6 ms·

>The biggest drawback of vertical farming is the high cost of the electricity required to run the large number of LEDS...One way of saving electricity is to use

by sxp 7y ago

>The biggest drawback of vertical farming is the high cost of the electricity required to run the large number of LEDS...One way of saving electricity is to use LED s that generate only the colours that plants require, instead of the full spectrum of plain white light. This is a big issue and I've been unable to get good data on it. Opponents of vertical farms say that the high electrical consumption doesn't justify the reduction in energy related to travel. Proponents say that it's possible to optimize LEDs and have continuous fake "seasons" which justify the cost of transportation & refrigeration for certain species of food. Does anyone have any good references that go into the details and provides numbers? Most of the pro-vertical farming information I've found is from companies who are investing in it so they consider the energy numbers to be a trade secret. But there must be some research group or open source team willing to publish all their data so that people can draw their own independent conclusions.

nkingsy 7y ago
Not sure what numbers you’re looking for. Lettuce with state of the art horticultural leds probably can be grown optimally with as little as 10 watts per square foot. Flowering plants need much more and more full spectrum.
- kragen 7y ago
  In non-medieval units, that's 110 W/m², 9 times less than direct sunlight. Couldn't you get those low-light conditions more cheaply by stacking lettuce trays in a sunlit greenhouse, with lightpipes to shade the upper levels and get the requisite amount of weak illumination to the lower levels? (Edited to correct the calculated values.)
  - TaylorAlexander 7y ago
    10 W/sq ft is 107 W/sq m.
    - kragen 7y ago
      Thank you for the correction! My calculation error (I had written "11 W/m², 90 times less than direct sunlight"), though unintentional, is an excellent demonstration of why using medieval units is a bad idea.
      - Dylan16807 7y ago
        Being off by a factor of ten is very easy with SI units too. Centimeters vs. millimeters for example.
        kragen 7y ago
        Yeah, and I've certainly made that mistake more than once. (I try to avoid using centimeters or centi-anything for that reason, as well as deci-, deka-, and hecto-.) In this case, though, the calculation I biffed was a unit conversion from medieval units to modern units. It's harder to get calculations wrong when you don't have to do them at all.
  - rini17 7y ago
    Weather would then affect the production, making schedules unpredictable. Plus, I am no expert but I guess you can't make plants actually use much more than 100W/m2 for photosynthesis, the rest of sunlight consists of unsuitable wavelengths. It ends up as waste heat that you'd have to cool away. Perhaps if you could efficiently convert green and infrared parts of sunlight to red/blue, that could help.
    - kragen 7y ago
      You mean because sometimes it's cloudy? Couldn't you solve that problem by turning on LEDs just when it's cloudy? Plants are pretty inefficient, it's true, but I don't think they're very efficient even with optimal wavelengths. But, yes, solar cells and LEDs can indeed convert green and infrared sunlight to red and blue, with about 3% efficiency under normal circumstances.
      - infogulch 7y ago
        If your plan is "light pipes, but fall back to LEDs" that means you have to build two complete systems. You get double the installation costs, incur the combined complexity of both systems (plus overhead), and box yourself into the limitations of both systems.
        kragen 7y ago
        That might be true, but I'm not sure it is. It seems to me that you escape the limitations of both systems. Also, I think lightpipe daylighting generally costs orders of magnitude less than sunlight-comparable LED illumination, although I don't have firm numbers on lightpipe costs; so I don't think the installation costs double, just increase slightly. If we're talking about a greenhouse, where a leaky roof is a minor annoyance comparable to a leaky faucet, rather than a life-destroying disaster, lightpipe costs should go down quite a bit compared to their use in office and residential daylighting. The big question for me is, if you're going to build a hothouse, why would you build it with an opaque roof? That just seems perverse, like writing an HTTP server in bash or assembly language or something: http://canonical.org/~kragen/sw/dev3/server.s http://canonical.org/~kragen/sw/dev3/server.s
  - nkingsy 7y ago
    Building material units in the US are in feet and inches so it’s my point of reference for building projects eg indoor growing
    - kragen 7y ago
      I bet you don't know off the top of your head how many watts per square foot sunlight is, though --- and that's the most relevant point of comparison. (Or horsepower, or Btus per hour, or whatever crazy unit.)
- bjelkeman-again 7y ago
  That seems about right, based on our lighting plan for our pilot plant.
deleted 7y ago
[deleted]
bjelkeman-again 7y ago
There isn’t much to be secret about really. When you ask any of the big LED suppliers, like Philips or Hortilux, for a quotation, they ask what you are planning to grow and they give you a lighting plan. The energy usage is relatively predictable, if you know how the building you are in is insulated and you know your ventilation requirements. It isn’t trivial, but it is possible to do the numbers. We will be publishing some data from our pilot installation next year (approx 250 m2 building, 100 m2 active growing area, 30 m3 water). It isn’t a vertical installation, but a Deep Water Culture (DWC) aquaponics installation. We are in the final stages of building it right now. Spent all day working on the decking around the fish tanks.
- cagenut 7y ago
  anything you share will be much appreciated.
  - bjelkeman-again 7y ago
    It will be shared over here (not much content yet and ugly, but release early etc.) Translations to come. http://cirkularodling.se/ http://cirkularodling.se/
- Razengan 7y ago
  On a tangent, I gotta say I love HackerNews for getting to hear from people working on such projects.
- wallflower 7y ago
  On a tangent, in case you missed this https://medium.com/invironment/an-army-of-ocean-farmers-on-the-frontlines-of-the-blue-green-economic-revolution-d5ae171285a3 https://medium.com/invironment/an-army-of-ocean-farmers-on-t...
ajuc 7y ago
I heard about a startup that does specialized artificial lighting for farmers: http://plantalux.pl/en/home/ http://plantalux.pl/en/home/ They have some data http://plantalux.pl/en/plantalux-ex300w-en/ http://plantalux.pl/en/plantalux-ex300w-en/
lpasselin 7y ago
You might be interested in user superangryguy on Reddit. He experiments with led and has detailed information on LED and plants. He has a patent for growing smaller plants, by lighting with blue light on the stem.

by sxp 7y ago

nkingsy 7y ago

Not sure what numbers you’re looking for. Lettuce with state of the art horticultural leds probably can be grown optimally with as little as 10 watts per square foot. Flowering plants need much more and more full spectrum.

kragen 7y ago
In non-medieval units, that's 110 W/m², 9 times less than direct sunlight. Couldn't you get those low-light conditions more cheaply by stacking lettuce trays in a sunlit greenhouse, with lightpipes to shade the upper levels and get the requisite amount of weak illumination to the lower levels? (Edited to correct the calculated values.)
- TaylorAlexander 7y ago
  10 W/sq ft is 107 W/sq m.
  - kragen 7y ago
    Thank you for the correction! My calculation error (I had written "11 W/m², 90 times less than direct sunlight"), though unintentional, is an excellent demonstration of why using medieval units is a bad idea.
    - Dylan16807 7y ago
      Being off by a factor of ten is very easy with SI units too. Centimeters vs. millimeters for example.
      - kragen 7y ago
        Yeah, and I've certainly made that mistake more than once. (I try to avoid using centimeters or centi-anything for that reason, as well as deci-, deka-, and hecto-.) In this case, though, the calculation I biffed was a unit conversion from medieval units to modern units. It's harder to get calculations wrong when you don't have to do them at all.
- rini17 7y ago
  Weather would then affect the production, making schedules unpredictable. Plus, I am no expert but I guess you can't make plants actually use much more than 100W/m2 for photosynthesis, the rest of sunlight consists of unsuitable wavelengths. It ends up as waste heat that you'd have to cool away. Perhaps if you could efficiently convert green and infrared parts of sunlight to red/blue, that could help.
  - kragen 7y ago
    You mean because sometimes it's cloudy? Couldn't you solve that problem by turning on LEDs just when it's cloudy? Plants are pretty inefficient, it's true, but I don't think they're very efficient even with optimal wavelengths. But, yes, solar cells and LEDs can indeed convert green and infrared sunlight to red and blue, with about 3% efficiency under normal circumstances.
    - infogulch 7y ago
      If your plan is "light pipes, but fall back to LEDs" that means you have to build two complete systems. You get double the installation costs, incur the combined complexity of both systems (plus overhead), and box yourself into the limitations of both systems.
      - kragen 7y ago
        That might be true, but I'm not sure it is. It seems to me that you escape the limitations of both systems. Also, I think lightpipe daylighting generally costs orders of magnitude less than sunlight-comparable LED illumination, although I don't have firm numbers on lightpipe costs; so I don't think the installation costs double, just increase slightly. If we're talking about a greenhouse, where a leaky roof is a minor annoyance comparable to a leaky faucet, rather than a life-destroying disaster, lightpipe costs should go down quite a bit compared to their use in office and residential daylighting. The big question for me is, if you're going to build a hothouse, why would you build it with an opaque roof? That just seems perverse, like writing an HTTP server in bash or assembly language or something: http://canonical.org/~kragen/sw/dev3/server.s http://canonical.org/~kragen/sw/dev3/server.s
- nkingsy 7y ago
  Building material units in the US are in feet and inches so it’s my point of reference for building projects eg indoor growing
  - kragen 7y ago
    I bet you don't know off the top of your head how many watts per square foot sunlight is, though --- and that's the most relevant point of comparison. (Or horsepower, or Btus per hour, or whatever crazy unit.)
bjelkeman-again 7y ago
That seems about right, based on our lighting plan for our pilot plant.

deleted 7y ago

[deleted]

bjelkeman-again 7y ago

There isn’t much to be secret about really. When you ask any of the big LED suppliers, like Philips or Hortilux, for a quotation, they ask what you are planning to grow and they give you a lighting plan. The energy usage is relatively predictable, if you know how the building you are in is insulated and you know your ventilation requirements. It isn’t trivial, but it is possible to do the numbers. We will be publishing some data from our pilot installation next year (approx 250 m2 building, 100 m2 active growing area, 30 m3 water). It isn’t a vertical installation, but a Deep Water Culture (DWC) aquaponics installation. We are in the final stages of building it right now. Spent all day working on the decking around the fish tanks.

cagenut 7y ago
anything you share will be much appreciated.
- bjelkeman-again 7y ago
  It will be shared over here (not much content yet and ugly, but release early etc.) Translations to come. http://cirkularodling.se/ http://cirkularodling.se/
Razengan 7y ago
On a tangent, I gotta say I love HackerNews for getting to hear from people working on such projects.
wallflower 7y ago
On a tangent, in case you missed this https://medium.com/invironment/an-army-of-ocean-farmers-on-the-frontlines-of-the-blue-green-economic-revolution-d5ae171285a3 https://medium.com/invironment/an-army-of-ocean-farmers-on-t...

ajuc 7y ago

I heard about a startup that does specialized artificial lighting for farmers: http://plantalux.pl/en/home/ http://plantalux.pl/en/home/ They have some data http://plantalux.pl/en/plantalux-ex300w-en/ http://plantalux.pl/en/plantalux-ex300w-en/

lpasselin 7y ago

You might be interested in user superangryguy on Reddit. He experiments with led and has detailed information on LED and plants. He has a patent for growing smaller plants, by lighting with blue light on the stem.