The feasibility of turning food waste into energy

Food waste is a major environmental and economic issue around the world. In the United States, an estimated 30–40% of edible food is lost or wasted, costing billions of dollars each year. One solution is to divert food waste from landfills into renewable energy production, but this is yet to be done on a large scale. A study from the University of Illinois Urbana-Champaign has investigated the feasibility of implementing energy production from food waste in the state of Illinois.

Jason Uen, a doctoral student in the Department of Agricultural and Biological Engineering (ABE), the lead author of the study, said there is a lot of organic waste in the US which eventually enters landfills and emits greenhouse gasses. Anaerobic digestion is a potential solution to deal with excess food and contribute to sustainable energy production.

The researchers conducted an analysis of supply chain logistics to determine if an anaerobic digestion system would be profitable in Illinois, using geospatial data to identify potential sites and analysing technological and economic factors.

Luis F Rodriguez, associate professor in ABE and co-author of the paper, said, “Anaerobic digestion is not a new technology, but if it were profitable, I would expect it to be more widely implemented. That’s why it was quite surprising that our study showed promising results despite the very conservative assumptions we put into the analysis. There are some sectors that really ought to consider this as a potentially viable technology with an attractive return on investment.”

Anaerobic digestion is a process that decomposes organic feedstock using organic materials such as wastewater sludge, animal manure or yard waste. This can be accomplished at standalone facilities or wastewater treatment plants for a co-digestion process. The biogas can be used to produce electricity. The process yields additional bioproducts, including biofertiliser and animal bedding materials that can be sold to agricultural producers.

According to the study, installing anaerobic co-digesters at wastewater treatment plants with a total annual capacity of 9.3 million metric tons could generate an 8.3% return on investment while reducing carbon dioxide by approximately one million metric tonnes annually. These results are influenced by capital investment, operational costs and tipping price, a service charge for waste disposal.

Food waste availability is an important factor, including the challenge of sorting and transporting food waste from households. The study assumes food waste amount is directly related to population density distribution, meaning facilities would be collecting waste within a 10-mile radius from residential areas. To estimate revenues, the researchers included wholesale electricity price and current fertiliser prices.

According to Uen, there is still a gap between market demand for bioproducts and the amount of food waste there is. Expanding the marketability of those products will increase profitability. Government policies such as higher incentives for carbon reduction could also make it more attractive to implement these technologies.

The next step of the study would be expanding to a nationwide analysis. To improve food waste utilisation and the circular bioeconomy in agriculture, it is essential to estimate food waste availability on a larger scale and determine bioprocessing techniques.

Image credit: Marianne Stein