Sound May Soon Power Your Cellphone

New engineering prof plans to harness the energy in sound and vibration


Prof. Shohel Mahmud

Energy from sound? From vibrations? Yes, clean and green energy can be found in some surprising places, says Prof. Shohel Mahmud, who recently joined U of G’s School of Engineering as a faculty member.

“It’s obvious that we will eventually run out of the fossil fuels we currently rely on,” says Mahmud. “And while we’re using them, they’re harming the environment.” In fact, it may be that the only advantage these fuels have is their efficiency; there’s a considerable amount of energy packed into a litre of gas, for example.

Other sources, such as wind power and solar power, are less efficient, but Mahmud says they’re still worth investigating because they are free, renewable and less harmful to the environment. He doesn’t stop there. His research looks at other forms of energy that are rarely considered: sound and vibrations.

“Sound is a kind of energy that is usually just wasted,” he explains. “But our current devices for turning it into something useable ─ for cooling computers, for example ─ are very inefficient. Vibrations also produce energy that could be used.” Both of these produce only small quantities of useable energy, but like the sun and the wind, they are free and environmentally friendly.

Mahmud’s research is aimed at making the process of converting sound and vibration energy more effective. After all, it’s happened before. “The research I’m doing now is about advanced, cutting-edge technology,” he says. “Thirty years ago people knew there was energy in light, but it wasn’t used. Now everyone has those solar lights in their gardens ─ lights that store up energy from the sun during the day and then release it at night to light up the garden. They’re inexpensive.”

He adds that there are many practical applications for sound and vibration energy already in development. For example, the energy produced by sounds and vibrations in a cell phone could be harnessed to power the phone. These alternate energy sources could also be used for cooling computers, in cryogenic applications, or in new types of hybrid cars.

Mahmud was born in Bangladesh, a country he says “most people only hear of when there’s a natural disaster.” In the northeastern part, where Mahmud’s family lived, the country is quite industrialized; there were a number of engineers among his relatives and neighbours. Inspired by their example, he decided to go to the top-ranking Bangladesh University of Engineering and Technology to study mechanical engineering. When he’d completed his masters, he continued on at the university as a lecturer and lab instructor.

In 1999, Mahmud was awarded a scholarship to continue his studies and chose to move to Canada and the University of Waterloo. After completing his PhD and some post-doc research, he was hired by U of G in September.

As well as his research on sound and vibration as sources of energy, Mahmud is also trying to create improved versions of fuel cells. “There are hybrid cars now with fuel cells, but they are very expensive and have limitations,” he says. “They dry out fast in hot temperatures and freeze up in cold temperatures. My goal is to develop one that will work anywhere.”

Teaching is Mahmud’s other love. “I love communicating with students and adding my vision of where research can take us to theirs. If I can inspire them to work on green technology, that’s better for our country and the whole world. Research has no boundaries, so good research done here will benefit the people in South America, even in Bangladesh. You just don’t know who you have helped when you help a student or when you do your part in research.”

Mahmud found only a tiny Bangladesh community when he first moved to Waterloo; there more people from his home country in Guelph at the time, but the numbers were still small. That’s changed now, though, as more students from Bangladesh arrive to attend university in this part of Ontario. Mahmud’s wife is a PhD student at the University of Waterloo; they have a nine-year-old son.