The future of composting
Bloomberg January 30, 2023
The device blends right into the room. It looks like a trash can — one of those sleek, steel models, cream-colored with a small foot pedal at the base.
Matt Rogers skips across the room to show it off. He taps the pedal to open the bin’s lid and reveal a pile of what looks like thinly shaved brown mulch, the dehydrated remnants of three week’s worth of his colleague’s household kitchen scraps. This mush once included discarded fish bones, now unnoticeable. Fish, banana peels, eggshells, an entire turkey carcass after Thanksgiving — Rogers says it can all go in. He hired a mechanical engineer, who once built motorcycles, to design the grinders at the bin’s bottom, stainless steel paddles and hammer blades that churn and pulverize the foodstuff. It’s only meant for food but could handle errant objects.
“You could probably throw like a metal fork in there — it won’t break the machine,” Rogers says, leaning over the bin. “It’s ridiculously robust.”
Thirteen years ago, Rogers, then a manager for Apple’s iPod division, co-founded Nest, the company that made internet-connected thermostats and effectively invented the smart home. Now Rogers wants to revolutionize another commonplace appliance. But this time he’s not selling a smart gadget; he’s trying to reinvent an entire system for managing food waste, one of the most intractable forces warming the planet.
Rogers and Harry Tannenbaum, another Nest alum, have quietly built their new startup since early 2020. So quietly that they’ve hired nearly 100 people in California and other spots across the country without sharing the company’s name or what they do. It’s called Mill, both the company and its 2-foot-tall kitchen bin that, as Rogers puts it, “dries, shrinks and de-stinks” all the food heaved in. You can only get the bin by signing up for Mill on a subscription plan at $33 a month. When your bin fills up, you pour the dried remains into a cardboard box — Mill ships you these — and leave that on your porch, where it’s picked up and trucked to a facility that processes your kitchen scraps into a feedstock ingredient, before shipping it to a farm where it’s fed to chickens. It’s a neat little loop: farm-to-table-to-farm.
Uneaten food is the most abundant material in landfills. It wastes nutrients, costs money to sort and never gets to hungry mouths. And it rots, releasing enough methane gas in the U.S. alone to equal the emissions of 274 natural gas power plants. In 2015 the U.S. federal agencies vowed to halve national food waste by 2030; we’ve made little notable progress since. No one has managed to keep large quantities of food out of dumps and reuse it effectively, nationwide, as Mill is setting out to do.
“I am waiting with bated breath to see how it goes,” says Dana Gunders, a pioneer in food waste advocacy who runs the nonprofit ReFED.
To work, Mill must pull off a logistics feat, coordinating with trucks, farms, city governments and federal regulators. Hardest of all will be convincing people to change what they do in their kitchens. Rogers sees altering consumer behavior as Silicon Valley’s forte.
“That’s our special sauce. That’s what we did at Nest. It’s what we did at Apple,” he says. “We don’t need a fusion energy breakthrough. This is not like the pinnacle of physics and rocket science. This is keeping food out of the trash. It’s literally a solvable problem.”
Only we keep making it worse.
Food waste is difficult to measure, but the numbers we have are staggering. Some 35% of all food made in the U.S. is discarded or lost. Landfills, brimming with excess food, emitted 109.3 million metric tons of carbon dioxide equivalent in 2020, more than half the total from natural gas systems, according to the Environmental Protection Agency. Then there’s all the resources blown making food no one eats. The EPA estimates that each year food waste knocks out 14 billion pounds of fertilizer and enough water to quench 50 million households.
Project Drawdown, a research nonprofit, lists the solutions necessary to avoid global temperatures rising 2 degrees C by the century’s end. Topping the list? Eliminating food waste.
Composting helps. But, outside of some pockets of the country, rates are abysmal. Less than 6 million American households have access to curbside composting, according to research from Biocycle, an industry publication. Most composting facilities only accept yard waste. Besides, the better tactic, economically and environmentally, is to feed excess food to people or animals.
Nicole Civita, a food systems expert and the vice president for strategic initiatives at Sterling College in Sterling, Kan., recalls a flurry of activity around eight years ago to do this. There were apps to track edible, discarded food and “upcycling” products (i.e. making chips from banana peels).
“There were more bad ideas than good ones,” says Civita, who Mill recruited as an adviser. She collects horror stories of “garbage feedings,” where leftover Halloween candy or Skittles from a highway spill wound up in cattle feed.
In 2015 HBO’s John Oliver devoted a segment to food waste, and called Civita in as an expert. After she gave the show’s producers a primer, one asked for the punchline: “Who’s the villain? Who are we skewering?”
Civita didn’t have a good answer. She didn’t see an evil tycoon or corrupt politician pulling strings. She saw a faulty system that begins, more often than not, with people simply tossing food into the trash. ReFED estimated that, in 2019, households accounted for the largest portion of the 80.6 million tons of surplus food in the U.S.
“How do you put your arms around everyone’s household?” Civita asks.
Harry Tannenbaum began obsessing over this question in early 2020. He left his job as a director at Google, Nest’s owner, in search of climate-related work, and found himself sifting through PDFs on food waste.
“You just start seeing it everywhere,” he says. “It doesn’t exist in nature. We invented it.” Tannenbaum had a budding idea for a company and messaged Rogers, who, since leaving Google in 2019, had become an active climate investor. Rogers wanted in himself.
The pair rented an old Honeywell office in San Bruno, Calif., keeping the corporate sign up as a lark. (Honeywell was Nest’s old foe.) Like Nest, Mill didn’t have to invent an appliance from scratch. The bin works like other food dehydrators — tiny heaters and vents dry and remove moisture, and a charcoal filter, connected to the main bucket via a small hose, moderates odors. (Mill plans to use coconut husks for its filters because they’re greener.) The bin plugs in and is designed to grind the day’s food during the night, emitting a hum somewhere between that of a refrigerator and a dishwasher.
A room in Mill’s office is devoted to stress-testing the products. There’s a row of machines rigged up to slam hard on the lids and pedals, gauging their endurance. Others get the “stink bombs” — putrid concoctions meant to see how well the bin masks smell. During a December visit, a Mill employee prepared a baggie of rotting squash, eggs and unrecognizable stuff to pour into a receptacle. Rogers gave it a sniff: “That’s pretty gnarly!” It’s effective, however. For the past year, his staff have been trialing bins in their own homes. A batch of recent pulverized scraps from a household of four smelled faintly of a musty wood chips.
Home food dehydrators already exist and are gaining popularity in Asia. A corner of the Mill office is full of competing models the startup bought from Korean and Chinese e-commerce sites to tinker with. For U.S. consumers, these devices are sold as stand-alone items, without any directives for dispensing with the resulting scraps. Rogers likens them to the clunky MP3 players before the iPod arrived, with its nifty design and iTunes library. Mill isn’t selling its bins separately, but is pledging to handle all the maintenance and logistics for paying customers.
“No one had really thought through the whole end-to-end,” Rogers says.
The bin is equipped with a miniature scale to weigh discarded food. And it has Bluetooth, connecting to an app where consumers get FAQs — “Can I throw avocado pits in there?” Yes — and a regular report of their disposal and emissions impact, built to convince people to toss and even use less food.
After using the bin in his kitchen, Tannenbaum stopped buying bagged cucumbers that grew slimy in the back of his fridge.
“If something doesn’t get measured,” he says, “it doesn’t get improved.”
Once the bins are full and emptied into boxes — Mill predicts this will be every three weeks or so — U.S. Postal Service trucks pick them up along mail routes. Alyssa Pollack, Mill’s head of business, who joined from Uber, says the startup opted for the Postal Service in part, because of the limited carbon footprint. Mail trucks already visit homes, so pickups don’t add new vehicles to the road. The trucks will take boxes to Mill’s depots to strip out any contaminants and convert the foodstuff into chicken feed. Mill plans initial sites outside of Seattle and in the Northeast.
From there, Mill is more tight-lipped. The startup says it’s working to get its feed ingredient certified and has held discussions with farms, but won’t name any potential business partners.
None of Mill’s grand plans work if it can’t get enough paying customers. (They can also pay $45 month to month.) The cost is steep. Many in Mill’s natural customer base, coastal urbanites, live in cities with composting programs. Others may not want to pay to remove what they already trash.
“They’ll have an army of food waste warriors that are really excited about this,” says ReDEF’s Gunders. “But getting to the next rungs is hard.”
Mill recently surveyed potential customers, and that reveals how much inertia the startup must overcome. Nearly half the people self-described as “very climate concerned” in its survey reported that tossing food in their garbage “works fine.”
For Mill, there’s opportunity because the current alternatives don’t work fine either. Rogers lives in San Francisco and, like many residents, collected scraps for municipal composting in a small kitchen countertop bucket. With two young kids, kitchen life during the pandemic got messy. Fruit flies took over, which Rogers tried abating with sticky yellow paper. He gave up.
“It was too gross,” he says.
Civita lives on a farmstead in Vermont, ideal for composting. She had to stop in mid-December; her outdoor compost bin froze. She believes Mill’s fee is worth the ease.
“People who have the ability to pay are definitely willing to do so,” she says. Rogers puts tens of millions of households in this camp.
Investors believe him. Before launching, Mill raised multiple funding rounds from major climate backers including Breakthrough Energy Ventures, Prelude Ventures, Energy Impact Partners and John Doerr. Mill says it has raised more than $100 million but isn’t giving an exact number.
Food waste warriors welcome the arrival of the Nest alums.
“We need all the solutions,” says Rhodes Yepsen, executive director for the Biodegradable Products Institute, a nonprofit focused on composting. But Mill brings more appliances to plug in, trucks to take feed to farms and resources that could be spent on existing food rescue or composting programs. These efforts often need more political will than Silicon Valley pizazz or massive investment — Yepsen’s organization estimated that only $2 billion was needed to expand composting nationwide.
“Composting can be pretty low-tech,” he says. “Are we too attracted to the shiny objects?”
Mill says its bin uses about as much electricity as an energy-efficient dishwasher, and its overall energy usage will be canceled out by the emissions savings from keeping food out of the dump. By Mill’s calculations, each of its member households will shave off 521.2 kilograms of carbon dioxide equivalent a year.
The company also says it’s eager to work with the public sector, and has held conversations with municipalities about partnering. (Although it won’t say which ones.) Eventually, Mill believes it could bring its operation to an entire residential block or a sports stadium.
“The hardest part for a city is how to change those daily rituals for people in their kitchen,” Rogers says. “Our goals are the same. No one likes waste.”