[Mountain_Skies]

If (a really big IF) solar panels can get efficient enough while LEDs also become more efficient, in theory plants grown indoors being fed by LEDs attuned to the precise portions of the spectrum they need with the whole thing powered by the solar panels, you could get a better yield than outdoor growing. Figure out cost effective fusion, things get even better. But neither is the case right now.

As far as the urban agriculture crowd goes, they're concerned about the length of their logistics lines to their tables. Raspberries grown half a mile down the street in winter is better for the environment than flying them in from another hemisphere... provided you get the energy costs of the indoor farming system low enough.

[Retric]

Until you genetically engineer a more efficient plant and your back to a net loss even assuming absolutely free panels and LED’s etc.

Vertical farming only really works as either artistic preference for maximum visual appeal or the kind of science fiction where you assume only a small handful of technology advanced.

[pault]

If you can genetically engineer a more efficient plant for growing in a field, you can genetically engineer a plant that's more efficient to grow under LEDs, no? I don't see how a hypothetical breakthrough in generic engineering makes vertical farming a mad fantasy. There are certain crops that can't be grown in high yield monocultures and have to be transported from other parts of the world. I'm sure there are many cases where the math works, and I don't think most people are talking about growing corn indoors when they talk about vertical farming.

[Retric]

If a genetically engineered plant gathered energy equally across the full spectrum then frequency shifting using solar > LED is absolutely pointless even at 100% efficiency. Solar panels and leaves are solving the same problem using the same physical laws.

But that’s hardly required as solar panels to LED’s can’t reach 100% efficiency. Further, the limited lifespan of solar panels and LED’s means you need to cover their construction etc which requires resources.

Ultimately, looking at theoretical limits it’s simply a net loss.

PS: Monoculture is far from required, it’s an outgrowth of current automation rather than having any theoretical advantage.

[AngryData]

There is no need to breed plants specifically for LED lights. All the newest and most efficient and cost effective LEDs are white spectrum now and emulate the sun far closer than any other light ever has. What matters is how efficiently can you make the lights run, and right now it is pretty damn good getting about 200 lumens per watts on those grow LEDs (versus about half that for a shitty standard household LED)

[LargoLasskhyfv]

Isn't it counterproductive to waste LEDs optimized for our perception to plant growth which doesn't fully utilize the spectrum of sunlight? I thought that is WHY grow lights have this purple sheen, be it traditional flourescent ones, or contemporary LEDs, or a mix of red and blue ones.

[AngryData]

Despite the 'common knowledge', plants do utilize most of the visible light spectrum, even green, just in different amounts. And on top of that these white LEDs aren't just a single static white, their light spectrum are tuned to specific growth spectrum and can be ordered however you want, but all come out visibly to us as white of slightly different shades.

Those blurple lights are just awful, and not only do the LEDs have far less energy efficiency being old tech, but their supposed "optimal" wavelengths are anything but. They are blasting out extremely narrow wavelengths of light and trying to make it more continuous by using a bunch of slightly different narrow range colors, but it doesn't work as well as one would hope, especially when they are coming from different point sources.

[wallacoloo]

> As far as the urban agriculture crowd goes, they're concerned about the length of their logistics lines to their tables. Raspberries grown half a mile down the street in winter is better for the environment than flying them in from another hemisphere.

Aside from environmental effects, it’s also just a more secure logistics chain. A person needs water, food, and shelter to survive. Sometimes it feels strange to me that the trend of the past centuries has been to increase the distance between a person and those sources — to introduce more points of failure between you and the things you need in order to survive.

[fyfy18]

Another commenter mentioned it's more energy efficient to grow tomatoes in Spain - where less heat is needed - and fly them to the UK. That may be true, but an even better way is to just grow crops that are suitable for that season.

In the UK you can grow crops all year round outdoors [0], and the growing seasons could easily be extended with a passive greenhouse (polycarbonate is more insulating than glass). You can also use tried and tested preservation techniques like canning and fermenting to keep food for other seasons.

[0] https://www.gardenorganic.org.uk/vegetables-all-year-round

[AngryData]

Unless you do pull out fusion, you will always have too huge loss between solar panels and LEDs. As efficient as LEDs are now, and I know because I just built 1200 watts of the latest and most efficient LEDs that are available, they are nowhere near cost effective in comparison tot he sun. Plants are not nearly as inefficient as people believe, especially when you consider the fact that solar panels themselves can also only absorb a small fraction of the light spectrum.

That 1200 watts is only really covering a 6 by 6 foot square worth of growth area at about 35 watts a square foot at 200 lumens per watts. It could be slightly larger but only if you want most plants to grow extremely slow or be really weak, and you can go up to 50 watts per square foot before requiring supplemental CO2 but not all plants like that amount of light.

Converting that to 1 acre worth of coverage, which is what is about what is needed to feed a single human for one year, you are looking at about 1,500,000 watts running 12-18 hours per day. That is a ridiculous amount of energy. Even assuming you can get away with 1/3 of that area by super careful and efficient growth year round that is still a half million watts in lighting costs alone. Not to mention all the other work and costs.

I don't see indoor farms being good for anything other than extreme specialty plants or extremely fragile plants until we can pull essentially limitless energy out for far cheaper than we can get even with fossil fuels.

[bjelkeman-again]

I am curious about the 36 sqft (3.34 square meter) and 1200 watt. As we end up with considerably less watt per area. We use about 100 watt per square meter. You have about 360 watt per square meter. So we use less than a third. Preliminary tests show very good growth rates. We will have better data in a few months.

This is for an indoor leafy green, mostly sallad, aquaponics growing facility.

[AngryData]

Technically I can still get growth down to 11-12 watts, closer to your levels, but it is definitely much slower growth and it won't be enough later on. Technically I run about 20 watts during the initial vegetative state, but once plants start flowering or fruiting there is a markedly different end result if I don't turn the lights up to around 35 watts a square foot, which is what most other people ive seen report. I mostly just run it at 35 all the time because I want them fruiting and producing as much as they can as fast as possible. But if you are growing leafy greens your plants are never even entering the flowering stage because you will be picking it by then.

Perhaps with a bigger more automated setup I could do slower growth, but there are other costs like ventilation or dehumidification or possibly heating or cooling too that don't really change a lot whether the plants are growing fast or slow, which makes faster growth possible optimal financially, even if I might be losing out a few percentage worth of light absorption.

[bjelkeman-again]

Ok, we don't have fruiting plants. So that can make a difference.

[mrfusion]

Indoor you could surround the plant with mirrors so more light gets input into the plant. Also no wasted water.