Here is a great reply from the Low-Tech Magazin.
this post was submitted on 27 Sep 2024
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I really do want to like the idea of vertical farms, and hydroponics in general as there are lots of benefits versus wild growing, but whenever I see some article claiming sustainability or a reduction in climate impact, it's total bullshit.
All of these systems require massive amounts of nutrients to keep the plants alive and producing, and that essentially means all kinds of mining. The byproducts of these facilities are also toxic, and there is no regulation about how they have to manage that...yet. Essentially they are just taking the farm runoff problem and moving it from rural areas where it's already bad, and transplanting it to denser urban areas.
If they could find better ways to streamline the acquisition of the fertilizer components needed for these facilities, and also the treatment or or disposal of the byproduct, these would be a much better idea.
Where I am from, farmland is cheap because of restrictions that prevent development or building on the land to preserve the areas ability to produce food.
But this doesn't prevent the building of greenhouses, since it's considered agriculture.
This results in many hundreds of acres of perfectly fine agricultural land being dug up and covered in gravel and concrete to build greenhouses.
It would be the same for vertical farms I imagine.
There's no reason it couldn't be a closed system, where any fertilizer that doesn't become part of the crop biomass is recycled. In theory it should be more sustainable than existing agriculture and use less fertilizer per kg of crop produced.
Could be, but isn't, which is where some regulations probably need to come in. I'm familiar with the systems Plenty uses, and it's all automated.
Prime > start > feed > dump once dead
I've not seen another of these large scale startups doing anything different as of yet, which does make sense cost-wise. Any crop you grow won't ever use an exact amount of nutrients at cycle end with a completely neutral byproduct, and trying to reuse what is left would require a lot of expensive lab efforts which they don't care to invest in.
Example: say you start with a 9N-12P-34K solution, and after a month it degrades to 0-0-12. You can't just refill the nutrients with that same mixture you started with, or you'll damage or risk killing the crop with too much Potassium. You'd need to analyze the loop nutrients to know what level you're at for each nutrient, and adjust to get the mixture right to recharge properly. Currently all these systems just dump and recharge because it's cheap (for now) and easy, but these high concentrations of the various components just end up saturating an area the same as farm runoff. Even if you filter, that filtered medium needs to go somewhere.
There are fancier methods of nutrient filtration extraction and recapture just starting to become more feasible, and we should be looking at making sure these are being used for these large operations.
Could be, but isn’t, which is where some regulations probably need to come in.
I assume also that the technological side of things as far from perfected, but that will improve over time.
I mean, an urban environment flushes tons of fertilizer down the drain every day...
Human waste is not suitable for fertilizer.
/nightsoil has entered the chat
You should probably look up how most of your rice and beans are grown overseas.
See my other replies to this person.
It's not about the feasibility, but about the suitability.
I think a lot of people saw Matt Damon growing potatoes in human shit and thought it was legit and not specific to non-earth soil.
Of course it is. Or do you really think, cow and pig manure is fundamentally different from our shit?
The only difference are some germs, but that can be handled - otherwise water treatment plants would cause epidemics downstream.
It most definitely is not.
https://www.fda.gov/media/117422/download https://en.m.wikipedia.org/wiki/Night_soil
I believe some small pilot programs in EU allowed specific types of TREATED sewage to be used, but that's a whole different thing.
So your argument against treated waste is, that it has to be treated first?
I certainly didn't create the FDA, USDA, or medical science. Doesn't have anything to do with me.
If you want to take a chance on it, go for it, but seems a lot of people who specialize in the field all say you're wrong.
No, and if you would actually read the sources or dare to think for a few seconds you'd see that.
Human waste is not spent uranium that kills for millions of years with no way to mitigate that. If that would be the case, we would literally be drowning in shit right now.
Human feces contain some bacteria that can be dangerous, but that can be dealt with - again, this is exactly what every water treatment plant is doing. What do you think happens with all our shit? Do you think we fling it into space?
I don't see how vertical farming can make sense. There is only so much sunlight striking the ground and you just changed the angle and so shaded something else.
Artificial lighting exists.
Let's assume the energy for lighting comes from solar. Panels are only 20% effective. Now your vertical farm needs 5x the space of a basic farm, and you still have to pay for power instead of using free sunlight. There is some video on YouTube from a salt lake city university professor who works for nasa on growing plants in space about this topic.
Consumer panels are up to 23.5% now, and you can get bifacial cells that can boost that by up to 30%, so up to around 30.55%
Also the light is bouncing around that room, not bouncing off and then back into the sky like it would from the sun, and it's not necessarily all full spectrum, it's the spectrums the plants need, also reducing power compared to what the sun gives it.
Edit: Making shit up now, but what if photosynthesis only needs 30% of the spectrum, and the bifacial panels are 30% it might even be near equal.
Sure, but where does the energy for that light come from? If the answer is burning things (this is the most likely answer today!) then you are making the world worse. Renewable answers all go back to the sun so why not use the sun directly and avoid all the inefficiencies from turning the sun into electric and then back into light? Which leaves nuclear - which is dieing because of expense.
Photosynthesis only uses a couple frequencies. Using solar to generate electricity and feed that into target LEDs can be significantly more efficient.
while not wrong solar does not use most of the sun either and what plants use is where a large part of the energy is. Plus your add in the rest of the inefficiencies of the grid. So I'm back to not seeing how this can be enough better.
i'm sure you can grow plants this way I just don't think you can ever make it a good way