The Challenges of Vertical Farming
I am a microbiologist/ecologist by training, and for 27 years I conducted laboratory-based research on molecular aspects of intracellular parasitism funded by NIH. I also teach courses in the medical school and in our school of public health (e.g., Parasitic Diseases; Medical Ecology; Ecology 101). Many of them deal with parasitism and its effects on large segments of the poor that live in the tropics. Controlling soil-based transmission cycles of helminthes that cause significant health problems throughout the world is of prime importance to me.
I left the lab in favor of working on more globally relevant projects that address some these important problems. Since it is generally agreed agriculture is solely responsible for so much environmental disturbance and serves as the interface for the transmission of geohelminths, one area of focus of mine has been on how to raise food without further encroachment into natural ecosystems.
I have established The Vertical Farm as a theoretical construct to look at the possibility of agricultural sustainability within cities. The idea grew out of a class project to measure the effects of rooftop gardening in New York City on reducing the dome of heat that develops over us each year. From that original idea, I expanded the concept to include urban agriculture and finally to multi-story indoor farming. I have given this project to my students in my course, "Medical Ecology."
Dickson Despommier: Here’s what we know we can’t do first. We cannot just stack greenhouses on top of each other and get a vertical farm. We know this because people have tried this in the past, and they’ve failed miserably; because there’s no easy way to get water, nutrients, waste to energy schemes.
All of this fails when you start stacking it up and putting it inside of an urban setting. It’s very easy to do if it’s outdoors basically in a rural setting and you’ve got a big spread and you’re not worried about how much land you’ve used, but when you start to add constraints of how do I get enough sunlight to the middle of the building?
Then you have to get creative. It’s not impossible, and in fact basically nothing is impossible. We’re now discovering planets around the suns in different galaxies. That’s incredible. Come on. If that’s not impossible, then this is certainly not impossible. There’s a laboratory out at UC Davis which is a big ag [sic; agriculture] school, and high-tech ag school, and there’s a lighting laboratory. If you just ask them they’ll way well, you know you can solve that in many ways but the best way is to reflect sunlight with parabolic mirrors through a transparent building, and then another set of parabolic mirrors will bounce the light around inside, and pretty soon-- it doesn’t matter how thick your building is. You can get sunlight directly in the middle if you really want to do this.
The Japanese have another solution to that and it’s equally inventive and creative. They’re farming in basements of buildings where there’s no sunlight. Well, that’s not true actually. They bring the sunlight in with fiber optics. Cool. How cool can you get? That is about as cool as you can get. It is expensive to begin with of course, and primitive at a big level, but nonetheless it’s possible.
If you take a country like Iceland, it’s not energy-challenged in any direction. It’s got geothermal energy oozing out of the ground, basically. So you can tap that energy to make steam to make electricity to make the grow lights work. So grow lights would be a big answer here. Now what kind of grow lights are there? So that’s what the fifth year students addressed. I will focus. I will focus. I could exceed my two-hour limit, however. They did a series of really interesting calculations to say that a building that’s 30 stories tall in one square city block in a footprint that grows enough food for 50,000 people might consumer as much as 30 million kilowatt hours of electricity per year. That’s a big number.
However, they also said that all of the waste to energy schemes that you can imagine, plus passive capture of sunlight, wind power, solar power, tidal power, New York City is gifted in those areas. If you could harness that energy you might offset the energy but in fact, you might even exceed. You might even be able to produce energy this way. All right, that was very optimistic. Even if you broke even. Let me ask the question to the general viewing public, how much do you think it costs in energy to grow food? Forget about indoor farming. Just how much fossil fuel use do you think farming consumes on an annual basis? I know the answer already, so I couldn’t tell you what the answer is. No, no, no. You’ve answered too many questions. I want someone else to answer. This is fun by the way. Okay, so the answer is that it consumes one-fifth of fossil fuel use in this country. Agriculture alone consumes a fifth of what we need to make this country what it is. One-fifth is consumed by automobiles. You know how much that is? Another fifth is consumed by farming. Okay, if we didn’t farm that way then I’m entitled to include that into my energy budget, but I don’t even want to do that. No, no, no. It’s much better than that.
Let me ask you a question; a rhetorical question because obviously I’ve got the answers, right? Here is the question.
You just had a big meal. You drank two beers. You had some pasta, you had a very nice crème brulee at the end. It was a fantastic meal. Even the bread was good, some Annie’s Bread. It was wonderful. It’s about two hours down the road now. You’ve chatted with your friends. And maybe it’s three hours down the road now. Oh I’ll even give you four hours. In the meantime I’m sure you’ve gone to the john at least once. You’ve at least “had to pee” as they would say, “urinated” as we would say. In class that’s what we have to say.
But there’s one other thing that we have to do and that’s about once a day, each of us has our own different rhythm about this. We defecate. What happens to that event? I can tell you what happens. We spend billions of dollars trying to get rid of it. It’s called liquid municipal waste. What is it? It’s urine, feces, and gray water. The gray water is created when you take a bath, when you wash the dishes, when you flush the toilet and there’s nothing there, or there’s just a little bit there. Whatever. All that ends up in the same place.
Have you any idea how much a single bowel movement is worth in terms of energy? It’s enormous. When you have 7.5 million bowel movements per day, you add that energy up and what are we doing with it? We’re throwing it away.
What are we doing with the water part of it? In New York City I can tell you what we do with it. We treat it with chlorine and throw it away. You know how much water there is in Municipal Waste in New York City per day? Right.
And hardly anybody else does either, but I can tell you how much there is. It’s about one billion gallons of water a day. A billion gallons of water a day. Yeah, that’s right. My goodness. If you had that water as drinking water, you could trade that for one billion gallons of oil. I know you could because Saudi Arabia doesn’t have any water. What do they have? They have oil, but they can’t drink it. So they can trade it. They would gladly trade it for water and not have to distill the ocean using some of their own oil to do that. That’s a crazy scheme. It works. They don’t care how much energy it takes because they’ve got, they think, unlimited amounts. Of course it’s limited, but way beyond their lifespan. So if we could take the energy wrapped up in our defecation event, I’ll just leave it at that or bio-product number two as I like to call it, and dry it down, powder it, pellet it, and incinerate it I do not care how much energy the vertical farm needs. We far exceed that in our production of waste products that we generate from eating. Now, let’s connect the circle. Let’s make a circle. Let’s put food production here. Food consumption here, and then byproducts of food consumption here, and then waste to energy back into the farm here. And that water is included there too by the way.
So now what you’ve done is you’ve done something that William McDonough and Michael Braungart in their book Cradle to Cradle highly recommend doing, and that is you start out with a product, you use it, you’re finished with it, hup! It should come back to helping to manufacture the next round of product. There aren’t too many things like that yet. They’ve identified about 3000 manufactured items that fit into that paradigm but they’re using nature as the example of how to do it.
My big example here is just the Serengeti Plain in East Africa. It’s something that everyone’s seen on television, you know, “The lion is now stalking the gazelle.” And we’ve all watched David Attenborough and it’s been marvelous. It’s dramatic television right?
But if you really ask why does this whole thing work and why is it still here? This is where the origins of humanity began some three million years ago, and it’s still like that today! What makes it work? Okay, I’ll just be brief. Which is not one of my main features by the way: sunlight, grass, grazers, predators. That’s the story.
But what’s missing? What’s missing is what happens when a predator dies from natural causes? What happens when a grazer dies from natural causes? What happens to the carcass? And the answer is there’s something called detritavores. Those are microbes, and the microbes consume the carcass, return the nutrients locked up in the carcass and themselves to the soil, and that helps to fertilize the plains so that when the rains come again, and use that bolt of lightening in the background. Ah, finally the rains come. The catfish are saved. Up comes the grass again. Well, I left one other thing out, and that is the dung beetle. All right, dung beetles take gnu dung, which is by the way a palindrome if you’re interested in palindromes, and you take that gnu dung and dig a hole. The beetle takes the ball of dung, sticks it in a hole, lays an egg on it, covers it up and walks away. The next spring up comes a blade of grass and out comes another dung beetle!
When the Egyptians saw that, they thought the dung beetle was the symbol for eternal life. The sun and the beetle. Ra and the scarab. That’s the origins of that, and they thought that’s what agriculture was all about.
Okay, so that’s 3,000 years ago, maybe even longer ago than that. That paradigm still exists in the Serengeti. You can still watch it happen. What’s wrong with us? We’ve been watching this thing for three million years and we didn’t catch on to it. We said, if we behave like that we’d probably be just as happy as the Serengeti. Come on. So that’s basically my pitch if you will.
Dickson Despommier explains that vertical farming would constitute a closed cycle, thus solving many of the water and waste related challenges of modern agricultural methods.
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