Jun 14 2017
Innovative research carried out at Cornell University reveals that in the future, two disparate processes could be the desired dynamic duo to transform food waste into green energy. The outcomes of the research have been reported in the Bioresource Technology journal.
Food waste should have a high value. We’re treating it as a resource, and we’re making marketable products out of it. Food waste is still carbon—a lot of carbon.
Roy Posmanik, Lead Author of the study and a Postdoctoral Researcher
The research team has demonstrated that when hydrothermal liquefaction process is used prior to the process of anaerobic digestion, almost the entire energy from food waste can be extracted. During the hydrothermal liquefaction process, the waste is principally pressure cooked to generate a crude bio-oil, which can then be refined into biofuel.
The remnant food waste, which is in an aqueous state, can be anaerobically digested by microbes within a few days to produce methane. The produced methane can be used to generate commercial amounts of heat and electricity.
“If you used just anaerobic digestion, you would wait weeks to turn the food waste into energy,” stated Posmanik, who works in the laboratories of Jeff Tester, Professor of Chemical and Biochemical Engineering, and Lars Angenent, Professor of Biological and Environmental Engineering, both of whom are Co-Authors. “The aqueous product from hydrothermal processing is much better for bugs in anaerobic digestion than using the raw biomass directly. Combining hydrothermal processing and anaerobic digestion is more efficient and faster. We’re talking about minutes in hydrothermal liquefaction and a few days in an anaerobic digester.”
A report from the U.S. Department of Agriculture states that food waste is the sole largest constituent that goes into municipal landfills in the United States. The Food and Agriculture Organization of the United Nations has noted that nearly one-third of the food in the world (i.e. about 1.3 billion tons) is wasted or lost. Food waste in all industrialized nations amounts for approximately 680 billion dollars every year. Moreover, composting and digestion of food waste are also very gradual and inefficient.
According to Posmanik, the food-water-energy nexus can be quenched by performing the hydrothermal liquefaction process before the anaerobic digestion process.
We must reduce the amount of stuff we landfill, and we must reduce our carbon footprint. If we don’t have to extract oil out of the ground to run cars or if we’re using anaerobic digestion to make green electricity, we’re enhancing energy and food security.
Roy Posmanik, Lead Author of the study and a Postdoctoral Researcher
Co-Authors of the paper titled “Coupling Hydrothermal Liquefaction and Anaerobic Digestion for Energy Valorization From Model Biomass Feedstocks” are Rodrigo A. Labatut from Pontifical Catholic University of Chile, Andrew H. Kim ’17, and former Post-Doctoral Researcher Joseph G. Usack.
The United States-Israel Binational Agricultural Research and Development Fund (BARD), Cornell’s Atkinson Center for a Sustainable Future, the Cornell Energy Institute, and the Chilean Fund for Science and Technology supported the study.