Generating enthusiasm for green energy

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Margaret Plevak | April 16, 2017

WHITEWATER — Green energy doesn't always need a force of nature as great as the wind or the sun to set things in motion.

Sometimes it only takes the power of two feet.

Courtney Nelson, executive director of Downtown Whitewater Inc., had been playing with an idea of using some type of greener energy, like a bike-powered generator, for events her organization holds during the year in conjunction with the Whitewater City Market.

Traditional electrical hook-ups for outdoor events, she'd discovered, just weren't working.

“Last year the Whitewater City Market ran extension cords from Pumpers and Mitchell's, a local bar that generously donated its electricity to us,” Nelson wrote in an email. “That electricity allowed us to host a wider variety of music, serve hot food and allow educational demonstrations, but it also meant tripping hazards and water concerns when it rained.”

University of Wisconsin-Whitewater students working through the campus sustainability office already had created a pedal-powered blender, so Nelson brought her idea to Wes Enterline, sustainability coordinator. Enterline suggested Ozgur Yavuzcetin, a UW-Whitewater assistant professor of physics, who'd been working on a pedal-powered generator himself.

“The project sparked immediately,” Nelson said.

She got a local bike shop to donate a bike for the project, found an old treadmill she could dissemble for its motor and used a United Way grant to purchase some of the equipment. Under Yavuzcetin's guidance, she and some of the students working with her put the pedal-powered generator together, putting a belt on the bike and connecting it to a pulley and a battery.

The bike was used as a hands-on demonstration of a human-powered generator at a Public Power workshop during the last Whitewater City Market of the season in October. The energy the generator produced was enough to light the tent where Yavuzcetin presented a workshop on kinetic energy and building a pedal generator. 

Yavuzcetin's own first attempt at a pedal generator occurred years ago when he was teaching in Boston.  He'd spotted an old treadmill in the trash and rescued it for parts, then started researching how to create a pedal generator.

The result was a bike to which he could attach his laptop and, while pedaling, watch a movie on Netflix.

“It originally started as a hobby with an environmental motivation, but then I could see that physics was a direct application of the project,” Yavuzcetin said.

Students in an energy class Yavuzcetin taught in spring 2015 also created a pedal-powered generator bike that was on display at an Earth Day event on campus that year. That project was similar to the one he helped design for Nelson, with a few tweaks.

 “I used a pulley instead of a bike trainer design, where the tire makes a contact with a roller,” he said. “I found out that a pulley produced less friction, which means it is more efficient. I also modified it, adding a charge controller — a solar controller — in order to prevent under or overcharging of the battery.”

Although Yavuzcetin has experimented with an alternator-based motor from a car on a pedal-powered generator, he's found that a permanent magnet motor like the kind that is used on a treadmill is much more efficient and longer lasting.

Permanent magnet motors also have the additional benefit of being recyclable rather than dumped into a landfill, said Yavuzcetin, who drives an electric hybrid car.  

And while pedal-powered generators won't run factories, they do come in handy for smaller jobs.

“An average person can easily generate 75 watts of power — that's an untrained person who can output that much of power for a couple of hours,” Yavuzcetin said. “If someone is running this for a short amount of time, he can output more than 200 watts. But due to the conversions, only 100 watts is converted directly to the output as electrical power, which, most of the time, is adequate for many short-term applications like running lights, a radio or TV, charging a cellphone and such.

“Most people exercising use their energy to power up the equipment they are using. Most of it also goes to heat as the exercise intensity is increased. A pedal-generator would turn this energy directly into electrical power. Imagine a spin class of 10 students. They could easily generate two kilowatts of power.”

A battery is also part of the pedal-powered generator's setup, acting like a buffer and a storage unit. Extra energy is stored in the battery to be used later, so that you don't have to pedal all the time, Yavuzcetin said.

“You could get enough energy from a 10-minute pedal to charge a couple of cellphones,” he said. “Or, like I did by attaching my laptop to the bike, you can get enough power to watch a movie.”

Nelson hopes to eventually rent out the pedal-powered generator bike.

“Ideally, we would like to find a public, indoor space to keep the bike setup and allow the community to charge their phones, computers, etc.,” she said.

She said the workshop in October attracted people she hadn't previously seen at the markets.

“The most significant feedback I have received isn't necessarily about the workshop itself, but about what individuals learned and what that knowledge has inspired since,” Nelson said. “Prior to the event, I had never received emails or articles about green energy, but afterward the messages haven't stopped. ... I give all the credit in this to Ozgur. His ability to break down the process into digestible steps and to allow those of us without a background in electrical engineering and physics to question the possibilities is a real skill.

“The talk didn't end with a sense of 'well, that's it,' it ended with, 'And if we can do this, imagine what else we can do.'”

Yavuzcetin said he's seeing signs that people-powered generators are getting popular.

“When I first started this project in my apartment, using car alternators, there were not any generators for sale on the internet,” he said. “Now there are companies producing them. That means there is a demand for it.

“My design was just a hobby and a way to recycle used parts to build something useful out of that. Most people get bored with their treadmills and try to get rid of them, so there's an environmental benefit to this. And if someone has a few technical skills, it's not hard to build a pedal generator from an old bike and a few used parts. This becomes a little bit of recycling, a way to enable you to exercise and generate enough power out of it to charge your cellphone.”

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