[aeternum]

Are we all just ignoring that plants pull CO2 out of the air and produce usable energy in the process?

So clearly it is possible to do more efficiently.

[LinAGKar]

Plants aren't that efficient, there's just a lot of them. You could cover the requisite 764 GW with about 3000 km^2 of solar cells (assuming 250 W/m^2). That's a bit over the land area of Luxembourg. Minuscule compared to the amount of area on Earth taken up by plants, and sunlight that falls on those plants.