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Why vertical farms are a crock.

monbiot.com

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Re: Why vertical farms are a crock.

#91

Post by tocomment »

dalke wrote: post #89
tocomment wrote: post #88

Earlier quoted context omitted.

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 t…

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..

Re: Why vertical farms are a crock.

#92

Post by DennisP »

dalke wrote: post #90
DennisP wrote: post #81

Earlier quoted context omitted.

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…

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.

Re: Why vertical farms are a crock.

#93

Post by dalke »

DennisP wrote: post #92
dalke wrote: post #90

Earlier quoted context omitted.

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…

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…

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.

Re: Why vertical farms are a crock.

#94

Post by DennisP »

dalke wrote: post #93
DennisP wrote: post #92

Earlier quoted context omitted.

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…

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…

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.

Re: Why vertical farms are a crock.

#95

Post by dalke »

DennisP wrote: post #94
dalke wrote: post #93

Earlier quoted context omitted.

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…

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…

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.

Re: Why vertical farms are a crock.

#96

Post by DennisP »

dalke wrote: post #95
DennisP wrote: post #94

Earlier quoted context omitted.

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…

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 t…

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.

Re: Why vertical farms are a crock.

#97

Post by dalke »

DennisP wrote: post #96
dalke wrote: post #95

Earlier quoted context omitted.

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 t…

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…

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.

Cheers!

Re: Why vertical farms are a crock.

#98

Post by DennisP »

dalke wrote: post #97
DennisP wrote: post #96

Earlier quoted context omitted.

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…

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 a…

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!

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