“Stacking a bunch of plants on top of each other cannot change that the lower plants must receive less power, and therefore cannot grow as much“
That assumes all light comes from straight up. That isn’t even true if the sun is straight overhead, and definitely not true close to the poles.
I don’t know whether it’s profitable, but I would think the economics of vertical farming on Iceland (sun lower in the sky, greenhouse heating cheap, imports expensive) are different from those in Equatorial Guinea.
No, it assumes that power is delivered based on surface area with respect to the sun. Vertical/3d farming can't work more than ~2 plants deep, where "depth" is measured as the number of plants between a given plant and the sun. Sure, build it vertically on the north pole, but it's still gonna be essentially "flat". You can't magically get power deep into a 3D farm when there 20 other plants on every side that would get the light first.
I have never heard anyone suggesting that vertical farms enabled 3d planting. It simply removes the linear relationship between square foot of land and number of plants.
That assumes all light comes from straight up. That isn’t even true if the sun is straight overhead, and definitely not true close to the poles.
I don’t know whether it’s profitable, but I would think the economics of vertical farming on Iceland (sun lower in the sky, greenhouse heating cheap, imports expensive) are different from those in Equatorial Guinea.