How to recycle food scraps: Composting vs. Mill’s bin.

Nov 22, 2023

A few weeks ago, a friendly PR person helped me lug a 50-pound kitchen appliance up the stairs to my Brooklyn apartment. After she left, my roommate and I stood staring at “the bin.”

The bin is white and rounded, with subtly textured sides. Its heft is luxe; it will not be easily tipped over. It has some of the functionality of a trash can, but it is technically a food dehydrator. As soon as we plugged it in—it plugs in—a light started slowly blinking beneath the wood-grain lid, gently but firmly nudging us to set up the app.

The bin is in our home courtesy of Mill, a new startup from Google Nest alums Harry Tannenbaum and Matt Rogers. Their team designed the bin to help solve the problem of residential food waste. Most U.S. food scraps go straight to landfills, where they release loads of planet-heating methane. Landfills are the third-largest source of methane in the country, after fossil fuels and gassy cows; swift methane reductions by 2030, along with a swift decrease in oil and gas production, may help keep climate goals in reach.

Simply wasting less food is one important solution. But for many of us, the back of the fridge will remain a scary place. Composting is one backup; Mill’s solution is to dry kitchen scraps—which are 80 percent water—so that they can be shipped to Mill and then fed to chickens.

To convert consumers to the cause, Mill is relying on what Tannenbaum calls “a kickass kitchen experience.” For the privilege of being responsible with your pizza crusts and apple cores, Mill is charging $45 a month after a one-time fee of $75 (or $396 billed annually, which works out to $33 a month). Users who tire of the experience can cancel the plan and send the bin back.

After weeks of testing, I can confirm that this is, in fact, a kickass kitchen experience. I’m not yet convinced that the bin will meaningfully help fix food waste—but if it does, the chickens will be key.

I babysat Mill’s prototype for two weeks. At first, as I stepped on the bin’s foot pedal, popped open the lid, and casually brushed onion skins off a wooden cutting board, I felt as if I had stepped out of my tiny, windowless galley kitchen and into a Magnolia Magazine spread.

The foot pedal really won my heart. I fed the bin avocado pits without getting guacamole fingerprints everywhere. I tipped 5 pounds of soggy soup-stock vegetables from a pot into the bin, spilling nothing. If it sounds as if I’m describing the joys of a cheap foot-pedal trash can, I am. But I don’t usually trash my scraps: I drop them into a bowl on the counter while I cook, then stuff them in a bag in the freezer. I’ve been composting my entire adult life. Not since my childhood garbage disposal have I had such a hands-free waste experience.

At night, the lid locked shut, and an orange light flickered beneath the wood veneer. The bin made a low hum as it shredded my scraps in what the app calls a “dry and grind” cycle. (For a while, it also made a sound like a loud fart, which trailed off into a snore—this, the product team assured me, was a quirk of the prototype.)

The bin ran all night using negligible energy: We put it on the same breaker as our microwave, but (unlike the microwave) it never dimmed our lights. Each morning, the previous day’s sloppy pile was reduced to a delicate, feathery heap. I was able to go weeks without emptying the bin. This was even easier than tossing food in the trash. Still, the bin does have a dark side.

The night we set up the bin, I glanced through the (comfortingly brief) instructions as my roommate made us tea. “Coffee grounds OK, eggshells OK,” I said. “But no large bones.” My roomie grimaced, and, unbidden, I pictured the wood chipper from Fargo. (The website clarifies no beef, lamb, or pork bones.)

“Chicken bones OK, though,” I said helpfully, and my roommate yelped. “It’s chicken cannibalism!” she said.

I asked Tannenbaum about this. “Nothing that’s happening here isn’t happening in nature,” he told me. He’s right: Chickens are omnivores. Among the closest living relatives of the Tyrannosaurus rex, they do, in fact, tend toward cannibalism. And feeding chickens turns out to be a clucking good solution to a few specific climate challenges.

Left to rot in landfills, biodegradable materials like paper, cardboard, and food scraps emit methane—a potent greenhouse gas. Landfills are responsible for 15 percent of U.S. methane emissions, and of the food waste they contain, food from home kitchens makes up around half. So, getting food waste out of landfills is a good thing—that’s why people compost.

Feeding chickens may be even better than composting. Both the U.N. Sustainable Development Goals and the U.S. Environmental Protection Agency agree that the best thing to do with unused food (besides feeding it to people) is to feed it to animals. Agriculture is energy-intensive; the process of growing things at a large scale produces a lot of emissions. More than a third of what we grow actually goes to feed animals we later eat. Feeding them directly with food scraps cuts out a whole piece of the cycle, and uses a lot less energy.

If you are going to feed food waste to animals, chickens make a lot of sense. Right now, according to a recent study in the journal Nature Climate Change, the world is on track to exceed Paris Agreement climate goals based on agricultural emissions alone. To turn that around, rich countries need to cut back on beef and dairy. The study found big climate gains if everyone stuck to the healthy eating recommendations from Harvard Medical School, which include no more than one serving of red meat a week.

The Chick-fil-A cows are on to something with their “Eat Mor Chikin” campaign—but mostly, we need to eat mor chickpeas; raising chickens is still more emissions-heavy than cultivating plants. This made me pause. Couldn’t building a chicken-feed supply chain give Mill a perverse incentive to promote poultry, in ways that could actually harm the environment—a tech company solving one piece of the climate problem only to exacerbate another?

When I asked Tannenbaum this, I quickly realized that my sense of scale was wildly off. “Even if we took every single ounce of food out of the landfill,” he told me, “we’re only feeding 7 percent of the chickens in the U.S.”*

We could stop eating a lot of chickens without Tannenbaum’s chicken-feed market drying up, because, as it turns out, this planet is an uncomfortably large percentage chicken.

“There are 27 billion chickens on earth right now,” Tannenbaum told me. Collectively, chickens weigh around three times more than all wild birds. From an emissions standpoint, beef and dairy have the worst climate impact per calorie; eating poultry is better, but still not great. Eggs, however, are better than you might expect.

“We feel great about eggs,” Tannenbaum said. From an emissions standpoint, eggs are not much different than kale. Beans and lentils are the climate-friendliest protein options overall, but eggs are the climate-friendliest animal product.

Feeding chickens is already a popular small-scale food waste solution. Towns in France and Belgium, for example, give out chickens to serve as walking, clucking garbage disposals. The town of Mouscron in Belgium confirmed that it gives away around 200 chickens every two years to villagers and will continue to do so: Chickens eat scraps, lay eggs, and don’t take that much work.

Mill has its sights set on a very different chicken demographic: not idyllic village chickens, but the many, many chickens living in industrial farms.

Chicken feed is a carefully balanced mix of grains and animal byproducts; Mill is currently partnering with a university to make sure it can get the nutritional profile of its scraps approved by the FDA. If it can, the company hopes that a scraps-to-chicken-feed supply chain can have a positive climate impact.

I’ve been composting for a decade. I’ve tried the gloppy countertop bin (moldy, gross), the “box of worms in the kitchen” approach (the worms escaped), and, more recently, one of Mill’s closest competitors, the Lomi, which churns scraps into a soil amendment that you can sprinkle around your backyard. (Our cat liked watching the Lomi do its thing, but I don’t have a backyard.)

The compost strategy that works well for me is simple. I call it “bag of scraps in the freezer.” Right now, I have a brown paper lunch bag of scraps in my freezer door. At my last place, I had an entire freezer drawer lined with a large green compost bag. Freezing scraps prevents putrescence. It neutralizes weird smells. And hypothetically, because a fuller freezer is a more efficient freezer, freezing scraps can lower your electric bill.

Even with this method, however, the scraps do eventually have to leave the house. New York City has convenient compost drop-off sites. As of this year, California requires all cities to accept food scraps in residential yard bins. In most of the U.S., though, municipal compost is still a pipe dream; dropping compost off at a community garden or farm can be a big hassle. By picking up waste from consumers anywhere, Mill fills a big gap.

Still, it’s a lot to pay for the privilege of feeding chickens and avoiding emissions. “It might be cheaper to just buy a chicken!” my mom said when I mentioned Mill’s price tag. (The Wall Street Journal recently explained that chickens are not really that cheap—they can run $5 a pop but can entail steep housing and vet costs.)

Mill’s monthly subscription makes sense for people who can afford Magnolia-ready kitchens—as well as for people whose garbage bills depend on how much garbage they produce. The city of Tacoma, Washington, which recently partnered with Mill, estimates that families could shave $26 off their monthly garbage bill by diverting their food waste, making a Mill subscription more accessible.

The bin could also be a great first step for people who want to compost—in theory—but keep not getting around to it. Think of this as Blue Apron but for kitchen scraps: The Mill bin makes separating waste fun, but you don’t have to use it forever. Try it for a few months; get in the habit of doing something with food besides chucking it in the trash; then switch to whatever strategy works best in your region and for your life. (While chicken feed is arguably better than composting, compost is still better than landfill).

“There’s a little bit of a mantra internally that imperfect action is better than perfect inaction,” Tannenbaum told me. The Mill bin is an imperfect first step, but Tannenbaum hopes it will prove both the possibility of a viable scraps-to-chicken-feed loop and the possibility that consumer behavior can change.

Of course, better consumer behavior alone will not solve food waste: good old kitchen-table climate organizing also matters, as does public-sector action. Mill will not solve food waste alone, and plenty of other global challenges also need tackling: things like cooling, drying, and storing food after harvests in developing countries. But if people get on board—and if Mill’s chicken-feed supply chain actually works—the company will be well on the way toward creating a new market for kitchen scraps.

That could be a win for the climate. It might or might not be a win for chickens—I did not evaluate how the scraps taste compared with regular chicken feed—but I hope it will be. While I will be sticking to my bag of scraps in the freezer, I enjoyed my time with the bin more than I thought I would. The last night we babysat the bin, my roommate and I solemnly fed it the remains of a rotisserie bird, along with our best wishes for that chicken’s brethren—and for the planet.

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.

Correction, April 5, 2023: This piece originally misstated that Mill’s chicken feed could potentially reach 2 to 3 percent of U.S. chickens. Mill hopes to feed 7 percent of U.S. chickens. This piece also misstated Mill’s internal mantra, which refers to “perfect inaction” rather than “perfect action.”

Update, April 5, 2023: This article has been updated to clarify the subscription options offered by Mill.