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Vertical Farming
SolFire writes "The BBC is running a look at the potential for Vertical Farming in the Big Apple, a concept that promises to reduce the environmental impact of farming and increase the efficiency of food production by building multi-story farm complexes in urban areas. The vertical farm is envisioned as a self sustaining complex of greenhouses stacked on top of each other. More details can be found on the project web site."
A pdf on the site, besides containing many interesting sketches and models, also makes the claim that cleverly integrated wind power generators allow the building to be 'off the grid' http://www.verticalfarm.com/images/design/ip/Waimo nd_Ip.pdf I'm suspicious, but it sounds like they're making the attempt.
I once did see something like this that was actually useful. One year, California had a serious drought, and alfalfa for horses was hard to get. So one company sold a hydroponic grass factory. This was a shipping container with a stack of trays and grow lights. Each day you removed and "mowed" one tray, did some maintenance on it, and put it back in the stack to grow new grass. The grow cycle was about three weeks. Not very energy efficient, but needed little water, which was what mattered that year.
You see smaller trays like that full of alfalfa sprouts at Jamba Juice outlets. Same concept, smaller scale.
There are some huge indoor farms in Saudi Arabia, where they have sun, space, energy, and money, but limited water and poor soil.
There's some grumbling in the "eco" community about the "3000 mile salad", and how much energy is used shipping produce around. But in fact, the biggest transportation fuel cost is the SUV trip to the grocery store. If the customer drives further, to the farmer's market, it's even worse. What's actually happening in transportation is that railroads are making a comeback, simply because their energy costs are lower.
Transport does take a heavy toll on food, usually because it is harvested before it is ripe so that it doesn't rot in transport. That usually results in fairly tasteless food, especially fruit and tomatoes. Let me see if I can put the costs of this into perspective for you. First of all, you have the cost of the land. Prime farm land in the midwest (which is the best soil in the world) goes for about $4500per/acre +/- $2000 for infrastructure conditions, etc. To give you an idea of the profits, my families most profitable crop is corn. Each acre produces between 120 and 175 bushels/acre of corn on average, though my families farm hasn't seen below 210 bu/acre in the last 10 years. Last year the price of corn was about $2.85 per bushel, though this year is is threatening to hit $5 because of ethanol. 100 acres is about all that you could reasonably expect one building to be able to hold while still getting enough light. (fyi 1 sq. mile = 640 acres) To buy 100 acres would cost $450,000. The INCOME off of 100 acres next year for my family should be 100acres x 180 bu/acre x $5/bu = $90,000!! Profit is usually less than 20% (I am a little fuzzy on exact numbers on that though). How much does transport cost? LESS than ten cents per bushel. $1800 max. It would take YEARS to pay off this land at this rate. (Hence why my family only owns 640 acres) A 4 acre lot in NY, 25 stories high, is going to be TENS of MILLIONS, just for the lot and construction costs. Then you have to haul in the dirt, (or set up the hydroponic tanks), pay the hand laborers, pay the MUCH HIGHER energy costs to produce this way... Theoretically it may work. In Practice? Nope. "Energy savings" aren't going to make a difference either, sorry.
http://en.wikipedia.org/wiki/Wind_turbine_design
/. because I am a self sustaining geek :)
It looks like from reading this that the cost of producing many little generators would incur a higher cost and make lower returns on the cost.
So building many small ones to get the power of one big one is not cost effective for them , or so it would seem.
I would like to put a small fan on a car alternator , removing the rectifier of course and see what one of these bad boys could generate for power.
Hopefully enough to power my laptop as I surf
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Did you actually read their website? There are a wide-variety of designs being proposed, not the least of which is this slanted building:
http://www.verticalfarm.com/images/design/skyfarm
If I'm not mistaken, that's one of the concepts you were just accusing them of ignoring?
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Wired.com had a very good article on this last year. It's an interesting concept. You treat lettuce growing the same way you do chip fabrication -- high density cleanrooms in optimal conditions. So, you get perfect organic produce, no pesticides, no fungicides, no herbicides, grown as fast as physically possible -- natural light supplimented with LEDs of optimal frequencies, water and mineral recapture (so only a tiny fraction of what is normally used gets used).
The downside is obviously the cost. However, the numbers still work out nicely. 85% of our lettuce is grown on the west coast at about 18 cents per head. This lettuce is more expensive (albeit near perfect, organic, and uberfresh), at 27 cents per head to produce. However, the cost to ship a head of lettuce from the west coast is as much as 50 cents. So you end up saving an awful lot.
As for energy usage: a semi gets 120-200 gross ton miles per gallon. Let's go with the middle, 160 ton miles/gallon. This means 320000 heads of lettuce per mile/gallon, or ~118 heads of lettuce per gallon from LA to NYC, i.e. ~0.0085 gallons per head of lettuce. That's 1.25 MJ of energy. The lettuce needs 2-3 months -- let's say 75 days. Let's say that half the light (compared to a sunny farm in SoCal) is supplimented -- perhaps 3 kWh/day. Let's say that they use diode lamps, so it's really 4 kWh/day consumed: 300 kWh total. That's 1.1 MJ. So, growing locally wins. But it gets better because you use 1/5th the fertilizer, no pesticides, and so on.
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why do wind farms consist of all those huge windmills? wouldn't 100 times as many smaller windmills generate a similar amount of power?
Generally speaking large wind gennies, er mills, have lower rpms so there's less vibrations and it's thought they are less of a threat to wildlife. However because of the large blades the speed of the tips of the blades are actually faster. Some studies have shown the faster blade tips create the elusion of a solid object, however others have shown they create a strobe effect like strobe lights.
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