Solar efficiencies, photosynthesis and photovoltaic

That is where I am, comparing solar conversion efficiencies, especially the prospect of artificial photosynthesis.

So far I find that iridium is big, iridium is you can use it in either artificial algae or voltaic will use up a great deal more sunlight than either natural green or silicon. Its a race, which approach gets iridium into the mix sooner. Except:

Iridium is one of the rarest elements in the Earth's crust, with annual production and consumption of only three tonnes. Wiki

But, absent a solar fix, our algae may be limits to 250 watt/sq meter. Stay tuned, I am still the human search engine.