Yeah, just burn terawatts of fossil fuels to generate light for growing your crops instead of using solar energy and natural photosynthesis.
One thing that does occur to me is that artificial lighting wouldn't be limited by the passage of the sun, so crop growth could potentially continue 24 hours a day.
It's extremely costly to provide sufficient light to grown plants, as photosynthesis isn't terribly efficient. Natural sunlight is significantly stronger than what people tend to expect.
Not only that, but you would need to move massive amounts of air to keep the plants happy, plus the humidity from being underground and all the water they need. Beyond that, you need to go quite a bit underground to feed a sufficient number of people, which isn't always feasible depending on the type of soil and water table, etc
Final note, most plants do better not getting 24 hours of light. They can only grow just so fast and need to photosynthesize just so much.
That's a lot of work (meaning higher prices for people who need to eat) for very little gain.
As for LED grow lights, you typically use about 30-40 watts / square foot. That's a not insignificant added cost compared to growing above ground.
The added challenges to growing underground simply make it irrational.
https://sustainabledish.com/vertical-farms-thermodynamic-non...
"It turns out it would take about 4.5 acres of solar cells for every one acre of plant growth space" well that implies that the 100x efficiency factor has actually been met for lettuce but jaegerpicker didn't seem too keen on telling you. The obvious problem though is that solar panels are only 20% efficient hence roughly 5 acres of solar per 1 acre of vertical farming grow space.
I have other resources should you wish and I ton of personal experience. I have 3 Hydroponic systems (1 off the shelf, 2 custom designed by me) and 2 Aquaponics systems. The custom ones took 3 months to recoup the costs of materials vs the cost of produce, though the liquid fertilizer is a cost and input that I don't love. I've switched most of my effort to Aquaponics (Aquaculture - raising fish, which provides a natural fertilizer), I have 1 microsetup growing herbs and microgreens that has been running for 1 year. Only inputs are water and fish food, I clean it 1 once every 3 months since the plants act as a natural filter to clean the water.
One is being built minutes from my house https://verticalharvestfarms.com/locations/westbrook-maine/
Also The Netherlands are leading the world at this type of farming, here is a short video about it https://www.youtube.com/watch?v=5clOYWsNhhk
[1] https://www.statista.com/statistics/196104/total-area-of-lan...
[2] https://en.wikipedia.org/wiki/Solar_irradiance
[3] https://www.eia.gov/energyexplained/electricity/electricity-...
PPFD is a measure of photosynthetic active radiation, PAR for short. PAR is not a measure of anything itself but is more of a description. PAR light is all the visible wavelengths of light which cause photosynthesis, found within the 400-700 nanometer range. PPFD is a ‘spot’ measurement that tells you how many photons from the PAR range hit a specific area of your canopy over time. It is expressed as micro moles per square meter per second (μmol/m2/s). For this reason, PPFD is the most accurate measure of light power. First, unlike other measures, it considers the entire spectrum of light that plants see. PPFD also takes into account the amount of light that will actually reach the plant instead of focusing only on the point of origin. A light source can be very bright and powerful, but if it is too away from the plant, or obstructed in some way, the plant won’t be getting all the light it needs for photosynthesis. PPFD controls for this kind of inaccuracy.
With LED's you can place the plants much closer to the light source and control the color spectrum along with the obstructions 24/7. It allows you to grow indoors at an extremely efficient rate. Your formula has almost nothing to do with indoor farming.
https://www.freightfarms.com/blog/indoor-grow-lights#:~:text....
Here are some additional sources: https://archipel.uqam.ca/1619/1/1998_025_Gendron.pdf https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1066711/pdf/pln... https://www.researchgate.net/profile/Paul_Hanson7/publicatio... https://www.horti-growlight.com/en-gb/par-ppf-ypf-ppfd-dli#:.... https://www.sciencedirect.com/topics/medicine-and-dentistry/...
Quick summary: PPFD measures the amount of light wavelengths that the plant captures that kicks off the chemical reaction of Chlorophyll. Red and Blue lights are the vast majority of wavelengths that interact with Chlorophyll. That's a major reason why the solar irradiance measure of pure Wattage is irrelevant.
>That's a major reason why the solar irradiance measure of pure Wattage is irrelevant
You are quite literally missing the tree for the forest. Parent assumes that photosynthesis is 1% efficient with sunlight so he added the 100 factor to estimate how much energy plants would need if photosynthesis was 100% efficient and you could skip photosynthesis just feed plants energy straight from the power grid and on top of that he is assuming you can turn 100% of solar radiance into electricity.
If we assume 20% efficient solar panels your growing lights need to be 500 times more effective or power efficient than sunlight.
You should have based your argument on arguing that the vast majority of acres that the parent used are e.g. suitable for solar panels but not for farming plants and hence the number of acres is unfairly bloated. But all I see is excuses in trying to tell people how your growing lights are going to be 500 times more efficient when we know that isn't going to happen.
He already abstracted over that by using efficiency.
>none of the math you did matters at all.
One would have expected an increase in coverage to increase efficiency by 10 vs sunlight which would have require explaining another factor 10 which could have been explained by e.g. saying that converting useless wavelengths into useful wavelengths increased efficiency by 10.
You're arguing that the things you have said do not increase efficiency. That is even more damning than a ridiculous efficiency gain.
Vertical farming uses a lot of electricity.
>You need light coverage not heat wattage!
The 100x efficiency factor already implies that the plant can absorb heat for photosynthesis. None of that "heat wattage" is being wasted.
The math that shows how much electricity must go in to have the equivalent amount of plants come out.
Watt per PPFD or something along those lines.