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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.
Earlier quoted context omitted.
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 befor…
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.
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. "
Maybe roses or saffron?
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.
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 highl…
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 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…
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.
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.
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. Go…
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.
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 ce…
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…
Hydroponics uses a fraction of the water that soil-based agriculture uses, and generally uses a very lightweight growing medium. (Vermiculite, hydroton balls, etc...)
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.
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…
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.