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Comment by onlyrealcuzzo | Hacker News Reader

It takes 9 acres of solar panels to light 1 acre of vertical farm crops.

Theoretically, you could cover all of Nevada (~70M acres) & Arizona (~73M acres) with solar panels.

That would only give you enough vertical farm space for ~16M acres, and apparently the US only has ~10M acres for farmland for fruits & vegetables.

Point being - this seems implausible - and I'm not sure how you work around that.

IIUC, it takes about 1 acre to produce ~.12MW solar (obviously differs based on where the panels are). The world installed 168GW of solar in 2021 - so that's 1.4M acres of solar.

It'd take 100 years of solar production to cover that much area with solar panels.

And for what?

Cattle uses 4.5x more land by itself. We use 3x as much space to grow most of our calories (grains and oils) - replacing that with vertical farms seems like something from an alien civilization that is way to far away to imagine.

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Note that vertical farms have about 3-4x yield compared to an equal area of land. They also require significantly less pesticides, water, or fertilizers. Though currently they struggle with many types of vegetables.

3-4x yield for which crops exactly? They are only used for growing leafy greens and low volume high cost fruits such as strawberries. Do they produce 4x corn and soy? 4x potatoes?

The capital investment required to grow corn indoors would be enormous relative to the per bushel cost. I reckon the operational cost would even outweigh the revenue.

Average corn yields in Iowa were 205 bushels per acre in 2021. Let's say corn is $10 a bushel (trading around $7 on the spot market right now). So $2050 per acre for conventional ag.

Let's assume 4x yield for indoor production, so roughly 1000 bushels/acre. Or $10k per acre at $10.

I had trouble finding any good information on energy consumption in an indoor cropping system, but I'd bet lighting energy consumption would eat up the additional revenue from higher yields.

Edit: Please let me know if anyone has access to scientific literature/experience on indoor farming energy use, I'm genuinely interested to know

Perhaps you can collect light vertically as well? And deliver it to crops either via the conversion to electricity and back, or even by some sort of optical/waveguide/handwave thing?

There's only so much sunlight that reaches any point on the Earth throughout the day. You could build something really tall to collect more light from the sun at more angles, but that will cast a shadow and reduce what's available for other collectors. So you end up with a lot of collectors receiving little sunlight or fewer collectors spread far apart.

It is also unreasonable since there are better competitors like artificial starch synthesis where you can use bioreactors to produce starch directly from CO2 and electricity at 8 times the efficiency of corn. If you add artificial lighting then vertical farming is at least 16 times worse than artificial starch synthesis. The freed up land would allow us to then grow normal non nutrient dense food in its place instead which obsoletes the need for vertical farming.

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