Is Your Lunch Trashing the Planet? Top Three Ways to Deal with Food Waste

We waste almost as much food in the U.S. every day as we should be eating--about 1,400 calories per person. Wasting less is best, but if we really can't eat it, where should we put it?

Lunches like these are typical in American schools. Nothing good is likely come of the disposable tray, but large amounts of food waste from cafeterias, restaurants, and homes can be put to good use through municipal-scale composting.

I will never forget the day my sixth-grade teacher started crying in front of the whole class. The tears capped off a long, loud, after-lunch rant about wasted food and the starving children in Ethiopia who would have been happy to eat it.

Like most of my peers, I responded with both shame and defiance. Who wants to make her teacher cry, let alone singlehandedly starve a bunch of little kids? On the other hand, people threw out that food for a reason: it was only nominally edible. On the rare occasions when I bought school lunch, I privately believed that even a starving child wouldn't choke down more than a few bites before dumping the rest in the garbage.

That said, I have always been horrified by the very thought of throwing food away. I was raised to clean my plate regardless of whether I liked what was on it or not. Why? This was the era of super-cheap generic canned goods with white labels and bold black lettering, so we didn't lack adequate calories. And you couldn't really send your leftovers to Ethiopia. Wasting food was just categorically, viscerally wrong; you didn't need a why.

Food waste and global warming

It still is wrong, but we have ever more urgent and tangible reasons for paying attention.

First are the immense resources that go into producing our food--most notably, petroleum and water. While you might be able to justify gaining sustenance from the most resource-intensive foods (beef, for example, is notorious), you are needlessly throwing out oil and clean water with every unwanted morsel.

Also, most wasted food goes to landfills, where it contributes to global warming by producing tons and tons of methane. Even if people wasted less--something we should obviously try to do in our own kitchens by buying less food and perhaps owning smaller refrigerators--there would still be apple cores, potato peelings, chicken skins, coffee grounds, and many other unwanted parts thrown in the trash from millions of homes every day.

Food waste isn't going away. What, then, should we do with it?

Food down the drain?

A new study finds several environmentally preferable alternatives to sending our food to landfills. The best ones involve treating our wasted food as an asset rather than a liability. Luckily, this is an attitude shift that people can make fairly readily--at least when compared with the idea of reusing human waste, a possibility people find much harder to face. The trick is to implement this attitude shift at the municipal level.

The life-cycle analysis was commissioned by InSinkErator and conducted by independent research group PE International. While the manufacturer has touted the analysis as proof that processing food waste in a kitchen garbage disposal system is environmentally preferable, the results were actually much more complicated: if you don't know the gruesome details of how your municipality deals with your wastewater sludge and its biogases, you can't truly assess how green your garbage disposal is.

In my back yard, please!

In fact, while the scenarios studied covered a wide spectrum of environmental impacts, only one wastewater treatment scenario stands out as a truly sustainable option. Here's a rundown of the top three ways of dealing with food waste, according to the life-cycle analysis:

• Municipal compost--Composting is the real winner in this life-cycle analysis. Industrial "advanced" composting is becoming more popular in municipalities around the U.S. and Canada, and this study's results suggest they need to become more common. In most such systems, the pile is covered and aerated to create high-heat aerobic digestion, and emissions are captured. The resulting compost is used as fertilizer and releases a small amount of CO2, giving this method the second-smallest global warming potential of all methods studied, (2.1 kg of CO2 equivalent per household per year).
• Waste-to-energy--In this scenario, solid waste is separated into landfill trash and food waste. The food waste is burned to run steam generators to make electricity, giving this method a comparably small carbon footprint (3.6 kg of CO2 equivalent per household per year).
• Wastewater treatment--Most wastewater treatment methods use a lot of energy, and only a few do anything to offset the global warming potential of this energy. The method with the most promise uses anaerobic digestion, capturing the methane for heat-and-power cogeneration and using the spent biosolids as fertilizer. This method has negative global warming potential. Other wastewater treatment methods had much higher carbon footprints than composting and waste-to-energy.

Sink over garbage can

All that said, if your only two options are washing the food down the drain or filling the landfill with it, your choice is fairly clear, according to this study: go with the garbage disposal. Even though processing all that wastewater takes way more energy than just trucking and dumping your food scraps, the global warming potential (GWP) of any method of wastewater treatment is dramatically lower than that of the landfill.

What about the water?

You might wonder, as I did, about the constant running of water while the food is getting ground up in the drain. Oddly, the study only gives cursory treatment to water use, estimating a slight increase in usage per household but not considering that as an environmental impact. When I asked an InSinkErator spokeswoman why that was, she replied that the water use was negligible and pointed me to a couple of studies on the topic. Another industry expert told me that it's very difficult to find controls for such studies because "almost everyone" has a garbage disposal, but apparently some have shown that net water use is actually less. A study done by New York City showed a negligibly slight increase in water use.

My visceral reaction to wasted water is similar to my visceral reaction to wasted food, so I wish this study done more to study the impact of water use in its otherwise pretty comprehensive life-cycle analysis. I can't stand watching clean water run down the drain, so I won't be installing a food disposal system anytime soon. Luckily, we have both a backyard compost pile and the option of municipal composting.

Your next move

In my Vermont county, our composting program started with restaurants and other businesses, and it is slowly being extended to households. Soon there will even be curbside pickup in Brattleboro.

The program accepts a lot of trash that you can't normally put down the drain, recycle, or compost in your back yard--making it even more awesome. Everything from pizza boxes and waxed paper to dog poop and chicken bones can go to the compost facility. Every week here at BuildingGreen, we divert a large number of used paper towels from the landfill by composting them; between the compost and the recycling, we are getting very close to being a zero-waste-to-landfill business.

While waste-to-energy and wastewater treatment with cogeneration both look like low-impact ways to deal with food waste, a composting program should be much easier for a community to put together. It also diverts a lot of heavy trash that many municipalities would otherwise have to pay tipping fees to get rid of, making it a very good investment. If you want to move your community toward a cheaper and more environmentally sustainable way of dealing with solid waste, pushing for a municipal composting program would be a very good idea.