Press "Enter" to skip to content

The Leading Voices in Food

E193: Challenges and opportunities: turning food waste into valuable products

Hosted by: Norbert Wilson (Duke), Brenna Ellison (Purdue)
January 17, 2023

According to the Environmental Protection Agency, food is the single largest category of material sent to landfills in the US, where it emits the greenhouse gas methane. It would be a win for climate if food waste could instead be transformed into commercially valuable products. Today, we’re talking with two researchers who are working out the feasibility of just that. Welcome to the Leading Voices in Food podcast. Our guests for today are sustainability and energy science researcher Thomas Trabold of the Golisano Institute for Sustainability at Rochester Institute of Technology. And second, we have food science and technology researcher Ned Spang from the University of California Davis Food Loss and Waste Collaborative.

Thomas Trabold teaches courses in the fundamentals of sustainability science, sustainable energy systems, sustainable mobility systems, and green chemistry. His primary research focus is in the development of alternative energy technologies including fuel cells, bio-fuels, and waste-to-energy processes. In 2014 and 2015 he was nominated for the Richard and Virginia Eisenhart Provost’s Award for Excellence in Teaching, and in 2007 he earned the General Motors McCuen Award for “Neutron Imaging Facility and Methods for Fuel Cell Water Visualization.” His students say he has a system-level perspective informed by fundamental understanding and experiential knowledge. When Dr. Trabold isn’t in the lab or classroom, he enjoys soccer, basketball, trail hiking, biking, and gardening.

Ned Spang’s research focuses on characterizing and optimizing the efficiency of linked water, energy, and food resource systems. He is particularly interested in applying methods for measuring and monitoring these systems and their interrelationships in high-resolution and across multiple scales, both geographic and temporal. He further seeks to understand the influence of external markets, technological innovation, and policies on this integrated food-water-energy nexus. His recent publications explore the linked relationship between water and energy resource systems, the drivers and environmental impacts of on-farm food losses, and an in-depth review of the academic literature on food loss and waste.

Interview Summary

This podcast is cosponsored by the RECIPES food waste research collaboration, led by American University and funded by the National Science Foundation.

Norbert: So Ned, how does wasted food contribute to climate change?

Ned: That’s a great question, Norbert, and something we should be thinking about when we are talking about food loss and waste. Really, at all times. As you said in your intro, there is a close connection between food waste and greenhouse gas emissions along the pathway of methane. When we dispose of wasted food in a landfill and it gets covered up with dirt and other waste, it creates an anaerobic environment. Microbes that thrive in that environment break down the organic material and release methane to the atmosphere. So, if we can divert organic waste and food waste from landfills and put it to productive use, we avoid that methane being released to the atmosphere. Another way I want people to think about food waste releasing greenhouse gases or being related to climate change is thinking about it from a food systems perspective. Because the other thing we need to keep in mind is that it takes a lot of resources, and effort, and investment, frankly, to get food from the farm to your table. So, if we think about growing a tomato, for example, we need to put fertilizer into the soil, which requires a lot of energy to create that fertilizer. We need to run tractors over the field. We need to harvest. We need to store the crop. We need to refrigerate the crop, and we need to transport that crop. All of those steps of the food supply chain require energy inputs. If we are using fossil fuels, that is leading to carbon dioxide emissions as well.

Norbert: So this is a really big issue. It seems like it’s what happens once the food is in the landfill, but there are all these other places where there can be climate challenges throughout the supply chain. So this is a critical point: to not only think about the end, but also all along the supply chain. Is that a fair assessment?

Ned: That is exactly right. I think that is the piece that really makes food waste such a challenging issue. There are so many pieces to the puzzle. Food losses and food waste can occur anywhere across the food supply chain. It’s not just with the consumer. We have losses in the field, we have losses at distribution, we have losses in storage. So just as there are resource inputs at every step of the food supply chain, there are also losses at every step. And so when we think about solutions, there is not going to be just one single solution. We have to think about many different solutions and the role of many different stakeholders as we bring food from farm to table.

Brenna: Thomas, if we can take a moment and turn to you, how can we turn food waste into something of economic value? And, how does that transformation help mitigate climate change?

Thomas: I’m glad you asked about economic value, because to really facilitate change in this area and valorize food waste, we really have to think about how to make that economically viable. That’s ultimately what’s going to drive sustainable change. We’ve done a lot of work in food waste at different scales. I would say the number one thing we need to do to convert that waste into something of economic value is to understand the nature of the waste itself. For example, we need to know how much is generated and where is it generated. Is it generated in large quantities in a few locations? Or, as is the case in household food waste, it’s generated in relatively small quantities at millions and millions of different locations. Is it generated at a constant rate throughout course of the year, or is it more seasonal? Ned mentioned crop born food waste. Well, that’s going to really occur at a more seasonal rate than, say, household food waste which is generated more uniformly over the course of the year. And we also have to know what are its characteristics. Food waste that is generated in, say, a food processing plant tends to be rather homogeneous, and that material will have a larger number of potential valorization options. Conversely, food that’s generated in, say, a university cafeteria is by nature heterogeneous. So it’s going to be more difficult to define viable valorization pathways for that kind of material. And how all these valorization options can help mitigate climate change is number one – keeping that material out of the landfill so it can’t generate methane – but then also by mitigating or offsetting other sources of greenhouse gas emissions. For example, if we take food waste that’s currently going to the landfill and divert that to an anaerobic digester, now we’re using that material to generate a gas that can offset fossil natural gas use. So we’re combining the benefit of methane reduction, but also generating bio-based gas that can offset fossil natural gas. So combining all these different benefits can enhance the economic viability of the overall system and help us mitigate climate change.

Brenna: Those are really helpful examples, and just good illustrations to help you think about the different ways we need to think about food waste. I thought about when I was doing food waste research in university cafeterias, and it is very heterogeneous. Although I will say there was an absurd quantity of ketchup, from what I remember while physically sorting the waste. I was just going to bring that up. I really appreciate the illustrations. Those are very helpful, different ways to think about it.

Norbert: I’m interested, are there other kinds of products that you can make out of wasted food?

Thomas: Oh yes, and this is where we spend a lot of our focus – looking at different options for converting food waste into different products. Of course, if food waste can’t be used to feed human beings, which should always be our first objective, there’s certainly animal feed. But we’ve done some research looking at the example of university cafeterias. We’ve found that the mixed food waste from our cafeteria to RIT, based on its characteristics, is actually well suited as fish feed, if you go and look at the specs on typical commercial fish food. Beyond that, of course, we often think about composting. And composting is a great option, because we’re taking the inherent nutrients in the food waste and returning those to the soil, and that’s going to help facilitate the next generation of food products. The challenge with some of these options, and compost in particular, is that you have to look at the entire supply chain. If you’re generating lots of food waste in the middle of an urban center, do you really have an outlet for compost? Is there really a market for the compost? Certainly if you’re in more of a rural area closer to the center of food production, there will be an obvious outlet for your compost. But in an urban setting, that may not be the case. Other products that can be generated from food waste, certainly energy is a big one. There’s lots of interest now, and this is an area where Ned and I are collaborating on anaerobic digestion. So we can take the food waste and, by the same biological process in the landfill, generate methane gas, which can be used to offset fossil natural gas and other fossil fuels. We can also use that material in fermentation processes to make, say, ethanol or butanol for vehicle fuel, or even organic alcohols that have many many industrial applications. Beyond the animal feed, compost, and energy options, another area where we’re really focusing our research is biochar. So if we take this organic food waste material and process it at high temperature, in the absence of oxygen, we’re creating a very stable carbonaceous material we call biochar. The interesting aspect of that material is it effectively sequesters carbon for very long time periods, hundreds or even thousands of years. So now when we use that material in manufactured products, such as, say, concrete, now we’re converting that food waste into a material that can sequester carbon for long periods of time. And, offset other materials like fly ash, let’s say, used in conventional manufacturing processes. So again, I would just emphasize that to look at different options for valorization in different products, you really have to understand that complete supply chain, and understand your markets. Because that is going to really dictate the scale that you need to work to utilize that food waste material.

Norbert: Ah, that’s really fascinating. Thank you for sharing those options.

Brenna: So Ned, Tom hit on some of the technologies, in terms of aerobic and anaerobic digestion, and then this cool new biochar, which I was not as familiar with. But can you add on a little bit where we are, in terms of technology to convert wasted food into economically viable products?

Ned: There’s a lot of great examples of some smaller pilot projects and people exploring different options, which is fantastic. But if you think about it in terms of utilizing this technology and society at scale, we still have a ways to go to really make holistic change in how we think about food waste and how we treat it. There are roles here for policy. Here in California, we’ve put in an aggressive policy: Senate Bill 1383. And the goal of this larger bill is to reduce short-lived climate pollutants. But one of the short-lived climate pollutants is methane. And we actually are specifically targeting organic waste here in California, and we’re trying to divert 75% of organic waste that previously went to landfill to more productive uses. 75% by 2025, which is a very ambitious goal. So that means that we have to start getting these technologies deployed rather quickly. We would be using a lot of composting, a lot of anaerobic digestion, and we’d need to build out that infrastructure to really handle 75% diversion. We also included a component that we want to recover 20% of edible food that’s currently going to landfill. And so I think this is an important way to think about food systems, again, when we think about food waste, is that we’re not just trying to deal with this as a waste product, but can we think about it still as food? When we say wasted food, it doesn’t mean that it’s not edible anymore. In fact, a lot of this wasted food is perfectly edible. So let’s think about ways we can keep as much food as possible in the food system before we rely on some of these technologies that treat it more as a waste. If we sort of zoom out, I do want to think about it sort of at that scale. What’s the role of policy, how do we spur investment in a lot of these technologies that Tom mentioned, and how do we really make change at significant scale?

The other way I want to think about the technologies is that many of these are well known. Some of them are pretty well known, but not yet widely adopted, and some are really emerging. Tom mentioned two probably of the most well-known pathways, which is animal feed and composting. Two things that we’ve been doing for as long as people have been eating food: we have been diverting some of our leftover food to animals, and we’ve also been returning it back to the soil as compost. So certainly there’s more opportunity to divert food from landfill to those two pathways. Anerobic digestion that Tom mentioned has been known for quite some time in Europe. It’s widely used. Here in the US, we’re a few years behind, but we are looking to expand the use of anerobic digestion. And, there’s a lot more investment in that space. An interesting question for anaerobic digestion, this is one of the research topics I work on, is what is the right scale of anaerobic digestion? Is it better to have large centralized facilities that we transport waste to over longer distances, but we get the economy of scale of a large treatment facility? Or is it better to have distributed small scale anerobic digestion? Where we can bring the food waste, it doesn’t have to travel as far, there’s a lot of food waste in urban areas. Perhaps we can embed some of that treatment directly in the urban landscape to reduce the transport of this material over great distances. One other known but not widely adopted technology is upcycling. So this is getting back to the using edible food. So, a juicing company. And they’re taking all these great fresh fruits and vegetables, and juice is coming out of one side of the juice press, but a lot of this great nutritious fiber material is coming out the other side of the juice press. And we can actually use that; We can incorporate that into products. Another example is making beer. We have a lot of great grain material left over after the fermenting process for beer. So there’s companies out there that are using these byproducts and actually returning it directly into the food system, as chips, as granola bars, you name it. There’s a lot of excitement in this area. It’s been identified as a growing food trend the last few years, and we’re starting to see a lot more of these products actually on the retail shelves.

One more pathway, which is really some truly emerging technologies that are focused more on extraction, so looking again at byproducts and trying to extract high value products. These can be things like antioxidants, or nutritional supplements, things like oligosaccharides, which are known as a prebiotic. So the food to feed your probiotics in your gut to ensure a healthy micro flora in your gut. All of these things can be extracted from different food byproducts. One example we’re working on here is extracting both of those things, antioxidants and oligosaccharides, from grape pomace. So whenever you’re making wine, you’re expressing the sugars and liquid out of the grapes to convert into wine, but you have a lot of the leftover skins and seeds, known as grape pomace, and we’re working on ways to valorize that material.

Brenna: Thanks for sharing all of those pathways, Ned. California is typically ahead in terms of policy, so I really appreciate you sharing what you all are doing on the West Coast. A note on the upcycled food, I do think that’s a really interesting pathway, and I study a lot on consumer food labels, and so I know there are increasing studies trying to understand what consumers might be willing to pay for foods labeled as upcycled. But I’ve also seen, I believe it’s a yogurt brand. They have a label that, I think says it’s certified rescue fruit, certified rescued food maybe. So I think that’s kind of been an interesting development that we see in the retail setting.

Ned: Yeah, and I think we’ll see more of that as time goes on. There’s a lot of creativity, and we even did an upcycled project with our students, and I’ve never really seen their eyes light up and get so excited about this, because they love to make new food products, and that’s always exciting. But this little extra piece of having this sustainability component and this extra challenge of working with something that hasn’t been traditionally seen as an ingredient really got them so excited. And it really caught on here on campus. In fact, we’ve been running sort of a challenge every year on upcycled food products. I think the last three of five business competitions we’ve had at the business school here on campus have been people presenting upcycled food products. So it’s not just the sustainability component. There’s a great story behind it that I think really catches people’s imagination.

Brenna: Super interesting. I would love to connect more on teaching notes.

Norbert: That is wonderful. Both you, Ned, and you, Tom, have talked about new products and new ways of doing this, but there’s an important issue. And Ned, I remember you mentioned this particularly, that there’s an infrastructure concern here. And so my question to both of you is what kinds of infrastructure would need to be in place to make food waste streams economically viable for commercial product manufacturing?

Ned: That’s a great question, and I think I might just take the opportunity to zoom out again to think of this at a high level. There’s lots of different particular infrastructures for the technology we talked about, but if we think about it in terms of domains, I would say we need the physical infrastructure. And by that I mean composting facilities, anaerobic digestion, even labs to think about some of these emerging technologies, opportunities for extraction and upcycling, et cetera. But we also really need that informational infrastructure that Tom was talking about at the beginning of the hour here. We just don’t have a great picture of where the waste is, and what the waste is, and how much, and when. And all of that information is going to really allow us to have better opportunities to come up with viable decisions about what to do with this material. So that’s part of the focus of the project Tom and I are working on, is not just looking at the technologies, but thinking about how we can improve access to information and the information we need to really open up opportunities for others. Because there might be great ideas out there, but people might not be able to estimate how much they can scale that idea. How much tomato pomace is there if I have a solution for tomato pomace? And when is it available? How far would I have to travel to go get that material, and at what cost? We just don’t have that information. So I think really coming up with a database that starts to track this information would be incredibly helpful. We still suffer from the out of sight out of mind when we think about waste. You know, we think about the primary products, and we’re very good at measuring those things. But as soon as we don’t see value in a material, we don’t tend to track it. So that’s a place I think we need just as much investment in thinking, is that informational infrastructure as well as the physical infrastructure.

Thomas: I would add a couple of thoughts, and Ned had touched on these earlier. One is just thinking about the scale of some of these systems. Traditionally, as engineers, we always learned about scale up. Everything has to be bigger. If you want to get your unit cost down, it’s got to be bigger, bigger, bigger all the time. However, we’re now looking at a scenario where maybe things at, say, a community scale make more sense for a variety of reasons. One is, at a community scale, the people that actually generate the waste can benefit from its valorization. Let’s say for example, we can develop anaerobic digestion systems that are suitable for, say, a neighborhood of 25 or 50 homes, or a large apartment complex. Now the residents who are generating food waste that can be converted into methane can now actually benefit from that material, maybe offset their own energy usage. The other advantage of doing things at smaller scale is you can more reasonably valorize multiple co-products. For the biochar example I mentioned earlier, that’s a pyrolysis system that makes the biochar, and that operates at high temperature. Well, that’s an exothermic reaction. So if we were making biochar at a community scale, you could also use that waste heat to heat the homes. So if we can start looking at community scale deployments that can valorize multiple co-products, I think we can move a lot of these technologies forward and also eliminate some of those transportation impacts that are really running counter to some of the benefits. If we’re transporting food waste a hundred miles, we’re generating a lot of greenhouse gases to do that, and we’re eliminating some of the benefits that we’re trying to realize in the first place. The other infrastructure need that I did mention early on, we need to figure out the logistics. The technologies that are out there for converting food waste into useful products, they’re generally pretty well known, been done for hundreds of years. The real challenge is how do we collect, and pre-process, and move around all of this food waste that, again, at the household scale, is generated in fairly small quantities, but at many, many, many individual locations. So how do we develop the systems to economically and sustainably collect that material and make it available for upcycling and to value added products?

Norbert: Thank you, Tom. It sounds like what you’re suggesting is this idea of having to rethink the way our food system works, both in terms of how we’ve thought about waste, but also thinking about waste as something local, which is an interesting idea that I think coincides with people’s interests in local foods, that there are ways of capturing the cost of that, but also capturing the benefits. And Ned, I really appreciate your comment about not only just physical infrastructure, but information. Creating new databases, new ways of sharing what is actually being developed in terms of food waste, and making sure that that’s available to the people who can actually use that.


Explore Related Podcasts:

Other Climate Change, Environment & Food Podcasts:

MITRE podcast
Sally Thomson podcast
Jasmine Crowe Houston podcast
More Episodes

Other Food Policy Podcasts:

Christina Roberto podcast
Frohlich podcast
Eleanor Davis podcast
More Episodes

Other Food Waste & Implications Podcasts:

MITRE podcast
Jasmine Crowe Houston podcast
Podcast Kathryn Bender and Brian Roe
More Episodes