Ohio State University study shows food waste-to-energy profitability potential
In a recently published study in the Science of the Total Environment journal, researchers collected a total of 46 waste samples, including 14 from large Ohio food processing companies, and divided them into four broad categories: vegetable, fat-rich, industrial sludge and starchy. They then characterised the sample contents’ physical and chemical properties and tested some starchy wastes they determined were good candidates for fermentation into the platform chemical acetone.
The energy density of a waste type, based on calorific value, and carbon-to-nitrogen ratio were major determinants for repurposing potential. For example, fatty waste and mineral-based waste can be digested anaerobically to generate biogas, and soybean waste has enough energy density to be used for biodiesel production.
This work is known as valorisation, or determining the potential value of something “that is otherwise valueless or even a drain on resources for a company – when you have to spend money to get rid of it,” said Katrina Cornish, senior author of the study and professor of horticulture and crop science and food, agricultural and biological engineering at The Ohio State University.
“The bioeconomy is becoming much more prevalent as a topic of conversation. In this case, don’t get rid of food waste – make some money from it,” added Cornish, also an Ohio Research Scholar of Bio-Emergent Materials. “Here, we’re putting the base model in place for food manufacturers who are wondering, ‘What can I do with this stuff?’ Our flow chart guides them in a specific direction and prevents them from wasting time trying something we know won’t work.”
About 2% of the 80 billion pounds of food discarded annually in the United States is attributable to food manufacturing and processing – with food waste solids sent to landfills or composted, and liquids poured into sewers.
“We aligned this work with the Environmental Protection Agency goal to reduce 50% of food loss and waste by 2030,” said first author Beenish Saba, a postdoctoral researcher in food, agricultural and biological engineering at Ohio State. “So, how can you reduce this waste? Valorisation is one method.
“In Ohio, corn is being grown to convert into biofuel, acetone and butanol, and here we’ve identified other sources already available as wastes that you can also convert into those products.”
The proposed conversion technologies require energy to operate and also yield some secondary waste, but the valorisation modeling lays groundwork for further “cradle to grave” analyses that would help quantify the environmental benefits of large-scale food – and other industry – waste reduction, Saba said.
While this study is a starting point, it ideally will offer incentive for food producers to consider the possibilities of making something out of waste products that are currently treated as rubbish, the researchers say.
“What we hope will happen is that food producers will actually look at their costs and their footprint, and see which of these approaches for their particular wastes will work best – which will be the least financially negative, and preferably profitable, and also minimise any carbon footprint,” Cornish said. “In terms of global warming, any waste that can be valorised has a direct impact on global warming because it has a direct impact on emissions and on the ecosystem.
“This is all about improving energy security and lowering the financial and environmental impacts of food waste management,” she said. “If your waste has enough value for you to do something with it that prevents it from going into the landfill, that’s a really good thing.”