I have gone back and forth on vertical farming. There are scams in the field, but there are also some merits (most of them apply to urban farming in general).

The main issue you have with vertical farming is that there is only so much stacking you can do before you get out of light. A pillar like in the illustration projects a shadow, in which you can't really put plants.

However right now sunlight is not the limiting factor for plants growth. IIRC depending on the plant it is either water or CO2 so you can do some amount of vertical farming. To me, the interest is not to come as a replacement for regular farming (so growing grains is not the issue, you will have a hard time beating the efficiency of a flat field + tractor), the interests are:

• freshness. Having herbs that you can cut as you need them is really a taste changer.
• air cleaning. Some plants do have the ability to fixate some VOCs.
• less transportation. Having the plants grown in the same building block means that the CO2 footprint will be much lower
• more efficient water usage. Careful with this one, in some places water will be more scarce in city than countryside, but water consumption of such systems is generally lower.
• less refrigeration. If the food has less transportation it also requires less refrigeration
• local fruits all year long. Assuming they are put in a controlled environment like a greenhouse, getting food that normally requires a lot of transportation locally becomes possible.

So to sum up, it is less of a solution to make regular agriculture sustainable and more to make sustainable agriculture more enjoyable. Actually one does not need tasty herbs and exotic fruits, but the ability t have them without poisoning the planet is nice and, well, solarpunk.

So I am currently switching careers into vertical farming and have done a lot of work and research on this subject and here is just a bit of my 2 cents.

• Vertical farming can be less water intensive then traditional farming. Combined with an aquaculture system it can have negligible to no water loss which is great for arid climates.
• Hydroponic/Aquaponic systems have a huge upfront cost yet a comparably negligible year over year cost.
• This method has proven perfect for growing certain fruits, vegitables and leafy greens however has shown so far that its not the best for growing things like fruiting trees or staple crops like corn/wheat.
• Financing for vertical farms are virtually non-existant. So generally you have to go to private equity for financing. This is a problem as vertical farms are not the most profitable even after recovering $$ from upfront startup costs.

So it has great potential to seriously change our current food system and allow us to keep producing food in spite of drought. However it has a long way to go as a technology and will need serious federal legislation to create financing programs for this method of agriculture so farmers are not saddled with insane debt and growth projections that they will never be able to meet.

Honestly, this seems like a solution looking for a problem. We already have a lot of agricultural space available and in use. We just use that space very inefficiently to actually produce food. There are huge benefits to be gained from switching to sustainable farming, and probably a largely vegan diet too (just based on Ressource use alone). Once farming is focused on producing food and preserving nature, instead of creating profit we can look to further improvements. Even hydroponics or mixed use gardens are likely a better next step here. There simply isn't a need to cram our food production onto a wall yet, especially if that requires costly infrastructure made of difficult to recycle materials.

I think it's a good way to grow specialty crops (berries etc), and a great idea in space limited countries (Singapore mentioned).

I also think the inputs are pretty big, but you can control things better.

I don't think it's the solution to our food issues, but I think it can be used to build robustness into our system and decrease chemical inputs (mostly)

I think space efficiency is not really a big factor. As others have said, every tower casts a shadow, so the sunlight is not being used.

However, it is good for indoor planting, because under a roof, space efficiency is necessary. So, we could have some sort of climate controlled greenhouses, and they would surround a vertical farm. The greenhouse "shadow" would be outside, and it means your plants are safely indoors, protected from heat and cold.

I think even more important than saving space is making the food more local so they don't need to be shipped so far.

We misuse/underutilize a lot of the farm land we already have. I dont think the issue is lack of space.

I actually did a big project on this and we basically found that for people in flats wanting to grow small plants they're amazing, but there's very little point for actual farming

This is a hard one for me because I love technology and especially plant-related technology. However, I'm also a big advocate of appropriate technology. Vertical farming seems, to me, to be a niche technology, not a total solution. Vertical will be a part of total food production, but only for specific crops in specific circumstances.

A crop needs to have certain properties to be a candidate for vertical. I've seen close up two examples of crops that seem very well suited to vertical: leafy greens (with numerous exceptions and caveats) and saffron. Peppers and tomatoes and other watery fruit crops are also good candidates.

Leafy greens fit the profile for a crop that is better to grow near to the consumer, for reasons of wastage. The really savvy lettuce growers have coupled their indoor facility design with plant breeding programs to optimize the plant for indoor conditions and even improve the nutritional value of the greens. The potential for optimizing the crop is immense. Being such a uniform product, efficiency gains from automation are already possible, too.

Saffron is a very high value spice produced from the male flower parts of a crocus. There is now commercial production of saffron in vertical farms. Individual crocus plants are very short, so the planting density is very high, because the shelves can be very close together and still be reachable by workers. Saffron is almost the opposite of leafy greens as a crop. It is value-dense (about $50 an ounce) and nutrient-dense. It also has a longer shelf life and is vastly more economical to ship.

Vertical farming is inherently capital intensive. Each crop is somewhat unique, enough so that a dedicated R&D effort is required for every new crop. Once some of these early ventures weather the current capital drought and the whole capital lifecycle of vertical farming is better understood, I hope to see continued capital investment bringing a greater variety of crops to vertical production.

We already know so much about how to make good soil and farm outside well and sustainably. There's still a role for concentrated capital in dirt farming, too. I'm most familiar with the case of automation in farming, like laser weeders. For us to make real progress in improving dirt farming, the innovations will need to be social and political, a much harder row to hoe.

It got a bit of a bad rep lately because of some venture capital funded start ups trying to dominate the space, but in general the technology has its niche for growing easily perishable vegetables near or inside population centres.

we already produce enough food to feed the entire planet (industrial food waste seriously hampers that effort) – add in several claims that US could double food production just by breaking up factory farms and converting to family farms

one of the solarpunk short stories (forget which collection) posited a competition set up on separate islands, one group with industrial farming, one group with permaculture, one group with vertical farming – obviously for the story, the permaculture group did best (worked with what was in place and what actually grew there), industrial farming required too much input (importing expensive fertilizers, pesticides, herbicides), and vertical farming required too much technical maintenance

the technical aspect is what I see as the biggest issue – I could see vertical farming being a great solution in a sterile environment (ie. a space station or an arctic greenhouse), but in everyday practice having a stable power supply for water pumps and constant maintenance (clogging from nutrients and fertilizers, filtering hard water to prevent calcium build up, roots binding up emitters) and having to compensate for the lack of soil microbiology would all take its toll

We're doing some vertical farming in our backyard. I think it's a good way of moving food production more locally to urban centers and reducing transport costs (and thereby related emissions). I don't think they're the solution for everything, and I do think using our current farmlands more efficiently is critical. In certain ways, I think vertical farming might be able to provide some of the improved green spaces in urban areas that Garden Cities were meant to before it turned out that Garden Cities deepened the divides between classes and races in urban centers.

Overall, I think we need not think of vertical farming as "How do we solve the food crisis" and instead as "How do we provide people without land the opportunity to experience the joys of gardening their own food"

Agricultural researcher here, working in this field (hydroponics, aquaponics, vertical farming) for approx nine years.

Here is my TLDR:

1. The comparison "traditional agriculture vs vertical farming" is misleading. Water saving and many other benefits come from hydroponics and crop protection (CEA - Controlled Environment Agriculture aka greenhouse). So a more accurate comparison has to be "CEA vs vertical farming".

2. Plants consume light. Seven photons for one photosynthesis reaction (one sugar molecule). One Mol photons (or more) for one gram dry biomass. Artificial light is very space inefficient compared to just using natural light for the plants. 23% efficiency for photovoltaic cells, 50% efficiency for LED light and some losses for transformation and transportation of electricity. In total when lighting the growbeds with electricity from photovoltaics for each square meter of growbed, ten square meters of PV-modules is needed somewhere else. I fail to see the space efficiency argument of vertical farming unless we are using nuclear for generating the electricity. Total efficiency losses of artificial lighting are >80% compared to using natural light, leading to a huge carbon contribution. This alone is not sustainable.

3. In CEA, and thus in vertical farming also, we are mainly producing leafy greens, herbs and other vegetables. This is known as horticulture. Taking a look at statistics of the products of agriculture it can easily be seen, that the staple crops, grains and tubers, are by far (!) the major products. These can not be replaced by CEA production. And these are actually supplying the calories to feed the people. The amounts of agricultural area dedicated to these crops dwarf the horticultural production.

My takeway: VF is by no means a solution of the challenges we are facing in agriculture. Energy demand of the plants for lighting can not be optimized away, and thus will remain a major cost driver. IMHO the vertical farming industry is creating a hype aiming to harvest and burn venture capital. Recently Aerofarm filed for chapter 11 and also the company Infarm is broke. These were the poster childs of this industry.

Except for very specific niche applications to me VF does not make sense.

Looks like a lot of plastic.

I would vote for more efficient means by removing highly inefficient food "production" - aka meat. That would free up a lot of potential. Vertical farming can probably be used sustainably in some cases but I feel it should not be used on a bigger scale.

I don't know about grains, the examples I've seen so far are all growing green leafy vegetables.

Ask me again in 5 years, here in Singapore we're trying to start it up in a big way.

Looks like a lot of plastic.

Yeah so much amazing potential, I've working on some ideas for a semi automated wall system, the idea is you have rows that are basically rails and you slide a pod in with seeds one side and take out the top one to harvest and reseed - the unit has a glass front so it's like a thin greenhouse, provides a little extra insulation and protection for the house as well as using the escaping heat in winter to keep the plants a little warmer, probably not ideal for a hot climate but somewhere like the UK it would be perfect.

It would be for things like leaf greens, maybe radish, short carrots, or other quick growing veg that would be good to have on a continuous cycle. I want it to have a single place to put water in and possibly a tap connection or tank so people can pretty much fill and forget - the glass should keep it safe from burgling little birdies that like to sneak into greenhouses and eat all the shoots, as well as other pests.

For the test ones I'm going to build I got some big bits of perspex used as COVID screens that shops were going to bin, well worth looking out for as such a waste otherwise. I made some clay from a hole I dug in my garden so would love to make a lot of it from earthenware, if I can get some good designs I'd love to make 3d printable molds. It's energy intensive firing ceramics but I saw some amazing solar concentrater kilns which would be great for a small collective or something making something similar.

it works pretty well for some kinds of produce - bushes/lettuce, fungus, root vegetables, etc but fails for other things (tree nuts, fruit, corn/grain, etc).

the benefit is that you can use existing infrastructure like high density residential/skyscraper buildings so there's potentially less distance between farm & table

Love it, but it has pretty niche utility.

It's great for improving frest fruit/vegetable access in small urban communities, without massive transportation costs and preservative use.

Also very cool for small, isolated environments like ocean voyages and space, where production space is severely limited.

And extremely interesting from an ecological perspective when combined with a full circle microsystem, as in aquaculture.

But overall, it remains wildly inefficient for large scale agriculture needs.

Lower part of my garden receives less sunlight. So I will have to raise the bed up. My concern is not grains but vegetables and herbs. I don’t believe I can justify growing grains in the garden. What I have to experiment next season is if raising the whole table is better (more soil) or use stacking to raise the height(vertical farming).

It sounds like a good idea for the crops in which it can be a solution for. I was thinking of ordering my own vertical garden for mushroom variety.