% and what’s more, in taste tests with 100 coffee drinkers, the samplers detected no differences between the sonic coffee and espresso made using conventional methods. This suggests that the sound waves had successfully released the usual flavors and aromas of the beans in the way that hot water usually would. In fact, in another set of taste tests focused not on espresso but brewed coffee, the testers actually preferred the sonic version to the regular brew.
There’s some fine-tuning to be done, such as working on the fineness of the grind and determining the optimal amount of ultrasonic exposure to make the perfect cup. In the meantime the researchers have set their sights on producers who make commercial coffee drinks at industrial scales, settings where they believe their technology could be scaled up and applied with real potential to reduce coffee’s global footprint.
“The 75% energy saving is particularly beneficial at that scale,” they say.
Trujillo et. al. “Ultrasound enables espresso-strength coffee brewing in 2–3 minutes at low temperature with lower energy consumption.” Journal of food Engineering. 2026.
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