Americans waste a lot of food — about 133 billion pounds a year, or roughly one-third of all the food produced in the U.S. In addition to squandering money and throwing away a precious resource, all that waste creates an enormous environmental problem. Food waste often winds up in landfills, where it rots and releases large quantities of methane, a potent greenhouse gas that contributes to global warming.
Scientists have been looking for solutions to the food waste problem, and now researchers at Cornell University in Ithaca, New York, think they've hit upon a possible fix. They say that by making use of a pair of simple chemical processes — hydrothermal liquefaction and anaerobic digestion — we could turn food waste into environmentally friendly biofuel.
The point is to “turn food waste into a valuable resource,” Roy Posmanik, a postdoctoral researcher at Cornell and lead author of a recent paper about the research, told NBC News MACH in an email.
Hydrothermal liquefaction involves heating food waste under high pressure — essentially pressure-cooking it — to create an oil that can be refined into fuel.
Next, the watery food waste left over after the liquefaction undergoes anaerobic digestion, a process in which microbes break down the waste into biogas that is primarily composed of methane and carbon dioxide. This converted gas can be used to produce electricity and heat, according to the researchers.
Other methods of capturing methane directly from landfills and processing facilities exist, but combining hydrothermal liquefaction and anaerobic digestion is a more efficient way to process food waste, Posmanik said. “We’re talking about minutes in hydrothermal liquefaction and a few days in an anaerobic digester,” he said in a written statement.
Plus, the liquefaction step produces an additional resource from the wasted food, he added.
Posmanik foresees a day when food waste from homes, supermarkets, restaurants, and other institutions would be trucked not to landfills but to treatment plants.