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Power generation from gym
2

Power generation from gym

Power generation from gym

(OP)
What are the possible methods of generating electrical power from stationary bike and elliptical trainers?

RE: Power generation from gym

Hook up a generator in the drivetrain. (What else do you possibly think could be done?)

Since the operating speed and power will not be consistent or repeatable, doing anything useful with that power will be a challenge. You can use an inverter to convert DC to line voltage and frequency AC. I can assure you without doing any calculations whatsoever that it will not be cost-effective.

You've asked similar questions before, and I have a question in return. WHY are you asking these questions? A forum on the internet is not capable of making something out of nothing.

RE: Power generation from gym

A Stirling engine, with the gym interior as the hot side. Works best in the winter.

RE: Power generation from gym

Probably the most cost-effective approach would be to connect the stationary bikes to a fan (mechanically or electrically) blowing on the rider. That would possibly let you turn the AC back a notch or two.

RE: Power generation from gym

Big fluid (water?) tank up on the roof (or water tower like in the movies).

Another big fluid tank as low down as you can get it (i.e. the basement if possible).

Each exercise device is connected to a pump that pulls fluid from the lower tank and pumps it up to the higher tank. (For steppers a linear pump, for bikes a rotary pump...)

The Upper tank in turn drains down to a generator that outlets into the lower tank.

You now have a built in accumulator which will smooth variations in power and also if large enough allow you to store energy to be used when needed.



Or, you just use the water pumped to the roof tank to ensure a nice high pressure shower after all that exercise - heck maybe leave some devices generating electricity and use that for an immersion heater on the tank.

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RE: Power generation from gym

Oh, the other option just have a giant treadmill for multiple users installed in a correctional facility.

If you don't generate enough joules in a given day then you get put on a gruel regime or similar.

https://en.wikipedia.org/wiki/Treadmill#Treadmills...

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RE: Power generation from gym

Exercises in engineering and musings of Rube Goldburg-esque inventions aside, unless this is for purely novelty or demonstration purposes, or truly a subsistence means of acquiring some juice to charge a cell phone or other device, bicycle generation, while not completely useless, is pretty close to it. (imho)

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Power generation from gym

WADMW,

I was a judge at a STEM event for school children. One of the kids proposed a mat that would generate power as someone walked across it. I could design a cinderblock that someone could lift up and down while standing on the mat. You could arrange a bunch of these mats into a circle, and ride a bicycle around the circle, again, generating power.

--
JHG

RE: Power generation from gym

"Big fluid (water?) tank up on the roof (or water tower like in the movies). Another big fluid tank as low down as you can get it (i.e. the basement if possible)."
At such a small scale, a Lithium battery + inverters would be much more cost effective. Or forget the battery and push the energy straight into the grid as already suggested.

je suis charlie

RE: Power generation from gym

The OP asked for possible methods.

They didn't ask for the most appropriate methods, most cost effective methods or any other evaluation of the 'goodness' of the suggestion.

Since an arguably silly question was asked, I proposed a moderately silly answer.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
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RE: Power generation from gym

(OP)
Thanks a lot for all those tips and the silly stuff as well.

RE: Power generation from gym

WADMW, hopefully you can tell the difference between both.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Power generation from gym

Somehow, this discussion came up in the recent past and again take a look at a bicycle dynamo. If you have ever used one, you will feel the difference.

RE: Power generation from gym

Kenat, et al,

Pumped water is exactly what is used at full size power plants for load leveling/peak demand handling. No reason it is inappropriate here. In the larger scale it is how hydroelectric power is gotten using dams and turbines. It only seems odd to some because, really, people are such poor sources of power.

People are such poor sources of power that it does make the question bizarre. Might also ask how hard is it to stir water with a teaspoon in a teacup to boil the water. Followup - since reducing pressure makes liquids boil more readily, will it be easier to heat the water at higher altitude.

I would point out that stationary bikes and elliptical trainers are expensive, so putting them on Craig's list and taking the money to buy batteries or an extension cord would be more reliable.

RE: Power generation from gym

3DDave. How many reasons would you need, to satisfy you that pumped storage would be totally inappropriate in this situation?

je suis charlie

RE: Power generation from gym

I don't think we can really address the appropriateness of design suggestions because the OP doesn't really spell out the conditions.

Are we talking about a home gym in a western civilization, a corporate chain like Anytime Fitness with 100s of locations, or is this a very remote location with little to no infrastructure, but can cobble together some simple machines... that last case would throw out a lot of complaints about being impractical.

I'm curious if the OP is trying to make a 'green gym' in San Francisco, or trying to keep the lights on in the Outback.

RE: Power generation from gym

Shackle everyone to a big turnstyle and call it a new crossfit exercise.

RE: Power generation from gym

BYU students design system to be powered by kids on the playground...

gbangs
TC 8.3.3
NX 8.5.3.3 MP11

RE: Power generation from gym

"Shackle everyone to a big turnstyle...."

And 10 years later the lone survivor is RIPPED.
As around 2:30 in one of my most fondly remembered movie scenes.
https://www.youtube.com/watch?v=z5KYZ74OAak

RE: Power generation from gym

gruntguru - reading my entire response might help you understand why pumped water would work best. If not, then please suggest a workable solution for the original problem. Solutions will be graded on cost, system efficiency, and total power output, with no extra credit for snark.

RE: Power generation from gym

No snark intended. However:
- Pumps and turbines are high efficiency machines in large sizes. Power output of a gym doesn't suggest large pumps/turbines.
- High efficiency is obtained in a defined operating range. Gym output probably varies constantly between zero and 100%
- High efficiency pumps and turbines are normally high head machines. Gym in multi-story building might qualify.
- If high head is not available, the mass of the stored water will be significant.

The best storage system for such a small energy source is the grid.
Next best would be battery storage. Buy a Tesla Power Wall.

je suis charlie

RE: Power generation from gym

I assume a "gym" to be a place where less than 100 humans are simultaneously feeding energy into exercise machines. Provided that assumption holds, I will stick to my assertions.

je suis charlie

RE: Power generation from gym

There is a Randy Couture gym in my neighbourhood with a room full of punching bags. This could be a fun way to generate power.

--
JHG

RE: Power generation from gym

I wonder if E-bikes have regenerative braking? If so, after getting home on your 25mph E-bike, instead of plugging it in to recharge and then going to the gym for the workout you missed while riding your E-bike, just put it on rollers and ride with the regenerative braking engaged for a few hours... thumbsup

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: Power generation from gym

At this point, I'll shift to using the equipment to mechanically drive a belt that brings coal to the surface for burning in a steam generation plant. But then cut out the middle men/women and use the electricity to operate sealed electric motors to drive the belt.

RE: Power generation from gym

You are merely transferring energy from one form to another, all at the cost of the energy required to accomplish this transformation. If you starved all those gym people, they wouldn't have any energy that needed to be transformed thus saving this transformation energy. A penny saved.............

RE: Power generation from gym

BUGGAR,

Do gyms pay for everyone's food?

You generate energy. Someone else pays for the fuel.

--
JHG

RE: Power generation from gym

Good idea, extracting energy (in computing power) from humans without paying for it. And we could connect it to the cloud. And we could call it Windows 10.

RE: Power generation from gym

Quote:

Now, if you get those guys to buy Teslas and have them charge their own cars, that might be interesting, but equally not cost-effective.

Why wouldn't it be cost-effective? The total output wouldn't be much, but you could probably do it for less $/w than solar cells, as long as the storage is provided by the gym members in their cars.

When electric cars become common place their use as temporary storage devices for excess power from solar and wind will also become common place. Because they spend a large part of the day in a parking space, and the cost of connecting parking to the grid is negligible, compared with other options such as pumped storage the marginal cost is negligible. It's just a matter of time.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

RE: Power generation from gym

(OP)
gruntguru was right. I was referring to a gym, sorry I wasn't very specific at first.

Storage of water would also be an good idea, though would it be cost efficient to connect a machine a piece to a pump??
Plus, what I want is to combine several bikes, mechanically; will a power split device, a back drive differential work, of is it possible to use something like an automatic derailleur set, what I mean by that is, a chain sprocket mechanism, one end connected to the bike and the other to a common shaft that connects at least 2 bikes in series, which automatically shifts gears in order to maintain uniform speed. I'm not sure u'll get the latter part though... ! Just imagine something like a tandem bike or a sociable

https://en.wikipedia.org/wiki/Tandem_bicycle
https://en.wikipedia.org/wiki/Sociable

I'm just referring to their mechanisms.

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