# Make Electricity While You Exercise

Most treadmills and stationary bikes use electricity, but what if you could produce electricity while exercising? With a pedal-power generator, you can! And you can use the electricity immediately to power a television, computer, stereo or other electronics — or store it in batteries to use it later.

| October/November 2008

Why not convert your workout into useful power by using a pedal-powered generator?

Photo by Stephen Hutchings

While you probably won’t produce enough electricity to power your entire house, pedal-powered generators can play a small but useful role in some homes.

## Pedal-Powered Generators

My neighbor Linda Archibald has an off-the-grid house that is powered by an array of photovoltaic cells (solar panels). When she asked if she could recharge her backup batteries with a bicycle adapted to generate electricity, I was skeptical — at first.

After doing a little research, I found that an efficient bike generator pedaled by a reasonably fit person can produce about 100 watts of continuous output. An experienced biker can produce a peak of more than 400 watts, but peaks don’t count for much when it comes to pedal power generators. Assuming an ambitious exercise period of one hour, a person could produce about 100 watt-hours of electricity. That is one-tenth of a kilowatt-hour (1 kilowatt-hour = 1,000 watts for 1 hour).

Most of us pay our local utilities about 10 cents per kilowatt-hour for electricity, including taxes and surcharges. By getting our heart rate up and breaking a sweat for an hour, we could produce 1 cent worth of electricity. Not much incentive, I thought.

With the electricity produced by an hour of pedaling, we could light a 100-watt incandescent bulb for an hour, or power a 20-watt compact fluorescent bulb for about five hours.

Pedal power is a fun idea that does generate usable amounts of electricity, but it’s easy to understand why a human-powered device can be viewed as a trinket without a meaningful role in a household’s energy supply. Nevertheless, some pedal generators are used regularly to do serious work. The critical factor to making pedal power a viable option is matching expectations with realistic output.

deepikareddy
3/28/2015 12:17:23 AM

I have an Idea to regenerate the power from an electric bike by connecting a battery to the wheels. But for this we have many problems like efficiency,load so on. what improvements can be done for this to make it more effecient?

ruth martin
12/11/2012 9:57:37 PM

This is very interesting. I have a rather old exercise bike and I'm wondering if a generator could be attached to that. I'm sitting here remembering the bike I had hooked up to my wheat grinder years ago and I and my kids would grind the wheat for our bread and pizza. That's a good idea to put all those people at the gyms to work.

rhonda watts
12/8/2012 2:25:27 AM

I've often thought all the people with nothing better to do with their time and effort than go to a gym, ought to have their exercise machines hooked up to generators. As noted, one person on a stationary bike doesn't create much electricity, but think of the thousands and thousands of people (pedaling or treadmilling or whatever they do instead of *productive* physical work!) and what amount of electricity that would be altogether! The reason I know this could work is that when my dad was stationed in India during WWII, all electricity for the base was provided by banks of Indian workers who pedaled in shifts on stationery bikes. If it worked then, it could work now! Put those people in gyms to use!

pj
8/22/2011 4:15:52 PM

There are 35,000 Indoor Cycling facilities World wide.They usually have a minimum of 10 cycles going at once, many have 50 or more at once. They could probably generate enough electricity for their clubs if they could all be hooked up together. Since they use the "Spinner Bike" flywheel technology, they would probably be more efficient at electricity generation.

kenzo_1
8/19/2010 2:43:56 AM

This concept has actually been implemented in a Texas Jail (go to http://www.dogengine.com/us/used-stationary-bikes.php and scroll at the bottom and read "Stationary Bikes Used For Generating Energy") where prisoners used stationary bikes to power a TV.

sblack
10/5/2008 9:33:36 AM

Are there any fitness centers out there that have used or thought of using this technology to help with their energy costs?

eddiecycle
9/19/2008 10:25:16 AM

I think it's worth noting that this article ignores the potential power generation of trained athletes, who can output 200-300 watts continuously for multiple hours. A strong cyclist can generate a kilowatt hour in one workout. With the popularity of spinning classes and indoor trainers for winter workouts, there's quite a bit of human-power currently being converted to heat. I always cringe when I see a room full of spin bikes generating heat that must then be removed by the HVAC, wasting even more energy.

eddiecycle
9/19/2008 10:22:27 AM

I think it's worth noting that this article ignores the potential power generation of trained athletes, who can output 200-300 watts continuously for multiple hours. A strong cyclist can generate a kilowatt hour in one workout. With the popularity of spinning classes and indoor trainers for winter workouts, there's quite a bit of human-power currently being converted to heat. I always cringe when I see a room full of spin bikes generating heat that must then be removed by the HVAC, wasting even more energy.

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