Researchers examine anaerobic digestion, hydrothermal liquefaction as landfills fill up

In Colorado, the expected decline in the number of landfills across the United States coupled with bans on disposing large amounts of organic waste in landfills that have been enacted in multiple states has prompted researchers at the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) to examine other ways to grapple with the issue of food waste disposal.

About 75% of food waste winds up in landfills. NREL researchers discovered that many landfills are running close to capacity and a significant number are scheduled to close by 2050. With funding from the DOE Bioenergy Technologies Office, NREL researchers examined the economics involved in five different ways to handle disposing of food waste, including tossing it into a landfill. The researchers determined that no single solution exists in the United States for dealing with food waste disposal, but all the investigated ways to handle food waste show some economy of scale and all the different types of waste management facilities would benefit from developing technologies to produce biogas or related products.

They examined five options for what to do with food waste, including the continued dumping into landfills. The other four options are:

• Anaerobic digestion, in which microorganisms break down biodegradable material in the absence of oxygen
• Composting, a biological process involving decomposition of organic matter in a controlled environment to produce compost
• Incineration, where trash is burned for heat and/or power
• Hydrothermal liquefaction, in which wet organic material is converted into biocrude.