How RIT researchers are closing the loop on wasted food

Food is about much more than what’s on our plates. How we make it, grow it, transport it, eat it, and even throw it out has real, lasting impacts on our world. A team of researchers at Rochester Institute of Technology (RIT) are exploring the industrial and natural systems behind food and finding new ways to make them sustainable by minimizing and recycling food waste.

In the United States, as much as 20 percent of the country’s energy is spent on food in some way, largely due to inefficient industrial methods. Worldwide, half of all the available fresh water on the planet is consumed through the production of food. Large-scale agriculture puts dangerous amounts of nitrogen and phosphorus into local ecosystems, which is harmful to many species of life. Overall, the production and consumption of food contributes nearly 15 percent of all human-made greenhouse gas (GHG) emissions.

But much of the food produced using these critical resources never gets eaten.

Over 100 million tons of food are wasted each year in the United States, meaning that all of the money, resources, and labor that go into its production and all the nutrition it contains are lost with it. Most wasted food ends up in landfills where, as it breaks down, potent GHGs are released, like methane. In fact, if the amount of food wasted globally was a country, it would have the third largest impact on climate change after the United States and China.

Food waste on the side of a street

Ending wasted food is not a simple issue; a food system doesn’t exist in a bubble, but intersects with other industrial, natural, and social systems. It takes energy and water to grow food, energy to treat water, and water to produce energy. Yet food waste recovery offers a way to reduce demand for these resources and replace fossil fuels with greener waste-to-energy alternatives. This interplay of food, energy, and water systems is known as the food-energy-water (FEW) nexus. 

Transforming the U.S. FEW nexus

Recognizing the complex challenges that food wastage presents, the National Science Foundation created the Innovations at the Nexus of Food, Energy and Water Systems (INFEWS) grant program. It funds U.S.-based scientists who are developing new knowledge to enable better policies and scientific understanding of the FEW nexus. According to the NSF, the program’s goal is to “catalyze well-integrated, convergent research to transform understanding of the FEW nexus.”

A team of RIT researchers, led by Callie Babbitt, an associate professor at RIT’s Golisano Institute for Sustainability (GIS), received nearly $1 million from the INFEWS program when it launched in 2016. Babbitt was instrumental in putting the original proposal together. The NSF’s vision for convergent research required that at least three different areas of study were brought to bear on solving FEW-related problems. With this in mind, Babbitt met with faculty from different RIT colleges to discuss the issue of wasted food and to learn how they would approach it using their own disciplinary lens. She eventually formed a proposal team with faculty from the following RIT schools or departments: Life Sciences (College of Science), Interactive Games and Media (Golisano College of Computing and Information Sciences), Public Policy (College of Liberal Arts), and the National Technical Institute for the Deaf. Her approach reflects closely the multidisciplinary strategy that underpins how GIS works as a whole. 

Babbitt and her colleagues wanted to learn why promising innovations for converting food waste into energy or value-added products weren’t being put to use. They found that a general lack of knowledge about food waste, technical challenges to recycling mixed-waste streams, and inconsistent policies around how wasted food is addressed inhibited the adoption of sustainable practices.

Babbitt worked closely with Thomas Trabold, head of the Department of Sustainability at GIS. Like Babbitt, he pays close attention to opening industrial pathways for wasted food in the circular economy, but from a chemistry perspective. An area of study he has researched extensively is the potential of thermochemical conversion as a sustainable solution for wasted biomass.

Over the last few years, the collaboration has led to new ideas about how wasted food can be recovered in a closed-loop economy that cycles energy, water, and nutrients, much like natural ecosystems do. The underlying research methodology is rooted in industrial ecology, a field that frames production economies through the lens of ecology in order to better assess flows of resources, energy, and waste.

“The more we learn about ecology, the more we realize that nature has already created solutions for many of the challenges we now face,” Babbitt explained in a 2015 presentation. “But it has taken millions of years of trial and error, a luxury we simply do not have for responding to climate change, water scarcity, and pollution.”

Creating smarter policies

The purpose of the INFEWS grant program is to accelerate the discovery of new knowledge about how FEW systems work so that better solutions can be realized. When it comes to wasted food, this means challenging some long-held assumptions underpinning existing policies.

Food waste policy in the United States is best captured in the Environmental Protection Agency’s (EPA) food recovery hierarchy. A triangle, it’s not unlike the dietary hierarchy many Americans might know from grade school (except that it’s upside down). It outlines prevention as the most preferred method for addressing food wastage, followed by methods to recover the value the food still contains, including feeding animals, converting waste to energy, or composting. This is a powerful tool at a time when awareness of surplus food loss remains low—nearly half of all food in the United States does not get eaten. However, as research in this area has advanced, scientists like Babbitt have found that models like the EPA triangle, though instructive, risk overlooking opportunities because they flatten the local variations that inform individual FEW systems. Avoiding reduction is especially important in regards to tackling wasted food, where a solution may work well in one region, but not in another.

So, how can policymakers take into account regional variability in order to make smarter decisions around food waste?

To answer this question, the team turned to Eric Hittinger, an associate professor at RIT studying policy and sustainability, and Kanwal Shahid, a student at GIS. They created a model to identify which technologies could recover the most food waste, create the most energy from its conversion, and cost the least to key stakeholders.

Hittinger and Shahid’s model helped show that food waste solutions will vary in different places, depending on how far waste has to be transported and how much it will cost to build new waste-to-energy facilities to process it. The team then collected data from local groceries, schools, and universities to estimate how differences in the volume of wasted food changed over time. For example, schools produce a lot of waste when students are in school in fall and spring, but none at all over summer and winter breaks. These findings are important for designing a waste management system that is flexible to variation over the course of a year.

Babbitt was able to put these ideas to work in 2019 when she received a Fulbright U.S. Scholar Program award to study food waste management in Croatia. She chose Croatia because it offered an ideal case study for observing how a region’s food system is affected by seasonal tourism. The economic value that tourists bring to the Balkan nation has put a heavy toll on its regional FEW systems, with food waste making up most of its municipal waste. 

Croatia offers an unusual geography: A thin strip of coastline with many islands to the west and a mountainous border region inland. Its capital city, Zagreb, sits in the middle of Croatia’s northern stretch into the Balkan Peninsula. Babbitt wanted to assess how food waste was managed over such a challenging terrain, where it is transported by trucks along limited coastal roads or by ferry across water to be put into landfills. Only six percent of all wasted food is recycled in any way.

Babbitt was interested in how the seasonal flux of tourists impacted the volume and movement of food waste in Croatia. A major shift over the course of a year makes a one-size-fits-all food waste policy unfeasible. Instead, a more dynamic, responsive strategy is needed, one that is in constant communication with changing conditions on the ground. Babbitt studied four cities as part of her field work and will soon publish the results of her research.

Making the circular economy real

An early realization in the project was that technology solutions could not be created without considering their potential ecological impacts. One such technology they evaluated was anaerobic digestion.

Anaerobic digestion is a process that occurs naturally in the environment when bacteria break down organic matter in the absence of oxygen. Humans exploit it by using a “digester” to make energy (biogas, a form of natural gas) and agricultural products like animal bedding and soil amendments. It has grown in popularity recently among dairy farmers as a cost-effective method for generating more value from cow products like manure.

When wasted food is managed in an anaerobic digester, some by-products have less immediate applications, like digestate, a nutrient-rich effluent. Typically, solid material is extracted from digestate to make bedding for dairy cows. (It’s more durable than hay and resists rot.) The remaining liquid, rich in phosphorous and nitrogen, is then sprayed on crops as an alternative to conventional chemical fertilizers. It is made up of all the materials that the micro-organisms can’t breakdown into biogas.

While avoiding the need for inorganic fertilizers is a sustainable outcome, prolonged use of liquid digestate as a crop fertilizer has been linked, in some places, to nutrient losses through run-off and leaching, contaminating surface and ground water and even causing toxic algae blooms. Led by Christy Tyler, an associate professor in RIT’s Thomas H. Gosnell School of Life Sciences, the team studied the ecological impacts of digestate management options, finding that much of the land closest to available anaerobic digestion sites was vulnerable to excess nutrient pollution.

This discovery led to a new direction in the initiative: How can circular economy thinking be used to recover all nutrient value in the food waste management process? To answer this question, Diana Rodriguez Alberto, a doctoral student at GIS, conducted a study with Trabold, her advisor, to find a circular solution for digestate that could create more value, save costs, and prevent ecological impacts.

Rodriguez Alberto and Trabold saw a possible problem coming down the tracks: New York State’s Climate Leadership and Community Protection Act of 2019 (CLCPA) looks to bring more biogas made through anaerobic digestion into New York State’s energy mix as a carbon-neutral alternative fuel. They anticipated that more anaerobic digestion would mean more liquid digestate being sprayed on fields, leading to increased pressure on New York’s FEW nexus.

The researchers led an investigation to see whether pyrolysis—the thermochemical process for making biochar—could be used to recover nutrients from the liquid portion of digestate. Their hypothesis being that, if possible, it would produce a nutrient-rich form of biochar that could be used as a solid fertilizer. As a replacement to liquid digestate fertilizer, it would be more stable and reduce the chances for ecological contamination.  

But Rodriguez Alberto and Trabold also found something that they hadn’t anticipated: A novel method for producing magnetic biochar.

Typically, magnetic biochar is made using a specialized industrial process. But the nutrient-rich biochar made from the digestate needed no further processing than conventional pyrolysis. The study demonstrated the first known instance of iron oxide occurring without the use of an iron-based precursor during pyrolysis.

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