Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Vertical farming does not save space

lowtechmagazine.com

Post reply on HN
Print view View original

331–340 of 464 posts

Re: Vertical farming does not save space

#331

Post by modriano »

tvanantwerp wrote: post #304
modriano wrote: post #301

Judging vertical farming based on the performance of wheat is not valid. When I saw the test crop was wheat, I scrolled to see if there were any other crops, saw that there weren't, and abandoned the article because wheat has among the worst yields per area (in terms of kg of edible product per sq meters). Since the pandemic started, I started experimenting with hydroponics and I've been growing basil, kale, mint, ch…

As a new homeowner who has never gardened before, I'm curious how to get started doing something like your hydroponics setup.

For someone looking to get started, with the knowledge I've gained over the past year, I'd recommend starting with a Kratky grow [0]. It's extremely simple and extremely inexpensive (you basically just start some seedlings in rockwool [1], then when seedlings are an inch or two tall, transplant them into a container with nutrient solution in it. A lot of videos and online articles are very finicky, but from trial and error, the only things I've discovered that really matter are A) the pH of your water (pH impacts plants ability to absorb nutrients [2], anywhere in the range of 5.0 to 6.5 has been fine for me), and B) the amount of light your plants get (suspend your light(s) so you can always keep it a few inches above your plants).

To do any kind of hydroponics grow, you'll need (and you can pick up most of this locally (for far less than on Amazon) at a garden center or hydroponics store if available):

  - a way to measure pH (you can get strips for next to nothing, or an electric meter (~$15 for a cheapo one, maybe $40 for a reliable one))
  - a way to adjust the pH [3]
  - nutrients (I have just used FloraDuo 5-0-6 [4] without issue, 2ml per liter of water has been perfect)
  - a way to start your seedlings (I've used rockwool [5] in a clear rubbermaid bin)
  - lights (doesn't have to be fancy [6])
  - containers for nutrient solution (could be a bucket from home depot with a hole drilled in the top for net cups [7])
  - seeds (any home improvement store with a garden center will have a stand with all kinds of seeds to pick from)
Things that make it much nicer (but are unnecessary if you don't know if you want to stick with this hobby):

  - Timers for your lights [8] 
  - Basically everything in this kit [9] except for the netting, grow bags, and "odor control filters" (unless you want to grow that specific plant with the very particular and easily identifiable odor, and you don't want the odor).
Regarding my own build, the setup I built was needlessly complicated, as I'm an engineer and I tried to automate as much as possible. I made a germination station (with a heating pad and tray [10] with a temperature controller [11]) for seedlings, and I picked an aeroponics setup (aeroponics is a form of hydroponic growing where plant's roots dangle above the nutrient solution and are intermittently sprayed or trickled on; this is approximately the build [12]), and if I hadn't been in my house all the time, I probably would have abandoned it in June (but I'm really glad I didn't, it's been a lot of fun). After I got everything built, it's been maybe 40 minutes of work a week (mostly checking the nutrient levels, mixing up nutrient solution, and harvesting plants). Maybe someday I'll make an even more automated system like this [13] where I don't even have to think about pH level and nutrient solution is automatically mixed and added.

  [0] https://youtu.be/5z0NaYpVHMs?t=7
  [1] https://youtu.be/AMlCdm_yVvc
  [2] http://rodsgardening.com/pH.htm
  [3] https://www.amazon.com/General-Hydroponics-pH-Control-Kit/dp/B017XTFKE6/
  [4] https://www.amazon.com/General-Hydroponics-FloraDuo-Mineral-Nutrient/dp/B004PPY750
  [5] https://www.amazon.com/Rockwool-Starter-Twin-Canaries-Chart/dp/B07KJVQ6T5
  [6] https://youtu.be/lT8acb5WTT0
  [7] https://www.amazon.com/xGarden-Lightweight-Economy-Hydroponics-Aquaponics/dp/B07W9H8ZRH
  [8] https://www.amazon.com/Century-Indoor-24-Hour-Mechanical-Outlet/dp/B01LPSGBZS
  [9] https://www.amazon.com/Spider-Farmer-Complete-Spectrum-Compatible/dp/B088R3JHHD
  [10] https://www.amazon.com/CK64050-Germination-Station-Listed-72-Cell/dp/B000HHO1RO/
  [11] https://www.amazon.com/Century-Thermostat-Controller-Germination-40-108°F/dp/B01I15S6OM
  [12] https://youtu.be/edtYDsMthC4?t=67
  [13] https://youtu.be/nyqykZK2Ev4

Re: Vertical farming does not save space

#333

Post by AngryData »

klodolph wrote: post #28
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…

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…

Blurple and magenta LEDs seem to be on their way out last time I looked into growing lights. It is white (or white appearing) LEDs now, which are getting 190+ lumens per watt. The light spectrum is still tuned for plant growth efficiency, but it is a broader spectrum per LED rather than more specific spectrums from specific diodes.

It is worth noting too that these newer white LEDs are spectrum efficient enough that people growing with them have had to turn up the overall room temperatures to compensate for the drop in leaf temperatures created by "waste" wavelengths that the sun and old sodium bulbs use to provide.

Re: Vertical farming does not save space

#334

Post by Seb-C »

pfdietz wrote: post #275
tinco wrote: post #267

Earlier quoted context omitted.

It was an honest question. I don't know which specific regulations, I've never built one but I have heard those who did lament the cost and trouble in even obtaining a site. From what I can see fission reactors are doing just fine in France and Belgium. I don't know the specific numbers but the French don't seem worse off economically, despite having the greenest grid on the planet. Fission has a number of disadvanta…

It was a leading question, pretending to claim that regulation was the cause. Nice walkback, though. Nuclear is in a bad state in France. Their recent attempts to build new reactors have gone massively over budget. Existing reactors are aging and it looks like they cannot replace them. Fission has some disadvantages over fusion, but those disadvantages won't make fusion cheaper than fission (the costs of fuel and was…

> Nuclear is in a bad state in France. Their recent attempts to build new reactors have gone massively over budget. Existing reactors are aging and it looks like they cannot replace them.

This is a political problem which has nothing to do to with technology or costs themselves.

Most infrastructures are aging and in a bad state in France, and the skills and knowledge to build or replace it has long been lost.

Add on top of this politically strong ecologist-extremists who decided that nuclear is evil and must be gone, and who will do everything to sabotage any project.

To take a counter example, nuclear is doing fine and growing in many countries, including China.

Re: Vertical farming does not save space

#335

Post by selectodude »

southerntofu wrote: post #314
exporectomy wrote: post #226

Earlier quoted context omitted.

What makes you think fusion power will be cheaper than solar, wind, fossil fuels or fission? Efficiency isn't really a good metric when the fuel is free. We see that in solar power where expensive high efficiency devices lose out to cheaper less efficient ones. It's more about capital cost and operating cost per unit of energy.

To elaborate on the topic, there is ample evidence that nuclear energy is by far the most expensive source of energy, when you take into account the government (for example here in France) entirely subsidizing the construction and hypothetical demolition. I say hypothetical because french attempts at "safely dismantling" nuclear power point are not going so well and are over-budget by an order of magnitude. Then thes…

I'm always kind of curious as this "expensive" line of thinking. Yes, nuclear is expensive. Extremely expensive. But is it more expensive than a week's worth of catastrophic grid collapse due to global warming? We have the ability to build nuclear plants. We can reprocess the waste to make more energy with. We can get better at it to drive down the price. It's more reliable as a base load than any renewable.

My state gets over fifty percent of its energy from nuclear power plants. I pay a few pennies more per kWh than neighboring states. I'd pay a few more pennies than that to figure out the rest of this issue.

Re: Vertical farming does not save space

#336

Post by Armisael16 »

klodolph wrote: post #139
bsder wrote: post #114

Earlier quoted context omitted.

> It’s worth remembering that the reason why plants only absorb certain parts of the spectrum is the same reason why photovoltaic panels only absorb certain parts of the spectrum Plants are green because they value light consistency instead of total energy . Green light has too many peaks and valleys and can overload the photosynthesis systems so they reflect a lot of it. It's the "renewables without batteries" probl…

> Green light has too many peaks and valleys and can overload the photosynthesis systems so they reflect a lot of it. This doesn’t make any sense to me. Why would peaks and valleys overload something? Why would green light have more peaks and valleys? I was a bit sloppy with the way I phrased that—what I really meant was “the reason why plants use specific quanta of light is the same reason why photovoltaics absorb s…

I don’t know if this is what the previous poster was getting at, some there is some theoretical evidence that the absorption wavelengths used in photosynthesis are not tuned for maximum power input but for stable power input: https://arxiv.org/abs/1912.12281

If this is the case it would be a motivation that is fundamentally very different than that of a multijunction solar cell.

Re: Vertical farming does not save space

#337

Post by olliej »

@maxharris pointed out the article’s fib about power generation, but the ignore the other important aspect.

Vertical farming does not require the farm be in the same location as the power generation. This allows production closer to population centers, and in climates where production would be otherwise non viable.

Re: Vertical farming does not save space

#338

Post by mortdeus »

isn't vertical farming just moving land that was in the horizontal direction, into the vertical direction then creating a complication where the plants grown under the top rows need to be fed by an artificial source of light?

I mean I think this is actually pretty logical because you can't place the solar panel above the top plants because then you are losing the advantage typical horizontal farming gets from being able to directly be fed by the sun, so then you have to place the solar panel next to the plant?

The real question is whether this can save space, is whether you can generate more energy from a solar panel that takes up the same amount of space a plant would require if planted horizontally, than said plant could absorb from the sun directly.

Plants take up much more space than one would expect because their roots branch out further than the actual circumference of the actual plant body itself. So in that way a lot of sunlight is wasted because it hits the extra area of soil the roots need but the actual plant body doesn't. Now if instead of hitting soil, it is instead hitting a solar panel then the general question is whether or not this is creating more efficient use of the sun, because even with a minor improvement in efficiency you should "theoretically" be able to save a considerable amount of space when growing at scale.

Whether it will be cheaper to grow this way, probably not because with vertical farming obviously will come with a ton of logistical problems when it comes to harvesting or maintenance/construction of infrastructure. But I don't see how growing three plants vertically with a solar panel that feeds the bottom two is technically not saving space unless you need more area of solar panels sitting next to them than all 3 plants would consume had you just planted them all next to each other.

In other words would you need 2 or more solar panels + the sun to feed 3 horizontal plants? If so then just plant them horizontally and let the sun do all the work.

Re: Vertical farming does not save space

#339

Post by Armisael16 »

frankus wrote: post #324
LeifCarrotson wrote: post #134

Earlier quoted context omitted.

Close, it's 1/10th of the spectrum not 1/10th of the intensity. The 'fancy mirrors' required would simply be a prism. You'd separate out the red and blue light and aim it at the plants, and send the green and infrared light to solar cells, to be used for running red and blue LEDs. (Or you could use flourescence if you had something that glowed red or blue when exposed to green or IR light). Check out this spectral pl…

Are there materials that fluoresce at a shorter wavelength than what they absorb? I was under the impression that it was a one-way thing (absorb short wavelength and emit longer wavelength).

Yes. Some materials absorb multiple photons for each one they emit and thus have enough energy to emit at shorter wavelengths. Cesium vapor is one (though probably not a good choice for this application!).

Re: Vertical farming does not save space

#340

Post by grawprog »

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…

Not only that, but, even if we were just talking straight solar, solar panels don't have to be built on arable land. There's a lot more land available for building solar panels than there is available arable farmland.
Post reply on HN