Terminology
Food “loss” refers to things like the crops left in the field or edible items damaged in-transport
Food “waste” proper refers to things like an unfinished meal in dining or the edible but bruised bananas ending up in the landfill
As consumers of food, we don’t have much control over the food loss, so on MIT campus we decided to focus on food waste instead.
Why are we separating food waste?
Other than the moral obligation a lot of us have grown up with – “Finish your veggies, there are hungry children elsewhere!” – we have a lot of reasons to reduce and separately manage food waste.
Landfills and sewers comprise a big part of where our uneaten food ends up. There, that food rots in low oxygen conditions, producing large quantities of methane. If incinerated for energy, that food waste still ends up producing a weaker, but still a greenhouse gas, CO2.
According to the Food and Agriculture Organization (of the United Nations) report, food waste is responsible for one sixth of humankind’s annual greenhouse gas emissions. In 2017, it was responsible for the same amount of emissions as the US and the EU combined.
Unfortunately, according to ReFED, a national non-profit, more than a third of United States uneaten food ended up in landfills, with 8% in the sewer and 5% incinerated in 2022. Composting and anaerobic digestion are growing, which is great news and should encourage MIT to join the trend!
The EPA Wasted Food Scale, an updated (2023) guideline of what to do with food waste
The EPA and USDA are the federal government agencies tasked with dealing with food waste. On a local level, cities choose their own program. Our food waste collection system is part of Cambridge’s push towards household curbside food waste pickup.
The diagram above, modified by the EPA, shows all the methods of dealing with food waste and loss. The older version of this guideline, the pyramid of food waste, has more details about Cambridge’s choice of anaerobic digestion.
From the City of Cambridge Food Waste Management Fact Sheet
Beyond on-campus initiatives, we can help by individual action and consumer demands for the companies. One way to help reduce produce and dairy food waste is learn the difference between different expiration date labels.
Unlike in other countries, in the US the dates are actually an indication of quality, not safety, and most shelf-stable foods can be consumed for a while after their “best by” or “use by” date. The exception is infant formula.
This USDA guide will help you learn more about these dates.
- A “Best if Used By/Before” dateindicates when a product will be of best flavor or quality. It is not a purchase or safety date.
- A “Sell-By” date tells the store how long to display the product for sale for inventory management. It is not a safety date.
- A “Use-By” date is the last date recommended for the use of the product while at peak quality. It is not a safety date except for when used on infant formula
- A “Freeze-By” date indicates when a product should be frozen to maintain peak quality. It is not a purchase or safety date.
If you want to learn more about other ways to help, go to this EPA guide on Food Waste Prevention
What happens to MIT’s food waste?
Our food waste gets processed with the rest of the City of Cambridge’s waste stream in a bioslurry factory just east of Somerville. The WM CORe® facility in Charlestown uses its bioreactors to mix up and digest our residual food into an organic slurry, which then is transported to the Greater Lawrence wastewater facility to be further digested into biogas. That renewable alternative to natural gas is then used circularly to power and heat the WM CORe® plant, and the remainders go to keep the lights on for the rest of the Boston area.
The solids left after wastewater digestion (the technical term is anaerobic digestion, AD) can be still used for fertilizing, just like regular compost. This figure from the literature study by Biocycle.net shows how this process (GLSD AD) has a higher reduction of CO2 emissions per 2.2 lbs of food (1 kg) compared to both traditional composting methods (Windrow and Aerated Static Pile).
Figure 2. Global warming potential results for five food waste recycling and disposal systems. Error bars represent a low and high range of estimated impact potential. AD: anaerobic digestion, ASP: aerated static pile; CHP: combined heat and power; GWP: global warming potential; WTE: waste-to-energy
B. Morelli, S. Cashman, C. Ma, J. Turgeon, and J. Garland (2020) Food Waste Recycling — Environmental And Economic Assessment
To learn more about the process, we have attached the video from WM about their facility, as well as the EPA assessment of the life-cycle climate effects of bioslurry to biogas method.
The YouTube video about MIT’s and the City of Cambridge’s food waste processing facility
Morellis, B., S. Cashman, S. Arden, Xin Ma, J. Turgeon, J. Garland, AND D. Bless. Life Cycle Assessment and CostAnalysis of Municipal Wastewater Treatment Expansion Options for Food Waste Anaerobic Co-Digestion. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-19/094, 2019.