MS. MARIA HINOJOSAThanks for joining us. I'm Maria Hinojosa from NPR's Latino USA and I'm sitting in for the amazing Diane Rehm. What a great three days it's been. And as I leave today, I'll actually be going to Chicago, which is a city where I was raised, but I never imagined that in that city a 90,000 square foot facility provided vegetables to city resident year-round. It uses LED lights, no soil and no pesticides.

MS. MARIA HINOJOSAIt was once an abandoned warehouse, but now it's one of many large indoor farms that are popping up around cities worldwide. With me in the studio to talk about these new trends in urban agriculture, Sabine O'Hara, who is with the University of the District of Columbia, Dickson Despommier, who is with Columbia University. Joining us from WBEZ in Chicago, Matt Matros with Farmed Here and joining us from WUGA in Athens, Georgia, Stan Cox with the Land Institute.

MS. MARIA HINOJOSAAnd I just, you know, right before we started, I asked you a question. And I said, I don't think that most Americans realize that there is actually something big, different and permanent that's happening in terms of these indoor farms. So give us a clue, the rest of us who are not living in this space, what's it really like? Is this a moment that's changing forever how we get our food? Sabine.

MS. SABINE O'HARASo thank you for tackling this topic, Maria, because I think it's very, very important. And you're quite right. It is a movement that is in progress, but it's growing very, very quickly. And while we may be a little bit behind, certainly, other parts of the world are ahead in terms of, you know, the scope, the scale of...

HINOJOSASo give us an example of a country where it's really ahead and really big and what that looks like.

O'HARAWell, Germany is one. Holland has actually started the trend of indoor growing, if you will, hydroponics, aquaponic systems. That goes back all the way to the 1960s and '70s when it first started and with these very high intensity growing systems. And, of course, these are small countries and they have much higher population density per square mile, if you will, than we do and so that's where some of these trends started. But it's really becoming a worldwide movement and it's growing very quickly.

HINOJOSAAnd we're gonna be taking your calls and questions throughout our show. The number here is 800-433-8850. Your email can be sent to drshow@wamu.org. You can also join us on Facebook or on Twitter. Dickson, you wrote a book, "The Vertical Farm: Feeding the World in the 21st Century." Again, before we jump into more of the specifics, can you just describe for our audience what they look like?

HINOJOSA'Cause I was thinking about Chicago and I was like, you know, when I'm driving, you know, in the outskirts of Chicago, would I be able to turn around and say, oh, look, it's an indoor farm? What do they look like? Do we even know? Describe them for us.

MR. DICKSON DESPOMMIERWe do know because there are many, many examples of these now, Maria. If you were to go instead of Germany and Holland, which I've been to, of course, and seem some of the examples, if you were to go to Japan, for instance, you could see hundreds of examples. They call them plant factories, but they're more than a story tall. They grow food indoors and they essentially take advantage of the greenhouse technologies that were in existence for some 50 to 60 years.

MR. DICKSON DESPOMMIERSo they're not revolutionary in terms of how to do it. They're revolutionary in terms of how much to do it. So if you go to Taiwan, they've got 50 or 60 versions of these vertical farms. Singapore has lots of them. So Asia is really in dire need of this technology to see them through the next millennium. China, of course, is going to be a world leader in this as well. So what do they look like? They vary greatly from transparent buildings that make use of sunlight, for instance, Sky Greens in Singapore has a transparent four-story vertical farm that rotates the crops past the windows to get the light to them.

MR. DICKSON DESPOMMIERSo he doesn't even use scroll lights. Jack Ng is a traditionalist. He uses soil inside just to grow the plants.

HINOJOSABecause, again, I think people need to realize what we're talking about is growing without soil in some cases.

DESPOMMIERWell, some do, but most don't. That is true. So there are two technologies that are pretty old now.

HINOJOSAAnd I, you know, I want to ask Matt Matros. You're joining us from Chicago where you're the CEO of Farmed Here and you basically -- you run these large scale indoor urban farms. You say they use less water, that they cut down on transportation costs. So as a business man, tell us a little bit about why this makes sense from a business perspective and why you decided to jump in now to large scale indoor farming.

MR. MATT MATROSAbsolutely. First of all, it's super flattering to be part of this panel, so thank you for that, and also to be here with Dickson so the founders of Farmed Here were motivated and inspired to do what they're doing now after reading Dickson's book so it's a pleasure to be a part of it.

HINOJOSALike, seriously, you read the book and you just said, we're gonna go do this?

MATROSI'm not one of the founders of the business, but the four founders of the company that did read it in '09 and then in 2010, started Farmed Here as a result of reading Dickson's book.

HINOJOSADickson, his smile is really wide right now. His eyes are just popping because that's pretty incredible.

MATROSHe's a true pioneer.

DESPOMMIERNo, it is true because the city of Chicago started a taskforce called Vertical Farm Project and I served on that taskforce. The two original founders for Farmed Here also served on that taskforce so the learned about that firsthand and that's when they took off and did this.

HINOJOSAOkay. So Matt, describe it. Just describe for us and tell us...

MATROSThe best way for us...

HINOJOSA...give us the business argument about why this makes sense.

MATROSYeah. So I like to tell people when I see friends or people at cocktail parties, I say that indoor farming is picture a big Costco or a big Wal-Mart and you walk into Costco and you see floor to ceiling pallets and pallets that have Cheerios and Huggies and Crest toothpaste. Well, we're kind of the same way. We're in a big building similar to what Costco would be in, except for instead of floor to ceiling pallets of Cheerios and Huggies and Crest, we have grow beds. And the beds are stacked vertically so we can stack, you know, in our example now, we have six layers of beds that go from floor to ceiling.

MATROSAnd in those beds are pools, pools of water. The water replaces the soil so that's where you get the expression hydroponic. And it's that soil that’s fertilized with organic fertilizer that feeds the plant and then the plants grow. These plants are growing under LED lights so it allows us to grow 24 hours a day, 365 days a year. Something about the...

HINOJOSAI'm imagining that some people hear that and they just think, okay, that's a lot of electricity. And what do you say to that criticism, Sabine?

O'HARASo our approach is a little bit different. I would not call it exclusively indoor growing, but urban growing. And, of course, food production has been largely associated with rural areas or maybe peri-urban areas. So we're taking the food production into urban areas and that can take many forms. It can certainly take the form that Matt just described, indoor growing with LED lights, but it can also be rooftop gardens that actually produce food and then, of course, you use photosynthesis and all of the other elements that impact food production.

O'HARAIt can be small production systems on the ground in small greenhouses or hoop houses that let natural lights in. So we're really exploring what works in what kind of urban environment because urban environments are diverse. Look at Washington, D.C. We have eight wards. They're all very different. And so what works in one place doesn't necessarily work in another and so we look at how can we maximize the use of nature's gifts, you know, the natural systems and to work with that as much as possible.

HINOJOSAStan Cox, you are a senior scientist with the Land Institute, which is a nonprofit research organization based in Kansas. You're with us from Athens, Georgia. I want you to just jump in and answer that question when there might be the critique of is this really the smartest way to grow our food now. Stan?

MR. STAN COXYes. Thanks, Maria. Among the many energy and resource consumption issues that we have in vertical gardening, the real deal breaker is the huge quantity of energy required for lighting. When grown indoors, if you got a plant like tomato or sweet corn plant that produces a fleshy product, that requires about 1200 kilowatt hours of electricity for lighting to produce one kilogram of food minus the water that's in the food. That's about the annual energy consumption of the average American refrigerator for a year, all to produce just two and a quarter pounds of dry matter.

MR. STAN COXAnd that's just for lighting, not for climate control or other energy needs. So in practice, to my knowledge, it has always been leafy greens or herbs that are produced in these systems because they're, of course, mostly water like most vegetables are. Most of the above ground plant can be eaten and you can use somewhat less light than that 1200 kilowatt hours of electricity...

HINOJOSASo Stan, if, for example, these are all glass buildings and you are using natural sunlight, are you okay with that in terms of vertical farming?

COXThe light -- if you have any kind of floor space, the light that can come in from the side through windows is not going to be enough to support plants. Maybe some greens can be grown that way, but generally a room that, to us, looks well lit does not look well lit to a plant. They need quite a high light intensity. So don't get me wrong. I'm all for growing as much fresh produce as we can in and around population centers as Sabine was saying.

COXBut it should be, as she was saying, in on sun-exposed plots of land, rooftops, green walls, greenhouses. And if we did that, though, we would still only be growing a very tiny percentage -- we have 350 million acres of crop land in this country, vegetables occupy only about 3 percent of that and we would not even be able to grow that vegetable crop in that space.

HINOJOSAAnd we're gonna continue our conversation about indoor urban gardening in just a moment.

HINOJOSAWelcome back. My name is Maria Hinojosa, and I'm the anchor and executive producer of NPR's Latino USA, and I am sitting in for the amazing Diane Rehm. It's such a great pleasure to be here. We're talking about vertical farming, indoor farming on the Diane Rehm Show. Now I'm joined by Sabine O'Hara, who is with -- she is the dean of the College of Agriculture, Urban Sustainability and Environmental Sciences at The University of the District of Columbia. Dickson Despommier is a professor emeritus of public health and microbiology, at Columbia University and the author of the book, "The Vertical Farm: Feeding Ourselves and The World in the 21st Century."

HINOJOSAJoining us from WBEZ in Chicago, Matt Matros, who is the CEO of Farmed Here, a 90,000-square-foot indoor vertical farm in Bedford Park, outside of Chicago, and from UGA in -- WUGA in Athens, Georgia, Stan Cox, who is a senior scientist with The Land Institute, a non-profit research organization based in Kansas. Matt, so Stan raised some real critiques, and I'd like you to respond, Matt, if you wouldn't mind.

MATROSYeah, you know, we hear the controversy a lot around energy use, and while that is true, we do feel that indoor farming, just in general as an industry, combats many more issues. So while there is a relatively high energy use, just because of -- as Sabine was saying about Stan, some of the issues that we do tackle maybe perhaps offset that, namely transportation of food. So when you think about 85 percent of the produce that the country consumes is grown in California, Mexico or Arizona, so you think that produce has to be trucked somehow.

MATROSSo if you're in Maine, and you want to eat lettuce, it's got to get from Arizona to Maine. So that's whole lot of carbon emissions that are out on the -- in the environment, a lot of food miles that that produce goes under. Water use, so we use about 97 percent less water than a traditional farm because we can capture the water, recirculate it, and the water that's used is only the water that goes into the roots of the plant.

MATROSWe can also grow year-round, and we can grow around the clock. So think about areas where they may be subjected to poor weather, we can grow in any type of environment, in any type of weather. So when you add all those up, and you also factor in the fact that we don't use any pesticides, so those aren't getting into our environmental systems, we feel that that far offsets any sort of energy use.

MATROSAnd then specifically as it relates to energy use, much like the solar industry in the, you know, '90s and 2000s, where we saw the cost of solar panels just plummet, we feel the cost of LED lighting and the efficiency of LED lighting over the next several years is just going to continue to plummet, as well, plummet from a cost but, you know, rise from an efficiency perspective. So that's going to kind of offset that energy use.

HINOJOSAOkay, now Dickson, you know, I asked that question about, will -- because I'm fascinated by this notion of an all-glass building, structure. What is the challenge to using natural sunlight? Or what is it about the problem with using solar energy to then power the LED lights? You're shaking your head yes.

DESPOMMIERThat was the idea. That's exactly what's happening. I mean, the Jack Ng model of rotating crops past the windows using a pulley system, which is generated the same way that you would envision a grandfather clock, with pulleys and weights, and the weight is supplied by buckets of water, and in Singapore it rains every day, so there's no shortage of water in Singapore. So he's worked out this very interesting engineering system to allow him to overcome the need for grow lights.

DESPOMMIERBut, you know, if you walk around the world, I can show you places where energy is never going to be a consideration for whether you do this or not, and I can start with an island community of Iceland. They've got all the geothermal energy they could possibly use, so everyone taps into the ground and gets it all for free. So of course you need some engineering in order to bring it to a reasonable heat level so that you can handle the electricity produced from it.

DESPOMMIERAustralia is one gigantic solar panel waiting to happen. Italy has geothermal energy that it sometimes can't really use, remember Pompeii and Herculaneum, and then finally the north island of New Zealand is loaded with similar geothermal energy gifts. And so we've got wind power and solar power and geothermals to think about it, and I think Matt is absolutely spot-on. The efficiency of LED lighting over the last five years has gone from some 20 percent efficiency to Philips just announced last year a 68-percent efficient LED light. That's going to revolutionize how you do this.

DESPOMMIERAnd so Lumitex, which is a company in Texas, is taking advantage of that. they used to work for Philips, and now they're exploiting the focusing of LED lights to use less electricity to get the same amount of bang for your buck, so to speak, and they're successful. So I think you have to ask the business models whether that actually works. I think it does now.

HINOJOSADean Sabine O'Hara, you wanted to jump in.

O'HARAYes because, you know, sometimes the solutions are not necessarily high tech. Sometimes they can be very low tech. I give you example. We have northern exposed balconies on our campus here on Connecticut Avenue, and so the question was, you know, is it possible, if somebody only has a balcony that has complete northern exposure, can they still grow vegetables. And so we went about to try and use the reflective power of white sheets and of aluminum foil.

O'HARAAnd so we covered the soil of our balcony plots with these white sheets, one, and with the aluminum foil, and then we planted the seedlings through those covers. And the answer is yes, this reflection makes a difference, as opposed to dark soil. And so sometimes the solutions are not high-tech, but they are low-tech, and it's just a matter...

HINOJOSAI would love to know how that conversation happened, when somebody just said, well, let's try a reflector, maybe.

O'HARAWhat are we doing?

HINOJOSAWhat are we now doing? Right. Dickson, you wanted to jump in.

DESPOMMIERYeah, there's a larger issue at stake here as to whether we should or shouldn't be doing this, and that is climate change issues. I mean, where you grow your food now is not where you'll be able to grow your food in 100 years from now. that's obvious by the way the trends are going now, and there's nothing that says that this is going to stop soon.

DESPOMMIERSo if you're not going to address climate change in a way that stops and slows it down, then you're going to have to adjust, and part of that adjustment is going to be where you can grow your food, and I think indoor farming is a solution for that particular problem.

HINOJOSASo Stan Cox with the Land Institute, what's your response to the responses to what you raised, to these critiques about, no, it is doable, and it can be done saving energy?

COXWell, regarding energy and emissions, by my rough calculation, if we were to produce the entire U.S. vegetable crop, not counting potatoes under electric lights, it would require over half of our annual electricity generation every year for the whole country and produce 1.3 billion metric tons of carbon emissions every year. So if we instead talk about using wind or solar or geothermal to run these operations, then we're unnecessarily consuming green energy that could've been used to replace fossil energy running our refrigerators and air conditioners.

COXSo if we use solar arrays and wind farms, we are converting free sunlight into electric current so that lamps can convert a portion of that electrical energy into artificial sunlight to shine on plants so they can grow, so -- and with each of those conversions, there are big losses of energy and big infrastructure costs, it's about as inefficient a system as it can be. So we need to let crop plants do what they do best, which is capture the cost-free, emission-free sunlight directly.

HINOJOSAOkay, Jim from Columbus, Ohio, you have a quick comment. Go ahead.

JIMWell actually, I've been working on a greenhouse that addresses all of the issues that have just been raised specifically by this last gentleman's comments. It's a greenhouse that allows for the practice of aquaponics in a controlled environment, 12 months a year with virtually no external energy inputs.

HINOJOSAAnd you're doing this on a large scale or just a small greenhouse?

JIMIt can be scaled from a family up to commercial size.

HINOJOSAOkay, Dickson, when you hear someone like Jim saying hey, I'm doing, you're shaking your head.

DESPOMMIERNo, I am shaking my head yes because I have done a lot of traveling in the last five years talking about this subject, and I've had to address critiques that range from it's not natural, well farming is not natural, I hate to tell you, Stan, that farming is not a natural thing because only 10,000 years of human history have we been farming.

HINOJOSABefore, we were hunters and gatherers.

DESPOMMIERFor 200,000 years we didn't even think of it. So this is not a natural system in terms of taking care of the rest of the DNA molecule, which is the rest of life on Earth. So we have to have a little bit more respect for the rest of life on Earth. We continue to deforest. We continue to plant crops. We continue to grow our population, and we don't think about the ramifications of doing this over the next, let's say, 100 years.

DESPOMMIERIf this continues, we're in very, very deep trouble.

HINOJOSASabine?

O'HARAIf you're here in the Washington, D.C., area, you don't have to go very far. You can come to our research farm, the research farm of the University of the District of Columbia, which is out in Beltsville, where we actually pioneer a lot of these ideas about urban agriculture or urban farming, urban food production. So we have an aquaponic, actually several aquaponic systems out there that are pretty darn close to be net-energy neutral. That means, you know, the amount of calories that you're harvesting is at least close to the amount of energy input into the system.

O'HARAAnd then when you add to that the travel, that certainly changes the energy balance, as well. I want to pick up, though, on this idea of urban versus peri-urban and rural. Stan makes a good point. You know, we don't have the aspiration of growing all of our food in urban areas. So for example, we don't do corn and soybeans much at the University of the District of Columbia. It makes no sense. We're the only land grant university in the country that is exclusively urban, and so we focus on things that are high in nutrient value and highly perishable because the other thing that we haven't addressed is that when things travel long distance over a long time, their nutrient value actually cannot possibly be as high as what you've just harvested.

HINOJOSASo high nutrient, highly perishable? I always -- I thought you were looking for high nutrient, not perishable.

O'HARAThe one -- the goods that you want to -- the food that you want to produce in urban areas, where most of your population live, are those goods that are not -- that are high in nutrients but that would perish easily if you transported them over long distances and over a long time.

HINOJOSASo the quick transport is essential.

O'HARAAnd then you kind of do a triage, right. Then we go to the peri-urban ring, where we would grow things that are not quite as perishable. And then we go to the rural areas, where we can grow those things that are more easily stored, more easily transported. And so if you think of it that way, there is a role for every part of the country in the landscape in urban -- in food production, but urban areas really need to focus on those things that are particularly valuable in terms of their nutrient content but that also spoil easily.

O'HARASo you don't want them to be on the road between, as, you know, as Matt said, between California and Arizona and Washington, D.C., for two weeks before they even arrive in a distribution center before they arrive in our grocery stores.

HINOJOSAAnd we're having a conversation about vertical farming. That was Sabine O'Hara, who is the dean of the College of Agriculture, Urban Sustainability and Environmental Sciences at The University of the District of Columbia. Also with us is with Dickson Despommier, Matt Matros is with us from WBEZ in Chicago, Stan Cox is joining us from Athens, Georgia, and in a minute we'll be joined by someone from Milwaukee, a very important statement. And you're listening to the Diane Rehm Show.

HINOJOSASo you wanted to jump in, Matt, in WBEZ. Go ahead.

COXWell, this is Stan, who was wanting to jump in.

HINOJOSAHold on one second, Stan. I think it was Matt that we're going to go to, and then we'll come to you, Stan.

COXOh, sorry.

MATROSI want to say that, you know, we have a tendency as Americans, because we're such awesome capitalists, to just focus on America, right, and if you look at the obesity divide between wealthy countries like America, where we have high rates of obesity, and countries that are hungry and literally starving to death, when you start thinking about that as the problem and less about energy use and all these other things and try to solve that big problem of feeding the world, that's where I think urban and indoor farming can really kind of accelerate.

HINOJOSAAll right, so I want to know if -- we have someone joining us now from Milwaukee, Wisconsin. His name is Will Allen, and he's the founder and CEO of Growing Power, Inc., a nonprofit organization. Matt, you grew up on a farm in Maryland, one of six children of a sharecropper. You are -- I'm sorry, Will, I just called you Matt, sorry Will Allen. Sorry, Will, didn't mean to do that.

MR. WILL ALLENThat's okay.

HINOJOSAYour name is Will Allen. You are, in fact, considered a pioneer of urban agriculture. You received a MacArthur Genius Grant in 2008 for your innovative farming projects in low-income communities. Your organization now plans to build a five-story vertical indoor farm in downtown Milwaukee. Thanks for being with us. So Will, just give us a sense about growing power. You have a number of urban farming projects in Milwaukee and Chicago. Tell us what Growing Power is doing.

ALLENWell, this is our 23rd year of operation. I bought this farm back in 1993 to sell my farm produce. I have a farm outside of Milwaukee, a 100-acre vegetable farm, and I was looking for a place to sell my farm goods. I was wholesaling into -- back in the day when you could take product from the farm directly into grocery stores and not through their warehouse system. So I was looking for an area that needed healthy food. And I just found this place on the northwest side of Milwaukee.

ALLENAnd I wanted to make one correction. Our vertical -- proposed vertical farm is not downtown. It's in the community where our farm is located, on the same property, which is a three-acre property.

HINOJOSABut it will be, it will be five stories?

ALLENYeah, and the reason...

HINOJOSAI mean still, no matter what it is, when you think of a five-story building in Milwaukee city proper, what is it going to look like, and what will you grow there?

ALLENWell, it's both a research type of a building, as well as a functional growing facility to really figure out how to grow in this type of facility because Dickson, I know, has proposed some 50- and 100-story-type buildings in cities that will need this in the future like New York or Boston or Vancouver, cities like that. But we need to prove that we can cash-flow these farms to be able to grow vertically in each one of the greenhouses that are on top of each other, to be able to have a facility in a low-income area like we have on the northwest side, on Silver Spring Drive, that has a retail store, that has a commercial kitchen, that can house about 400 people for small conferences and meetings, to be able to have offices and be able to have students that are studying the food system to be actually right on the farm.

HINOJOSARight, and Will, you wanted this to be located in an urban environment. You wanted this in a residential community, in fact near a public housing project, in a place where there are not a lot of locations to buy fresh produce. Was that one of your key motivators, as well?

ALLENWell, that was my original purpose for purchasing this property, to bring food into what many people call these food desert areas. And we're five blocks away from the largest public housing project in Milwaukee, about a 75-acre facility. We have to travel -- folks that live in that community have to travel over four miles to the closest box grocery store. The only food that's available are a few, you know, corner stores.

HINOJOSAAnd we're going to continue the conversation with your calls and questions. Stay tuned.

HINOJOSAAnd you're listening to "The Diane Rehm Show." My name is Maria Hinojosa and I'm the anchor of NPR's "Latino USA," sitting in for Diane Rehm. And if you want to call us, the number here is 800-433-8850. You can send us an email to drshow@wamu.org. All right. So we have a comment from Lola on our Facebook page.

HINOJOSAAnd this is what she says, "This is what my family calls zombie food. It's not dead, but it's not really alive either. This is food raised with chemicals and unnatural light and in no way can provide the nutrition that organic food raised outdoors can." So, Will, you are hearing this critique from Lola. When she calls it zombie food, what do you say?

ALLENTotally not true. As we look into the future, we're gonna have to be able to grow in hoop houses and greenhouses because of climate change. We're already be affected by that. We grow our own soil. We have a large composting operation. Last year we composted over 40 million pounds of food waste and carbon waste to grow thousands of yards of compost to do -- we grow both on the inside and the outside.

ALLENWe also have some rural farms within a half hour of the city to grow food as well. To make this work, to really create a sustainable food system, you need both the urban and rural production. So when people try to say this is really high tech kind of growing and it's just using chemicals -- we no use no chemicals in our operation. We use worm castings for our fertilization. We have a soil scientist on our staff, who's also a farmer. So we approach everything in a very sustainable way. We collect water that goes into both our fish systems, as well as our growing. We also…

HINOJOSAAnd, Will Allen, you are with Growing Power Inc., which is a nonprofit organization. And I just want to know, you have a lot of financing. So how do you go about raising the money for these kinds of projects?

ALLENWell, we don't have a lot of financing, contrary to…

HINOJOSAI meant to say you have to raise a lot of money in your financing. There was a keyword missing there. You need to raise a lot of money, so how do you do it?

ALLENWell, you know, most of our money comes from our production. We grow food, we sell. We have seven wholesalers that we sell to. We have farm stands, farmers markets that we go to. We have various CSAs. We have a fish CSA, a fruit CSA, a vegetable CSA. So over 50 percent of our income comes from our own efforts.

ALLENWhat we've done is we've divided our programs from our production. In other words, our production, farm production really funds our social responsible things that we do in training youth, in working with schools, and training. We've trained over, in the 23 years, thousands of people. We have -- we do aquaponics on a very large scale.

HINOJOSASo, Will, you believe, basically, anybody has the capacity to be a farmer and to grow. That's really good for people who may think that they don't have a green thumb. Will Allen, you're the founder and CEO of Growing Power Inc., based in Milwaukee, Wis. You're also the winner of a Genius Award from the MacArthur Foundation for all of the work that you're doing in this area of changing the way we grow our food. Thank you so much for joining us, Will, from Milwaukee.

ALLENThank you very much. It's great to talk back to my home area, where I grew up.

HINOJOSAThank you so much. Thank you so much, Will. So, Dickson Despommier, author of "The Vertical Farm," you're very happy right now when you hear all of this kind of energy around this issue.

DESPOMMIERYeah, I am actually, because really at issue is you have two problems together. One is to restore the environment to a place where carbon balance on the Earth can be partially restored. Namely reforestation in places where the -- it's been deforested. In place of forests we have farms. So how can we address the issue of still having the food supply that we need and restoring the forests at the same time?

DESPOMMIERSo indoor farming is about 10 times more efficient at growing food than outdoor farms. So if you just did 10 percent of the food production in cities, of what they consume, that would generate -- of all the world cities -- I did a calculation, too, Stan. And I could tell you that that represents about 340,000 square miles of forest that you could restore, if cities could just produce 10 percent of what they consumed within the city itself.

HINOJOSAWhat do you say to that, Stan?

COXWell, I say the tenfold figure isn't to be believed. Now, in Dickson's original -- in his original vision he had an excellent critique of industrial agriculture and the soil degradation that results from it. And he proposed to protect soil, as he is today, by taking it out of production, moving crops to cities. And that could be done under the kind of systems that Sabine is talking about, to the extent of maybe that 3 percent of land -- of our crop land that's used for vegetable.

COXOr it could be done indoors with tens of thousands of Empire State Buildings to come to -- even if it was much more efficient, it would take that much. But we can take vastly more land out of production by eliminating, for example, the feedlot system of meat production and the hundreds of millions of acres of corn and soybeans that supply it. There are also ways of keeping soil in production and still protecting the soil, water and the atmosphere. The best would be replacing annual crops with perennial food and pasture crops.

COXSo there are effective ways to address the problem of agriculture, but they don't include vegetable factory farming. Most of us agree factory farming of animal-based foods is not environmentally sound. And this is factory farming of plant foods, and it's also unsound.

HINOJOSAThank you, Stan. Sabine, I want you to respond to Stan. But also, we need to expand our own conversation, which is that it's not just about farming. Right? You're doing a lot of experimentation with aquaponics. What is that and how -- you're using fish tanks, right, to farm. How does that play into this whole conversation about vertical farming and urban farming?

O'HARAAnd Will mentioned that methodology as well. So our systems are also completely organic. So we use fish waste as fertilizer for the plants. And then the plants take up the nutrients out of that water that is enriched with the fish waste. And once the plants have done their job and the nutrients are reduced, they go back into the fish tanks. And that's why these systems save an enormous amount of water if you recycle the water.

O'HARAEnhancing soil health by plowing under what's left after the harvest, you know, usually after the harvest, at very least, the root system is still there. So if you turn that under and this is sort of your low tech way of composting. You don't even have to take it out and put it in a compost bin. But you just turn it under the soil, those are all methods that enrich the growing environment. So the methodology itself, whether it's growing in soil, growing in water, that doesn't necessarily say anything about whether it's organic or not. Right?

O'HARAIt's how you do it and how you use each of these methodologies. But I also want to expand a little bit. You know, we've been talking a lot about food production. But our approach, as the District's only public university, is really more broad than that. It's food production and then food preparation because in many of our neighborhoods we've lost the art of using fresh food because we've been so accustomed to using processed foods. And then it's food distribution.

O'HARAWe think of the grocery store as the place where we get our food. But why not cooperative systems, like community-supported agriculture where you buy a share in your neighborhood farm and the produce is delivered on a weekly basis. We've launched such a cooperative model at the university in the last growing season and hope to expand it this growing season. So we're exploring different ways of marketing. And then particularly in an urban environment it's really, really important that we also close the loop through waste and water management.

O'HARAWhere do the leftover plant pieces go? How do we recycle them, reuse them in composting? But also, how do we capture the water? So we would actually say that some of these systems, if you do it right, they make a positive contribution beyond the food production. There are these positive externalities of taking water out of the circulation of your gray water system in the city and taking pressure off of that.

O'HARAAnd then Dickson already mentioned photosynthesis. You know, plants are green. So when they grow on roofs they help climatize your building, they add to the atmospheric health in your urban environments, they may even cut down on heat island effects. So…

HINOJOSASo, Matt, in Chicago, I'm just wondering, you know, it sounds very idyllic. Is, in fact -- is the food safer, are you using less pesticides, is it better for us, in your view?

MATROSWell, it just depends on how cynical you are in the world. We like to say that we are safer because our environment is fully controlled. So we have a -- literally a box that is airtight, you know, that we can control every element. We can control the temperature of the water, we can control the temperature of the air, the humidity of the air, and then we can also distribute our organic fertilizer into the plant. So we know everything that's going on there. It's almost -- it is basically manufacturing, but it's manufacturing of fresh produce.

MATROSYou know, the woman who wrote on your Facebook wall talked about this being zombie food. It's actually quite the contrary, you know. I bet if we were to look in that individual's refrigerator or pantry we would find gobs of American processed foods that actually are more akin to zombie food and that's it synthetic materials that are slammed together by capitalist scientists, which are awesome because they've been able to create food for the world. But they're just not real and not natural. So the food that we are making is as fresh and as natural as it can get.

HINOJOSAWe…

MATROSAnd because it's made in your backyard, we can get it to you, as Sabine mentioned, within, you know, a couple days of it being harvested. So it's just more nutritious.

HINOJOSASo we have an email from Gary, who asks a kind of basic question. "What about pollination?" What about pollination?

DESPOMMIERIndoor farmers have solved that problem by keeping colonies of bees, like bumble bees for instance. They're very good pollinators and very friendly and very easy to get along with, as opposed to let's say the African honey bee, which might be an aggressive species that you wouldn't want to put indoors. But, yeah, and then there's hand pollination, too. And not all the crops require pollination. I wanted to add a comment though about fresh food.

DESPOMMIERI had dinner last night in Washington, D.C., at a restaurant called Bidwell. It's in Union Market. And it produces its food on the roof. Most of the leafy greens and a lot of the other ingredients of the meal that I ate last night was so fresh that it was measured in food inches, rather than food miles. And it was as fresh as a minute ago.

HINOJOSAOh, you mean the inches that it had to travel to get you.

COXExactly right. It was on the roof with tower grow systems, which are aeroponic. And the diets are controlled. And the food is unbelievably delicious. And I think Matt is spot on in saying this is not -- this is the opposite of zombie food.

HINOJOSAAnd I just want to let you know that all of you are listening to "The Diane Rehm Show." We want to continue our conversation with a call. Let's see, Jeremy, from Washington, D.C. How are you, Jeremy?

JEREMYI'm very well. Thanks so much for having me on and for having this awesome conversation. I was actually a student of Will Allen's and I am a -- I am one of the people that he has trained over the years. And so as a result of my work at Growing Power, we launched a company here in Washington, D.C., called Compost Cab, which was built expressly to do two things. Make it easier for people to compost and make it easier for urban agriculture to thrive.

JEREMYAnd so thanks to all the guests for doing -- for filling out their pieces of the puzzle. It is a system that we're all building together. My question for all the guests is how did you come to this area? Why urban agriculture? Why is that the place where you've chosen to direct all of your professional and personal energies? There's a lot of places to do good in the world, why urban ag?

HINOJOSAAnd you know I have to say, Jeremy, that's a really great question. I was -- and to kind of add to that, I was writing down nature. Right? The exposure to nature, what happens. And of course it's like, well, it's controlled nature. But exposure or in urban farming, but what was the passion that led this to you? Let's start with you, Dickson.

DESPOMMIERWell, I'm a parasitologist by training. I've taught at Columbia's Medical School for 38 years, and half of those diseases -- not the defective born ones -- but the other parasitic diseases are mostly food borne. And they're transmitted at the agricultural interface because half of the world is forced by economics to use a very simple fertilizer. It's called human feces. And in doing so, they, of course, fulfill all the requirements that the parasite needs to transmit itself from one host to another, namely humans.

DESPOMMIERIf we were to stop doing that and then handle production in another way we would not have to suffer the burden of diseases which are delivered by our own hands through our food supply. So that's a primary motivator for me to get involved in this. This indoor farming short-circuits that process.

HINOJOSAInteresting. Matt Matros, we know that the founders of your company were inspired by Dickson. But what made you jump in?

MATROSWell, I like to say that my life's been vertically integrated around food, starting from when I was the fat kid growing up. And then I lost, yeah, about 50 pounds on a high-protein diet. And then ended up working for a big food manufacturer, Kraft Foods. So I was the brand manager of Kraft Cheese, which I still have a hard time saying with a straight face. And so I saw kind of end to end what America's food system's all about and sort of the damaging chemicals that can be put into our body.

MATROSAfter that I ended up starting a chain of healthy food restaurants called Protein Bar. That centered around trying to feed people all natural and organic produce in a way that allows them to lose weight. And then I thought just the logical next step for me would be to continue kind of, "vertically integrate" down the supply chain and get into the production of fresh produce.

HINOJOSAAnd, Sabine, where did it start for you?

O'HARASo I'm trained as an agricultural economist. And I wasn't inspired by Dickson's book, because I'm really too old for that. When I was in grad school I was inspired by another book by Herman Daly, called "The Steady State Economy." And that turned me from an ag economist into an ecological economist because that book really said why don't we design the economy so it is in sync with the second law of thermodynamics. Meaning that when we use energy we generate entropy and heat. And that can't be recaptured.

O'HARAAnd so why don't we design an economy that minimizes entropy generation and waste and emissions and all of that. And design systems that are more in sync with how the planet works and how the physical systems of the planet works. And that's -- that took me down that road of ecological economics and food systems that really minimize emissions and waste, but looking at it in whole net calculation, if you will, of what's the energy balance here. And so that's why it's not sufficient to simply look at the production part of the system, but what's the value added, what are the positive externalities that we can contribute, so as a side effect, you might say, that typically are not evaluated in our economic calculations.

HINOJOSASo, briefly, all of you are extremely optimistic about where this gonna go? We're gonna see this -- it's gonna become commonplace in your hopes?

DESPOMMIERI just got back from Paris, where the mayor of Paris assembled a group of experts to rule on various architectural renderings for uses of properties in the periphery of Paris that were going unused. And they had nine bullet points that they had to address. And one of them was urban agriculture. So the city of Paris, the food center of the world in terms of cuisines, and the most critical of unnatural versus natural cuisines, wants to insinuate vertical farming and rooftop gardening and urban agriculture in all of its iterations into that city.

HINOJOSAI think you just said if they can do it in France, we can do it, too. I want to thank everybody for joining me on this conversation. Sabine O'Hara with the University of District of Columbia, Dickson Despommier, Columbia University, Matt Matros of Farmed Here, Stan Cox at UGA -- WUGA in Athens, and Will Allen. And my name is Maria Hinojosa. I'm executive producer and host of NPR's "Latino USA," sitting in for Diane Rehm. Thank you so much for listening.