Thursday, March 27, 2025
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Sound is a form of energy that travels in waves and when we listen to sounds, those waves are transformed into electrical signals inside our ear. Could this conversion process be reversed—using sound to generate energy for other purposes?
How sound works and how our bodies interpret it is both simple and fascinating. It all starts when an object vibrates, causing nearby air molecules to move. These movements compress and expand the air, creating pressure waves. When those waves reach our ears, the mechanical energy is transformed into electrical signals our brain can understand. If the process worked in reverse, we could capture the energy produced by sound and use it to power electronic devices.
The truth is that this reverse process has been explored for quite some time through various projects and experiments. One example dates back over a decade, when Xiaowan Wang, a Chinese student at the IED (Istituto Europeo di Design) in Madrid, developed a phone charger that could harness energy from ambient sound. "Sound waves are everywhere: in traffic, in airports, in construction areas. They're usually thought of as pollution, although they provide an energy that we often ignore and waste," he explained at that time.
A couple of years earlier, in the summer of 2013, South Korean researchers Sang-Woo Kim and Young Jun Parque unveiled another project, this time with mobile devices taking center stage. In this case, the researchers explored the idea of capturing the sound waves produced during a phone conversation. But more than a decade later, their work still hasn’t led to any commercial applications.
Years before, another industrial designer, Hung-Uei Jou, showcased Green Noise, a device that promised to convert transportation noise into energy. The news had quite an impact over a decade ago, but how did it work? According to the Asian inventor, the device would be placed on the ground of the runways of airports or on roads with high traffic flow to absorb the sound of aircraft and ground vehicles, although the energy generated would only be enough to power the lighting of the infrastructure itself.
More recently, the Japanese company Sony introduced an energy harvesting device that "efficiently generates energy from the noise of electromagnetic waves"—a development they presented just two years ago. According to the Japanese researchers, the objective of this project is “to help address the energy supply challenges caused by the growing use and complexity of IoT devices.” They have achieved this by applying technology derived from their tuner design processes. The "harvest" module captures ambient noise in factories, offices, stores and homes to power low-consumption devices, recharge batteries, or even monitor the internal state of equipment by detecting voltage fluctuations.
Why is sound not involved in the energy transition?
The potential benefits of using these technologies on a large scale are clear: they could turn something as disruptive as noise into something genuinely useful. Urban and industrial noise could become a source of clean, renewable—and nearly inexhaustible—energy. However, despite being feasible in theory, there are still major challenges holding back its implementation.
The first has to do with the amount of energy that noise can actually produce. That’s because sound waves carry relatively little energy compared to sources like wind and sunlight. To make this technology viable, we’d need to significantly improve the efficiency of energy conversion—along with finding effective methods to store that energy.
Where does the problem lie? The main challenges lie in two areas: the need for materials that can optimize electronic circuits, and the integration of these sensors into urban and industrial environments. Naturally, these devices would need to efficiently convert low-current signals while also being very resistant in order to function in harsh conditions.
But the obstacles don’t end there. While prototypes and research have shown that noise can indeed be transformed into energy, scaling this technology for widespread use would bring significant economic challenges. Right now, the investment needed for infrastructure, maintenance, connectivity and integration with the power grid makes these systems unfeasible.
On top of that, putting them into practice would require strict enforcement of current noise emission standards, as well as compliance with energy use regulations. This would also call for close collaboration between public institutions and private sectors, something that, unfortunately, doesn’t always happen. And although the potential benefits are significant, for now, the energy transition seems to be moving in another direction.
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