Update: I contacted Smithsonian Magazine and Modern Farmer. Though it took many attempts over some two weeks, I finally got a response from someone there. They have both since issued a correction and deleted their tweet. The correction reads as follows:
[Editor's Note, July 26, 2023: A previous version of this article incorrectly stated that vertical farms can use up to 90 percent less energy than traditional farms. In fact, that number referred to the amount of energy one vertical farm used in comparison to other vertical farms. We’ve updated the story to reflect this change. We regret the error.]
The effort to understand the universe is one of the very few things that lifts human life a little above the level of farce, and gives it some of the grace of tragedy."
― Steven Weinberg
A recent article on vertical farming in Smithsonian Magazine (archive link), which seems to be syndicated from Modern Farmer, contained the following claim:
"Additionally, vertical farmers gain the added benefit of consistent, year-round production without the uncertainties of climate or pests, all while utilizing 90 percent less energy and 98 percent less water than a traditional farm."
This struck me as mightily implausible. I have felt just how warm the sun is on my face, and I have looked around and seen just how much more of it is coming down everywhere, all for free.1 Surely recreating that in a building would take a lot of energy.
So let us investigate this claim. A quick search leads me to this blogpost, which claims that lettuce, the lowest energy crop possible, uses ~57KWH per square meter. We will use that number to be as generous as possible to our good friends at Smithsonian Magazine and Modern Farmer, though strawberries are also mentioned in that post, and they use almost triple the energy. Another quick search leads me to this Iowa State University PDF, which says that cereal crop production uses ~2 gallons of gas per acre (or 4046.86 m2) of crop; that's the equivalent of ~67 KwH. Let's say a growing season is 2 months, which is about right for most lettuce varieties. We can now compare how much energy we need to grow an acre of lettuce in vertical farms vs an acre of cereal crops in a traditional farm — this should be a very generous comparison to our friends' claim, since lettuce is such a low energy crop that human beings cannot live off it.
Energy cost per acre per season of lettuce of vertical farming:
4046.86m2 * 57kwh/month-m2 * 2 months/season = ~461342 kwh/season
Energy cost per acre of wheat of traditional farming:
1 acre * 67kwh/acre * 1 season = 67 kwh/season
In other words, vertical farming lettuce is 6885 more energy intensive than traditional farming of cereal crops per square meter. Just for perspective, that's about the amount (5972) you'd need to multiply the average American's daily commute distance (40 miles) to get the distance to the moon (238,900 miles). Remember, this is a generous comparison in favor of vertical farming, because we are comparing lettuce, which is basically water with the occasional calorie, with cereal crops, the kinds of crops that can and do sustain entire civilizations.
For a more direct comparison, and an experimentally determined one, we can turn to Low-Tech Magazine's (one of my favorite publications on the internet) write-up, "Vertical Farming Does Not Save Space." They discuss actual experimental results, and if we use their numbers for vertical farming, and stick to Iowa State's numbers for cereals, we conclude that that vertical farming is about 157,827 more energy intensive than traditional farming — a whopping 5 orders of magnitude, or the average American's daily commute distance vs the distance to Venus.
In fact, to even make this claim, the writer had to ignore the citation they themselves put in the preceding sentence, which says things like "vertical farms are very energy intensive, and it is important to ensure the facilities chosen can support these energy loads," and "vertical farms demand more energy to carry out growing operations."
What I find troubling about these kinds of errors isn't so much the errors themselves, but the way they warp our intuition for what is possible, pushing us back into Weinberg's farce.
The power of the sun is, and should remain, awe-inspiring. It is the single energy source from which all energy for all life comes. We are humble animals, living on a wet rock, doing the best we can with what we have, which, not coincidentally, mostly comes from the sun. We are not wizards. To think that we can recreate the sun in buildings for less energy than the sun itself gives us for free is to believe we are wizards — it is the kind of technological hubris that makes our conflict with the natural world so dire, be it through our food system, climate change, mass extinction, or the many others ways we are destroying this beautiful wet rock, warmed by the sun, upon which each and every one of us lives.
Vertical farms are a technological antisolution, and this article is the perfect example of the media's role in creating them2. Our food system is in crisis. This is a social and political problem. Dr. Sarah Taber has written at great length about this problem and how to fix it. Through her work, I have learned that the American farming system is based on a fundamentally unsustainable myth, about the impacts of market forces on global food supplies, and just how broken our food distribution system really is.
But no one wants to talk about that. It's boring. If I may be so bold as to quote myself:
No one wants to write articles about maintaining snow plows or the routine structural assessments of bridge pylons – we want to talk about robots. This is the appeal and the danger. Antisolutions offer us just enough purchase to envision a better world, distracting us from the bleak reality that our society is stagnating. We can barely maintain the infrastructure that previous generations actually had to go out and build, much less imagine a world where we expand it. It is unthinkable to the average American living in Manchester, NH or Columbus, OH that the town would break ground on a new subway system. In the few cities old enough to have a subway – itself a damning concept if you stop and think about it – even upgrading the rolling stock when the existing cars are past their end of service date seems an impossible hurdle to overcome. As our society becomes increasingly unable to fathom tackling its complex political problems, more companies offering technological antisolutions will step in to monetize our inaction and discontent.
This article is a smoking gun. Food insecurity, also known as hunger, is rising internationally and in the US. An increasing amount of us are hungry even though, as Dr. Taber writes, there is plenty of food to go around. Mark Fisher said that "it is easier to imagine the end of the world than the end of capitalism"; apparently, it is also easier to imagine the very sun's obsolescence than a just food distribution system.
1. It's only free because capitalists haven't figured out how to monetize it yet, though with the wildfire smoke covering so much of the US this summer, there is probably plenty of venture capital for anyone looking to try.
2. It's a puff piece. I will restrict this level of editorializing to the footnotes. The piece follows a few vertical farming companies and uncritically reports on everything they say. My best theory on how that 90% came to be isn't that the companies straight up lied and no one at Modern Farmer or Smithsonian Magazine has even a passing familiarity with basic physics, but that some PR person misspoke or misunderstood some stat about reduced water usage (or some other resource), and no one at Modern Farmer, Smithsonian Magazine, or that company have even a passing familiarity with basic physics.