4 ms·

I don't know who did the analysis on that, but this is easily fixed: Solar farming on top of the vertical farming. This pays for the electricity needs for the l

I don't know who did the analysis on that, but this is easily fixed: Solar farming on top of the vertical farming. This pays for the electricity needs for the lighting, and any excess power pays off the solar panel prices over about 8 years.

chipsa 6y ago
What excess power?
- coding123 6y ago
  Actually, you're probably right. However, in many markets you actually "make" more money by offsetting the price you would pay the utility. In my calculations, you get paid a fifth of the excess electricity than just using it (instead of paying the utility to use theirs). So when you're a heavy user, and you're in great solar area, every panel you add actually lowers your cost. So if you want, do a 4 acre solar farm for a 1 acre building, and over time this will pay for itself. Of course, this obviously depends on you making money on the wheat or other crops.
tlb 6y ago
The amount of energy you get from an acre of solar panels is approximately enough to run grow lamps for 1 acre of wheat. But not for 10 layers times 1 acre of wheat.
- qppo 6y ago
  Is that what it actually comes out to, accounting for the efficiency of current panels and what plants actually use in photosynthesis?
  - mlyle 6y ago
    Two main factors. First, plants lose about half the energy because of spectrum. There's lots of other losses (e.g. light falling on parts of the plant other than chloroplasts) but they apply to artificial light, too. And then, plants use only about 10% of the mid-day energy after all of these losses, because of saturation effects, but more the rest of the day-- we'll call it like 25% here. So that 50% factor and 25% factors multiplied are what you can try to exceed == 12.5%. Cheap solar panels are about 15% efficient. So you're not going to beat direct sunlight by much.
  - imtringued 6y ago
    https://news.ycombinator.com/item?id=24093941 https://news.ycombinator.com/item?id=24093941 That comment is using numbers that are overly optimistic. Using 22% panels requires you to construct an unaffordable PV facility for $400 million for a single vertical farm. If you go with lower efficiency panels you might be able to make it cost effective but then you are also consuming more land than a conventional farm. There is also a mismatch in energy demand. Solar panels only work while the sun is up but the yield promises of vertical farms entirely depend on 24/7 lighting.
unchocked 6y ago
It's not easy at all when you think about the amount of light required vs. the surface area available. In fact, it's not even thermodynamically possible.
dehrmann 6y ago
Unless you're capturing lots of wavelengths plants can't use (definitely green, maybe IR?), why would you add an extra loss into the system?

chipsa 6y ago

What excess power?

coding123 6y ago
Actually, you're probably right. However, in many markets you actually "make" more money by offsetting the price you would pay the utility. In my calculations, you get paid a fifth of the excess electricity than just using it (instead of paying the utility to use theirs). So when you're a heavy user, and you're in great solar area, every panel you add actually lowers your cost. So if you want, do a 4 acre solar farm for a 1 acre building, and over time this will pay for itself. Of course, this obviously depends on you making money on the wheat or other crops.

tlb 6y ago

The amount of energy you get from an acre of solar panels is approximately enough to run grow lamps for 1 acre of wheat. But not for 10 layers times 1 acre of wheat.

qppo 6y ago
Is that what it actually comes out to, accounting for the efficiency of current panels and what plants actually use in photosynthesis?
- mlyle 6y ago
  Two main factors. First, plants lose about half the energy because of spectrum. There's lots of other losses (e.g. light falling on parts of the plant other than chloroplasts) but they apply to artificial light, too. And then, plants use only about 10% of the mid-day energy after all of these losses, because of saturation effects, but more the rest of the day-- we'll call it like 25% here. So that 50% factor and 25% factors multiplied are what you can try to exceed == 12.5%. Cheap solar panels are about 15% efficient. So you're not going to beat direct sunlight by much.
- imtringued 6y ago
  https://news.ycombinator.com/item?id=24093941 https://news.ycombinator.com/item?id=24093941 That comment is using numbers that are overly optimistic. Using 22% panels requires you to construct an unaffordable PV facility for $400 million for a single vertical farm. If you go with lower efficiency panels you might be able to make it cost effective but then you are also consuming more land than a conventional farm. There is also a mismatch in energy demand. Solar panels only work while the sun is up but the yield promises of vertical farms entirely depend on 24/7 lighting.

unchocked 6y ago

It's not easy at all when you think about the amount of light required vs. the surface area available. In fact, it's not even thermodynamically possible.

dehrmann 6y ago

Unless you're capturing lots of wavelengths plants can't use (definitely green, maybe IR?), why would you add an extra loss into the system?