The sad vegetables at the back of your fridge won’t just be wasted when you finally throw them away: They could also contribute to global warming.
When food is buried under heaps of other trash in a landfill, the bacteria that would normally turn it into nutrient-rich soil can’t get enough oxygen to do the job. Instead, different bacteria gobble it up and release methane, a potent greenhouse gas.
Landfills are the third-largest source of human-related methane emissions in the United States, according to the Environmental Protection Agency, and food in landfills accounts for about 58 percent of those emissions.
“Diverting food waste from the landfill is one of the easiest things we can do to help solve climate change,” said Rebecca Ryals, an associate professor at the University of California, Merced, who has studied the environmental effects of composting for 20 years.
Some companies behind newfangled kitchen gadgets claim that they make it easier to keep food waste out of landfills by converting organic waste to compost in a matter of hours, not months. But what do these pricey contraptions really produce? And are any of them really good for the environment?
Read on.
Not exactly compost
A handful of appliances on the market have been advertised as household composting machines. But, according to experts, that’s simply not true: These machines do not produce compost, dirt or soil.
Rather than speeding up the decomposition process, many of these devices actually pause it by dehydrating the food, said Kate Kurtz, a soil scientist, composting expert and organics leader for Seattle Public Utilities. The toasted, ground-up result does resemble dirt, but as soon as it gets wet again, say, from rain, it’ll start to rot.
“It’s not something I would recommend putting next to your prize roses,” Ms. Kurtz said.
If you try to use these food grounds like finished compost, they’ll mold, smell, attract pests and scavenging animals, and might even hurt your plants, said Ron Alexander, who runs an environmental consulting firm that specializes in composting and recycling.
Some appliance makers acknowledge that their products don’t produce compost. Judson Cummins, a senior director at Vitamix, confirmed in an interview that what comes out of the company’s FoodCycler, a countertop food recycling machine, “is not compost and is not really fertilizer.”
Vitamix does not market the FoodCycler as a composting machine, and company’s promotional material calls the machine’s product a “nutrient-rich soil amendment,” not compost.
The makers of Lomi, a kitchen countertop food recycler that promises “garden-ready dirt” on its website, said in an email that the device produced “pre-compost” or a “nutrient-rich soil amendment” rather than dirt.
So, what are they good for?
While these machines don’t make finished compost, the food grounds they produce can be added to a traditional compost heap and perhaps make the whole process less of a chore.
The makers of one new device, Mill, say their goal is making shelf-stable food waste. That lets you preserve the potential in your food scraps until you’re ready to deal with them, according to the Mill co-founder and president, Harry Tannenbaum.
If you can’t compost on your own, Mill offers your scraps a direct path back into the food cycle: It recently received approval from the Washington State Department of Agriculture to use the food grounds from its appliance as an ingredient in chicken feed.
Subscribers can send their food grounds to Mill by mail. An analysis by Mill suggests that shipping the grounds emits less than 1 percent of the greenhouse gases saved by diverting the food from landfills, though that assessment has not been peer reviewed.
Feeding animals is one of the “highest and best uses for food waste,” Ms. Kurtz said.
She added that these technologies could also be a boon to people who live in areas where animal scavenging is a problem, for example, in places with a lot of bears. Or in places where municipal trash service isn’t available and organic waste is often buried or frozen.
What should I do about my food waste?
The unsexy answer is to plan and shop more carefully. “Reduce is the most forgotten but by far the most important of the three Rs,” Ms. Kurtz said.
And remember that composting doesn’t give you carte blanche to over-buy groceries or let leftovers spoil.
For unavoidable food scraps — things like eggshells, banana peels and broccoli stems — your first choice should be municipal composting, which is “spotty” but becoming available in more cities, Dr. Ryals said. Also check out your community composting options, since local gardens and farmers’ markets often have strong programs.
If you strike out there, Dr. Ryals suggested revisiting low-tech household composting methods before shelling out for the high-tech gadgets. While a Lomi or Mill could set you back $300 to $1,000, “we have so many different ways to compost that are essentially free,” she said.
“If you can take care of a goldfish, you can probably take care of a worm bin,” Dr. Ryals said. And don’t worry: with minimal effort, it won’t stink, she added. “You can be a lazy composter at home and have a good experience and a good product at the end.”
