Bmec #4: Device To Generate Power From A Human, Build a human power generator

Welcome to 2011īs BMEC #4, Build a human Power generator.

This months suggestion comes from our very own Jimbo (the wrenchwrencs own beloved
jimthecopierwrench), and sports the idea of you guys making a device that
is powered from your OWN body.

Now this could be interesting from a theoretical point of view, thatīs why itīs a
Bmec competition rather than a WEC...

Itīs very easy to just cough up a bicycle dynamo, put some pedals to the metals
and paddle away for some power, but that just wouldnīt be the same, now would it?

So..come up with some cool stuff that is human powered, Iīm going to give
you guys a hint: Piezo! Or so...

Good luck, and you have until March to do this!

I like. *gets out TinyCAD and a calculator*

Nice.

Can I enter this? I'm thinking of collecting flatus, and harnessing the combustion of said product. You guys want photo evidence of the whole process, right?

The Chemical Energy of Urine!

with as much coffee as I drink I could probably just build a water wheel

Thermocouple anybody?

I was contemplating this over a little nap and some thought experiments that almost damn near should work in practice seem to be a little too good to be true. the actual numbers obviously must be quite low, but when you just think about it...

It's fair to say that the more complicated a device you contrive, the more loss it should experience - and the less output one shoud have. Right?

Been thinking of some of the little brushless motors we use at work. Some once applied to their (external) transmisions are almost impossible to turn by hand from the final outputs, and some that can will windup pretty fast with only 5-10 degrees of final output motion - albeit with a pair of vice grips on the output and 40-50 foot pounds of manual input.

So if you were to use one of these to build a highly spur gear reduced hoist, to say lift 250 pounds 5-6 feet. they'd require a fair bit of energy input. Couple of Amps at 24V (The ones I have anyway) for god only knows how long.

So lets take it backwards...

I'm 260 pounds. My 'device' is a hammock suspended by a transmission driven by one of these motors. geared to however many (tens of?) thousands to one. The hammock frame is counterbalanced so that with a small lever I can meke the output freewheel and lift the hammock apparatus to a height of 6 feet with little effort. I then lock the drum, climb a small ladder and climb into the hammock to sleep. Over the next hour I generate electricity via the motor and gravity while the hammock slowly lowers.

My guts tells me I could charge up a 4Ah SLA with only the effort of climbing the ladder. Yes this is human powered. My original work input overcame gravity.

Likewise more mass over less distance., and maybe a more sane setup. Looking at 700 pounds of engine in the corner. Only takes a minute to (manual hydraulic) lift that 3-4 feet, and that lift can do a long ton.

I haven't even done rudimentary calculations, but my thoughts are that the perceived work from the human perspective drops to nothing significant. Climbing a ladder once per hour as opposed to a light but repetitive motion over the same period of time. My thought is this: The conversion apparatus contrived might be much more lossy, but the actual generation (food fuel to human work generation) process so much more efficient per work unit that this is offset actually producing an apparent gain.

Consider the amount of electrical power required to vertically hoist 200 odd pounds to the third floor of a house. Now consider that in theory, by walking up the stairs to the third floor you could generate and store areal world 50 percent of that. Cake for thought methinks.

Given that there are some muscle groups capable of relatively massive short term outputs - think leg press machine on the universal gym, 600 pounds lifted 20 inches in about a second, or say raising 100 pounds of water 30 feet in 90 seconds (two 5 gallon pails up 3 stair flights), I have a feeling that doing a lot of initial work over a short duration, and the key being to devising a device to meter that energy out over time is the way to go.

Just my thoughts. Discussion?

I dunno...just how big is your gut?

-Adam O.

The penis lives with no fear of sunburn or pigeon droppings

OK, but how big is the gut?


Put your generators in a pair of platform shoes, with collapsible platforms. You can do a lot with a 1" travel & 260lbs every second.

To charge up a 12 V, 4 Ah SLA with perfect efficiency would require a ladder 150 meters tall. 5-6 feet would charge a 12 V, 50 mAh battery.

Shit. Well I did say I didn't even bother with rudimentary calculations. That bad, eh?

Wait... wouldn't this imply conversely that a pair of half dead 9 volt batteries could produce 260 pound feet for 10 minutes... Oh, how many fractional HP is that? Uh, or as I reread that I realize I'm tired and have to get up in 4 hours. .

To charge up a 12 V, 4 Ah SLA with perfect efficiency would require a ladder 150 meters tall. 5-6 feet would charge a 12 V, 50 mAh battery.

Yes, but considering that he is actually napping while his fat ass pulls the genny, 50mAh sounds like a steal

-Adam O.

hmm.. are bonus points given for discretely generating from someone else's labours?..(professional laziness.. )

http://afrotechmods.com/cheap/tape_measure...e_generator.htm

The cat in that video looks genuinely frightened.

-Adam O.

@Jim,

Your post reminded me of something I had seen a few years back (2 - 3 may be). I came across a report on a student project on the Internet. This guy had designed a system to generate enough power to keep a lamp burning for overnight using gravity. There was a drawing included & the guy probably had a prototype that wasn't completely there yet. IIRC, He was using a worm screw about a meter long, mounted vertically. Steel plates weighing about 200 lbs were to be lifted to the top (human input) and the screw engaged. There were couple of bars on two sides to keep the weight plates parallel to ground as they descended. The screw had a pulley. A cable riding the pulley was driving the generator. As the weight came down (over something like 8 hours), the screw is supposed to rotate slowly and drive the generator. The project had won some competition or something.

I tried to find it again, but no success so far. I may have saved it somewhere. I will have to go through my back up CDs/DVDs to see if I did. In the meantime, someone here may have a better luck finding it.

I think I found it:

http://science.howstuffworks.com/environme...p.htm/printable

This is not the same drawing that I remember seeing. However, the other description is the same. Looks like the original design has been now finished in a marketable product.

Interesting concept. I wonder if it could be modified to automatically fill with rainwater from the downspout as the weight, then release the water at the bottom & automatically rise back to the top for another go.
That would be perfect for winter lighting here on the Wet Coast.

Too bad ballscrews are so expensive.

One of the early rain gauges worked on a small tilt-bucket system. When full, it tilted over and emptied, then righted itself when empty. On each cycle it worked a mechanical counter (or punched a paper or something, I forget) to record the measurements. Something similar on a large scale could probably do some work.

Or ya could just add water-wheel generators to all yer downspouts...

foolish man.. yer thinking of a novelty 'drinking bird' toy..

..maybe if i donned a piezzo wristband and kept posting stupid questions.. .. i believe we have a winner..

Not necessarily. Do a search for deer chaser / shishi-odoshi & you will see how that mechanism works.

foolish man.. yer thinking of a novelty 'drinking bird' toy..

Ever see the X rated version? Instead of a drinking bird, it's a bobbing bird.