Gravity powered generator

[Bruce]

I had this awesome idea this morning.

You know how old grandfather clocks work, right? You pull on a set of chains every morning to raise a set of weights. The clock essentiall runs on gravity power.

My thought was to convert gravity power to electrical energy. I would have a small number of workers raise a weight off the ground every morning using a system of classical pullies. I was curious over how much electrical power would be generated, but I didn't have enough engineering skills to figure it out, so I posed a challenge to our chief engineer this morning:

What is the maximum electrical power I could feasibly generate by raising one ton, one foot off the ground?

I was very disappointed in the answer. I could write a patent, but I don't think I would make much money.

Just for fun, I'll let you geniuses work it out and see if you come up with the same answer.

 

[shecky]

My question is: why would you even bother doing the math?

 

[Bruce]

My question is: why would you even bother doing the math?

Reminds me of a scene in a cartoon. I can't remember if it was Simpson's or Family guy.

"Hey, look at that doughnut display case. I wonder what makes it turn around like that?"

[The view pans down deep into the ground, following a shaft connect the the turntable. The shaft ends at man-powered wheel, being turned by ten slaves being whipped by a guy in a black mask.]

 

[MRC_Hans]

Any particular reason why you would lift a weight? Why not let the crew turn the generator directly?

I don't feel like looking up formulas right now, but I can tell you you wouldn't get enough power to run your PC long enough for it to boot up.

Hans

 

[The Don]

Mass 1000 kg
Accelleration 10m/s/s
Height 0.3m

Potential energy around 3000 Joules.

Enough to run a small lightbulb (60w) for a little under a minute.

edited to add....

Assuming 100% efficiency in converting the PE into electrical energy. A more reasonable efficiency range for a dynamo would be 80-90% so make that about 45 seconds.

A laptop runs about 15-25 watts, taking the middle value, I think you'd get nearly 2 minutes usage.

Pedalling gently on an exercise bike would get you at least 20 watts so maybe that would be better.

 

[kedo1981]

We already have gravity powered generators
They are call hyro-electric dams

 

[richardm]

Pedalling gently on an exercise bike would get you at least 20 watts so maybe that would be better.

Getting your workers to pedal on an exercise bike would be better still.

I think we may have found a way to hit our Kyoto targets and eliminate unemployment

 

[Matabiri]

I think we may have found a way to hit our Kyoto targets and eliminate unemployment

Attach small air-turbines to the filters of cigarettes, and install kinetic generators in the shoes of fat kids.

Everyone's a winner!

 

[Bruce]

We already have gravity powered generators
They are call hyro-electric dams

But I can't fit a river into my cubicle.

I can fit a one-ton weight into the corner of my cubicle, though. I was thinking maybe I might be able to get enough power to run a small electronic gizmo like a pencil sharpener or something. I could get one of the interns to raise the weight every morning. Then I could brag to everyone that I'm saving the company money by reducing energy consumption, and maybe ask for a raise.

 

[Rob Lister]

edit to delete because I'm too stupid to do math...much less read the other responses.

 

[Michael Redman]

Why not just use one ton of interns? They could grab the rope, bend their knees to lift their feet off the ground, and you could generate your electricity as they fell. When they're done you can make them leave, and you won't have a one ton weight cluttering up your cube.

 

[Bruce]

Why not just use one ton of interns? They could grab the rope, bend their knees to lift their feet off the ground, and you could generate your electricity as they fell. When they're done you can make them leave, and you won't have a one ton weight cluttering up your cube.

Nah. I could get more work out of our interns by burning them.

 

[Diamond]

Nah. I could get more work out of our interns by burning them.

Heat - yes. Work would be more difficult as you'd have to have a heat exchanger, a turbine, a dynamo and an endless supply of interns (and immunity from prosecution)

 

[Michael Redman]

Don't worry. Have you ever heard of anyone prosecuted for burning an intern?

 

[Dr. Popalot]

Burning interns would produce greenouse gasses.
Lifting weights (man hours) would cost more than using electricity produced from the power station, so don't ask for that raise.

 

[MRC_Hans]

Don't worry. Have you ever heard of anyone prosecuted for burning an intern?

Well, I have heard of people being prosecuted for doing other things to an intern .

Hans

 

[Art Vandelay]

What if the moon were collided with the Earth, and all of the KE and PE were converted perfectly to electricity. How much energy would be released? How about Jupiter and the Sun?

 

[Bruce]

What if the moon were collided with the Earth, and all of the KE and PE were converted perfectly to electricity. How much energy would be released? How about Jupiter and the Sun?

I have an even better idea. Let's wrap planet earth in copper wire, and put a bunch of magnets on the moon.

 

[neutrino_cannon]

Well, I have heard of people being prosecuted for doing other things to an intern .

Hans

Ah yes, but can you generate electricity with those things?

"You can't tax... thingy!"

By extension:

"You can't power something with... thingy! I guess it will make charted engineership much more exciting!"




Vandelay:

The moon is 7.36*10^22 kilograms, and orbits at ~1028 m/s. That comes to a kinetic energy of 3.89*10^28 joules. I'm not sure how to calculate the moon's potential energy because the dropoff in earth's gravity at that distance is significant, so multiplying the mass time acceleration times distance would give an innacurate answer.

 

[Donks]

Well, I have heard of people being prosecuted for doing other things to an intern .

Hans

Perhaps he was trying to burn the intern. He just forgot to light the cigar