Who needs hot water? Researchers made an ultrasonic espresso machine that brews coffee without heat, and drinkers couldn't notice any difference

Woman's hands holding cup of espresso coffee.

• The process makes espresso-strength coffee in under three minutes
• It brews at room temperature via ultrasonic waves
• The process reduces energy use by up to 75%

Scientists have come up with a way of making coffee at room temperature, and it's much faster than any cold brew: where that takes 12 to 24 hours, this new method makes espresso in less than three minutes. The secret? Ultrasound.