Human-Powered Bicycle Electricity Generator

In the summer of 2015, I took it upon myself to create a human-powered electricity generator using a bicycle and an old treadmill motor. I hoped to bring a more engineering and energy focus to university sustainability groups, and wanted to have it ready by the start of the next school year to impress and recruit like-minded individuals. Longer term, I hoped to set up an electricity stand in one of the campus squares to make smoothies and charge phones, to further generate buzz about our club, called Georgetown Energy.

I purchased the bicycle from a set of formerly impounded bikes at Michigan State University, an inverter online, and grabbed the motor from a treadmill my brother had gutted a few years before.

The electrical work was fairly straightforward. I managed to wire it up without any electrocution or sparks, largely thanks to the inverter, which managed the conversion from DC to AC and most of the wire connections. Most of my time was spent trying to solve mechanical problems with the bicycle, such as how to maximize energy transfer between the bicycle wheel and the motor wheel, as well as keep the bicycle stable while connected to the motor. I may have cut my hands on the gears a few times.

I took off the front wheel so it was less likely to roll away. The handlebars on the bicycle that I purchased were wrecked, so I actually took it out and added the handles from an old scooter laying around in our garage.

The motor apparatus: The motor (round thing) is directly above the inverter (gray, rectangular thing), secured onto a wooden block.

The biggest challenge was keeping the bicycle tire in contact with the motor wheel. If they were out of contact, the bike tire would spin without spinning the motor, and no electricity would be generated.

The generator ended up mostly functional: we were able to turn on some lights, run a small desk fan, and charge a phone (at separate times) using human leg power. Since there was no energy storage or switch, power only came out when someone was pedaling. Even then, the pedaling intensity had to be in a very specific range. Pedal too slowly, and there wouldn’t be enough power to activate the load (light, fan, phone). Pedal too quickly, and max out the inverter’s voltage capacity – above a certain threshold (which I’m forgetting), the inverter was not able to transform the DC power into AC power for fan and light plugs.

Sadly, I cannot find pictures or videos of the functional generator. I will search for surviving media in the coming months to hopefully illustrate the machine in action!