Can the Noise in Sports Arenas Be Turned Into Electricity?

Gyeongyun Lily Min spent the last seven months in a makeshift laboratory she set up in her parent’s garage as she tried to convert vibrations produced by sound waves in sports arenas into electrical energy. Her days were a long repetition of refining the concept, conducting experiments and analyzing the results.

The 17-year-old rising senior at Alfred M. Barbe High School in Lake Charles, Louisiana, was initially inspired by Disney’s Monsters, Inc. In the 2001 film, energy is generated from children’s screams. Sans the cruelty, Gyeongyun thought, the concept could help meet the global demand for sustainable energy.

“This imaginative concept sparked my curiosity about the potential of converting sound into usable energy,” explains Gyeongyun. “I began to wonder if, in reality, we could harness the abundant noise in environments like sports arenas and use it to generate electricity.”

Merging her curiosity with her passion for science and innovation, the young student set out to study the concept on her own. “This idea,” says Gyeongyun, “led me to explore the feasibility of acoustic energy harvesting as a sustainable and innovative energy solution that could contribute to meeting global energy demands and reducing our reliance on fossil fuels.”

Today, with over 60 percent of global electricity generated by fossil fuels, the world continues to be heavily dependent on non-renewable energy sources. Coal is the largest contributor to the industry at roughly 36 percent, followed by natural gas with a share of around 23 percent. According to a recent report by the World Nuclear Association, which promotes the global nuclear energy industry, over 40 percent of energy-related carbon dioxide (CO2) emissions per year are due to the burning of fossil fuels for electricity generation. The power sector is the largest source of planet-warming CO2 worldwide.

About a year and a half ago, Gyeongyun watched her mother garden and make her own compost. She observed the heat generated by the compost and wondered how this thermal energy could be harnessed and converted into usable energy. “This led me to explore the principles of heat transfer and energy conversion through experiments with composting coffee grounds,” says Gyeongyun.

A few months later, the student researcher found herself again intrigued by innovative new ways to harvest energy, this time from environments like sports arenas rich in noise levels, with the help of the piezoelectric effect.

Certain materials in the environment produce large amounts of mechanical energy as vibrations or shocks. This energy is largely wasted. However, with the piezoelectric effect, it is possible to convert this kinetic energy into electric energy. Piezoelectricity, in simple terms, is the production of an electric charge in response to natural or artificially applied pressure.

One of the best-known examples of electricity generated through the piezoelectric effect was found in the Shibuya train station in Tokyo. From 2008 to 2009, a piezoelectric mat measuring about 14 square inches was installed outside the station. The inch-thick mat generated electricity every time a person stepped on it. With some 2.4 million people passing through the station daily, the mat produced between 0.1 and 0.3 watts of electricity in each second it was stepped on.

“I chose a sports arena as the suitable location for my project because it represents a unique environment where noise levels are consistently high due to the cheering crowds, announcements and music,” Gyeongyun says. According to the American Academy of Audiology, the noise levels at a sporting event can reach 110 decibels. “Additionally, sports arenas are large, public spaces where implementing sustainable energy solutions could have a significant positive impact, making them an ideal candidate for exploring innovative energy harvesting techniques,” she adds.

To accurately simulate the sound environment of a sports arena, the young innovator built an approximately 22-inch by 12-inch model of a basketball stadium with the official NBA court ratio, crafted primarily from lightweight materials such as foam board and plastic to simulate the structural aspects of a real sports arena. She then found the best locations within it for piezoelectric generators by studying sound pressure in relation to the speaker’s position. For sound, Gyeongyun played audio recordings of typical crowd noise in a sports arena, including cheering and general ambient sounds at average sound pressure levels of 70 and 100 decibels, representing normal and peak noise levels observed during a live event. She designed three different types of energy harvester models—known as Cassegrain, Gregorian and front feed—that help focus sound onto the piezoelectric generators, thus improving their efficiency in capturing energy.

Regeneron ISEF 2024 - Gyeongyun Lily Min

Watch on

The voltage produced by Gyeongyun’s energy-harvesting models demonstrated a significantly higher voltage output than standalone piezoelectric devices. “While a regular piezoelectric device might produce minimal voltage under similar conditions,” explains the student, “the harvester models in the experiment produced up to several tens of millivolts, depending on the configuration and sound pressure level.” She adds, “This enhancement suggests that the design of the models, which focuses sound energy toward the piezoelectric materials, plays a crucial role in increasing efficiency.”

With limited resources, Gyeongyun faced some obstacles. For one, she struggled with relatively low-quality piezoelectric material she purchased from Amazon. “[They were] not as sensitive as needed for optimal energy harvesting,” she says. “This limitation significantly impacted the efficiency and accuracy of my experiment.” Nevertheless, she adapted her experimental setup and re-evaluated expectations regarding the voltage output.

The experiment revealed that the piezoelectric devices in the model generated relatively small amounts of electricity, with the voltage output varying depending on the sound pressure level and the location of the energy harvesters. “For instance, the Cassegrain model produced an average of 44.90 millivolts at 100 decibels, while the front feed model yielded around 38.60 millivolts at 70 decibels,” Gyeongyun explains. While that output is relatively low, scaling this to an actual sports arena suggests that there is potential for improvement with more sensitive materials and better design.

“The success of the experiment was evaluated based on the comparative voltage output between different models and setups, indicating that strategic deployment can enhance energy harvesting efficiency,” she says. “If I had access to better materials, I believe I could significantly enhance the effectiveness and reliability of my energy harvesting research.”

Her project demonstrates the possibility of generating electric energy with piezoelectric devices from environments with considerably high noise levels. When implemented on a large scale, the technology has the potential to reduce global reliance on fossil fuels, thereby decreasing greenhouse gas emissions and helping mitigate climate change.

“In urban areas with heavy traffic, the constant noise from vehicles could be harnessed to generate electricity, contributing to the energy needs of city infrastructure,” Gyeongyun says. “Manufacturing plants, which often have continuous machinery noise, could integrate piezoelectric devices to capture and convert these sound vibrations into electrical energy, thereby reducing their overall energy consumption and improving sustainability.”

Public transportation systems, such as subway stations and train terminals, which experience high levels of ambient noise from trains and passengers, could utilize this technology to power some of their operations, as well.

With her environmental sustainability technology, Gyeongyun secured a spot as a finalist in this year’s Regeneron International Science and Engineering Fair, the world’s largest global science competition for high school students. The top award was granted to a student who built a better organic electrochemical transistor to be used in implantable bioelectronics that can help detect and treat serious illnesses like diabetes, epilepsy and organ failure. The second-place prize was won by another student scientist who improved the speed and efficiency of software that is used in several fields, including machine learning, transportation and financial systems.

Maya Ajmera, president and CEO of Society for Science, which runs the Regeneron competition, calls Gyeongyun’s research “innovative.” “Gyeongyun at the age of 17, thinking about this project, I found it very inspirational,” she says.

Daniel Inman, a mechanical engineer at the University of Michigan and co-author of Piezoelectric Energy Harvesting, considers it a feasible technology. “There have been a number of studies on floor vibrations as a source of harvested energy, and this may be viable.” However, the expert points out several important factors that can affect how well Gyeongyun’s technology works. These include the type of material the stadium is made from, the amount of vibrational energy generated from the crowd walking or stomping, and how these vibrations are measured.

“The big challenge is that a reasonable amount of piezo material only has the ability to harvest microwatts of energy,” says Inman. “There are many issues and factors in determining how much energy can be harvested in a given situation. This makes it impossible to make predictions about a given situation unless one knows all the factors, such as the density of the available ambient energy and its properties such as frequency, amplitude, etc. Bringing these systems to scale would require hundreds of such elements.”

Gyeongyun remains hopeful for the future of the technology.

“Although this technology is not yet realistically applicable due to the current limitations in the sensitivity and efficiency of piezoelectric materials, further research and development could significantly improve its feasibility,” she says. “By advancing the quality of piezoelectric devices and optimizing their deployment, we can unlock a new avenue for sustainable energy production, contributing to a cleaner and more sustainable future.”

Ramsha Zubairi | READ MORE

Ramsha Zubairi is a freelance writer. Her work has appeared in BBC Travel, Dwell, Atlas Obscura and other media outlets.