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Using convex lenses to make electricity?

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Using convex lenses to make electricity?

Unread postby mekrob » Tue 02 Oct 2007, 10:50:51

So I was thinking about ways to generate electricity with low levels of technology. Kids often take glasses or hand lenses to burn ants by magnifying the energy in light to focus on the poor creatures.

How possible would it be to funnel a small stream of water through a translucent pipe that has a convex lens above the pipe which magnifies sunlight to turn the water into steam, which is then funneled to spin a turbine to power a generator to power our houses (much like geothermal energy)?
I want to put out the fires of Hell, and burn down the rewards of Paradise. They block the way to God. I do not want to worship from fear of punishment or for the promise of reward, but simply for the love of God. - Rabia
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Re: Using convex lenses to make electricity?

Unread postby gnm » Tue 02 Oct 2007, 11:35:08

Your primary problem would be tracking the sun for correct focus. Hardly a simple way of generating electricity. You could make homemade solar PV panels easier. You also lose efficiency with every conversion (like running a turbine). I would suggest a wind turbine or (if you REALLY want to do the steam punk thing) just use a parabolic trough to concentrate on a pipe. That has been done pretty effectively and even at commercial scales.

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Re: Using convex lenses to make electricity?

Unread postby Fishman » Tue 02 Oct 2007, 14:12:44

Mekrob,
Excellent idea to start with. The parabolic trough allows greater sunlight space to be concentrated. Imagine a 4 foot lens and the material required to make it vs a 4 foot parabolic mirror, easily made with some plywood and perhaps some mylar. Your collecting system would have to capture the energy, reguiring a black surface, then transfer the heat. Clear water wouldn't capture the energy (maybe a clear tube and a black fluid?)
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Re: Using convex lenses to make electricity?

Unread postby Fishman » Tue 02 Oct 2007, 14:14:08

Check out the solar sizzler for an idea.
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Re: Using convex lenses to make electricity?

Unread postby kokoda » Wed 03 Oct 2007, 11:09:31

Surely you have just described a solar hot water system.

Using parabolic mirrors to heat water has been tried on an industrial level ... and been found wanting.

The problem is that sunlight is low density energy and you need to concentrate a lot of it to generate any meaningful amount of power.
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Re: Using convex lenses to make electricity?

Unread postby steam_cannon » Wed 03 Oct 2007, 11:44:27

gnm wrote:...if you REALLY want to do the steam punk thing...
Did I hear someone mention steam? :-D

There are many ways to make lenses for concentrating light to generate steam or redirect sunlight for useful purposes. Here are a few links and ideas...

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Some info on solar concentrators
http://www.solarcooking.org/

Non-Tracking Evacuated Tube Collectors
Image
http://www.solargenix.com/company.cfm#n ... collectors
" Solargenix Energy has developed other technologies using the science of Non-Imaging Optics that can be used on existing buildings or ground-mounted. The basis for these units is the evacuated tube collector. These collectors use a copper or steel pipe containing a fluid that transports the thermal energy to the end-use. This tube is encased in an evacuated glass tube to limit heat loss. Although evacuated tube collectors have been around for many years, Solargenix Energy enhances the efficiency of these tubes through Non-Imaging Optics that converts them to "compound parabolic concentrating" collectors containing optical designs inside the glass tube. These tubes can achieve operating temperatures up to 450°F (232°C) and can be used for many of the same applications as the Power Roof™. "

Also, if you want to try a simpler project first. Using the sun to generate warm air to heat a house, cabin or tent is much easier then trying to generate steam and electricity.
Image
http://www.gizmodo.com.au/2007/05/canne ... built.html
However, this project would be even better with a few large mirrors...

Large Utility Mirrors
Image
Even simpler, you can do a lot of things with large mirrors and they cost hardly anything! You can point large mirrors on a tent to warm it up, make a large solar cooker, in theory warm up a side of a house with yard mirrors, possibly roof mirrors to keep a building cool, or point it at your neighbor as a joke (hahaha)...

So there are lots of things you can do with large mirrors and they are very easy to build. As mentioned earlier, you can make them with camping mylar (or potatochip bags) and sticky spray (or improvised adhesives), and stick it onto plywood, an old door, fibercrete, sheetmetal... Whatever you want to make into a large mirror.

Aluminum Foil VS Mylar?
As a side note I'll just mention that Mylar has better reflectivity then Aluminum Foil. But Aluminum foil may be more durable and less subject to sun damage. For a really good mirror Mylar is the way to go. But Foil mirrors work too and may be better for some applications...

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How to keeping your mirrors aligned with the sun is concern for some solar concentrators. Here is some info on that.

Summary of methods for tracking the sun and moving a mirror.

1. Adjusting the mirror by hand. This is the most common method for family solar cooking and for testing solar array systems.

2. Mechanical (This is used for large arrays and large scale cooking.)
* Mechanical timer, small solar powered motor on large gear
* Lever with dripping water or sand weight
* Simple light sensitive resistor to switch on small motor when light source moves.

3. Shape (passive tracking, no moving parts)
* Reflective cone or trough that directs light in one area for most of the day.
Image Image
http://www.angelfire.com/80s/shobhapard ... ooker.html

* Inwardly reflective fresnel concentrator
Image
http://www.freepatentsonline.com/6620995.html

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A few projects I've had fun with...

Waterlens, just a piece of vinyl over the top of a barrel.
Image Image

Parabolic Solar Cookers: Mylar, Sticky Spray, old satellite dish, box, vinyl...
Image Image
Image Image

Focusable Parabolic Reflector: Vacuum pump, bucket, mylar, sticky spray, twine...
Image Image

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Well that should be enough to get you started. Have fun! :)
Last edited by steam_cannon on Wed 03 Oct 2007, 12:29:21, edited 1 time in total.
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Re: Using convex lenses to make electricity?

Unread postby mekrob » Wed 03 Oct 2007, 12:09:36

Ah, thank you Steam and all.
I want to put out the fires of Hell, and burn down the rewards of Paradise. They block the way to God. I do not want to worship from fear of punishment or for the promise of reward, but simply for the love of God. - Rabia
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