Vertical farms offer a bright future for hungry cities

Jul 21, 2014 by Tim Heath
Vertical farms: coming to a street near you? Credit: Matthew Humphreys, University of Nottingham

The 21st century has seen rapid urbanisation and the global population is now expected to grow to more than 8.3 billion by 2050. Currently, 800m hectares – 38% of the earth's land surface – is farmed and we'll soon need to give over another 100m hectares if we continue to use current agricultural methods. That's not additional fertile land that actually exists though, so some are investigating the potential of vertical farming.

It has been suggested that a 30 storey 27,800,000 m2 vertical could be achieved within one New York City block. That farm could feed 50,000 people, providing 2,000 calories for every person each day. With results like that as a prospect, it's easy to see why enthusiasts see vertical farms as the future.

Growing up

Vertical farms are still very much at the conceptual stage. The idea is to cultivate crops on multiple levels within high-rise buildings in urban areas. It's not an entirely new proposition, with architect Ken Yeang suggesting a vision of high-rise plant cultivation in mixed-use skyscrapers as early as the 1980s. Professor Dickson Despommier, the leading international advocate of vertical farms, describes them as "a global solution" to the world's urban food needs.

Vertical farms do indeed have many advantages. They would enable us to produce crops all year round using 70% less water. We wouldn't need to use agro-chemicals and could avoid the adverse environmental factors that affect yield and quality in more traditional farming. And if food were grown in urban areas in the first place, we could eliminate the financial and environmental costs of importing food into towns and cities.

Section through a proposed vertical farm. Credit: Matthew Humphreys, University of Nottingham

Growing pains

In some respects, farming is now a practical possibility. The technology it requires, in terms of plant growth and construction, are available. We can already cultivate plants without soil and recycle the water used to deliver clean indoor farming, for example. Hydroponics, where plant roots are grown in nutrients dissolved in water, is one option. This plant-growing technique can be combined with traditional aquaculture to raise fish or prawns – a farming technique known as aquaponics. Another way to grow plants is aeroponics, which involves growing suspended plants by spraying the roots with a nutrient-rich water solution.

But even though it has been more than than 20 years since the concept was first proposed and the pressure of climate change continues to mount, vertical farming is still not a reality. The two biggest problems have been financial and technological viability, particularly when it comes to actually building these high-rise spaces.

Vertical farms need contemporary building materials and renewable energy systems. Sunlight reflecting and collecting devices such as light shelves, light pipes and fibre optics can deliver natural light deep into buildings to provide energy for photosynthesis.

The development of LED makes it possible for a vertical farm to operate without the need for sunlight but the cost and energy consumption are currently prohibitive. The initial cost could easily be more than $100m for a 60-hectare vertical farm, which makes it unrealistic at the moment. But this could change as the price should drop rapidly as the technology develops. The obvious solution is to integrate natural light where conditions are suitable and LED in other parts of the building.

Inside a proposed vertical farm. Credit: University of Nottingham

In the meantime, investors are likely to stay away. Vertical farms integrate advanced technologies and need to be relatively large-scale if they are to yield attractive results. It has been estimated that the return on investment for a 10-storey vertical farm would be be approximately 8%, whereas investors typically seek a minimum rate of return of 10-12%. And since there are risks involved in developing a new type of building, investors are realistically more likely to want an annual return of around 15%. Again though, economic viability will undoubtedly come with technological improvements.

Making it happen

Progress is being made towards resolving all these issues so the next step will really be to get a prototype up and running in an urban location. What few small-scale prototypes exist in the world are based mainly in research institutions. To be sure that the technique can work, we'll need to construct a high-rise structure in a more realistic environment. If it works, it could spark follow up projects.

To make vertical farming a reality, we need the support of governments and pioneering organisations willing to take a punt. If they do, we could make a huge contribution to food security and could transform the everyday lives of city dwellers across the world. There are more than 26 cities with a population of over 10m, each requiring up to 7,000 tons of food to be imported to feed their residents –- vertical farms could, be one of a package of more sustainable alternatives to feeding them.

Explore further: Berlin start-up pioneers fish-farm veggie garden

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User comments : 30

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Shootist
2.2 / 5 (5) Jul 21, 2014
yeah we all want to live in a vast cube.
antialias_physorg
4.8 / 5 (6) Jul 21, 2014
Vertical farms do indeed have many advantages. They would enable us to produce crops all year round using 70% less water.

What's the difference between a vertical farm and a greenhouse? Sunlight comes in as a function of area. If you split it up into a volume then that doesn't work without artificial lighting.

All that in a city at premium prices per square meter?
You need a lot of multy-story infrastructure that is a lot cheaper if you go to the countryside and do it side-by-side.

Greenhouses in the countryside (multi-storey if you really want to, with solar concentrators around them) seem a lot more sensible.
ryggesogn2
2.2 / 5 (5) Jul 21, 2014
Vertical greenhouses, say powered with a small, sealed nuclear reactor in the basement would provide the power the best light for each plant, recycle and pump water, ....

What better place to grow the best quality marijuana?

http://www.fastco...enhouses
bluehigh
2 / 5 (2) Jul 21, 2014
... and need to be relatively large-scale if they are to yield attractive results.

Attractive for investors profit?

Can I have a small scale vertical farm in my backyard? What size volume would I need to feed a family 2000 calories every day?
bluehigh
1 / 5 (1) Jul 21, 2014
I rushed my comment. Good comment AA. Perhaps a solar powered multi-level greenhouse.
bluehigh
2.5 / 5 (2) Jul 21, 2014
One advantage of doing it in the city is to reduce transport and storage costs.
Gigel
3.3 / 5 (3) Jul 21, 2014
Dude, forget about the multistorey vertical farm. It's not people that grow inside and which require storeys. You don't need huge heavy horizontal platforms with plants. All you need is a simple, cheap support that you can rise and lower as needed and then you can cram such supports to the maximum plant capacity; say to spaces in between of 1-1.5 meters. Just consider the crane technology and use it for the thing. It won't cast much shadow anyway.

Such supporting platforms can be set on a conveyor belt that takes them up on the edge and lowers them through the center.

Also, some inflatable structures could be considered, in order to reduce the use of metal. They could go up to heights of hundreds of meters and be anchored to the ground with cables set at some heights.

Such structures can also be used for collecting solar energy (there is always a lot of space above than you can get on the expensive ground surface).

The idea is they have to be simple, cheap, easy to use and repair.
Gigel
5 / 5 (1) Jul 21, 2014

What's the difference between a vertical farm and a greenhouse? Sunlight comes in as a function of area.

It also comes as a function of angle. Very important. Rarely does the sun move in a vertical plane. More often it goes on an inclined trajectory so that maximum energy per surface comes if your surface is inclined, not horizontal. Thus vertical buildings may be better for collecting energy and insolation.

Vertical greenhouses, say powered with a small, sealed nuclear reactor in the basement would provide the power the best light for each plant, recycle and pump water, ....


With a standard nuclear reactor you could build an autonomous farming factory that needs no Sun or heat. Such a thing may one day make agriculture more feasible in Scandinavia or Siberia than in Southern Europe or South-East Asia.
bluehigh
1 / 5 (1) Jul 21, 2014
Then just before taking my meds and sleeping I thought .. Hey, lets have vertical farms for animals, then we have meat. Oh, that's right - chickens battery farming. Complaints of mistreatment, animal rights. Let the chooks roam free range. Up go the prices and investor profits. Yeah .. As the article mentions investor profits and climate change, I best skip this thread.
Gigel
not rated yet Jul 21, 2014
Can I have a small scale vertical farm in my backyard? What size volume would I need to feed a family 2000 calories every day?

Cereals have some 3000calories/kg and yield at least 4000kg/ha or 0.4 gk/sq.meter of grain. At these values, for a family of 4 and a year of 400 days you would need about 2680 sq.meters or a cube of size 14 meters withe 14 layers on top of one another set at 1 meter distance. Or a horizontal greenhouse of some 50 x 50 sq.meters.

You would need about 0.67 kg (1.5 lb) per person per day to ensure 2000 calories.
FMA
not rated yet Jul 21, 2014
The average lettuces take about 30 days from seeds to the market, how much is the lettuces selling in the supermarket in NY? Say $3 /lb. Assume you can sell your vertical farm lettuces with some premium, $ 5/lb, I guess only few people would buy $10/lb lettuces (correct me if I am wrong)

How many lb of lettuces you need to sell to cover the daily cost? Say 200 lb, the daily revenue is only 1,000. You need to sell same amount of lettuces everyday, how big is the vertical farm is required ?
Lex Talonis
not rated yet Jul 22, 2014
Yeah but given the pollution.....

And the need for some kind of reasonable exposure.... large areas, not blocked from sunlight by other buildings.

It could be quite good and assistive to the production of vegetables.... If each storey is say 50 meters wide by 3 meters high... and the building is say 10 stories high - that is quite a large vegetable plot.
alfie_null
not rated yet Jul 22, 2014
If an entire city, or some region of a city were to embrace this produce-your-own-food model, it might consider burying the vehicular traffic. Gain that much more space for planting stuff and as a side benefit, increase the ambiance for its residence a whole lot.
antialias_physorg
not rated yet Jul 22, 2014
It also comes as a function of angle. Very important.

If the surrounding buildings are of similar height (which seems a sensible to me when talking about cities) then it reverts back to a function of area.
If you really want to build such a contraption and benefit from the vertical aspect build it in the countryside (make sure there is no usable surrounding farmland - otherwise you're just killing that at the expense of building an expensive structure)

Can't cheat physics (and geometry) that way.

With a standard nuclear reactor you could build an autonomous farming factory that needs no Sun or heat.

That would make sense off world on interplanetary spaceships. I'm not sure you want a nuclear powerplant in downtown central.

Can I have a small scale vertical farm in my backyard?

If you have no neighbors that object to having no sunlight half of the day (and you get a building permit): sure.
Doug_Huffman
1 / 5 (1) Jul 22, 2014
And the Luddites now complain about food costs. Bwahaha! Y'all get just what you ask for - good and hard.

Marijuana and nuclear power mix precisely as guns and alcohol do too. MOLON LABE applies to more than merely arms.
JohnGee
not rated yet Jul 22, 2014
Why are some people so dead set against progress? How can people like Doug be so consistently wrong?
Gigel
not rated yet Jul 23, 2014

If the surrounding buildings are of similar height (which seems a sensible to me when talking about cities) then it reverts back to a function of area.
If you really want to build such a contraption and benefit from the vertical aspect build it in the countryside (make sure there is no usable surrounding farmland - otherwise you're just killing that at the expense of building an expensive structure)

True. Vertical farms have to be higher than surrounding buildings and also sparse. You would build them best in areas with houses or at the city limits. In countryside you can use them anywhere as long as they are sparsely set. Their shadows move with the Sun, so they would cover surrounding vegetation for a short time.
antialias_physorg
not rated yet Jul 23, 2014
You would build them best in areas with houses or at the city limits.

Shading would still be an issue (in this case for the residents). And farmland does have the drawback of being somewhat smelly during the time when fertilizer is used. I would envision that a "3D" block of farmland would exacerbate that factor somewhat.

I'd build them at shores of lakes/oceans or in desert areas. But seriously: I wouldn't build them at all. The price of food generated within such structures would be far higher than if you just build the equivalent amount of regular greenhouses (because you don't need all the structural support that is required for highrise structures).
Gigel
not rated yet Jul 23, 2014
That would make sense off world on interplanetary spaceships. I'm not sure you want a nuclear powerplant in downtown central.

Some 40-50 years ago there were ideas about huge industrial complexes built around a nuclear reactor. A safe reactor type can sit close to a city. Huge industrial farming complexes can be built around such a reactor.

Also, their use comes here on Earth too. In the extreme North (e.g. Siberia or Canada) where there are long days but it is very cold you would benefit from an enclosed farm where you could control the temperature and humidity. A sea-based nation could build huge submerged vertical farms, powered by nuclear reactors, with cheap inflatable (or water-filled) structures; such a nation can become an agricultural power with no use of land. In a desert area enclosed farms can protect well the inside soil from drought and winds. Ensuring 24-hr light and stored heat would give good crops in such areas.
Gigel
not rated yet Jul 23, 2014
The price of food generated within such structures would be far higher than if you just build the equivalent amount of regular greenhouses (because you don't need all the structural support that is required for highrise structures).

Research is needed in order to give some figures of cost and also improve the structure and energy management for VFs. I think there is a lot of space for improvement.

One aspect that has to be taken into account is that food prices are largely inflated; there is a big difference between the price at the producer and the price at the supermarket. The consequence is that food production can be diversified based on the difference between production cost and market price.

But again, research has to improve structures a lot before they can be used. It is clear you cannot grow plants in a block of flats built for humans. It would not be efficient.
ryggesogn2
not rated yet Jul 23, 2014
food prices are largely inflated;

Costs are not inflation.
Gigel
not rated yet Jul 23, 2014
food prices are largely inflated;

Costs are not inflation.

Well, prices are not costs. You have to go to the producer and see how much he gets (a good cost estimate) and then compare that with the market price. At least where I live in Eastern Europe, there is a big difference between the two for wheat for example (prices for grain and flour are 3-4 times higher than grain prices at the producer).
ryggesogn2
not rated yet Jul 23, 2014
You have to go to the producer and see how much he gets

Go to the farmer, buy the wheat, grind it yourself, ...
prices are not costs

Prices reflect the costs, when there is a free, competitive market.
ryggesogn2
not rated yet Jul 23, 2014
A farmer gets $13.00/60lbs of flax seed, $0.22/lb
I buy packaged, ground flaxseed for $5.00/lb from a farmer.
Is this inflation?
Gigel
not rated yet Jul 24, 2014
A farmer gets $13.00/60lbs of flax seed, $0.22/lb
I buy packaged, ground flaxseed for $5.00/lb from a farmer.
Is this inflation?

I don't know the grinding process of flaxseed, but generally I'd say that it is an inflated price, i.e. the price is (personal opinion since I don't know the process) much higher than initial costs. It is essentially the farmer's policy and he can do it. But at that price I may be able to grow flaxseed inside my apartment, grind it and sell it with profit.
ryggesogn2
1 / 5 (1) Jul 24, 2014
But at that price I may be able to grow flaxseed inside my apartment, grind it and sell it with profit.


Go for it.

I'd say that it is an inflated price

Why?
How do you know the costs?
Even the socialist understand the concept of 'value added' because they tax it.

antialias_physorg
not rated yet Jul 24, 2014
A safe reactor type can sit close to a city.

Problem is: There is no such thing as a safe nuclear reactor. E.g. no design has yet proven safe against flooding or massive Earthquakes (or simply lowest-cost-bidder workmanship, or human error)
And if any of those hit you really don't want the additional trouble caused by a broken nuclear powerplant close to millions of people.

Also, their use comes here on Earth too. In the extreme North (e.g. Siberia or Canada) where there are long days but it is very cold you would benefit from an enclosed farm

Sure. But why build a highrise? Same number of greenhouses is cheaper. Trucking food would still be cheaper than building nuclear powered greenhouses by many orders of magnitude.

But again, research has to improve structures a lot before they can be used.

No structure is always cheaper than some structure.
Greenhouse: no supporting structure needed.
Highrise: some supporting structure needed.
Pexeso
not rated yet Jul 24, 2014
The amount of light is given already. Until the crop yield is given with photosynthesis and with intensity of solar flux, I don't see a big advantage in vertical arrangement of crops.
Gigel
not rated yet Jul 26, 2014
The amount of light is given already. Until the crop yield is given with photosynthesis and with intensity of solar flux, I don't see a big advantage in vertical arrangement of crops.


Trees seem to see such an advantage.
Gigel
not rated yet Jul 26, 2014
Sure. But why build a highrise? Same number of greenhouses is cheaper.

1. In the far North where light comes almost horizontally, greenhouses would be inefficient. The radiation normal to a horizontal surface would be very small (mostly given by scattering of light). If light comes horizontally, you get most of it with vertical structures, i.e. maximize the normal radiation on a given surface.

2. Generally greenhouses have a supporting structure, of which sometimes the most expensive part is the ground supporting it. E.g. it is not a good idea to build huge greenhouse farms in Belgium, where the place is crammed and there are lots of uses for the land, like having motorways everywhere.