Make Electricity While You Exercise

Enlarge Image Image Gallery Why not convert your workout into useful power? STEPHEN HUTCHINGS

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.

Will Pedal for Power

To find out what types of applications are practical for pedal power, I called Sheila Kerr, part owner and customer service manager of Windstream Power, which is probably the nation’s most successful manufacturer of pedal devices designed to produce electricity.

Sheila remembers pedaling the Bike Power Generator her dad built in the 1970s, and she couldn’t have imagined then that she would earn her living building and selling human-powered generators. Her father, Colin, is a physicist who went into the solar business in the quiet Eastern Townships of Quebec in the early 1970s.

After a couple of moves, the family and the business landed in Vermont, where it thrives today. The company also sells wind turbines. “Our Human Power Series is our bread and butter. We ship several hundred a year,” Sheila says.