Yep, big fresnel lenses off junked big-screen projection TVs can make solar power scary serious.  Like, melting rock serious.

Saw that on Doomsday Preppers. Guy in FL builds one, cooks (sets on fire) a chicken.

Cool.

Saw this as a project in 1963 Popular Mechanics IIRC...

They had paper back then???

OP, very cool video. I didn't realize there was quite that much power to be had.

That makes me wonder why this hasnt been tried on a larger scale, get a field of those focused on some piping.  Insta steam.  Hook up to your nearest Steam Generator.

Seems like it would be easier than those steam towers in the desert and far less birds getting insta fried.

I miss that show.  It and Finding Bigfoot were my favorite laughs.

I was thinking that EXACT same thing.

 

Because there's a fundamental difference between KW of HEAT...

And 'concentrated temperature'...


Just because a few square foot focusing device can concentrate a little sunlight on a small area and raise the temperature to a high level...


Doesn't translate to being able to do much work...


The sun's radiant energy on a 1 square meter surface at peak is IIRC ~1300 watts.

Converting that radiant energy, considering efficiency/losses, into the ability to do WORK, is a considerable challenge...

A challenge that has been pursued with extreme intensity in one way or another, probably as long as man has been on the planet...


Arguably one of the most convenient means of conversion on smaller scales, are solar panels...

The 3 I'm sitting under plus 3 on the other container,  will potentially be  cranking out >1200 watts in a little bit, with one arm tied behind their backs...    

So much that some 'energy opportunity' must be lost so as not to charge the batteries at too high a rate.



Solar panel cost presently can be as low as ~90 cents per watt, efficiency approaching 16% or better,  and lifespan is likely greater than 30 years with no maintenance.


Absolutely amazing...

That said, only PRACTICAL in limited settings...

Yes, but (At least I) am not necessarily talking about turning that heat into electricity. I'm thinking hot water heating and also cooling.

 

Would be easy to heat a shitton of water. Heated pool, domestic hot water, etc.

my water heating bill is only high in the times of year that the sun isn't near as hot... I'm happy with gas

You've MISSED THE POINT about 'the ability to do work'  and the radiant energy falling on a unit of 'surface'

'Work' includes heating your water...

I'm aware

 

But I've played with on demand water enough to know that the kind of heat in the video could easily be captured to keep my domestic hot water tank full of hot water, only needing a small pump to move it around and be heated as needed. Arduino and some sensors and stepper motors can control the lens quite easily.

The on demand hot water is what I thought when I saw this.

My heater heats roughly 50 deg water to 120deg , but if that initial water source water was say 80-100 the energy to heat to 120 would be less.

I'm using a propane water heater by the way so I don't think solar would help much for the water heater.

I've wondered about coils in a black box in a fulltime sun area to preheat in the summer.

In the winter here in the high desert it can get below zero and -20 sometimes and a box would be risky and not be worth heating itself to prevent freezing.

Interesting application the panel to direct rays and make such heat.

For me lately i've been cooking on the grill to cut down on indoor cooling cost.

With a setup like that I could bake me some brownies outside.And put some sunshine to good use.

Passive solar water heating is already routinely used in many applications, just by putting a heat exchanger on the roof, or a black painted water tank, or even just a run of black water piping.  The fresnel lens concentration isn't needed for that application, and would be less desirable because it can create dangerous, very high temperature hot spots, versus more moderately capturing and redirecting the heat.

Right ---

It boils down [no pun intended] to the surface area of the collector that determines how much heat that is collected...

It isn't a matter of how HOT

That is completely irrelevant



For example...

We designed this solar collector about 6 years ago and it will keep a 120 gallon tank of water from freezing all winter and provide warm water a decent part of the year.

It's located behind the south end of the shipping container we live in a lot of the time.

It collects a lot of HEAT because of the sun facing glass on the top and front

But doesn't get too HOT



Here's the front of it and the bear is chewing on some insulation we keep over the glass in the warmer months...

Just don't leave that thing leaned up against something outside, or even near a window.  Even smaller stuff like snow globes have started fires after sun came in the window before.

I guess where I was going with this was not using just one, but hundreds of these.  and a rigging of pipes all feeding heat to a central steam turbine.

Look up solar "power solar"

EDIT - I guess those towers are the bird friers - Oh well.

I remembered seeing a mirror field that focused on a single point once. I dont remember if it was a rendering or a photo. So I googled it and came up with this new electrical plant idea

http://www.drroyspencer.com/2013/06/update-on-enviromissions-arizona-solar-tower-project/

Solar updraft chimneys or towers have a long historical precedent.

The  ancients used them to create a cooling draft through their 'buildings'

I built one of these things.  It is crazy powerful.  Like, dangerous



It will instantly ignite a 2x4 when brought into the focal plane.



I tried making a stand for my "stuff to be burninated" out of a concrete patio brick, but the heat will boil the concrete.  Like magma.





I may have set the yard on fire once or twice

And that kind of power can't keep my hot water heater hot?



 

Rat- do you have a physics text?


Look up the difference between HOT

And watt/hours/joules of HEAT ENERGY


OR

Think about VOLTAGE AND CURRENT...


Static electricity has high voltage but little CURRENT

Ergo--- can do LITTLE WORK


The Fresnel lens is sorta like that

Big hat -no snap...

I see what you did there.

Can a plasma cutter keep your hot water heater hot?  No - it's too concentrated, meaning it cuts through the tank instead of transferring its thermal energy to the water THROUGH the tank by conduction.  Same for a welding torch - yet the same amount of heat energy, applied at a lower temperature, like a burner/spreader, does the job quite nicely and much more safely.

Yeah, heating water is pretty straightforward.

I want to make ICE with the sun.

One day I might know enough to make one of these babies,
http://www.free-energy-info.com/P13.pdf
He claims he can make 20lbs of ICE per cycle.

See Also: Crosley Icyball.

ancient technology today.

A copper plate thick enough, or just a thick enough copper tank, insulated elsewhere with that focus on it could indeed heat the water.

 

It's not as simple as "it's so hot it will burn through".  If you do reasonable heating by using a lesser focused area, and then insulate the tank you could do some good heating.


Of course,  you have clouds, night time, etc. as the usual drawbacks of using solar anything.

This has me wondering about bodies of water, such as a pool or pond. maybe something like this aimed at a black or dark rock underwater can heat the water up. The water circulation would keep the rock from melting as well as disperse the heat and the rock can keep the light from causing any damage to other structures. would that work?

There seems to be a lot of mis-understanding in this topic...


Confusion over HEAT vs. TEMPERATURE ---They are NOT the same thing...  

You can have a target that is very high in temperature, with very little HEAT ENERGY [equivalent/watts] applied...  The filament in a tiny incandescent lamp [Christmas tree bulb] , for example

The high temperature isn't going to heat much water for your shower...  



To prevent "spot melting" simply reduce the focus of the light to a larger area... Not much, so the 'heat' is distributed over a larger 'heat sink' THE SAME AMT of heat will be collected...

The same amount of HEAT will be collected by the target.


This leads to what seems to be the greatest misunderstanding...

The Surface Area of the Collector --whether it be a Fresnel lens or the window of a roof mounted solar water heater --determines  the amount of Heat Energy collected...


A 2 foot by 2 foot area for the sun to shine on, will collect the same heat energy by a Fresnel lens or a sheet of cardboard...

In the case of the Fresnel lens, the heat can be concentrated on a smaller area, depending on how far from the focal point the target is located...

If the target is at the optimum point for max rise in temperature, its ability to do 'work' i.e., make hot water for your shower...

Is the same as if the water were heated by a roof solar collector of the same 'aperture' as the Fresnel lens...


As far as heating a rock under water, the sun's radiant energy will be quickly absorbed in the first short distance as the light penetrates...


A Fresnel lens is not some magical device that somehow multiples the actual energy that it collects over it's frontal surface area...

Laws of SIMPLE physics still apply to Fresnel lenses

Unfortunately...

I've got a lens that focuses it's beam on about a half inch little circle.

It will melt a penny into slag in about 20 seconds in the mid-day sun.