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Let me start out by saying that this is actually one of the best critiques of vertical farming that’s out there. And I’m not surprised, the author, Stan Cox, works at the Land Institute, one of the most important groups for agricultural transformation out there . They do some really incredible things and I have a huge amount of respect for their work. Unfortunately, it seems they still fall into the same trap as everyone else that wants to talk about how the sun is free and how important soil is; they assume that because vertical farming can’t solve everything, it should solve nothing.
I’m going to go paragraph by paragraph and respond to Stan Cox’s article and address the misconceptions there. This is not a fluff piece, this is not a blog post meant for internet readability. This is a take down.
First, a definition of what vertical farming actually is: Vertical farming is the practice of producing food in vertically stacked layers or vertically inclined surfaces.
Before we get started, I’ll say that some snark definitely seeped into this response, and I’m sure Stan Cox could go through one of my pieces and do the same thing to me. I copy and pasted each of his paragraphs in order and responded to them in an open response; I will be editing it as my argument/view changes. But, the bottom line is that it’s ridiculous how vertical farming is being written off by the very people that should be embracing it as part of the ongoing challenge to industrial agriculture. Don’t let that be you.
One of the biggest issues right off the bat is that people are for some reason mentally stuck on this concept of vertical farming as skyscraper greenhouses or multistory complexes radiating purple light. Yet, any one who is at all actually involved in this industry knows that’s just not the case and it’s unfortunate that conceptualizations are getting conflated with the actual practice of vertical farming.
His article in quotes
Five-plus years after the publication of Dickson Despommier’s book The Vertical Farm: Feeding Ourselves and The World in the 21st Century, his dream — originally conceived as the production of food in the interior of tall urban buildings — is gaining momentum, despite many unanswered questions about its feasibility.
Although the fanciful skyscrapers depicted in countless architectural renderings of vertical farms have never materialized in the real world, less ambitious indoor food-growing operations have been popping up in cities on every continent. And the buzz is growing even faster than the plants.
This is just some fluff to set the stage but I will respond to the last line. I’m not sure you can make a dig about the speed of plant growth; just anecdotally, I have basil plants in a dummy test system growing around 3 times as fast as their outdoor compatriots.
There are projections that the vertical farming market will hit $4 billion by 2020. In a recent segment of NPR’s Diane Rehm Show (in which I participated), several guests argued that vertical farming could revolutionize agriculture and even supply most of our food needs. The show’s guest host, Maria Hinojosa, declared it “something big, different, and permanent.”
However, in their efforts to develop a system that sustainably supplies cities with a large share of their food, theorists and practitioners of vertical farming face insurmountable obstacles. These include the limited range of crop species that can be grown; the tiny proportion of our population’s total food needs that indoor crops could supply; the elite market being targeted; and the irrelevance of indoor agriculture to the lives and diets of people living in economically stressed rural regions where the bulk of our food is grown.
Let’s look at some of these “insurmountable obstacles,” which seem to be a recurring theme in Cox’s piece.
First, “a limited range of crop species that can be grown.” Critiquing a farming method for specialization is ridiculous. This is like saying because people are only growing rice in rice paddies, rice paddies aren’t useful for agriculture. Not only is vertical farming in its infancy, with research already coming out how to address growing root and rhizome crops hydro- and aeroponically, and with plenty of time to adapt the growing to different crops, but who’s to say specializing in leafy greens is really a bad thing? If we have found the best way to grow lettuce, would Cox advocate that we stop growing lettuce in this way because you can’t grow a carrot?
Second “the tiny proportion [sic] of our population’s total food needs that indoor crops could supply.” How much of our nation’s food needs do the rolling corn and soy fields of industrial farming supply? The answer: not much. According to just this study, only 27% of the calories grown in the United States are used for food. Most of the calories grown and produced in the United States go to ethanol biofuels (almost 40% of our corn crop) and concentrated animal feedlot operations (CAFOs), not feeding people. The point is that if you’re going to criticize farming for not supplying 100% of a population’s calories, there are a lot bigger targets than vertical farming. Especially when vertical farms put food directly into local communities without many of the environmental issues that come with industrial farming. Vertical farms are feeding people in an efficient way, and just because they aren’t feeding every single person doesn’t mean they should stop.
Third “the elite market being targeted.” Vertical farming is novel. It’s also pesticide free and local (meaning it can be harvested at peak nutrient density without having to worry as much about shelf life). Much like organic farming, there is a high price premium on vertically farmed products right now because of their quality compared to industrial farming. As more people join the industry and it becomes more competitive, that could easily balance out. For now, people who can afford the value of these crops are free to pay for it just like people who can afford the value of a car are free to buy one. Just because cars aren’t affordable to everyone does not suddenly mean that the challenges presented by the concept of cars are “insurmountable.” It seems that the underlying problem here is poverty, not the method of food production. Vertical farms potentially have a leg up in poverty alleviation through employment compared to traditional farms as well. While it’s true that more people work in traditional agriculture (there is more of it), vertical farms are directly integrated into dense communities and actively foster the relationships there. Additionally, employment at a vertical farm is year round, and not as dependent on seasonal vagaries as outdoor agriculture.
Finally “the irrelevance of indoor agriculture to the lives and diets of people living in economically stressed rural regions where the bulk of our food is grown.” There are more things than either Stan Cox or I can count that are relevant to one of those population subsets but not the other. Clearly there are different issues for urban and rural people, but vertical farming is focused on solving urban problems, so get out of the way and let it.
Meanwhile, looming largest among the many factors that will restrict the growth of vertical gardening (a term I believe is more apt than “vertical farming,” given the potential scale and the types of food that can be produced) are its extraordinary energy requirements and heavy climate impact.
Cox should have read the Urban Vertical Project before writing that. We’ll get to the energy requirements in a second, but for now, just remember that he’s trying to call something “gardening” that’s producing more as much as 100 times the amount of food/square foot (according to a Google X projection) than the outdoor agriculture he compares it to and that we have a whole piece about vertical farms addressing climate change.
No one would consider stacking photovoltaic solar panels one above the other. In such a system, only the top panel would produce electric current. The leaves of plants also need to be directly and strongly illuminated if they are to activate the photosynthesis that powers their growth.
Great observation. No one is doing that.
If plants are living indoors, even if they are in an entirely glass-walled room, they can’t capture enough sunlight to perform those functions. Plants nearest the windows will receive weak sideways illumination for part of the day, while interior plants will get much less than that; for both, the light intensity would be wholly inadequate to produce a significant quantity of food.
This study shows 1,023,330 acres of vegetables in greenhouse production globally. This is a huge industry. Saying plants can’t capture enough sunlight in a glass-walled room to do photosynthesis is just ridiculous and we’re going to move on.
Grown indoors, plants need much more intense artificial illumination in order to produce food than our eyes need in order to see. A real astronaut, for example, could not grow potatoes indoors on any planet under a sparse lighting setup like the one depicted in the film The Martian; however, the scene was adequately lit for filming and viewing.
Guess what? Star Wars isn’t real either. Attacking the realism of a fictional work to prove a point is just a waste of word count. Also, The Martian was a great film.
Based on figures in a 2013 paper published by indoor plant-growth expert Toyoki Kozai of Japan’s Chiba University and on the assumption of efficient LED lighting, I estimate that plants like potato or tomato that produce a fleshy food product require about 1,200 kilowatt-hours of electricity for each kilogram of edible tissue they produce, not counting the water stored in the food.
That requirement approximates the annual electricity consumption of the average American home refrigerator — and that’s a big energy bill to produce just two and a quarter pounds of food dry matter. This kind of thing could not be scaled up very far. At that rate, producing America’s annual vegetable crop (not counting potatoes) in vertical systems under lights would require well over half of the electricity this country generates every year, and that would crank out 1.3 billion metric tons of carbon emissions per year. Heating and air-conditioning would add considerably to power demand and the emissions.
Now we’re getting somewhere close to valid criticism. Too bad it took half the article to get here. Energy use in some vertical farms is a definite concern. However, just as there are better and worse systems for soil-based farming, there are better and worse systems for vertical farming as well.
In other words, some vertical farms use way less energy than others. In fact, some vertical farms get all their light from solar sources. Sky Greens is a great example of that, as are the numerous rooftop greenhouses in operation.
The article also fails to even consider one of the most promising iterations of vertical farming, and that is building integrated agriculture. Instead of the narrow conception of vertical farming as a dedicated glass skyscraper teeming with veggies, building integrated agriculture essentially means growing food in a space that’s also being used for something else. In order to make a practice like this worthwhile, it has to grow above a certain amount of food in a limited space. Vertical farming introduces the efficiency that makes this possible. Furthermore, the coolest examples of building integrated agriculture (like the article above) use the natural light that’s already hitting the facade of a building to grow plants. This, combined with the biophilic and climate control benefits of indoor growth means there is actually a lower energy footprint for the building.
Another benefit of vertical farms is their ability to exploit unique urban synergies and explore a new urban ecology. In cities, buildings are densely packed, and despite growing LEED trends, usually energy inefficient. A clear example of that is heat exhaust. Imagine building a greenhouse on top of a building and then using the same building’s waste heat for climate control in that greenhouse. Or, another example is using anaerobic digesters like what’s in operation at The Plant. Food waste is fed into the digester which produces enough gas to power an electricity generating turbine – closing the production loop.
This does not even take into consideration the growing efficiency in solar panels and PAR specific lighting. There are many people who know much more about the solar and LED industry than me, but here’s one theory from Kyle Simpson, one of the contributors here, and it’s a clear winner. The fact is that not all of the light from the sun falls into the spectrum of useful light for plants. While solar panels may not ever reach 100% perfect conversion, what if they can take those wavelengths of light that aren’t useful to plants, convert it to energy, and then finally to PAR that crops are actually able to use? That could potentially mean that solar panels and LEDs are even more efficient than the sun.
Given the energy hunger of indoor cropping systems, their designers typically assume that the product will be vegetables. Fresh produce has a high value per pound, and out of each 10 pounds of product harvested, 8 to 9½ pounds is water — and light is not needed to produce water.
I’m not really sure what Cox is trying to get at with this whole paragraph. The first sentence is misleading though; designers assume that the product will be vegetables for a lot more reasons than energy requirements so that’s just wrong. The next part is where he really lost me though. I’ll just say that while light might not be needed to produce water, it is needed to grow plants.
In practice, the choice of food crops facing indoor gardeners is even narrower. Existing indoor systems all focus on growing leafy greens or herbs, because most of those plants’ weight can be sold and eaten. If potatoes, tomatoes or green beans were being grown, much precious building space and costly electricity would go into producing inedible leaves, stems and roots.
This is true so far, though there is plenty of time for the industry to develop. But as stated above, if we’ve come across a way to grow lettuce better, let us (and we got the pun in there).
I suspect that much of the current interest in indoor gardening is stimulated by the success of indoor cannabis production. But that resource-intensive system, which in 2011 was already consuming as much electricity as two million American homes, is economically viable thanks to its product’s $8-to-10-per-gram price. That compares with a fraction of a penny per gram for fresh vegetables or grains.
What a revelation; different products sell for different amounts. There are plenty of examples here of farms making money without that price premium.
Warning: This Chard Is Not For Everyone
In Despommier’s original vision for vertical food production, he was both wrong and right in his analysis of the problem to be solved. On one hand, he claimed we are running short of rural farmland. That is nonsense. In the United States, we produce 4,000 calories worth of food per resident daily, twice what’s required. We have ample land; we just need to stop abusing the soil we have. So Despommier, recognizing that need, also presented a mostly on-target critique of industrial agriculture and the resultinbg [sic] soil degradation that results. On balance, his analysis was solid, but his proposed remedy — to take most or all rural land out of food production and move crops into cities — was doomed from the start.
This is what is known in the academic literature as the land sharing versus land sparring debate. However, this is an inaccurate framing of where vertical farming fits. There are many ways to restore soils but with most there is a short term loss in yields before the soil can regenerate from industrial agriculture-induced degradation and start performing at peak. As part of stopping soil abuse, vertical farming can move production closer to consumption and facilitate that regeneration.
Don’t get me wrong; I am all for urban cultivation of fresh produce. But it should be grown on sun-exposed plots of land and rooftops and “green walls” and in greenhouses. That would greatly improve the lives of urban-dwellers. But it would also leave the bulk of our 350 million acres of farmland untouched. Filling the sunlit land and rooftops in cities with crops could accommodate only a portion of U.S. vegetable production. And vegetables occupy only 3 percent of our total cropland.
If you’re “for urban cultivation of fresh produce,” you should be for vertical farms because it is the most space efficient way to do it. And didn’t you just try and explain why greenhouses didn’t work? Again, some good is better than no good and there is no reason why vertical farming can’t be a part of a strong urban food system just like the systems the author advocates.
Whether we were to use traditional or indoor gardening to urbanize food production (one consideration in making that choice: The indoor option would require tens of thousands of Empire State Buildings), we would still leave the vast bulk of our agriculture out on the rural landscape where it happens today.
This is a false dichotomy and we can easily do both.
Given that, suppose vertical gardeners were to backpedal to a goal much less sweeping than the salvation of America’s farmland. Consider what it would take to provide fresh produce to just 15,000 city dwellers; that would be about 2 percent of the population of the District of Columbia.
While this is rather a meaningless conversion, there is no reason to let the good be the enemy of the perfect. It might be worth adding at this point that letting vertical farming develop will do nothing to stop any of the practices that Cox advocates. Vertical farming isn’t taking away from soil farming- it’s just another part of a broad solution.
That was the objective of a favorable 2013 analysis of vertical gardening by GIZ, a German engineering group. They estimated that the project would require a 150 x 150 square-foot building with 37 stories. It would cost a quarter billion dollars to construct and equip and would consume $7 million worth of electricity annually. Those estimates led them to conclude, “It is possible to grow only high value crops for consumers who have disposable income for such products.”
I’m not sure what kind of system these researchers used, but I know a farmer in DC producing literal tons of produce using recycled and stacked styrofoam buckets with natural lighting. This goes back to the earlier point that conceptualized vertical farms are getting conflated with the real thing.
In other words, such buildings would not serve 15,000 people of modest means. Were vertical gardeners ever to venture beyond leafy greens into growing a full range of vegetables, the sky-high inputs of capital, resources (especially electricity) and labor would limit the reach of their produce to a boutique market.
This is a bold assumption and there quite frankly isn’t enough data to support it. It makes just as much sense to say that as the technology develops, capital inputs will drop and prices will lower as the market becomes more competitive. I will also underscore here that there is no reason Cox needs to be so fixated on electricity when natural lighting works very well for vertical systems.
So the original aim of vertical cropping’s proponents — to protect the soils of America’s farm country by taking much of that land out of production — was well-meant but futile. It also completely ignored the people who live on farms and in rural communities across rural America. They produce the bulk of the country’s food but often have even less access than city dwellers to good-quality food for their own families.
Small towns and rural areas are suffering disproportionately from food insecurity. The food bank network Feeding America estimates that while 43 percent of all U.S. counties are classified as rural, 62 percent of the counties with the worst rates of food insecurity among children are rural. The problem of poor access to affordable, nutritious food out here in flyover country is being addressed neither by the mainstream urban-food movement nor by vertical-gardening enthusiasts.
Rural poverty and food access, though extremely important, are not the fault of a burgeoning vertical farming industry. There is particular issue with this sentence “The problem of poor access to affordable, nutritious food out here in flyover country is being addressed neither by the mainstream urban-food movement nor by vertical-gardening enthusiasts.” Just because a solution to a problem doesn’t save the world does not detract from the validity of that solution. Would Cox be using the same derision if he were talking about mosquito nets in Africa, which, though they save countless lives, also do nothing for food access and nutrition in flyover country?
Much could be done to protect our lands while improving access to good food for all Americans, rural and urban. As a start, we could slow or stop the degradation of the nation’s soils by eliminating the feedlot system of meat production and the scores of millions of acres of corn and soybeans that supply it. The land thus spared could be converted to soil-conserving pasture, rangeland or orchards as well as to a diverse array of food crops and cover crops that could be grown more sustainably. That could bring more income and better living conditions to rural areas while ensuring better nutrition for everyone, rural and urban. In the longer term, the replacement of annual grains and oilseeds with perennial food crops will completely eliminate soil and water degradation in agriculture.
Some forms of sun-and-soil-supported local food production that are being practiced in and around cities could also be implemented in rural America. Gardening has always been popular out here, and there’s a lot more land on which to do it — enough land that not only vegetables but also staple foods like dry beans and grains can be produced for local consumption. That could be augmented in rural areas by community gardens and farms producing for local sale, and community canning centers and greenhouses that could make local food available year-round.
No Free Lunch, No Free Salad Bar
But even if funding and popular support can be found for all such good-food initiatives, the root causes of rural food insecurity will remain. Poverty, loss of family farms, the boarding up of small-town storefronts and ecological degradation are all attributable to exploitation by agribusiness, and they can’t be fixed by growing salad greens under lights.
The roots of urban food insecurity are as economic and political as those out here in farm country. Sun-fed urban gardening, fruit and vegetable cultivation close to cities, and people’s food initiatives all are important and need to keep expanding, but a still more profound economic transformation is needed.
I can 100% agree with this and simultaneously see how it does not detract from the validity of vertical farming. Why can’t Cox?
As an aside, the idea of replacing annuals with perennials is particularly exciting and everyone should check it out.
By claiming to be “revolutionary,” vertical-gardening advocates are seeking to be viewed as part of such a transformation. But thanks to their hefty electric bills and limited crop range, they will have a hard time venturing beyond the elite market, let alone reducing their climate impact.
This is another point where I will agree. I started with vertical farming as if it were some type of revolutionary silver bullet that would fix our broken agricultural paradigm, but I’ve since realized that it’s something more incremental than that. It’s a step in the right direction (towards sustainability), but it’s not a magic pill that will make everything bad go away. There are various reasons for it, but the truth is that there is a lot of hyperbole around vertical farming. However, that should not detract from its underlying value.
With the green façade crumbling, there is much loose talk in the vertical-gardening world about using renewable energy sources to power their grow-lights. That discussion spirals into some interesting circular logic: that we would use solar arrays and wind farms to convert sunlight’s energy into electric current that would feed lamps that would convert a portion of the electrical energy into artificial sunlight to shine on plants so they can convert that light energy into food.
At each of those conversion points, there are big losses of energy and heavy infrastructure costs. It’s about as wasteful as a system can be. Better to let crop plants do what they do best: capture cost-free, emissions-free sunlight for themselves, directly.
Not only is that not exactly what “circular logic” means, but it’s missing the point. If you’re limited in the space you have to grow food, it makes sense to do it in the most productive way. It seems that way is to stack the produce.
If you’re further limited by the type of structure you have to grow food in or on, it also makes sense to start using artificial lighting. While there might never be perfect efficiency with converting sunlight to LED light, the closer we get, the better we do with balancing things like food miles against electricity use.
In other words, whatever source you use to power the lights for your vertical food-production system, you’re giving a boost to greenhouse warming. Grow crops under lights, with climate control powered by fossil fuels, and you add directly to greenhouse emissions. Grow them under lights powered by wind turbines or solar arrays, and you consume green energy that could have been used instead to displace some of the fossil energy that’s now running home refrigerators, air-conditioners, electronics, etc.
I feel it’s my duty to also let you know that by this logic, whatever source you use to light your house and cook your food, you’re giving a boost to greenhouse warming.
One also hears vertical enthusiasts argue, without providing any numbers, that they can compensate for the excess energy consumption required by electric lighting by growing their lettuce or basil close to markets rather than burning fuel to haul them across the country.
A quick Google search found that food travels 1500 miles to reach a diner’s plate in Illinois and over 1600 in MD. There is no downside to slashing these numbers. Local food production, while again, not a silver bullet, is extremely beneficial and vertical farming benefits this transition to local economies. And remember, vertical farming is not as dependent on “excess electricity” as alleged.
Reduced energy consumption for transportation is an excellent argument for urban gardening and farming within or close to cities, but it’s no justification for indoor gardening. The climate impact of shipping food over long distances is significant, but the impact of energy-intensive food raising methods can be far larger than that. Dependence on artificial lighting in particular makes the impact of food production vastly larger than the impact of food transport.
To reiterate an earlier point, just as there are good and bad types of soil farming systems, there are good and bad models for vertical farms. Some bad models may use too much energy but there is nothing to support that every farm using vertical farming principles has a higher food production impact than the food transport impact it is offsetting.
Defenders of vertical gardening claim that it can produce much more food per acre of land per year than sun-and-soil agriculture. But not only are many of these comparisons exaggerated; they are also irrelevant. No matter how big the improvement in production per square foot per year, it will have no effect on the key number in vertical gardening’s energy predicament: the quantity of photosynthetically active light required to produce each and every kilogram of plant tissue. That’s a basic biochemical requirement. Increasing a food-production building’s yield by stacking in more and more plants per floor or operating year-round only increases the demand for electric lighting.
The increased production of vertical farms is so far from irrelevant that it could take a selfie with Alpha Centauri and send it to Stan Cox just to let him know how wrong he is.
This increased production has allowed hundreds of vertical growers around the world to succeed and make money doing it.
The energy efficiency of lamps or production systems can be improved, but not infinitely, so indoor crops will always be deeply dependent on electricity and other industrial support. That means that with every kilogram of food we produce under artificial lighting, we will have passed up an opportunity to harvest free sunlight, and will thereby contribute to the Earth’s warming.
Remember, we can do both. We can use natural sunlight where it is appropriate and we can use artificial sunlight where it is not.
In a country that desperately needs to achieve food justice, diversify agriculture, end soil abuse, abolish factory farming and slash greenhouse emissions, vertical gardening will have a net negative impact. Our country’s food system, in cities and in the countryside, has been broken by our deep distortions of economic and political power. We need a broad-based political, economic and ecological uprising—and that will neither start nor finish in high-rise vegetable factories.
In a country that desperately needs to achieve food justice, diversify agriculture, end soil abuse, abolish factory farming, and slash greenhouse emissions, vertical farming will have an important role to play. Our country’s food system, in cities and in the countryside, has been broken by our deep distortions of economic and political power. We need a broad-based political, economic and ecological uprising – and that’s going to happen when we embrace all available solutions. Stop staring at your feet, it’s time to start looking up.