Generation of Electricity by perpetual motion of turbine

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Generation of Electricity by perpetual motion of turbine

Postby Aditya Shankar » Fri Dec 14, 2007 10:28 am

Though this is not strictly concerned about my project, I couldn't help thinking about it.

My question is simple. Is it possible to generate electricity for a long time by using just a very small turbine and set of good plumbing and control systems ?

Water is made to fall on a very small turbine (say of 0.5m radius) from a considerable height ( of around 3-4 metres) the water when it falls on the turbine rotates it which in turn produces and electric current. However the water is collected below and transported back to the height of 3-4 metres by capillary action. This is again made to fall on the turbine and thus the cycle repeats producing electricity perpetually without the loss of much energy and considerably less use of resources.

Is this idea feasible?
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Postby staryl13 » Fri Dec 14, 2007 3:05 pm

Hi Aditya!
I think it seems feasible, this link has some pretty good information about this topic-
http://www.otherpower.com/otherpower_hydro.html
hope this helps, good luck!
"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -Isaac Asimov
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Postby elin105 » Sat Dec 15, 2007 3:21 pm

Hi Aditya!

Here is a website from an expert who has worked in this area.
http://wildwaterpower.com/

Good luck!
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Postby ChrisG » Sat Dec 15, 2007 6:15 pm

Aditya,
Welcome to the Science Buddies forums. You have presented some very interesting and useful thought exercises.

Just as a caution, using the term "perpetual motion" in the title of a science fair project is sure to get a lot of skeptical responses. A perpetual motion device, as it is typically defined, violates the law of conservation of energy. It is not realistic to create such a device under any circumstances. The most you can hope for is to create a device that is very efficient, such that the amount of useful energy generated is very close to the amount of energy put into the system.
http://en.wikipedia.org/wiki/Perpetual_motion

For the example you gave, capillary action would not add any energy to the system. The lift of water provided by capillary action would be offset by the energy required to extract the water from the capillary tube. In other words, the adhesive forces are active when you put the water in and when you take the water out. Consider a paper towel. The water goes in and it stays in unless you do something (provide energy) to get it out agan. Furthermore, capillary lift only works when there is a meniscus, or an interface between air, liquid, and a solid surface. Once you start pumping water out of the top of the tube, the meniscus is broken, and no net lift provided by the tube. Making matters worse for energy efficiency, there would be a some loss of energy to heat generated by friction between the water and the walls of the capillary tube. Because of the large surface area in capillary tubes, they are less efficient than large diameter tubes for transporting water. If you want to know more about these topics, there is a lot of research done on capillary forces to study unsaturated flow through porous media.
http://en.wikipedia.org/wiki/Capillary_action (see examples)

I like the creativity of your ideas. Keep them coming. :)

Chris
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Postby Aditya Shankar » Sun Dec 16, 2007 9:33 am

Staryl13, Elin105 and dear Chris ,i thank you very much .... i saw the websites you had mentioned and was astonished about the amount of material that was available which i didn't get when i had googled about it . Thanks to your efforts.
Now i have sufficient material to read about and understand the concept as well as conduct the project.


To Chris-
Dear sir , i finally understood the concept of capillary action and am terribly sorry on using the term "perpetual motion" , I as an engineering student should have known better.

Nevertheless i was thinking about your example of the 'towel' when another thought struck me -
After we bathe ( or else get our entire body wet for that matter) it is true that the skin dries drastically faster than our hair (Water is retained for a longer period of time)... Why is this so ?is it due to the different surface tensions of the skin and hair ?
Please clarify this for me.

Once again thank you everyone. :D
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Postby Craig_Bridge » Sun Dec 16, 2007 10:30 am

After we bathe ( or else get our entire body wet for that matter) it is true that the skin dries drastically faster than our hair (Water is retained for a longer period of time)... Why is this so ?is it due to the different surface tensions of the skin and hair ?
Please clarify this for me.
Surface tension plays a role; however, things like air currents, convection, evaporation, and thermodynamics all play a role for people with long hair.

If you ran an experiment with two bristle paint brushes, one that was 1" wide by 1/2" thick and another one that was 2" wide by 1/4" thick with the same length bristles, dip them both in water and hang them to dry. I would expect the thinner brush to dry faster even though they have very close to the same number of bristles and surface tension effects. In this case, the thickness of the brush has the biggest effect. This thickness attenuates the flow of moisture and thermal energy to supply the heat of vaporization required by evaporation.
-Craig
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