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Growing up: Welcome to vertical farming

April 7, 2020

Closed system processes food waste and produces organic produce in record time

Editor’s note:  This story is being highlighted in ASU Now’s year in review. Read more top stories from 2020.

A new word will have to be coined to describe Zhihao Chen. Is he a farmer if there’s no farm?

Chen, a chemistry instructor at Arizona State University, has created a new system for growing food. Forget farm to table. Chen has skipped the farm entirely.

In a time when grocery stores are struggling to keep shelves full, Chen’s vertical farm could sit in the corner of a market parking lot, sending lettuce grown from a completely organic closed system to the shelves in as little as three weeks.

The system, which Chen describes as "cleantech," is contained within two standard shipping containers. One 160 square foot space contains a system for breaking down food waste — anything from potato peels to rotten carrots to egg shells — and transforming it into fertilizer and methane gas. It’s capable of processing 2,000 pounds of food waste per day – the amount an average grocery store tosses out daily.

The second container hosts shelves of produce grown in a carefully-controlled environment.

 Zhihao Chen, inside the digester container, talks about the vertical farming system

Zhihao Chen, inside the digester container, talks about the vertical farming system he and his colleagues have developed at the Environmental and Resource Management lab, a part of Arizona Center for Algae Technology and Innovation (AzCATI) on the Polytechnic campus. Photo by Charlie Leight/ASU Now 

The 320-square-foot space can produce 1,200 heads of lettuce per month — the equivalent of two acres of farmland production. Traditionally, it takes lettuce 30 days to grow to maturity. Chen’s system produces a mature head in three weeks. It also doesn’t depend on climate. And the system uses 95% less water than traditional agriculture.

This could work on an island, in space, at sea — anywhere.

Chen came up with the idea two years ago. An instructor in the College of Integrative Sciences and Arts on ASU’s Polytechnic campus, he assembled a team to work on the project and created a startup called Homer Farms.

He takes food waste from the campus and grows lettuce, which goes back to ASU Dining Services.

“We want to achieve zero waste at ASU,” Chen said. He plans to expand operations to the other campuses. He is also in talks with grocery chains Fry’s and Kroger right now. Fry’s is interested in putting the system in their parking lots to use their food waste.

“The customer can actually see what’s going on,” he said. No pesticides, no chemicals or artificial fertilizers are used. It’s completely organic.

And, he adds, “You pretty much don’t emit any greenhouse gas emissions.”

Lattice of lettuce roots in ASU vertical farm

A lattice of roots float in the fertilizer brine in the racks for the week-old butterhead lettuce. Photo by Charlie Leight/ASU Now 

The process is called anaerobic digestion. Certain bacteria under a certain temperature with the proper pH will break down the carbon chain in food waste and feed the carbon into the biogas. (Biogas is a mixture of CO2 and methane.) You can combust the methane for energy to run the unit and heat it to keep growing conditions optimal.

“We process the waste, it becomes liquid fertilizer and biogas,” said faculty sponsor and Assistant Professor Taylor Weiss. “Some of the liquid fertilizer is used in algae production and some is used in the vertical farm to feed the lettuce. When the lettuce is mature, we send it to ASU Dining Services to close the loop.”

It saves long-distance transportation. How about using this in a major metropolitan area like New York or San Francisco?

“We’re able to produce on-site, so the lettuce doesn’t have to be transported from Arizona to New York,” said Chad Geelhood, assistant director of Environmental and Resource Management. “We cut down energy costs, we cut down greenhouse gas emissions, and we make the city more resilient.”

Right now, with the supply chain overwhelmed, “if you have something like that on-site, the city can self-sustain,” Geelhood said. “You don’t have to worry about waste and the food will be supplied on time."

Arizona ranks second, following California, in production of lettuce. Lettuce production in Arizona includes head, leaf and romaine lettuces and is the state's leading cash crop, averaging more than $300 million in value.

“If you air condition the container, it can be year-round in a New York environment,” Geelhood said. “Here we don’t have to add as much heat because we’re in the desert.”

The system can grow any type of vegetables.

Zhihao Chen and Chad Geelhood inside vertical farm at ASU

Instructional professional Zhihao Chen (left) talks with assistant director of Environmental and Resource Management, Chad Geelhood, inside the growing room with racks of week-old butterhead lettuce. Photo by Charlie Leight/ASU Now

“Lettuce and leafy greens are a good target because they’re high-bulk and it costs a lot to transport them relatively, but also growing them in a closed space makes them more nutritious as well,” Weiss said.

The fertilizer is super-concentrated and has to be diluted. Inside the grow container, temperature, humidity, light intensity and plant temperature are all intensely monitored.

“In that way we can predict the quality we need,” said Yujin Park, an assistant professor in the College of Integrative Sciences and Arts who researches what types of light wavelengths are best for growing. Conditions can be optimized for different crops.

Homer Farms is currently under incubation at University of Arizona Center for Innovation.

Top photo: Assistant Professor Yujin Park checks the week-old butterhead lettuce plants at Environmental and Resource Management (ERM), a part of Arizona Center for Algae Technology and Innovation (AzCATI) on the Polytechnic campus on March 26, 2020. The plants will be ready for harvest at three weeks. With the goal of creating a circular economy, the lab takes food waste from the university's food services and turns it into a fertilizer by way of a digester. The fertilizer is diluted and used as a hydroponic medium to grow lettuce, which is then returned to the food services. Photo by Charlie Leight/ASU Now

Scott Seckel

Reporter , ASU News


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Dissecting hope

April 7, 2020

ASU professor says the difference between hope and hopelessness is choice, followed by positive action

Hope isn’t a word that’s getting tossed around much these days.

Let’s face it, COVID-19 has turned our lives upside down. People around the world are dying or being hospitalized, the economy is taking a beating, and people have been forced to separate from one another. To many, it feels like the sky is falling.

But Arizona State University Professor Rick Miller said despite what’s occurring now, humans are lucky because we’re the only species who understand the concept of hope. And that’s extremely important.

“The idea of resiliency, though, is to survive — to take a body punch and get back up,” said Miller, clinical director of ASU’s Center for the Advanced Study and Practice of Hope and a Professor of Practice in the T. Denny Sanford School of Social and Family Dynamics. “The other skill set required is hope. Hope is about thriving — not just surviving.”

ASU Now spoke to Miller about the meaning and research behind hope, its healing powers and its ability to enable us all to bounce back.

Man in glasses and black shirt and jacket

Rick Miller 

Question: How do you find hope in times of uncertainty like today regarding our situation with COVID-19?

Answer: During times of uncertainty and challenges — and we are presently living in such a time — we trust we have two basic skill sets that will help us navigate troubled waters. The first is resiliency and the second is hope. Each of us has a different ability to bounce back when things go against us, physically, emotionally or economically.

We build a reservoir of “antibodies” that help. We exercise, sleep and eat well. So, if we experience a physical setback, we may recover faster than if we weren’t vigilant about our health. To protect ourselves and remain emotionally healthy, we learn to manage stress, meditate, recreate and surround ourselves with positive and supportive family, friends and co-workers. To prepare for an economic setback we live within our means, avoid debt as best we can, budget carefully and invest wisely.

Like all living organisms, human beings share the responsibility to first survive and second to reproduce. Those two responsibilities connect us to a shared system of life forms. But human beings are truly differentiated from our shared biology with animals, plants, fungus and microorganisms by our unique ability to hope. No other species shares that gift. It truly is what makes us human.

Q: What really is hope and can it serve as a compass to help us navigate ourselves through these difficult times?

A: Since the first century of the common era, hope has lived alongside with faith and love in the New Testament. The Old Testament also addresses hope dating back to 1200 B.C. But it wasn’t until the 1990s that hope took its place at the research table beside other scientific interests.

Science began to examine the “DNA” of hope to better understand why some people have a lot of it; some a little; and why so many people have none of it at all, considering people who are found to be of high hope do better in life, physically, socially and economically, than those who score low in hope measures.

We now better understand that hope is a more a cognitive function than a series of loosely defined emotional sensations.

According to Dr. Shane Lopez, whose groundbreaking work is in hope science, hope is “the belief that the future will be better than the present, along with the belief that you have the power to make it so.” Dr. Richard Snyder defined hope as having three major constructs: goals, pathways to those goals, and the agency or personal energy/motivation to pursue those pathways in order to achieve one’s goals.

ASU’s Center for the Advanced Study and Practice of Hope suggests we think of our goals, pathways and agency as four domainsAs stated above, the four domains are: home and family; education and career; community and service; and hobbies and recreation.: home and family, education and career, community and service, and hobbies and recreation. The thought here is keeping the brain busy about possibilities rather than calamities. In other words, we are wiring our brains to be hopeful.

Q: One of the premises of your research is that there’s a choice between hope and hopelessness. What exactly do you mean by that?

A: We are often asked if hope is a conscious choice we make or are we shackled to a genetic predisposition where nature trumps nurture? The good news is hope is a choice — as is unfortunately, hopelessness.

Hope can be taught and learned like other skill sets such as learning to ride a bike, understanding math, practicing reading and writing, or learning to cook. We also know that when you choose to hang around people who are pessimistic or hopeless you begin to pick up on their traits and behavior. Conversely when you choose to be with people who are positive, optimistic, resilient and hopeful you find yourself adopting their behaviors. As a social species, we want to belong. It’s a lot healthier physically, emotionally and intellectually to associate with hopeful, positive people who know they are able to control their own destiny.

Q: What’s the difference between hope and optimism?

A: There is quite a difference between hope and optimism. Simply speaking, optimism is a positive way of thinking about the future whereas hope requires both positive thinking and positive action to achieve one’s goals.

There is, however, a symbiotic relationship between hope and optimism in which both benefit. Individuals who are found to be optimistic and hopeful benefit greatly and holistically from those two constructs. The proverbial phrase that states a pessimist sees a glass half empty while an optimist sees it half full can be extended to include that hopeful people know they can fill the glass.

Q: Beyond surviving COVID-19, how do we decide what the next chapter of our lives will be?

A: Right now, we are consumed with bad news. Our lives, our dreams and our goals are interrupted. The future appears less secure.

Viktor Frankl, an Austrian psychiatrist and holocaust survivor, illuminated our understanding of the human spirit in his celebrated book, “Man’s Search for Meaning. His deep, profound and poignant examination about the primary purpose of life in the face of great hardships revealed three sources: purposeful work, love and courage. We believe that hope activates those sources.

We need to take advantage of the gift of hope to help us keep our brains nourished with meaning, purpose and passion. We need to think about the future and use (the) four domains to offer our brains a sense of direction. What are our goals within each of those destinations? Where are we today and where do we want to be in two to three years in each destination? What pathways do we need to consider? What happens if a pathway is blocked? And finally, on a scale of one to 10, in which one is low commitment to the goal and 10 a high commitment to the goal, are we ready to put gas in our own gas tank to purposefully move toward achievement? The brain loves questions, particularly positive questions, so make sure you are offering the brain what it needs to thrive.

Q: You have a very popular online HOPE Forum. Tell us what it’s about, who you’ve had on the show and what you focus on?

A: To help hope along, ASU’s Center for the Advanced Study and Practice of Hope in partnership with Kids at Hope, a not-for-profit organization, is hosting a series of free online HOPE Forums titled “Strategies for Life’s Challenges.”

We have invited individuals whose lives have been defined by hope, including Antwone Fisher, whose journey from hopelessness to hopefulness inspired the movie “Antwone Fisher” starring Denzel Washington; Erin Gruwell, whose work with “throwaway kids” resulted in a bestselling book “Freedom Writers Diary” and the major film “Freedom Writers” starring Hilary Swank; and brothers David and Danny Diaz, who along with their family, school and community discovered hope, which was chronicled in the Disney film “McFarland USA” starring Kevin Costner. 

Top photo courtesy of