How exercise can keep the lights on

This morning, as thousands of runners lined up for the Austin Marathon and Half-Marathon, I couldn’t help but think of how much human power each athlete generated as he or she covered 26.2 or 13.1 miles. What if we could harvest that energy and use it to supply electricity to part of Austin? One of the most widely known examples of human power being used to supply energy is Lance Armstrong’s 2005 Sports Center commercial.

So what does this mean for us? While funny, the commercial is a little bit off the mark. Not even Lance Armstrong could power an entire building. And well, none of us are Lance Armstrong. Sure, mapawatt says Lance can produce 400 to 500 watts while climbing up the French mountains, but he only generates about 250 watts when cruising. Mapawatt’s blogger estimates that he would need 1o of the world’s best cyclists working at their hardest to power his house with max air conditioning. Given the price of electricity, these highly-trained athletes would be making chump change.

In 2008, Portland’s Green Microgym became a leader in the harvesting of human energy, using the exercise of gym members to help power the 3,000-square-foot facility.  Closer to home, Texas State University is using its Student Recreation Center to make students aware of their energy consumption habits. The center’s “human power plant” is the largest in the world and uses 30 elliptical machines to give electricity to the campus power grid. It’s thought that the $20,000 project can pay for itself within 7 or 8 years. How Stuff Works estimates that during a workout, the average person can produce anywhere from 50 watts to 150 watts of electricity per hour, depending on the machine. Some machines even have outlets to power appliances using less than 400 watts of electricity. To put that in context, one could likely power a large TV during a workout but not a refrigerator; lightbulbs would be no problem.

Sure, using human power to provide electricity to our homes is not the most efficient or most cost-effective way of doing so, but the concept inspires each of us to not only put our workouts to good use but to also seriously contemplate our energy consumption. To find ways to make your home human powered, take a look at The Human Powered Home by Tamara Dean.



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3 responses to “How exercise can keep the lights on

  1. sgaurav

    The concept of Human energy expressed in this blog entry is really good though it is not very new.

    People have been harnessing their own energy (burning calories) to generate some useful energy since long, for e.g: a bicycle light powered by a dynamo attached to bicycle or a human pulling a cart (means of transport many decades ago) or a human powered cloth-stitching machine.

    But the major difference in the earlier form of useful human energy and the one expressed here is that the in the new concept of human energy, production of useful energy is not the prime objective but a secondary result. Recreation is the prime objective here.

    I have few observations to make on this new concept –
    1) Human energy is non-renewable : we are not generating energy from something which was not already there.
    2) Human energy is less-efficient : If we add humans to the energy cycle (coal/petroleum>power plant>food industry>human body>useful energy), it would be a much less efficient process to produce. For example, it would be less efficient to produce energy if Lance Armstrong consumes energy bars to produce it compares to simply produce it.
    3) Are we consuming more energy than we require : If yes, then probably it is best to produce human energy.
    4) Cars consume hundreds of hp, and a horse would be equivalent to atleast 5-10 humans.

    The concept is good and its execution on a very small scale (like human powered gym etc.) is feasible as well as commendable. But on a big scale there are many issues along with the infrastructure needed to support the conversion.

  2. utpqd

    I actually designed and built a device like this last semester for my electrical engineering senior design project. We called it “PedalPower” and it essentially powered loads (like TV’s and computers) by either using only AC power from a wall outlet, only the DC power produced by a user when pedaling a bike with a DC generator attached, or a combination of the two sources. When the user isn’t pedaling, the load would be powered from a wall outlet (12o Vac, 60 Hz). But once pedaling began and the generator voltage was constant, the load would be powered by the user-generated DC power. If the load was large enough, the wall outlet could also supplement the user-generated power. Unfortunately, we weren’t able to run any tests that estimated yearly savings from powering loads with user-generated power. However, some quick estimates showed very small savings (like less than $1 a year) if you exercised regularly on our machine. All in all, my perspective is that the idea is a good one, especially when multiple exercise machines are connected together to generate power. However, the actually savings are not as large as one would expect.

    Final Report:


  3. Patrick Pace

    I second the minimal impact arguments. If someone is generating ~150W for 1hr / day for exercise we have about 4.5 kWh generated per month, knocking $0.45 off your monthly electricity bill. The best scenario is that 300million Americans use some connected exercise machine for an hour a day and we can get 1.645E10 kWh / yr from exercise! GREAT, except that it works out to 5.6E13 BTU, which is a big number, but only 0.056 Quads, or .0000056% of our annual energy usage. Humans are very weak on the energy scale.

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