# Pedal generator math **URL:** \ **Category:** Factual Questions\ **Created:** [November 18, 2015, 2:19pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886 "2015-11-18T14:19:46Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [November 18, 2015, 2:19pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/1 "2015-11-18T14:19:46Z")
You may have seen (on social media) links to a guy who claims to have invented a pedal generator that supposedly you run for an hour and it supplies power for a whole day. My back of the envelope calculations: Assuming a (generous) 200W output for the rider, that leads to about 8W for the day (I’m ignoring losses in conversion and storage) - enough for some LED lamps and maybe a radio - but not much else. (One laptop per child are about 12 W) Certainly better than burning (expensive, dangerous) kerosene, but that is the best I can say about this idea. Is there a good link with a more rigorous examination? Thanks, Brian ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [November 18, 2015, 2:32pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/2 "2015-11-18T14:32:54Z")
I debunked this on a friend’s Facebook page. Basically, yeah, the numbers don’t add up. Humans can only generate a few hundred watts of power, even with a generator that’s 100% efficient. [An Olympic cyclist pedaling all out for a few minutes can just barely toast a piece of bread.](https://www.youtube.com/watch?v=S4O5voOCqAQ) Powering a large appliance like a refrigerator? Forget it. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [November 18, 2015, 6:43pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/3 "2015-11-18T18:43:55Z")
You only have to pedal 32 hours a day to cover the average American’s daily household energy usage. So you and 32 friends could do it in an hour. But then you’d have to go help them with their energy, too, so you’re still taking 32 hours a day. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [November 18, 2015, 8:36pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/4 "2015-11-18T20:36:27Z")
There is a nice discussion of the general problem of how work is needed to “keep the lights on” throughout human history on a Planet Money episode. > **[Episode 534: The History of Light](https://www.npr.org/sections/money/2014/04/25/306862378/episode-534-the-history-of-light)** > > On today's show: How we got from candles made out of cow fat to as much light as we want. The history of light is the history of economic growth, of things getting faster, cheaper, and more efficient. Spoiler- we have it REALLY easy compared to just about everyone in history before the 20th century. IIRC, it took about a days labor in ancient times to generate an hour of after sunset illumination. Caveman Og would have really liked that pedal power device (and it coulda also kept his smartphone going 10,000 BCE). ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [November 18, 2015, 9:15pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/5 "2015-11-18T21:15:24Z")
> [@DrCube](#): > > You only have to pedal 32 hours a day to cover the average American’s daily household energy usage. So you and 32 friends could do it in an hour. But then you’d have to go help them with their energy, too, so you’re still taking 32 hours a day. I’m surprised it’s so little. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [November 18, 2015, 10:26pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/6 "2015-11-18T22:26:03Z")
> [@Princhester](#): > > I’m surprised it’s so little. I agree. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [November 18, 2015, 11:44pm UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/7 "2015-11-18T23:44:00Z")
I saw a TV program where they had a team of cyclists generating the electricity for a family. The object was to illustrate how much energy it takes. They had a whole bunch of racing bikes hooked up to generators and a large team of amatuer riders. As each appliance was switched on, they had to add more bicycles. When the kid’s laptops and the electric kettle were on, everyone was pedalling like mad. Just the lights, needed half a dozen, cruising. To this day, whenever I turn the oven or the kettle on, I remember those sweating cyclists. > **[Cyclists power family home on BBC show to highlight energy wastage](https://road.cc/content/news/11779-cyclists-power-family-home-bbc-show-highlight-energy-wastage)** > > How many cyclists does it take to power a kettle, iron, light bulb? Quite a lot… [![](https://img.youtube.com/vi/C93cL_zDVIM/hqdefault.jpg "Human Power Shower - Bang Goes The Theory - BBC One") ](https://www.youtube.com/watch?v=C93cL_zDVIM) ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [November 19, 2015, 12:11am UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/8 "2015-11-19T00:11:55Z")
You could run 30-50 laptops for the amount of energy that an electric kettle takes… ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [November 19, 2015, 1:09am UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/9 "2015-11-19T01:09:46Z")
> [@Princhester](#): > > I’m surprised it’s so little. I did the math a while ago, and I think I used the maximum measured human power output from pedaling. Like an Olympic medalist during a sprint. So it’s not something an actual human could keep up for a whole hour, let alone 32. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 19, 2015, 2:47am UTC](https://boards.straightdope.com/t/pedal-generator-math/737886/10 "2015-11-19T02:47:40Z")
There’s a lot of slack on the other side of the calculation, though. By using more efficient appliances, you can slash energy usage dramatically with almost no change in lifestyle, and of course you can change even more with a lifestyle change too.