Water activated light...no more batteries

[Nink]

Hi Brad,

The 72% efficiency is a combined result of the solar cell and concentrated heat usage at the same time, see this description from 2010:
http://www.greenoptimistic.com/zenithsolar-z20-chp-efficiency-20101020/#.VrywO0CnwqQ
A video from ZenithSolar of Israel:
https://www.youtube.com/watch?v=4izFzVCzx6A

Here is a system that concentrate sunlight by mirrors to get 72% efficiency:
https://www.youtube.com/watch?v=8M-wHBDes-8

Of course, concentrated sunlight by mirrors has the issue of heating up the solar cells, so they need cooling.

Here is an 'official' chart (i.e. confirmed) on solar cell efficiencies to date, (no sunlight concentration),  see the chart in this link:
http://phys.org/news/2016-02-solar-cell-efficiency-nrel.html 

And news on achieving 46% efficiency (direct conversion of sunlight to electricity) by multi-junction cells (this result is included in the above chart):
https://www.ise.fraunhofer.de/en/press-and-media/press-releases/press-releases-2014/new-world-record-for-solar-cell-efficiency-at-46-percent

Gyula

80% http://www.computerworld.com/article/2487947/emerging-technology/ibm-solar-energy-tech-claims-to-harness-power-of-2-000-suns.html
but has to be constantly water cooled.  Ideal for situations like water pumps etc.   

[sm0ky2]

Basically, the new industry standard is to combine the Archimedes "Solar Death Ray", with the conventional solar PV cell.
This allows for a much greater light concentration per ^2 area. Thus an increase in performance of each cell in the plant.
also, they have to buy less cells to gather the same amount of sunlight. = lower cost per watt.
Heat is discussed primarily as a "problem", but some intuitive minds are seeing it as an additional energy benefit.

All of these efficiency %'s are based on a theoretical value of the amount of energy coming from the sun,
were we able to harness 100% of it. It is based on the ^2 area perpendicular to the sunlight.
of course higher altitudes get more sun, but there is a standard at sea level.

Our estimate of this value is based on a limited set of data, which we know not to be consistent.
Thus the value is an average Watts per square meter, and admittedly there can be errors in instantaneous power levels
ranging to the order of 3 magnitudes.

so, % efficiency of a solar conversion system, is essentially an arbitrary rating based on the amount of power one can obtain from a solar-based system, given a set ^2 area of land.

[sm0ky2]

Hi smoKy2
You are right that a combination of any of those two elements and salt water is a battery. This technology is not a battery so to speak except you will consume the anode. It is more like a fuel cell technology and consumes oxygen. The problem with just using two dissimilar metals (which works fine) is energy density. Try an experiment where you put a piece of carbon and say magnesium in salt water. measure the amps across (short) You will see it is high at first then drops to around 20 or 30% of the initial measurement.  The difference with this it will climb much higher with the same piece of metal (whatever you choose for the anode ) and climb to a level many times higher than a  traditional battery.
It is still based on old and well known technology. Thanks for the information
Kind Regards
Mark

Thanks for the clarity Mark.
So your system is not based on the same principal as the saltwater car in the video I posted?

Does oxygen need to be supplied into your system, to sustain the electrolytic decomposition of the metal?
And does this process build-up oxide deposits on the cathode?

[hartiberlin]

Many thanks to Mark Dansie by bringing this finally to the market.
I guess their new Website URL had not been posted here,
so here it is:
http://www.hydra-light.com/

I think this is also an metal-air battery so the graphite plates have to be able to breath air, that is Oxygen...
as Oxygen is needed to be converted at the graphite electrode to go into ions to decompose and magnesium alloy
and to produce current...
So if other persons try to replicate this, make sure your graphite plates are not always under
water or fully inside the electrolyte bath, cause otherwise they can not "breath" air and thus they only can convert the air, that was stored in the graphite matrix, before they were put into the saltwater....
I also always wondered myself earlier, why my saltwater cells became more and more weaker, when I realized
that the graphite electrodes can not breath any air anymore, when they are almpst completely inside the saltwater...
So the best thing would be to put these graphite plates on one side as the wall of the container and with the other side in contact with the electrolyte,
so on the one side they can fully "breath" the air and at the other side are fully immersed into the saltwater electrolyte...
It seems they have exactly done this as you can see here:
http://www.hydra-light.com/#!technology/c24vq

Especially seen in this great picture:
https://static.wixstatic.com/media/4b4cbd_bc14c62da3a5423d9f92d4e3f7e83c26.png
The graphite plate seems to breat air from the other side not beeing in the saltwarer electrolyte...
Well Done Mark Dansie and Team !

Regards, Stefan

[hartiberlin]

Here is still another shot of the cell case:
https://static.wixstatic.com/media/4b4cbd_07d07ccd9e104a3f95bbbc9248c6687d.jpg
where you can see, that the graphite plate will seal the electrolyte container with one of its sides.

I wonder how leakproof is the graphite plate versus the saltwater electrolyte.
The graphite plate must be pressed probably pretty hard against the container, so no saltwater will spill
out... As Graphite plates are sometimes very soft material , I wonder how long these graphite plates
will last in this unit and don´t get clogged by Magnesiumchlorid saltes....I wonder how expensive will
be replacement graphite plates for it..
I also wonder what kind of ohmical resistance these graphite plates will have...
Does Hydra Light manufacture these plates themselve or are they being bought by a third party ?

Also one could probably easily substitute the magnesium rod with a piece of aluminium foil
rolled up and put in there instead of the Magnesium rod... okay, you will only
have then around 1.2 volts with saltwater, but if you take Sodiumcarbonate-water  or Firewood-Ash-water as the electrolyte,
you will also get around 1.5 Volts as in the Magnesium case... so you could save a bit of money and
use your used up coke cans ( Aluminium-Metal) or alufoil to power this lamp...so you spare the 4 US$ for the magnesium rods...

Regards, Stefan.