Sixty-million tons of produce is destined for the landfill every year, according to Goggy Davidowitz; the U.S. Agriculture Department says food waste accounts for up to 40% of the total food supply.
But Goggy Davidowitz has an idea for how to divert those fruits and veggies. It’s a solar-powered drying tower; it looks like a tall greenhouse and uses the sun to dry that produce that otherwise would be thrown out. That dried food could then be used for animal feed —or maybe even food for people to eat.
Davidowitz is a professor and University Distinguished Scholar in the Department of Entomology at the University of Arizona. He joined The Show to talk about how this would work.
Full conversation
MARK BRODIE: First off, where did the idea for this solar-powered drying tower come from?
GOGGY DAVIDOWITZ: About six years ago, seven years ago, I started looking into the idea of growing insects for food and feed. It's a huge industry now. At the time, companies that were growing insects were using — they wanted to grow human-grade food. Human-grade insects, so insects that people can eat. They fed them human-grade food, which didn't make a lot of sense to me, because insects are grown as an alternative source of protein to feed the growing human population. If you're using people food to make people food, it didn't make a lot of sense.
So I thought, well, can we use food waste? In the United States, about 40% of all the food that is produced ends up in the landfill. So, what I thought of doing was, can we capture some of this excess fruits and vegetables that is destined for the landfill and use it to feed the insects?
Well, it's a great idea. The problem is, as we know, fruits and vegetables, if you don't do something with it, they'll rot ... in a matter of days. So that's where the solar tower came in. If we can dry the fruits and vegetables, we can then store it as a dry ingredient and then feed that to the insects.
BRODIE: And of course, if it's dry, it lasts infinitely longer than it does if it's just sort of a fresh fruit or vegetable, right?
DAVIDOWITZ: That's correct. So we have some fruits and vegetables that we dried three years ago that are sitting on an open bin on our shelf in our lab. And we purposely don't do anything with it. And it is still completely dry. There's no mold, there's no decay, nothing.
BRODIE: So, obviously the process and the thought of drying food is not a new one. You point this out yourself. What is new about what it is that you're doing here?
DAVIDOWITZ: Right. So people have been drying fruits and vegetables for millennia. I mean, for thousands of years. It's kind of probably the oldest method of food preservation. And typically when you dry, you lay out your fruits and vegetables on a table or on the ground on a tarp, something like that.
And that's good, it works. But you can only do small amounts with that. We're, what we're doing is we're looking at a way to do this at a commercial scale. So literally processing tons at a time and using no energy input. So we're just using the power of the sun to do the drying. So what's unique in our system is instead of going to the sides, like just having a lot of tables side by side, we went up.
BRODIE: Well. So, yeah, looking at it, you know, I saw a photo of it. It looks almost like a greenhouse kind of turned on its side. So as you say, it goes up instead of out. How exactly does it work? I mean, I saw you have trays sort of on, stacked on top of each other. Do you just put fruits and vegetables on those trays and let the sun do its thing?
DAVIDOWITZ: Pretty much. So the advantage of going up is we can make a thermal gradient. So, you know, hot air rises, the solar radiation goes into the solar tower through the transparent walls and heats up the inside. So to give you an idea, our towers, it's a research prototype. It's not what a commercial tower would look like. Those would be much bigger.
But we have about a 25 degrees Centigrade, about a 70 degree Fahrenheit, difference between the top and the bottom. So at the bottom where you're standing, it's about 140 degrees Fahrenheit, and at the top it's about 185 degrees Fahrenheit. And then we can use this gradient to accelerate the drying process.
BRODIE: So, what kind of dent do you think this could put in the food waste issue? And also maybe the problem of people not having enough to eat or not having access to fruits and vegetables. Can you dry enough of these products that would otherwise end up in the landfill to really reduce that amount of waste and also maybe get food to people who need food?
DAVIDOWITZ: So first of all, I don't think we're going to solve the problem of wasted food, but we can help mitigate it. So the — our ultimate goal is to build solar towers wherever there are these excesses of fruits and vegetables that would normally be shipped to the landfill. So, for example, the ports of entry from Mexico, where a lot of the fruits and vegetables come into the United States.
That's where a lot of the stuff gets diverted to the landfill. So if we can build solar towers there, it can go into the solar tower. Instead of the distributor paying shipping costs and tipping fees at the landfill, we could dry it down, and then they can make money off of it because it's a dry ingredient.
Places like Yuma, Central Valley, California, wherever there are large farms and processing of fruits and vegetables, we can have solar towers built there and process any of this excess.
BRODIE: Well, so is the goal to eventually produce food that people can eat, or are you aiming to dry it and use it elsewhere?
DAVIDOWITZ: So we're looking at different customers. One possibility or one direction is for human food. So if you think about it, you know, we can dry stuff down, and then you can make pasta with it, you can make bread with it, you can make cereals, things like that.
Another is in the feed industry. So this could be used for as ingredients for livestock feed. Fruits and vegetables are 95% water. So when you are shipping fruits and vegetables across the country, you're really shipping water. So we have in the solar tower a dehydration system that pulls the evaporated water, water vapor, out of the air inside the tower and then collects that water.
And this is fresh, perfectly good drinking water. So in theory, for every ton of fruits and vegetables that we dry, we get back about 950 liters of good drinking water back. So it's a way to also generate water, drinking water, which is becoming scarcer and scarcer as our climate heats up.
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