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Why vertical farms are a crock.

monbiot.com

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Re: Why vertical farms are a crock.

#81

Post by DennisP »

mechanical_fish wrote: post #27
jdietrich wrote: post #26

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…

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…

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.

Re: Why vertical farms are a crock.

#82

Post by ajdecon »

slapshot wrote: post #56
parfe wrote: post #10

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…

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.

Re: Why vertical farms are a crock.

#83

Post by Vivtek »

rsheridan6 wrote: post #80
Vivtek wrote: post #73

Earlier quoted context omitted.

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,…

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

Re: Why vertical farms are a crock.

#84

Post by rsheridan6 »

Vivtek wrote: post #83
rsheridan6 wrote: post #80

Earlier quoted context omitted.

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,…

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.

Re: Why vertical farms are a crock.

#85

Post by ars »

DougWebb wrote: post #53
ars wrote: post #30

Earlier quoted context omitted.

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 inf…

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.

Re: Why vertical farms are a crock.

#86

Post by alex_stoddard »

hugh3 wrote: post #24
fleitz wrote: post #18

Earlier quoted context omitted.

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…

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'…

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

Re: Why vertical farms are a crock.

#87

Post by DougWebb »

ars wrote: post #85
DougWebb wrote: post #53

Earlier quoted context omitted.

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.

Re: Why vertical farms are a crock.

#88

Post by tocomment »

dalke wrote: post #75
tocomment wrote: post #71

Earlier quoted context omitted.

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 t…

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.

Re: Why vertical farms are a crock.

#89

Post by dalke »

tocomment wrote: post #88
dalke wrote: post #75

Earlier quoted context omitted.

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 t…

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…

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.

Re: Why vertical farms are a crock.

#90

Post by dalke »

DennisP wrote: post #81
mechanical_fish wrote: post #27

Earlier quoted context omitted.

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…

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.

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