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Why vertical farms are a crock. (monbiot.com)
74 points by jlangenauer on Sept 17, 2010 | hide | past | favorite | 94 comments

Farmland isn't just a place to put some plants while they grow. A farm is a giant solar power facility, one that converts solar energy, carbon dioxide and water into carbohydrate. Monbiot doesn't stress the point enough - it's all about light.

When we say that we have a shortage of farmland, what we mean in practical terms is that we have a shortage of flat areas with good drainage to function as solar collectors. Going vertical doesn't increase the amount of light you can gather, so it doesn't increase the amount of food you can produce.

Vertical farming is only remotely feasible if we see the cost of energy fall ten-thousand fold. That's only likely if we crack nuclear fusion. Of course, such an abundance of energy would render any worries about food production moot.

Unfortunately, we appear to live in a world where supposedly educated adults are unfamiliar with such advanced scientific concepts as photosynthesis.

When we say that we have a shortage of farmland, what we mean in practical terms is that we have a shortage of flat areas with good drainage to function as solar collectors.

Well, it is a bit more complicated than that. A huge problem in agriculture is the depletion of soil. For example, over time intensively irrigated soil tends to become contaminated with excess salts which destroys its fertility, yet still leaves it as flat, well-drained, and sunny as ever.

I completely agree, however, that the first-order consideration in growing plants is the availability of light.

Of course it's a bit more complicated, but we again come back to energy - soil improvement is essentially an energy input, be it oil-derived fertilisers, organic matter or fallow.

Aquaponics actually gets you pretty close to a closed-cycle ecosystem.

I read the other day about a family of four which grows all its food from an old in-ground swimming pool in their back yard. They put a greenhouse covering over it, filled a couple little ponds inside with tilapia, added vegetables and chickens. After one year they're extracting all the veggies, fish, and eggs they can eat.

Potatoes give about 6 million food calories per acre. (Wheat and most other plants yield less.) Assuming 8,000 calories per day, the family would need at least 1/2 an acre to survive. An Olympic-sized pool is 0.3 acres, so it's a bit beyond the edge of possible. I doubt their pool was that large, and since most other vegetables, to say nothing of fish and chickens, are less efficient food sources, I suspect they get a good fraction of their calories from elsewhere.

To check myself, this seems like a good thread: http://urbanevolution.org/thinktank/viewtopic.php?f=6&t=... . The strongest advocates for intensive and efficient agriculture say "less than half an acre (~ 0.2 hectares) can support a family of four" and "a vegan diet can meet calorie and protein needs from just 300 square metres using mainly potatoes. A more varied diet with plenty of fruit and vegetables, grains and legumes would take about 700 square metres." Say it's 2500 square meters for a family of 4 = 0.6 acres.

So, no, I don't think they get most of their food from the area of their backyard pool.

Your arguments are compelling but I'm not yet convinced it's impossible. One of their main crops is duckweed, an aquatic plant that grows very rapidly, though I haven't found specific numbers. Duckweed feeds their tilapia, which also breed and grow quickly. They say they extract eight tilapia every day, along with eggs and vegetables. Their chickens eat a lot of insects, a reserve of calories neglected by your potato field.

Their website is at http://gardenpool.org. It doesn't yet have as much detail as I'd like but hopefully more is forthcoming.

Here's someone else who harvests 6000 pounds of food per year from a tenth of an acre, with 350 different crops: http://urbanhomestead.org/urban-homestead

It seems to me that exploiting a lot of ecological niches might be more productive than monoculture. You can't extract more calories than sunlight provides (not counting insects from surrounding areas), but maybe sunlight is not the most limiting factor.

Vegetables have about 100 calories per pound. (See http://www.beyondveg.com/billings-t/cal-par/calorie-paradox1... ). You can get higher by picking the right plants so let's say 300 calories per pound. At 6,000 pounds per year that's 1.8 million calories. At 2500 calories per person per day that's enough for two people for a year.

For a family of 4 that's at least twice the area, or 0.2 acres needed, and likely more as the web page says their max was 6,000 pounds. It also doesn't say which plant those were, nor what the moisture content was. After all, if a watermelon is 15 pounds then that's 400 watermelons, and each one gets 11 sq. ft, but most of that is water weight.

And as for the gardenpool, as best as I could tell, duckweed is 6 times more productive than corn, and tilapia at best consume 1.5 lbs to produce 1 lb of weight. Not all that weight will be edible, and corn isn't as productive as potatoes, but the numbers work out that it might be 2-3 times more productive than my potato number for the same area.

However, I think the numbers for duckweed yield are in pig waste water or something else with a lot of nutrients in it, and everything is here is under best conditions, which also means a lot of care taking. Which potatoes don't need.

BTW, the web site says 8 eggs per day, not 8 fish. It looks like it takes 5 months for tilapia to mature to eating weight, and 8 fish a day would mean stocking 1,200 fish at a time. What they don't say is, is duckweed the only food source for the fish or are they adding other feed?

They also mentioned that they need a swamp cooler to keep the temperature in check. Assuming that's 200W average over 24 hours, that another 4,000 kcal ("food calories"), or almost enough for two people. They get that off the grid, but if they needed to provide their own fuel source for heating and cooling (tilapia can't handle cold water) then that's another factor in the energy equation. Potatoes are hardy in northern, cool climates.

Oops, yep, 8 eggs. They say "unlimited" tilapia but I imagine the limit there is how much of it they're willing to eat!

The aquaculture idea is that wastes from the fish, and in this case the chickens, puts lots of plant nutrients in the water. Maybe not as much as pig waste water, I don't know.

200W doesn't sound like that much power...solar panels on the roof, where you can't grow crops anyway, and/or wind turbines could provide that. Those are local resources you can't otherwise use to produce food, sort of like exploiting another ecological niche.

Potatoes are certainly convenient and productive, though I wouldn't want to subsist on them alone. Some people are growing them in tall boxes for easy extraction, and I was startled to see how much they claimed to produce.

Re: 6000 lbs/year, that must be why they sell their stuff instead of eating it.

This has been very interesting.

Which leads me to ask - what do the chickens eat?

I see that gardenpool gives a timeline on the side. They didn't stock the pool with tilapia until May 2010. Their page at http://gardenpool.org/?page_id=242 says "A tilapia matures from egg to harvest size (1.5 lbs) in only 6-9 months."

It hasn't been long enough for the new spawn to reach edible size. How can they say "unlimited" when they don't have the experience to know if it's stable? I suspect they are being overly optimistic.

Regarding 200W - I don't know what their swamp cooler needs, and they say they installed solar power. I picked 200W because that looks like a common size for portable home devices.

Looking now, I think solar cells are about 20 sq ft for 200 W. Since they need to work during the night as well (though not as much), call it 40 sq. ft of otherwise unused space. I was thinking that that would go into the area calculation, but as that's about 0.1% of an acre, it's not a big contribution.

And yes, I've found it interesting as well.

In part they eat bugs but I wouldn't think that would be sufficient in such a contained area. It's not like they're set up in a swamp.

Polyface Farms seems to feed their egg layers entirely on bugs, cattle droppings, and maybe a bit of greenery:

"The Eggmobile is a 12 ft. X 20 ft. portable henhouse and the laying hens free range from it, eating bugs and scratching through cattle droppings to sanitize the pasture just like birds in nature that always follow herbivores as biological cleansers." http://www.polyfacefarms.com/products.aspx

Of course that's a much larger operation. They keep moving, so cleaned areas can recover. They've got forested areas nearby which play a part in the ecosystem. They claim higher overall productivity than conventional farms producing the same stuff, but nothing extreme.

The peril of aquaculture is sometimes everything suddenly goes haywire and dies. Eventually the kinks get worked out and it's pretty stable, but the pool people may well have surprises in store.

I do love the idea of a little self-contained ecosystem, almost like a space colony. I hope people do a lot more experiments along these lines.

One idea from Marshall Savage's Millennial Project is edible algae, like spirulina. According to him it's absurdly productive in a small space, and the numbers from the "algae for fuel" people seem to bear that out. A turnkey system for producing it safely would be pretty neat, but I haven't been able to find much information. Everybody's talking biofuel. I wouldn't exactly want to subsist on algae but it could be great as a supplement in flour or stews, as fish feed, etc. How healthy it would be to eat large quantities seems to be a little uncertain, but supposedly it has a long history as a food.

If power isn't a concern (which it would be for the original topic of this thread) then the space programs have done research into small self-contained ecosystems, as you mentioned. I haven't looked them up before, but I see now that BIOS 3 (early 1970s Russia) had a 3-man crew for 180 days, with only some import of external food and air. It did need 400 kW of power, which if my 10W/sq.ft solar power is right means about 1 acre of solar panels. More if there's darkness.

Some other links: http://en.wikipedia.org/wiki/Controlled_Ecological_Life_Supp... and http://settlement.arc.nasa.gov/designer/regen.html . The latter says "The present crop growth chamber ... is about 12 m^2. The energy requirement of the system is about 15 kw of which 13 kw ... The present system provides complete nutritional needs of 1 person (a vegeterian)."

That power, at retail levels of about $0.10/kW hr, costs $36 per day. $18 if you can be diurnal. Sunlight puts out about 1kw/sq.m so that power is mostly going into replacing sunlight.

Which means, if that link is correct, that 12 sq.m is enough for a single person. But I'm at the end of my stamina for researching this topic.


I'll cap off my contribution with this guy who's eating nothing for the next two months but potatoes. Twenty every day. He's the Executive Director of the Washington State Potato Commission. http://20potatoesaday.com/

It's been fun!

"Going vertical doesn't increase the amount of light you can gather"

I am not sure that is true everywhere on the planet. If you get closer to the poles, the sun will, on average, stand lower above the horizon. That is why, in winter in Moscow, people sun while standing up.

Also, in summers close to the equator, getting less light per square meter may be a good thing, depending on what you are trying to produce.

I don't buy his argument that the cost of artificial lighting alone would be ~100x the current market value of the produce, especially when you use the solar collector analogy for farmland. Some quick googleing puts wheat in the 1% efficient range or less when converting light into carbohyrates. I have no idea where to find the exact number but it's not efficient at all. In a controlled environment the remaining 99% of the energy could be recycled. On top of that his calculation was based on the average sunlight for a day in England but that's probably more than wheat needs to grow optimally. I would love to see a more realistic calculation of this number.

That said I don't think vertical farms will ever be practical.

"In a controlled environment the remaining 99% of the energy could be recycled."

Thus violating the second law of thermodynamics. Do tell how we can recycle that energy, turning waste heat back into light, since that would also make solar cells more efficient, increase farming capabilities in cloudy/cold regions, and reduce our dependency on petroleum by making biofuels easier to grow.

For a starting point of the calculations, see http://en.wikipedia.org/wiki/Photosynthetic_efficiency .

Obviously you just put buckets under the plants to catch all of the light that falls through, and you have a machine that picks up the buckets and dumps them out over the top of the plants again. I think it'll help to paint the inside of the buckets white... or maybe black; not sure. Oh, and the bucket-dumping machine should be solar powered.


Oh, of course - Maxwell buckets will do the trick! Just need little robots with mirrors on each one to let light in and not let it out.

Put mirrors on the walls and ceiling and put reflective particles over the soil. That should let more light eventually end up on the plants.

You'll need mirrors which don't block the light. One-way mirrors are only half-silvered, which means they'll block more light than they'll recover. What you'll have to do is figure on something on the other side of the plants than the light source.

Take a look at the link to "Photosynthetic efficiency". Only about 13% of the light ("incomplete absorption") could be reused this way. Most of the rest of the energy is turned into heat.

Now, it is possible to be more efficient through layers. Take a jungle, where most of the energy is absorbed by the top level while lower-level plants make use of what energy comes through, eg, more efficient in dim light or better use of other parts of the spectrum.

You will be able to get some more efficiency by doing this, but it's going to be expensive, and nothing like "99%".

I think you're imagining something else. Here's what I mean:

   _________   Mirrored ceiling
   L  L  L     lights
  |        |   Mirrored walls
  |        |   
  | P P P     Plants
  | M M M     Mirrored surface with holes for plants
  | S S S     Soil
So any light that misses a leaf, reflects off a leaf or goes through a leaf will simply bounce around the room until it hits a plant.

I'm sure mirrors still convert some light to heat, but it seems like it would be a big improvement.

I see - you are talking about artificial lighting of the plants, while I was thinking of sunlight. With sunlight the ceilings will block the light going to the neighboring plants.

What you are saying seems to make sense for some circumstances, though I earlier pointed out there's isn't that much light which is going to waste which could be used for photosynthesis. I looked around for "mirror garden", on the thought that home gardens would be the most likely candidate for using mirrors, but the only mentions there were for decorative purposes.

I suspect there's a strong economic reason which makes it not practicable. Perhaps it's that a greenhouse with glass is more efficient because it makes better use of free natural light.

Maybe when my kid is older we will do this as ascience experiment. See if a "mirror garden" plant can grow with less light and how much less. Expect a blog post in ten years..

I don't know if Despommier suggests this, but mightn't his idea make more sense if the towers were used for growing things like mushrooms?

Hogs and chickens don't run on sunshine.

They stack pretty well.

And in urban areas the pipes are already in place.

Agriculture is messier than we all like to pretend.

As important as the specific theme (Vertical Farms are a crock) was this line, "Magical thinking is a universal affliction. We see what we want to see, deny what we don’t. Confronted by uncomfortable facts, we burrow back into the darkness of our cherished beliefs. We will do almost anything – cheat, lie, stand for high office, go to war – to shut out challenges to the way we see the world."

So many of the inane approaches to solving some of our economic and environmental challenges make absolutely no sense, have almost completely consensus that they violate laws of physics, and quite often result in Net-Negative results. "Local Growing", except as a hobby, is one of those insane ideas that seems to be underlying the silly "Vertical Farms" concept. (http://www.nytimes.com/2010/08/20/opinion/20budiansky.html)

Ironically, if there is government funding, the fact that an idea makes no economic sense doesn't mean it won't be pursued. There may be peripheral advantages or developments in technology that take place, while we tilt at these windmills.

So - I say let's build a couple of these vertical farms, see what we discover, do the math and realize it will never make sense, and maybe discover something else that we never even considered!

So - I say let's build a couple of these vertical farms, see what we discover, do the math and realize it will never make sense, and maybe discover something else that we never even considered!

You're suggesting doing something that we already know makes no damn sense in the hopes that we might learn something useful in the process. This argument could be used to justify an awful lot of things which make no sense.

This is, of course, just fine, as long as you're spending your own money on doing nonsensical things, and not mine. Good luck rustling up the hundred million dollars you'll need to build a skyscraper though.

you could build just a two story house, glass side walls, high enough ceilings, and see what happens on the first or second floor.

Vertical farms are a crock because transport of crops is easy. Moving people is much harder. This is why economic centers are densely populated, but can still eat food shipped from 1000 miles away. There is no reason to spend millions to build vertically when you can buy cheap land and transport the products to the most profitable markets on demand.

This. People should be dense, farms should be sparse.

Taking city land to grow crops is NOT carbon-efficient. The far more carbon-efficient method would be to use city land for more housing, and use suburbia for farms.

Think of it this way: people commute both ways every day, but food commutes only once.

I'm not even going to get into the idea that it's more carbon-efficient to grow bananas in South America and ship them to New York than it would be to heat and light a greenhouse in New York...

I agree with most of this post. But, a small correction: food only commutes in, but then waste commutes back out again. Unless you propose to build landfills in the city.

I have to admit to being astonished that there was a need in the first place to explain that vertical farms are a crock[1].

The long list of articles from prominent news sources was actually rather sad.

[1] The question how do you propose to grow over a thousand bucks worth of wheat each month in your tiny apartment? comes to mind.

The profit margin for a grain farmer in the US is about $100/acre in a good year. There are 43,560 square feet per acre. The ballpark estimate for construction of 10-20 story office space is $125-150 per square foot.

To break even, you'll have to build something that requires zero maintenance that also lasts about 60,000 years and of course you'll need zero point zero interest rates over those sixty millenia just to break even.

And of course you need to worry about pest management when growing that much of anything in such density. What sort of mechanisms you would need to harvest? Can't see a combine harvester fitting in the freight elevator.

There's a million and one things wrong with this idea. It's depressing how many news outlets haven't done any real journalism and checked with someone who actually grows any kind of plant for a living.

If farmland is as scarce as Monbiot proposes then vertical farms could work. Most of the value of a $1000 a month apartment is in consumer surplus. Yes, a vertical farm in manhattan will probably never work, but one on some existing farm land in New Jersey probably will. Vertical farms currently won't work but any real scarcity in farmland will drive up prices until it becomes economical as the price of food is highly elastic.

Farmland isn't actually scarce, though. Right now the world has plenty of farmland for all its people, which is why food is so cheap and why we can afford to consume massively space-wasting crops. People may be starving in Africa, but it's for political reasons which have nothing to do with the amount of arable land there (significantly more than China or India which have similar populations to Africa).

If the world's population ever does increase to the point where farmland is scarce, there's a lot of other things which become economical before skyscraper farms do... even if fusion energy comes along to solve the lighting problem. Switching to land-efficient crops is one thing. Irrigating the world's deserts is another. Even farms on barges out in the ocean make a lot more economic sense than skyscraper farms.

I am genuinely interested in references for available arable land in Africa vs China & India.

While George Monbiot is often wrong about a lot of things, it's nice to see him being right in comparison to someone even wronger than he is.

A quick calculation: the total floor area of the Empire State Building is 63 acres. You can do your own calculations for the cost of building the Empire State Building vs the cost of buying 63 acres of land (which, incidentally, gets light) in upstate New York, but I'm pretty sure that one is much, much, much larger than the other.

And with that number in mind, you also see another problem with vertical farms: pure space availability. Modern farms are hundreds and even thousands of acres to grow enough food to feed the masses we have today. You would need > 100 of these buildings (ignoring all the other issues for now) to be able to replace one major farm.

Frankly hydrogen vehicles are more feasible than this, but only barely.

"You would need > 100 of these buildings (ignoring all the other issues for now) to be able to replace one major farm."

So what if it didn't replace one major farm and just a small local one? And what if the vertical farm and office building idea were combined, so that you had alternating floors of greenhouses for plants and office workers that ate them?

I'm surprised I haven't seen the ideas brought together before, it seems more pragmatic than a dedicated building just for the farm and there's a growing movement to eat healthier at work. We order from FarmFresh at my offices, which supplies us with fruit and veggies from a local family-owned farm and we've been loving the results.

And what if the vertical farm and office building idea were combined, so that you had alternating floors of greenhouses for plants and office workers that ate them?

It takes 1-2 acres of farmland to support one person's eating requirements, which is two floors of the Empire State Building. Alternatively, there's 21000 people working in the ESB so that's about 200 people per floor. If you devoted every second floor to agriculture (and magically solved the lighting problem) then each worker could acquire 0.25% of his daily caloric requirements from the floor below... maybe a couple of strawberries?

Oh, and the ESB rents for $38 a square foot, so working out the effective cost of each strawberry is left as an exercise for the reader.

Pretty sure the 1-2 acre number is quite relative to diet. Perhaps for heavy cattle grazing, bush meat, etc. but not for a vegetable based diet. For an alternative reference see: http://books.google.com/books?id=hwAHmktpk5IC&pg=PA819&#...

two floors of the Empire State Building (two floors)

(two floors) x 200 people = 400 floors

(two floors) x 300,000,000 people = 600,000,000 million

Hmm, the world must be really big, or the floors must be really small. If we double that number to include Europe, indeed, lets increase it slightly as Europe has a bigger population, that is 1.5 billion floors of the Empire State buildings to feed only about 1/6th of the world. That does not sound right to be honest.

$38/year or per month?

Per year.

I also looked up the average cost of agricultural land per acre in the US, which comes down to about $1200 per acre, or about 0.3 cents per square foot.

This means that for the cost of buying outright the average agricultural square foot somewhere in the country, you could rent that same square foot in a big-city skyscraper for about 45 minutes.

Alternating floors would be kinda harsh on the environmental systems of a modern building (one problem: humidity). The other problem is economic. The builder will make more money on more office space than farming.

Also, a lot of farmers really don't want to live in skyscraper land.

Every time I read of these, my thought was always "how do they get light?". I just assumed that this was somehow solved, otherwise why would everyone be so excited about it? I figured some day I would have some time to properly investigate it and find some cool tech.

It saddens me greatly, and in numerous ways, to find out that "How do they get light?" is a killer question.

I always assumed that the light would be artificial. And that they were relying on hypothetical cheap energy of the kind that reliable fusion would provide. This may be possible a hundred years from now but surely not in today's energy economy.

But once you've got reasonably cheap and plentiful energy, what's the big incentive for growing locally. If trucking it from Kansas to NYC doesn't pollute as much, reasons for building those towers diminish somewhat.

Of course, it's slightly different if you've got plentiful energy, but no good way to transmit/store it. Lots of solar panels all over the city to power its greenhouses. Or windmills in Chicago.

Production prices for solar energy are now below $0.80 / watt (http://www.123jump.com/market-update/First-Solar,-Inc-Q4-Ear...), although skyrocketing demand has caused wholesale prices to remain much higher. It seems likely that we may in the next 10 years be in a place where we can turn sunlight into electricity, and then electricity into the exact wavelengths of light used in photosynthesis more efficiently than allowing the plants to sit in the sun.

If this is the case, than we may be able to grow crops more efficiently indoors than out. But we will be replacing acres of crops with acres of solar panels. And it's unclear to me why we would want these buildings to be skyscrapers, which are much more expensive per square foot than large warehouses in the middle of nowhere.

How in the world did you get +8 mod on this?

That's utter nonsense!

You can only get as much light as you have surface area - so now instead of fields of crops, you have fields of solar collectors!

Did you think there was some magical light multiplier device that could give you more output light than you started with?

Plants already use the best parts of the visible spectrum to collect light. The small amounts of infra-red you might barely be able to collect and frequency up-convert are not worthwhile - especially since you'd need to throw away all the energy from the higher frequencies in order to get it.

Solar cells are terrible as far as efficiency is concerned - and not because of engineering, because that's simply how they work. (Unless you want a multijunction solar cell but those are very very expensive.)

And for engineering challenges there simply doesn't exist in the world enough rare earth elements to make enough solar cells for everyone - and that's just for regular electrical usage, forget about growing plants. We do have enough silicon, but silicon based solar cells have poor efficiency.

I think the idea here is that plants need a narrow set of frequencies and throw the rest away. If solar cells could capture the frequencies plants don't use, convert them to energy, then convert the energy to frequencies plants like, you've increased the efficency of your light-collection area.

You'll also have a garden full of black plants, which is both creepy and cool.

Solar cells work the same way: they capture a narrow frequency, and throw the rest away.

More accurately, below the frequency cutoff they ignore the light, above the cutoff any, extra energy is wasted as heat.

And plants don't need a narrow frequency anyway.

They don't seem to be using the green light, at least.

You might be able to beat crops in that way if you dispensed with photosynthesis and crops altogether and came up with a completely different way to convert solar energy to carbohydrates. Somebody else in this thread said that a wheat field converts 1% of its solar energy to food calories. They didn't cite that and I don't have time to look it up, but if it's true it should be beatable.

Assuming three billion years of evolution is beatable is generally a fool's game. I do like the idea of chlorophyll-tuned lasers, though.

Evolution can be stuck in local maxima determined by some path it went down a long time ago. If life happened to evolve an inherently inefficient metabolism, it would be stuck with it forever because you can't really go back on something that fundamental (we share glycolysis mechanism with bacteria).

And, even if evolution automatically did win, plants did not evolve to feed us. They evolved to reproduce themselves, and we have incidentally hijacked them to use as food sources.

But they did evolve to extract useful energy from solar radiation. Assuming it would be easy to tweak photosynthesis is ridiculous.

Evoltution is great at tweaking, and would be hard to beat, but it might be possible to build something completely different. It would also be hard to tweak a bird's wings, but we have built aircraft with completely different designs that fly many times faster than any bird.

A solar cell collects energy over a range of frequencies, while a plant (if I recall) uses only two. You can think of it this way. Wheat is say 1% efficient at solar collection, while even crappy solar cells are like 8%.

Of course you need to transmit electricity and re-emit the light efficiently. You will still end up with acres of solar panels, as I said. Before you jump on someone for getting their science wrong, make sure YOURS IS RIGHT!

"a plant (if I recall) uses only two [frequencies]"

You mis-recall. It has two peaks in the absorption spectra but they are not narrow. In other words, a plant is green. There's no way to absorb only two frequencies and still be green.

"Wheat is say 1% efficient at solar collection"

Using http://en.wikipedia.org/wiki/Photosynthetic_efficiency as a guide, about 28% of sunlight energy is collected by chlorophyl. Of that, much is used to keep the plant alive (sugar production, respiration, growing roots). About 1% is left for human use.

It's the 28% that's relevant here, not the 1%.

In other words, 28% for plants beats "crappy solar cells" at 8%. Now, 47% of the energy is outside the 400-700nm range that chlorophyll can process so you might be able to double the energy use if you can find a good way to upconvert/downconvert light into that range. That would at best double what you can grow.

Which is still nowhere close to getting viable farming in an urban center.

Vertical farms are kind of a crock, kind of. The idea of indoor agriculture is not, however (just look at Thanet Earth), and there is an advantage of building up a few floors and using grow lights to supplement the loss of passive lighting.

A series of low-rise warehouses using hydroponics in the outer rings of a city makes a lot of sense.

However, the architectural games people are playing with huge spires in the center of Manhattan, those are ridiculous, and always have been.

I had always thought that the skyscraper version of vertical farming was more of a fantasy technology.

Everything real I've seen is focused on what you mention, low-rise warehouses with racks of hydroponics and skylights - making it essentially a robotic greenhouse. I don't see how this is outlandish

Perhaps improved lighting would make it more effective and efficient today, but I'm reminded of the Sprung Greenhouse in St. John's, Newfoundland. Now, before anybody gets on the "government involvement is bad" bandwagon, try to keep in mind that Newfoundland has next to no agriculture at all, apart from a few root vegetables (it's a rock that alternates between barren land and impenetrable forest) and has always had to import most of its non-fish foodstuffs. Even given the importation expense, the greenhouse production was incredibly expensive compared to the existing supply chain. Putting production into a building doesn't change external light levels or prevent snow from accumulating on top of the greenhouse (or solar panels, reflector arrays, etc.). Even the wind levels were high enough that safe operation of windmills would have been difficult (sustained wind speeds regularly reach levels where normal turbines would be parked and feathered). Not saying that it can't work, just that it won't be cheap (so it's likely that transportation and ordinary production costs will have to rise quite a bit), it won't be easy in a lot of locations, and it's not a panacea.

Can you identify a single instance of economic use of grow lights for agricultural (as opposed to pharmaceutical) purposes? Green Houses (Thanet Earth) are designed to trap the Sun's energy.

Using grow lights 100% of the time? No, that's definitely not going to work, unless major gains in efficiency are made. But using led grow lights to supplement passive solar and elongate the grow cycle is what I'm referring to, and designing low-rise greenhouses to capture the sun's energy for the light hours. If you capture excess solar energy, store it, and use it at night, then the energy pull from the grid for night-time grow lights is reduced, and then it's an economic question of cost of energy versus sale potential.

I'm not specifically thinking about staple crops (ie, wheat, rice, etc), but supplementary crops like tomatos, lettuce, cucumbers, etc. Mostly, what Thanet Earth is growing.

Go visit the Westland in the Netherlands at night, and you will be surprised at what you see. Assisting the sun with artificial lighting is nothing special.

I've seen this nonsense for a few years now in all kinds Architectural publications. One such example: http://www.mvrdv.nl/#/projects/research/181pigcity. Unfortunately, many architects and architecture students would buy any green (or otherwise hyped) BS thrown at them without questioning it.

I think the most prohibitive aspect of the "vertical farming" is the enormous cost (in materials, labor and energy) of building highrises or even buildings of more moderate heights, compared to the cost of growing any legal kind of crop on farmland and shipping it. Structure will have to be significantlly more massive to carry the loads of some soil and water. And not a word about competing land uses in Manhattan... But let's assume we can afford to ship the crop 10 or 30 miles into the city from a place with cheaper land, rather than a 1000 from far far away.

Otherwise, I actually believe the problem of lighting is solvable - for crops that require perhaps 3-10 times as little light as available in an open field on a certain location. Light can penetrate from the sides of the building. A structure shallow ebough compared to the floor height might suffice, say 10-15 meters for a floor 3 meters high. Close to the equator sunlight is abundant so even having less light by an order of magnitude is probably enough for some crops. Further away from the equator it's trickier: the sun is much lower in the south and so more direct sunlight is gained so perhaps only two thirds of it are lost compared to an open field. But then, the structure casts very long shadows which may prevent the land "behind" it from being used for farming (vertical or otherwise).

What about using vertical farms just for semi-exotic plants that fetch a higher price? Instead of expecting to feed a city of 15 million on skyscraper farms, just grow things that have to be 100% fresh in order to be tasty, and sell them to upscale restaurants and gourmet markets.

These ideas aren't new. I doubt that they are impossible but we haven't yet solved the technical problems that would make 'vertical farms' cost effective over regular farms. If farmland became expensive enough (really expensive,) I could see them seeming more viable.

If these were to happen, my entirely uneducated guess would be that it would start with rooftop farming, and that extending to storied greenhouses at the tops of skyscrapers. Depending on your crops, these both don't need artificial light and could lead to solutions for other engineering problems such farming would involve.

No it wouldn't.

The amount of usable farm space at the top of a skyscraper is so small it's a joke. You could feed 1 person for each skyscraper.

And if farmland got expensive, exactly where would you get your energy to make light?

I assume rooftop gardening is a completely different (and good) idea. There you have the sunlight already, just being reflected or absorbed as waste heat, it's simply a materials (weight) and cost or species issue. (also it's easier to design for one than retro-fit one on).

Quite possibly. Here's a group who are actually building one now, in Chicago, and blogging about it:


Be interesting to see how that works out.

It seems that many people here are making conjecture based upon little research. Vertical farms are very much possible and actually relatively efficient . The EPA has been funding small scale pilot farms to test the concept. The engineering hurdles which people are describing have mostly been dealt with. Food from these farms may cost more but it is fresh, local and organic instead of ethelyne ripened and full of pesticides. Take a walk to whole foods and you'll see that people are willing to pay for that.

The writer rambles on with setup and indirect arguments for a couple of paragraphs before even mentioning what he's attacking, but he raises some excellent points once he actually gets going.

This bit was witty:

"The only crop which could cover such costs is high-grade cannabis. But a 30-storey hydroponic skunk tower would be quite hard to conceal."

What about opium?

Maybe roses or saffron?


This guy sees your critique on expensive real estate, and uses an abandoned factory. Sees your argument about nutrients not just appearing, and uses aquaponics. Lighting... that I don't know.

I'm curious to see how it goes.

What if you covered existing skyscrapers with hydroponic trellises?

Structural issues. Adds weight, in ways buildings aren't designed to take. Requires soil, and water in the soil, which is more weight. Water causes damage to building structure. Some plants will be impractical because they'll want to burrow into the structure. It's dangerous to collect the produce. There are insurance issues around stuff falling off onto people. It becomes difficult to clean or replace windows. Once plants are on it will be difficult to change damaged trellises. Change to fire risk profile of building. Security and insurance considerations from people climbing on the structures. Buildings not designed to supply water to the plants. Freehold issues from one person's plant growing into another's area. Allergies. Bees. Rats. Effect of plants growing into air-conditioning systems. Council complications over the change to the view profile of the building from sleek thing to tentacled thing.

Tons of upvotes for a comment that says hydroponic trellises require soil? What's going on here?

Hydroponics uses a fraction of the water that soil-based agriculture uses, and generally uses a very lightweight growing medium. (Vermiculite, hydroton balls, etc...)

No soil.

Maybe vertical farms are a crock but at least people are starting to realize that local food production is a better idea than shipping factory farm food thousands of miles. Eating local, seasonal food is how it has been done for 99.99% of human history. We waste hydrocarbons in a criminal fashion and our ancestors will absolutely hate our guts for it. Why should we burn up billions of years of oil inside of ~200 years just so that we can eat strawberries in NYC during winter? It is INSANE. The decision-making process we use is only what will make money in the short term. The issue of cost externalization by companies is well documented by economists. Just because it appears "cheap" to use factory farm methods, N-P-K based fertilizers, etc., doesn't mean the long term effects already showing up are not going to severely impact the food chain inside of our lifetimes.

Ultimately though agriculture itself is a non-sustainable process. That is why the fertile crescent, cradle of civilization, is now a desert. We should start creating food forests, this is a very promising sustainable way to feed people and all of the unemployment we experience can be solved by transitioning a larger % of our population to food production as a job, just like our grandparents used to do it.

The desertification caused by agriculture and our increasingly desperate use of technology to cover up the fundamental flaws in how we feed ourselves is increasing rapidly. The water table in many places around the planet is being depleted faster than it can restore itself. These issues are NOT going away and they are far more important than coupons for cupcakes and the like.

The local food movement is quite silly. http://www.thebigquestions.com/2010/08/23/loco-vores/

99% of human history pretty much sucked. http://cafehayek.typepad.com/hayek/2008/06/the-real-life-o.h...

Saying "it sucked" doesn't address ANY of the points I made. Wake me up when you can make a serious rebuttal.

I think your comment was reasonable, but the point of the "silly locovore" link above is that insisting on locally grown food isn't the way fossil fuel conservation should be implemented, as locally grown does not imply fuel efficient. Rather, the nonlocal food market is a symptom of low fuel prices. But if fuel prices were $20 or $50 per gallon, as you'd probably like it, that would really hit the economy hard. If it turns out that by the time we run out of fossil fuels we have bootstrapped our way to some other reasonable forms of renewable energy, then arguably our resource allocation will have been pretty optimal. Cross your fingers!

"Ultimately though agriculture itself is a non-sustainable process. That is why the fertile crescent, cradle of civilization, is now a desert." It was a desert before as well. The Sumerians used irrigation to be able to turn dry but fertile soil into farmland. This requires a lot of hard work, ingenuity, and collaboration, which might be why civilization started there. It's relatively flat, with a hard subsurface, which makes salt buildup a problem, making farming there rather more fragile.

If what you are saying is true, then why is there still farming after thousands of years along the Nile and Indus river valleys?

In any case, what do you suggest the people of L.A. do? They grow a lot of their food locally, in the Central Valley, but that water is pumped from across the state and the Valley has the same problems as the Fertile Crescent.

Should they grow the food in their backyards (more locally), and if so, will there be separate water systems for crops, because it needs less water treatment than humans need?

Or should some large fraction of the population move, and if so, where? Since food forests aren't going to grow well enough in LA to feed its own population, at least, not without non-local water.

Personally, I would rather pay people to grow my food for me while I get to sit on my porch and enjoy reading and commenting on HN.

"Eating local, seasonal food is how it has been done for 99.99% of human history."

And while chewing nobody has been peering into computer screen reading nonsense comments on HN.

I'm seriously tired of getting downvoted for good comments. Later hackernews, have fun with your circlejerk.

Because your comments about local food are clearly written without a basic understanding of the breakdown of energy use. Freight shipping uses about 1 gallon of gas/ton/500 miles. Over 80% of the costs are in the final few miles - trucking from the shipping depot to the markets.

Getting food locally delivered is far less energy efficient than having it shipped in bulk by freight to supermarkets.

No, it is because the moderation policies on this site are absurd and comments saying "it sucks" get modded up while a reasonable comment gets modded down.

Bottom line the world is running out of hydrocarbons. Things that look "energy efficient" to you today won't look so efficient in 50 or so years. Peak oil already happened in the United States, Hubert's peak is reasonably well accepted, and the idea that shipping food thousands of miles is a long term sustainable strategy for feeding humanity or that the entire world can live like the people in Silicon Valley and New York City is laughable.

That is my last comment on HN - mods, please prove my point by voting it down.

There's not some crowd of elite "mods" voting you down, it's anybody who's reached a certain karma threshold (probably ~200). Sometimes rational comments will be downvoted right away by a few early and angry jerks, but the scores will later be corrected by upvoters. But, since that was your last comment, I suppose it is pointless to reply.

Some on-topic points:

1. Energy efficiency in terms of joules per kilogram per kilometer is a constant, regardless of the actual dollar cost of the fuel.

2. 50 years is a very long time to come up with the technology to replace fossil fuels, hopefully with cheap fission and eventually fusion.

3. Modern civilization thrives on being able to disregard geographic barriers. We could never have a global society if transportation of physical goods became impossible. So, since we (as a society) won't accept the defeat of modern civilization, we will simply find another way to continue to exist. If that means replacing fossil fuels, then it will happen.

Huh. You don't normally see a classic flounce like this around here.

This is what I hate about the times we live in. When someone comes up with an idea of how to solve a problem, all we do is discuss. We discuss and we discuss. We argue about the plausibility, we may even do some calculations to see how plausible the solution is. But we never actually try it.

In other words, if some guy thinks a vertical farm would be a good idea and a possible solution to a problem, then why the hell doesn't he just, you know, make a vertical farm and see what happens? If it works, then that's fuckin' awesome, we've got vertical farms! If it doesn't work, well then hey, no biggie. Let's try something else.

Of course some problems have very expensive solutions that are not feasible to just "try out", but I don't think it would cost a ton to make a small scale version of a vertical farm. Even if it was only like 10ft by 10ft and as tall as a two story house, you have to start somewhere.

But I guess we'd rather just talk about the possibility, and never take it any farther than that.

When someone comes up with an idea of how to solve a problem, all we do is discuss. We discuss and we discuss. We argue about the plausibility, we may even do some calculations to see how plausible the solution is. But we never actually try it.

That's not really true. An awful lot of the time, someone comes up with a solution to a problem, tries it, and it works.

In cases like this, though, it never gets beyond the discussion stage because the idea is a complete useless crock of shit and the major flaws in it are so obvious that a nine-year-old (or even George Monbiot) can see right through it.

And yet the discussion goes on, because the guy who has the idea (and a number of hangers on) is religiously wedded to it refuses to acknowledge that "wait, actually, yes, this makes no sense on the grounds of physics or economics", so I suspect we'll continue to see this idea pop up from time to time.

In conclusion, sane and workable ideas get implemented. Stupid unworkable ideas with horrendous flaws get endlessly discussed.

well, if the guy wants to put up his own money to build a vertical farm, I don't think anyone is going to stop him.

The problem is that the guy is asking other people to fund his idea, so it makes sense for other people, who know more about the subject, to weigh in and point out ways in which it is a good or bad idea.

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