Thermophotovoltaic Advances?? Anyone?

Probably not in your lifetime.....

Figure 1: Schematic of the proposed thermophotovoltaic cell. The receiver and the emitter layers of the intermediate are shown together with their idealized absorption spectrum (including the solar spectrum in yellow) and emission spectrum (the dotted line indicates the PV cell bandgap energy level), respectively.

..." The absorption and emission spectra of the intermediate can be manipulated to improve performance, limited by a theoretical efficiency maximum of 85% under direct illumination."...

http://web.stanford.edu/group/gcep/cgi-bin/gcep-research/all/ultra-high-efficiency-thermophotovoltaic-solar-cells-using-metallic-photonic-crystals-as-intermediate-absorber-and-emitter/

Now if we could build these for Radioisotope Power Conversion ie; atomic battery, then it wouldn't matter....you would probably only need to refuel once in your lifetime.....

https://en.wikipedia.org/wiki/Thermophotovoltaic

So this scheme could probably also be utilized with molten silicon as the emitting source?

silicon melt energy storage Australia company

this is what I refer to

3Drectenna could eventually reach 90% conversion

This seems pretty new, with single wavelength efficiency up to 90% (projected). The 3D rectenna can be tuned to various wavelengths. They are still working on the impedance matching of the nanotube-oxide-metal interface.

One technique to boost efficiency is to enclose the thermal emitter in an optical cavity so that the unabsorbed photons can be "reused".

http://www.johnholzrichter.com/lib/literature/TPV-Lecture-6-2016.pdf

What happens when photons are almost spent? Is there such thing as counting photons? Can we count them?

PMTs have facilitated counting individual photons since Christ was a colonel, but why would you count them in this context? For what purpose?

When I see arrows, I just think it can be counted.

Where would photons go when it is spent?

Photon Heaven, of course.

Most of the photons that are not converted to electricity are reflected back into the cavity and ultimately reabsorbed, increasing the temperature by a minute amount. Some are absorbed by the mirror and the energy eventually radiated to the outside. But most of the unconverted photons are reflected back causing the temperature to rise. The hotter the interior of the cavity, the higher the average photon energy and the better the chances that new, higher-energy, shorter-wavelength photons will become available to be converted to electricity. At some point the system will come to thermal equilibrium when the energy emitted by the source equals the energy lost by all the processes involved, and the cavity temperature will stabilise.

How does a photon react when he meet an electron? How did they move electrons given they must be dancing in different bandwidths? Aha, they might be interacting in beats and impulses, I guess. But I don't know the theory really. I pressumed the interaction might not ge electromagnetic. Who knows?

You could always read Einstein's 1905 paper and maybe find out a little something.

That is a good idea. I saw something akin to that in discussion of molten silicon energy storage. Basically they used dichroic mirrors to selectively pass band of interest to the TPV cells, these tuned to a narrow band, so that unusable portions of spectrum were routed back to the molten silicon (thus de-coupling energy losses). I am sure a lot more remains to be worked out for a high range efficiency device to be available.

I wonder why the green wavelength of light spectrum is not absorb by plants, but businessmen do.

Are you sure 75%? Is this a realistic figure?

Sunlight peaks in the green region (480-520 nm wavelength), so why don't they absorb light in this region of the spectrum, given that it is so abundant? Turns out chlorophyll-a and other pigments are easily destroyed by too much energy, and when the pigments break down and stop absorbing light entering the plant, that energy can cause damage to other plant tissues as well, including the plants' DNA. Think of it as a sort of plant sunburn. Plants have elaborate mechanisms to repair DNA that has been damaged by too much sun energy, but these repair mechanisms are costly, and require extra nutrients. A plant that is stressed by too little nutrients or too little water can die from excess sun exposure. Plants have adapted to balance their need for the suns energy with their need to protect themselves from sun damage by using regions of the spectrum that are not as abundant. In general, light absorbed in the blue region is used for plant growth and light absorbed in the red and far red regions are used as cues for flowering or orienting (that is, bending leaves and stems toward or away from light, growing tall to escape shading in a forest, etc). This is why so-called 'grow lamps' emit primarily in the red and blue parts of the visible-light spectrum.

Not enough prefixes yet. Add some more bingo buzzwords like nano, graphene, and quantum--and then you will really be talking turkey.