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Vertical farming does not save space

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Re: Vertical farming does not save space

#141

Post by throwaway894345 »

totemandtoken wrote: post #99
klodolph wrote: post #28

Earlier quoted context omitted.

Solar panels can be more efficient, but if your comparison is between “sunlight -> plants” and “sunlight -> solar panels -> electric lights -> plants”, you have to include the actual efficiency of e.g. photovoltaics and LEDs in your calculations. Photovoltaics these days have something around 15-20% efficiency and LEDs have conversion efficiency around 50-60%. The magenta grow lamps are colored for more efficient use…

Just for comparison's sake, aren't plants/photosynthesis something like 5% efficient?

I think that's correct, but that difference seems to be within the error margins for this calculation, and some other loss (e.g., transmission, storage, etc) could eat any hypothetical advantage that the vertical farming position might've enjoyed.

Re: Vertical farming does not save space

#142

Post by dragontamer »

dathinab wrote: post #117
dragontamer wrote: post #113

Earlier quoted context omitted.

> lot of land that isn't suitable for farming We're talking about powering a hydroponic greenhouse. The alternative to "Solar Powered LEDs" isn't "plant things in the ground". Its "make a glass window on your roof". -------- "Plant things in the ground" is also cheaper, though it does suffer from potentially poor soil conditions. Still, it seems to me that spreading fertilizer across soil (and conditioning the soil i…

> "make a glass window on your roof". Doesn't work as you can't stack plants with it nor can you grow them underground.

Where are you placing these solar panels? Why can't those locations be rooftop hydroponic farms instead?

Re: Vertical farming does not save space

#143

Post by kibwen »

falcolas wrote: post #78
kibwen wrote: post #63

Earlier quoted context omitted.

> plants are more efficient at capturing energy from the sun than solar panels -> light bulbs -> plants are This is a counterintuitive misconception that I mention elsewhere in this thread. Plants aren't optimized for raw sunlight utilization, because that's not the bottleneck for growth or survival. Plants deliberately reflect away 90% of the sun's energy ( https://en.wikipedia.org/wiki/Photosynthetic_efficiency ) b…

> deliberately reflect away 90% of the sun's energy They'll have that same efficiency with artificial lighting too… At least until our grow lights stop emitting light in the green spectrum (not something I expect to see anytime soon).

Grow lights are quite good at only emitting light in certain parts of the spectrum, and have been for some time now.

Re: Vertical farming does not save space

#144

Post by dale_glass »

Hammershaft wrote: post #89
marshray wrote: post #80

Earlier quoted context omitted.

Yes, please include the cost of nuclear power in the considerations. (The joke here is that the true cost is undefined because we here in the US have no method to store the long-term hazardous waste it produces. Current cleanup costs for just the military reactor waste are estimated at $500B, for civilian reactors the costs are said to be higher.)

In the short term nuclear energy is expensive, but in the long term nuclear energy is one the cheapest sources of energy available. Source - https://www.youtube.com/watch?v=cbeJIwF1pVY (this is even more true when you consider the cost of externalities)

I don't see how nuclear can win over the long term.

Solar and wind are simple and very amenable to mass production. Many parts of them are usable for other purposes -- we need generators for things other than windmills, inverters for things other than solar powerplants, etc. This means we're not making things as a one off, but doing mass manufacturing, and the different users all reap benefits.

They're easy to produce, which means there's lots and lots of competition, which pushes down price.

They're easy to install, scale and maintain.

They're easy to iterate, because it doesn't take billions to test a new design on a small scale.

They don't need most of the parts nuclear has -- if you think of it a windmill contains parts a nuclear plant needs too, but unlike nuclear doesn't have all the nuclear stuff along with it, which isn't cheap.

The way I see it, nuclear could have been successful but is going the way of the mainframe -- today mass computing is done on huge amounts of commodity hardware, and in the same way large, purpose built plants are already being overtaken by mass production of panel after panel being churned out of a factory, and that's not going to get any better for nuclear.

Re: Vertical farming does not save space

#145

Post by woeh »

macspoofing wrote: post #101
Nition wrote: post #44

Earlier quoted context omitted.

Might be significantly higher efficiency overall though vs. putting solar panels on the same roof?

I guess the devil is in the details but I can't see how mirrors will be positioned to support vertical farming. It's be interesting to see some viable ideas (if those exist).

Thinking aloud here; perhaps we could somehow use optical fibers to bend the light from rooftop to vertical farm?

Re: Vertical farming does not save space

#147

Post by marshray »

throwaway894345 wrote: post #138
marshray wrote: post #130

Earlier quoted context omitted.

Rarely does one hear the sunk cost fallacy advocated so enthusiastically.

The sunk cost fallacy is about continuing to incur additional sunk costs. The parent is arguing that we're going to have to pay $X/year to manage the nuclear waste we've already incurred and that the cost is fixed--adding more nuclear waste isn't going to increase the cost. Whether those claims are true may be up for debate, but it's certainly not a sunk cost fallacy.

He's arguing (to paraphrase) "Because we've already incurred such costs we should continue or even expand the policy which caused them."

Claiming that hazardous nuclear waste represents a fixed cost no matter how much you generate is simply absurd.

Re: Vertical farming does not save space

#148

Post by cthreepo »

Nition wrote: post #17
kibwen wrote: post #7

> Artificial lighting saves land because plants can be grown above each other, but if the electricity for the lighting comes from solar panels, then the savings are canceled out by the land required to install the solar panels. This doesn't have to be the case. Plants don't use all the sunlight that hits them, because available light isn't generally the bottleneck in plant growth. Note how most plants are green, whic…

Say a plant needs 1/10th of actual full sun during the day, could you theoretically remove the electricity step entirely but "just" (putting "just" in quotes because I'm sure it wouldn't be easy) having some sort of fancy mirror setup on a 10 storey building to send 1/10th of the sunlight hitting the roof to each floor?

maybe if the plants are fixed on a very tall pole, and spaced some meters from each other, because of the sunrays inclination, all the plants on the pole can get sunlight. this will not save space in a big farmland setup, because then the poles need to be spaced from each other in proportion to their height, or they will cover the sun from the neighbour pole, bit this can make small isolated empty spaces useful for growing a lot of plants.

Re: Vertical farming does not save space

#149

Post by eatbitseveryday »

jasonwatkinspdx wrote: post #125
kibwen wrote: post #7

> Artificial lighting saves land because plants can be grown above each other, but if the electricity for the lighting comes from solar panels, then the savings are canceled out by the land required to install the solar panels. This doesn't have to be the case. Plants don't use all the sunlight that hits them, because available light isn't generally the bottleneck in plant growth. Note how most plants are green, whic…

> Note how most plants are green, which is to say they're content with reflecting the most energy-dense range of the visible spectrum. Photosynthesis is very complex, and there are reasons why plants shed about 10% of green light: https://science.sciencemag.org/content/368/6498/1490 . It's not that evolution was too dumb to discover the simple fact of green light being more energy dense, it's that there's other more…

Plants desire more stability in energy output from photosynthesis (e.g., clouds moving overhead) at a lower level, rather than attaining maximum output. Trying to always maximize output means you'll have high fluctuations in energy output.

Re: Vertical farming does not save space

#150

Post by mytailorisrich »

Retric wrote: post #116
maxharris wrote: post #59

Artificial lighting saves land because plants can be grown above each other, but if the electricity for the lighting comes from solar panels, then the savings are canceled out by the land required to install the solar panels. The vertical farm is a paradox unless fossil fuels provide the energy. In that case, there’s not much sustainable about it. This entire piece is based on the assumption that the only sources of…

Commercial nuclear takes up a lot of space, to the point where replacing it with solar is surprisingly close. For example the the Brunswick nuclear power plant in North Carolina, covers 1,200 acres or 4,860,000 square meters for 1,858 MW = 382 w/m2. It’s stated lifetime capacity factor is 75% which is much higher than solar, but that’s ignoring the long construction and decommissioning process afterwards. You can fin…

That's the whole land belonging to the site, most of which is nature, not the plant itself, which looks like less than 200 acres, including the car parks.

In any case, it's not close at all either for that specific example or in general, not least considering that a nuclear plant can produce 24/7 and that solar often does not reach peak production because of the weather.

"A solar PV facility must have an installed capacity of 3,300 MW and 5,400 MW to match a 1,000-MW nuclear facility’s output, requiring between 45 and 75 square miles. For comparison, the District of Columbia’s total land area is 68 square miles." [1]

[1] Nuclear Energy Institute @ https://www.nei.org/news/2015/land-needs-for-wind-solar-dwar...

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