What to do with food waste? Well it depends

The expected drop in the number of landfills across the United States, coupled with a ban on disposing of large amounts of organic waste in landfills that has been passed in several states, has prompted researchers at the National Renewable Energy Laboratory (NREL ) from the US Department of Energy (DOE) examine other ways to tackle the problem of food waste disposal.

Researchers have determined that no single solution exists in the United States to address food waste disposal. NREL researchers Alex Badgett and Anelia Milbrandt came to this conclusion after looking at the economics involved in five different ways of handling food waste disposal, including landfill. The two researchers are part of NREL’s Center for Strategic Energy Analysis.

“If we’re trying to develop an optimized waste management system in the United States that diverts all food waste from landfills, there isn’t necessarily one technology that will work for all regions of the country,” Badgett said. “An optimized system would likely use different technologies in different locations and at different sizes.”

Badgett and Milbrandt are the co-authors of a recently published article titled “Disposal and Use of Food Waste in the United States: A Spatial Analysis of Costs and Benefits,” which appears in Cleaner Production Journal.

About 75 percent of food waste ends up in landfills. But many landfills are operating near full capacity and a significant number are expected to close by 2050, the researchers found. While there is enough land available for new landfills in rural America, residents of more populous areas will be forced to haul their waste long distances to dispose of it. Second, organic waste disposal bans adopted in several states require the disposal of food waste at facilities other than landfills. Given the need to invest in new waste management facilities, there is an opportunity for innovative and improved pathways for waste streams. Badgett and Milbrandt looked at five options for what to do with the food waste, including continuing to dump in landfills. The other four options are:

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

Incineration has fallen out of favor due to increasing environmental regulations and public opposition to building new facilities. The hydrothermal liquefaction remains at the pilot stage.

Researchers examined the economics of operating various types of facilities, taking into account the income each generates from users or from the sale of products. They modeled the financial viability of the technologies, taking into account the investment and operating costs of the facilities; income from the sale of electricity, heat, fuel and other products; and production credits such as Renewable Identification Number (RIN) credits under the Renewable Fuels Standard for the production and use of biogas as a vehicle fuel.

All of the ways of handling food waste exhibit some economy of scale (where costs decrease when facilities are built larger), but the researchers found that the rate at which financial viability changes with the size of the organization. installation is not consistent. For example, landfills and incinerators designed to handle municipal bulk solid waste, which includes food waste, need to be built to large sizes in order to take advantage of the economies of scale for these routes, while digesters and Composters can be constructed as a smaller cost effective alternative for food waste disposal.

All the different types of facilities would benefit from the development of technologies to produce biogas or related products, but the benefits are greater for those operating on a medium or large scale. Facilities that currently accept food waste in large quantities are better suited to maximize the economic benefits associated with the production of fuels, electricity or products, as they have a readily available raw material supply.

Waste management facilities charge users an entry fee to offset operating and capital costs. If a facility can produce enough biogas to reduce its dependence on costs, it either becomes more profitable or can reduce those costs to become more competitive.

The location of a facility plays an important role in determining its profitability, the researchers found. For example, states along the east and west coasts have the highest entry fees and are therefore more economically favorable.

The DOE’s Office of Bioenergy Technology funded the research.

NREL is the US Department of Energy’s primary national laboratory for research and development in renewable energy and energy efficiency. NREL is operated for the Department of Energy by the Alliance for Sustainable Energy, LLC.

– This press release was originally published on the National Renewable Energy Laboratory website

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