The other thing to remember is that there is a lot of land that isn't suitable for farming for one reason or another that can be used for solar.
Global Warming may actually open areas previously unsuited for certain crops; evidence pointed to much warmer climates in Europe with grapes further North in mans short existence, and the impact on existing uses is not fully understood.
The simple fact is, every time someone suggest were are running out of food or have too many people or water is not wet anymore we find out that it simply is because we don't look further than we are standing.
The biggest reason people starve today is repressive governments that respect neither the person or private property. that one percent, the ruling elite of the world, loses its grip in highly informed, rights driven parts of the world but they sure do fight to keep the pie to themselves even there.
And there are many other renewal energy sources.
Like geothermal power in some areas or water (fall or tide) based power in other areas.
And you can put this power sources in a lot of places which are fully unusable for farming.
We're talking about powering a hydroponic greenhouse. The alternative to "Solar Powered LEDs" isn't "plant things in the ground". Its "make a glass window on your roof".
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"Plant things in the ground" is also cheaper, though it does suffer from potentially poor soil conditions. Still, it seems to me that spreading fertilizer across soil (and conditioning the soil into a growable state) would be cheaper and easier than making large-scale indoor hydroponics.
> We're talking about powering a hydroponic greenhouse. The alternative to "Solar Powered LEDs" isn't "plant things in the ground". Its "make a glass window on your roof".
I think what they were getting at is that you can take land wholly unsuitable for farming or greenhouses (e.g. severe slopes), apply solar panels, and then funnel that energy to a vertical farm. Since the vertical farm does save space in the abstract (just not necessarily once accounting for space needed for electricity generation), the scheme overall is still a more efficient use of land.
I severely doubt that.
Solar panels are maybe 30% efficient. So 10-acres of glass-roofs need to be replaced by 30-acres of solar panels just to account for this inefficiency (let alone other inefficiencies: such as wiring, inverter, batteries, and LEDs). Maybe 50-acres of solar panels to be anywhere close to comparable against 10-acres of glass roofs once we include other inefficiencies.
Not remotely. Plants are also extremely inefficient, converting only about 1% of the solar energy that falls for their use. [1]
Most of this inefficiency is from solar energy being in the form of frequencies that the plants can't use, but solar panels can. So the panels can capture this energy, then funnel into the red and orange lights that are most efficient for plant growth.
I've read a bunch on this, and haven't been able to find an authoritative source for what the efficiency conversion is -- how many acres of solar panels power how many acres of vegetables, and is it greater or less than 1:1? -- but it's certainly not as simplistic as "solar would need 3x more land because they are 30% efficient."
1. https://phys.org/news/2012-01-energy-conversion-solar-cells....
That implies a 5% efficiency in the "total solar captured area" of the solar panel + LED lights compared to just sticking the plats out in the sun, which is totally independent of the plants own efficiency in photosynthesis.
(I guess coming from a site about Low Tech, their slant on the numbers might be questioned, but they certainly hold up to initial scrutiny from here...)
I own a townhome, so my only real ability to grow plants is through a grow-light connected to electricity.
As such, I've spent some time calculating the PAR values of a decent grow-light, as well as the amount of PAR that natural sunlight gives. Plants need a ludicrous amount of PAR (basically blue + red lights, green not needed cause green just bounces off of plants).
Sunlight is mostly broad spectrum: broader than plants need and therefore a source of inefficiency (green light is wasted) that LEDs can somewhat replace.
Grow-lights have a benefit that they can be placed very close to the plant (maybe just 1-foot away) to "focus" the energy a bit better. Nonetheless, the amount of PAR / PPFD from a typical day sun (or even a cloudy day) far exceeds what you'd get from 500W or even 2000W grow lights.
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Its just a hobby of mine, and I'm not growing anything especially hard (just Basil, which is really easy to grow... but Basil is a summer plant that really wants sunlight).
Still, once you start calculating PAR and actually mapping out how much electricity your "emulated sunlight" needs, you'll realize how grossly inefficient that "solar panel -> electricity -> LED" plan really is.
EDIT: Natural sun is like 2000 PPFD or something FAR in excess of what most plants need. Still, a good growlight solution might hit ~1000 PPFD constantly. Lets take this 650W LED and think about it: https://allgreenhydroponics.com/collections/american-made-le...
You'll get ~500 to ~1000 PPFD across a 4'x4' or 16-square foot area from that 650W LED (and most of that light is focused on the center: you'll want to overlap your lights a bit for more consistency).
Then think about how much solar panels you need to power a 650W LED for the 16-hours / day your typical plant would want (to account for the lesser PPFD indoor plants get, you run the lights for a bit longer than sunrise-sunset).
Just some napkin math. Nothing serious here: just guestimating the area in my head.
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EDIT: Now it should be noted: I've heard of good hydroponic greenhouses that have the "do both" approach: glass roofs to let the sun in most of the time, and LEDs to augment the natural sun (cloudy / rainy days, as well as winter-settings when you have fewer hours of sun). The sun isn't nearly as consistent as we'd like, but... that means that you need something aside from solar power powering those LEDs.
But the concept of building a all-LED underground (or "inside a building") without any natural light just... seems grossly inefficient to me. Such a setup only seems useful to those growing contraband IMO.
I was an engineer at a company called Heliospectra, we specialized in this and I personally built systems that on an industrial scale enabled above light/environment control down to umol of individual wavelengths every minute based on variables such as sensor feedback, algorithms for specific types of plants and traits as well as learning to adapt based on the environmental daily patterns from sensor feedback over time. It was actually quite fun to work on, I do still keep in contact with the company.
"Poor soil conditions" to include "soil" that is alkali dust, sand, dry for eleven months out of the year, frozen solid and under multiple feet of snow for more than half the year, and so far from either a river or reliable groundwater that any and all water used must be trucked in. In tanks. On trucks.
Plus, you only get to dump more fertilizer in the water if you filter it back out again.
Doesn't work as you can't stack plants with it nor can you grow them underground.
Do you mind if I ask why you're so against the idea?
Because it is clearly inefficient to convert sunlight -> electricity -> simulated sunlight.
You could also store it in or orbiting in a black hole, but good luck getting it back in its original form! https://en.wikipedia.org/wiki/Photon_sphere
If you were to use solar, then you'd need a country that has a lot of land that would be better used on solar panels rather than farmland, so maybe one that is mostly tundras or deserts.
But you need to remember that there are real costs to industrial farming on land. The use of pesticides, fertilizers and topsoil loss. There are a lot of benefits to vertical farming if it can be made to work economically.
IMHO a key point of the article is that solar is not really a suitable source of electricity for vertical farming. There are other sources of clean electricity that more suitable in order to reap the benefits of vertical farming (less transport and less use of land, and also less water and pesticides).
A while back I saw a plan for a greenhouse that used solar desalination to provide water for plants but don't know if was ever built
edit: Looks like they exist https://www.researchgate.net/figure/The-seawater-greenhouse-...
Not a rhetorical question, I genuinely don’t know. I assume it varies by desert, but farming and power are both way out of my domain.
So the question is whether a greenhouse/farm in the desert is easier than solar in the desert connected through grid to vertical farm somewhere else.
I have no data. My guess is the ongoing logistics of piping electricity out of the desert is easier than fertiliser into the desert and produce out to where people live.
https://assets-global.website-files.com/5ef8b3d80f5e290ff335...
Not "per se" a knock against greenhouses, but definitely one of the things you're looking for is a closed system rather than the sort of greenhouse you'd get in many places in America, where it's just a robust plastic tent-on-a-concrete-slab, and they don't care much if the water runs off. In a desert you'd be really concerned about making sure the whole works has very, very low water-losses.
The key thing to make this useful is to conceptualize it not as the sort of area, like the Nile, where they've already got an ample water supply. To make this useful, it's best to think of something where there's basically no water supply at all, and we're trying to crack the problem of "okay, how could we grow crops here?" Something that right now, is just bone-dry barren desert. Most of the solutions we rely on in the wetter world just don't really care much about water loss.
Something that could fit the definition of a greenhouse, with windowed ceilings, might well be a viable solution. But I do suspect there's some correlation between making a grow site more bunker-like and lowering water loss (especially if it's recessed into the earth).
The other huge upside of a truly sealed system is it's another approach to pest control. Sealing the system could potentially completely eliminate the need for pesticides and herbicides. Right now those have huge negative externalities.