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.
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.
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.
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.
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:
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.
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.
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.
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.
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."
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.
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.
It's been fun!
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.
That said I don't think vertical farms will ever be practical.
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 .
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%".
_________ 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
I'm sure mirrors still convert some light to heat, but it seems like it would be a big improvement.
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.
They stack pretty well.
And in urban areas the pipes are already in place.
Agriculture is messier than we all like to pretend.
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!
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.
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...
The long list of articles from prominent news sources was actually rather sad.
 The question how do you propose to grow over a thousand bucks worth of wheat each month in your tiny apartment? comes to mind.
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.
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 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.
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.
Frankly hydrogen vehicles are more feasible than this, but only barely.
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.
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.
(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.
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.
Also, a lot of farmers really don't want to live in skyscraper land.
It saddens me greatly, and in numerous ways, to find out that "How do they get light?" is a killer question.
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.
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.
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.
You'll also have a garden full of black plants, which is both creepy and cool.
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.
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.
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!
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.
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.
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
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.
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).
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.
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?
Be interesting to see how that works out.
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."
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.
Hydroponics uses a fraction of the water that soil-based agriculture uses, and generally uses a very lightweight growing medium. (Vermiculite, hydroton balls, etc...)
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.
99% of human history pretty much sucked.
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.
And while chewing nobody has been peering into computer screen reading nonsense comments on HN.
Getting food locally delivered is far less energy efficient than having it shipped in bulk by freight to supermarkets.
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.
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.
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.
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.
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.