I just can't see how this can replace conventional farming at scale. Currently, outdoor farming uses 4.62 billion acres [1]. The article says indoor farming has 25x the yield per acre. So that would be 177 million acres. Today, there are only about 44 million acres of total buildings in the world [2]. So to replace conventional farming, we'd need to build 4x as many buildings as currently exist; what's the environmental impact of _that_?
But the real deal-breaker is energy. Outdoor farming gets energy naturally from sunlight. Indoor farming is powered by LED lights. LEDs could be more efficient than sunlight by only emitting the frequencies that are most useful for plants; but on the other hand, I suspect that they might need to be brighter than sunlight to achieve 25x the yield per acre. So let's estimate it's exactly as bright as sunlight. To light 177 million acres exactly as bright as sunlight, you'd need somewhere around 3,000,000 terawatt-hours per year. For comparison, global electricity consumption is around 25,000 terawatt-hours per year [3]. So to replace conventional farming, this would need about 100x as much electricity as the current global electrical grid can supply!
So until we get fusion power, I doubt this is practical.
That's until they manage to stack vertically six layers of planted wheat, then you have 156x the yield per acre. You don't need to move all farming indoors either to create a big impact, if some countries manage to move indoors only 20% of the farming for instance, that's already a huge change by any possible measure, be it environmental, economic or geopolitical.
And also your remark about the energy cost doesn't seem correct, if that were true any kind of indoors agriculture would be too expensive to be possible.
But if you stack six layers, each layer needs its own set of LEDs, or else the lower layers wouldn't get any light; so the energy usage per unit of wheat is the same.
(In fact, if you look at the photos and video on https://www.infarm.com/vision, it seems like they're already doing multiple layers, each layer with its own set of LEDs; so the energy-usage-per-acre is probably already significantly more than direct sunlight.)
> And also your remark about the energy cost doesn't seem correct, if that were true any kind of indoors agriculture would be too expensive to be possible.
My understanding is that commercially-viable indoor agriculture works by focusing on expensive foods that are not very energy-dense, like fresh leafy greens. According https://www.nature.com/articles/s41586-018-0706-x, the cost of electricity to grow fresh leafy greens indoors is 1% of what they can be sold for. But to grow tomatoes, the cost of electricity is 18% of the selling price; and to grow grains, the cost of electricity is 10,000% of the selling price!
Ok so let's run with this a bit. The US uses on average 90 million acres of land annually for grain production. If we stack 10 deep we'd need a 8-10 story structure the size of Vermont.
I've been doing this for almost a full decade, so can say with quite a lot of certainty that you can safely put your suspicions to rest. We even have tech to grow various crop types to harvest stage without needing light at all.
Sorry, but I'm still quite skeptical; I'm going to need you to make a specific case, not just ask me to trust you because you're in the vertical farming industry.
> so can say with quite a lot of certainty that you can safely put your suspicions to rest
I took a closer look at https://www.infarm.com/vision, and it seems that the way they achieved 25x the yield per acre was by stacking multiple layers. So each layer needs its own set of LEDs. How bright is each layer of LEDs, compared to sunlight? According to https://en.wikipedia.org/wiki/Photosynthetic_efficiency, only about 45% of sunlight is in the part of the spectrum that plants can use; so if you grow crops with purple LEDs, you could use only 45% as much energy as sunlight. But if you're getting 25x the yield-per-acre by having 3 layers, then you're using 3*45%=135% as much energy-per-acre as sunlight.
I admit I'm not an expert, and these numbers are very rough estimates. Feel free to point me to a source that gives more specific numbers for yield-per-acre of an energy-intensive crop; number of layers used; and electricity usage per layer per acre.
> We even have tech to grow various crop types to harvest stage without needing light at all.
It's physically impossible to produce food without an energy source. So if you're not using light as the energy source, then what are you using? And if you look further upstream, where is the energy ultimately coming from?
> Energy usage? Think about all that fuel those tractors you no longer need are burning to till soil, harvest crops, and do general field work on top.
According to https://energyeducation.ca/encyclopedia/Agricultural_energy_..., the total energy use of the agricultural sector worldwide is roughly 2,000 to 3,000 terawatt-hours per year. That includes fossil fuels too, not just electricity. So the energy used to run a tractor is tiny compared to the amount of sunlight falling on the field.
The picture is me over a decade ago, doing microscopic analysis of live plant tissues growing under targeted-spectrum LED lighting in a vertically-stacked hydroponics building, and proving the viability of the very technology being discussed in the thread article.
This isn't even new tech. We've been using it since the 90s. The LEDs are new, everything else is exactly the same as it was back then. Maybe better nutrient profiles.
On the other side of the picture, behind the camera, was a grass-growing system that didn't require light for the grass to grow at all. We were doing artificial photosynthesis over there.
What's REALLY the big thing here is the NFT hydroponics technique being utilized.
Even several decades ago, you got great yields on regular land using far less water. Not even multiple stacked systems.
Now that we have good LED tech, stacked grow systems indoors makes a lot of sense. 1/8 of an acre to produce what 1 acre does, using much less in the way of resources. Water? Hugely reduced depending on the hydroponics system. Yields? Comparable or greater in a reduced footprint. Energy usage? Think about all that fuel those tractors you no longer need are burning to till soil, harvest crops, and do general field work on top.
Everything slowly combines to become an economically and ecologically-sound system.
Not so fast, you just skated right past capital requirements for build out, maintenance costs, and the sun. There was an article posted in here not two weeks ago detailing how the entire stacked grow startup industry is imploding due to increases in energy costs and I'm quite certain you haven't figured out how to grow tomatoes in pitch blackness.
I don't understand "artificial photosynthesis". Glucose in the water?
Elsewhere you write "electrocatalysis-based artificial photosynthesis". Wires clipped to the roots?
Solar Foods, in Finland, has a strain of Xanthobacter agilis that eats hydrogen, nitrogen, and CO2, and produces tasty protein (70% by dried weight) and carotenes. Their plan is to electrolyse water for the hydrogen, using renewable power.
But what if you _couldn't_ farm outdoors, because your outdoor farm is now a dust bowl, or a desert, or a recently inundated coastal plain, submerged by sea water?
Financial practicality is not a concern if this is the only way a region has to make food.
I had the same thoughts initially. It's interesting to think about with the way the climate is heading. The people that are working on this are likely also working on breeding plants that are more suited to growing indoors. Useful genes would be dwarfing genes or genes that speed up the growth cycle. What breeders would be looking for is completely different than what's been selected for throughout history. Most grains are also annuals but there is work being done on breeding perennial grains.
Do you know why strawberries from California are available at the supermarket all year round? It's because farmers and breeders found a gene that made strawberries daylight neutral, meaning they didn't have to go through a "winter" season to produce fruit again. Plants will keep bearing fruit all year round.
This is just a proof of concept. A first attempt. Assume increased yields over time through engineering improvements, maybe some genetic engineering, etc. You end up with a more favorable situation.
Also with vertical farming, you have to think in terms of vertical and time dimensions. You have no more seasons and you get to harvest throughout the year. And you can stack vertically. So, it can be pretty efficient in terms of land usage depending on how high you stack.
As for energy and light needs. Yes, it would need lots of energy but nowhere near what you think. Your back of the envelope math is talking about acres which isn't that useful of a metric for your energy needs. This is the fallacy in your argument. It's not about the light emitted but about the light delivered to the plant. Which depends mainly on the distance to the plant of the light source.
You can actually grow herbs with a kitchen light LED. I've done so. They sure aren't anywhere near as bright as the sun or particularly efficient. But it works. You just have to put them pretty close to the plant to minimize the light losses. That's the whole point of a vertical farm: minimize the losses by maximizing the light usage. Lots of low energy LEDs centimeters away from the plant are much more efficient than big light sources a meter or so away. And what happens to the light that "misses" the plant? Very simple it either gets absorbed by something and turned into heat or reflected by something back to the plant. And of course you'll find lots of reflective surfaces in vertical farms for that reason. Ultimately a lot of it gets transformed into heat. Some of that is useful. Plants grow faster at higher temperatures. And some of that is a cooling problem. Which takes more energy.
Vertical farming feasibility is mainly going to be a function of price and availability of energy. And as energy is the most costly component, yields measured in tonnes per mwh are a more sensible way to think about the feasibility than tonnes per acre. Acres are not that useful as a metric for measuring energy usage. They are useful for traditional farms mainly because land is expensive and you can't stack your crops on it. But it's a useless notion for measuring vertical farm production. How do you even measure acres in a 3 dimensional environment?
So the real feasibility just depends on cost per mwh. As that comes down, a lot of things become feasible. Including vertical farming all sorts of things. It's a cost curve. Right now energy is to costly and yields are to low. There's a point where those curves cross and things become feasible.
> As for energy and light needs. Yes, it would need lots of energy but nowhere near what you think. Your back of the envelope math is talking about acres which isn't that useful of a metric for your energy needs.
It's true that acres were an awkward way to do the calculation. Let's redo the calculation in megawatt-hours.
- According to https://www.nature.com/articles/s41586-018-0706-x, grain crops yield about 0.24 grams of dry weight per mol of photons. (This assumes 100% of the photons are delivered to the plant, e.g. the LED is shining directly on the leaf with nothing lost.)
- One mol of photons embodies about 0.1kWh of energy. (That's for red photons; higher-frequency photons would require more energy. And note this is a physical limit, where we're assuming the LEDs are already 100% efficient.)
- So we'd need 1,125,000 TWh/yr of energy to grow the world's supply of grain through indoor farming, or 45x the world's current electricity production. And this calculation is just for grains; to grow all the non-grain crops too, you'd need even more energy. So I stand by my original estimate.
What about genetic engineering? Looking at https://www.nature.com/articles/s41586-018-0706-x, the "0.24 grams of dry weight per mol of photons" calculation is taking into account that e.g. grain plants are not as efficient as some other plants at absorbing light, and not all of the grain plant is edible. The most efficient plants (leafy greens) produce 1.33 grams of dry weight per mol of photons. So if we could genetically engineer a grain plant that absorbed as much light as the most efficient plants, and didn't have an inedible stalk, then we'd need 203,000 TWh/yr of electricity to grow the world's supply of grain, which is "only" 8x the world's current electricity production.
And at that point, we've squeezed out all the obvious sources of inefficiency; to do better, you'd need to fundamentally change plant biology, or just do photosynthesis directly in a vat, or something.
But the real deal-breaker is energy. Outdoor farming gets energy naturally from sunlight. Indoor farming is powered by LED lights. LEDs could be more efficient than sunlight by only emitting the frequencies that are most useful for plants; but on the other hand, I suspect that they might need to be brighter than sunlight to achieve 25x the yield per acre. So let's estimate it's exactly as bright as sunlight. To light 177 million acres exactly as bright as sunlight, you'd need somewhere around 3,000,000 terawatt-hours per year. For comparison, global electricity consumption is around 25,000 terawatt-hours per year [3]. So to replace conventional farming, this would need about 100x as much electricity as the current global electrical grid can supply!
So until we get fusion power, I doubt this is practical.
[1] https://www.producer.com/news/worlds-farmland-total-bigger-e...
[2] https://guidehouseinsights.com/news-and-views/the-global-bui...
[3] https://en.wikipedia.org/wiki/Electric_energy_consumption