GeekWire reporter Lisa Stiffler tested a Mill composting bin in her Seattle kitchen — and got the attention of her cat, Rushmore, during the process. (GeekWire Photo / Lisa Stiffler)

I don’t like food waste. One of my mottos is, “No food left behind.” I’ll toast the heel of the bread loaf and microwave sketchy leftovers from the fridge (luckily I have a strong stomach). The items that really can’t be eaten I dutifully deposit in our yard waste bin, which Seattle Public Utilities collects for converting into garden compost that’s sold locally.

So I was definitely interested to learn about Mill Industries, a startup that takes composing a step further by turning household food waste into a chicken feed ingredient. Based in San Bruno, Calif., Mill has its chicken feed R&D facility in the Seattle area.

Mill’s goal is to make it as easy and pleasant as possible to keep food out of landfills where it’s both wasted as a valuable resource and rots, producing planet-warming methane gas. It’s a serious issue. The U.N. estimates that if food waste could be represented as its own country, it would come in third behind China and the U.S. for greenhouse gas emissions.

The company has developed a high-tech bin that grinds and dehydrates the food, reducing the hassle, odors and fruit flies associated with other composting methods. Once the bin is full, customers follow a simple process to mail the processed waste to a facility that preps it for chicken chow.

Mill operates as a subscription-based service, charging $33 a month or almost $400 annually.

My current compost solution is admittedly inelegant, consisting of a crockery that I line with old grocery bags or scrap paper and cap with a clumsily repaired lid. I was ready to give Mill a try.

The bin is in

The delivery box is the first indication that the Mill composting bin is quite large, as Rushmore investigates. (GeekWire Photo / Lisa Stiffler)

Mill came out of stealth in January and has a waiting list for bins. In February I emailed Mill and asked if I could test the service for a month.

In May my Mill box arrived.

For a couple of days, it sat in the basement while I mustered the courage to schlep the big, heavy box upstairs and confront whatever tech challenge would be required to set it up.

I had seen photos of the Mill bin, but after unboxing it, the device was larger than I’d anticipated. It’s bigger than your standard under-the-counter trash can, measuring 27 inches tall, 16 inches wide and 15 inches deep.

But it was attractive — which was not a surprise. Mill co-founder Matt Rogers is a former senior manager at Apple and founder of Nest, the smart-home device company. Rogers and Mill’s other co-founder, Harry Tannenbaum, worked together at Nest, which Google acquired for $3.2 billion almost a decade ago.

My husband took one look at the Mill bin’s curving white lines and noted the likeness to a super-sized AirPod charging case.

Mill’s supporting documents, app and labels were also visually pleasing, straightforward and clever.

My kitchen is on the smaller side, so I nudged two dog bowls aside and tucked the bin in a corner. But its lid is thick and pops open, requiring some clearance from a wall. I tried to imagine where the bin would go in the similarly modest-sized kitchens of my friends and family members and had a hard time envisioning convenient spots, particularly since it can’t go inside a cupboard or under a sink.

I inserted a charcoal filter into the back of the bin, made sure it was scooched out from the wall, and plugged it in.

Run of the Mill

The ground, dried food in a Mill bin that’s ready to be emptied. (GeekWire Photo / Lisa Stiffler)

The app prompts you to name the bin, a silly step but I played along, christening the device Hugo after the food-obsessed pooch owned by GeekWire co-founder John Cook and his family.

The bin’s default schedule, which can be adjusted through the app, is to sit quietly most of the day, allowing you to drop in chicken bones and apple peels at your leisure. At 10 p.m., the big metal screw in the bin’s bucket starts grinding away and the contents are heated and dehydrated, shrinking their volume.

“When we think about the problem of keeping food out of the landfill or keeping food in the food system, it’s really a behavior change problem.”

– Harry Tannenbaum, Mill Industries co-founder

The bin, and ultimately the chickens, accept most of the items we were used to composting. But there were notable exceptions, such as compostable food and drink containers, paper plates, larger bones, houseplants and flowers, and “a bunch” of sugar, cake or cookies. The app has a searchable database to double check questionable items. In our house that included cherry pits and the tops of pineapples, which were allowed.

The device performed smoothly. The processing seemed to take a few hours, the sound was easy to ignore, and there truly wasn’t an odor. I didn’t miss the daily or twice-daily exercise of taking out the countertop crockery to empty it in the curbside yard waste container.

But there were downsides. The bin took up more space than we liked and we had to set aside non Mill-able items. My husband grumbled if there were coffee grounds or other scraps that he needed to toss in the evening after the bin started processing. It’s possible to interrupt the cycle, but if the bin was really cooking, it was a wait before it cooled enough that the lid would unlock.

For the most part, “Hugo” did its thing, producing each day a beauty bark-like material with a mild, smoky smell something like a Mexican mole.

Lisa Stiffler’s low-tech solution for composting. (GeekWire Photo / Lisa Stiffler)

The exception was when we fed it a pineapple peel and core, plus other daily scraps. The processing cycle started in the evening and was still going 12 hours later. I eventually forced it to stop and after it cooled, peeked inside. The contents looked sufficiently ground and I tossed in an apple core. That triggered the start of a new cycle, which the app predicted would run five hours. I overrode the program, forcing it to wait until the normally scheduled cycle.

Given that this is an environmentally motivated device, its energy consumption matters. Mill reports the average use is similar to running a dishwasher load every other day. The startup goes further to tally the whole system’s environmental impact. It compared the emissions caused by letting the food rot in a landfill to the carbon footprint required to produce and run the bin, ship the food grounds and make the feed product. By its calculations, that rotting food’s harm is four-times higher.

Mill’s broader reception

In addition to our household, there are now Mill subscribers around the country, though the startup won’t say how many.

The company also launched a pilot project with the city of Tacoma, located south of Seattle, to promote the Mill service. The Tacoma households still pay the full subscription, but were able to skip the membership wait list and receive “white-glove customer support,” according to the company.

The startup is promoting the idea that Tacoma residents can potentially save about $25 a month on their utility bill if they’re able to downsize their city trash can by using the Mill bin — though they could also realize that savings by putting their food waste into their yard waste bin.

But a lot of folks weren’t.

Mill shared survey results from Tacoma customers after a month’s use. More than half reported that they had not previously disposed of their food waste as compost, and nearly half of the Mill users noticed a reduction in their trash volume. Many became more aware of the volume of food they were tossing out.

“When we think about the problem of keeping food out of the landfill or keeping food in the food system, it’s really a behavior change problem,” Tannenbaum said. The early feedback suggests the service could help.

Mill is eager to start more partnerships like the one in Tacoma. The co-founders pursued a similar playbook at Nest, teaming up with electrical utilities to drive adoption of smart thermostats in homes.

Waste not

The box for sending in the ground and dried food is approximately cat-sized. (GeekWire Photo / Lisa Stiffler)

After nearly four weeks, my household’s Mill bin was close to full. The company provides a collapsed cardboard box that pops into shape and is prelabled and prepaid for shipping to Mukilteo, Wash., where the food waste is turned into a chicken feed ingredient. (Mill plans to open additional processing sites in the future to reduce the distance the waste is traveling.)

I lined the box with a heavy-duty Ziploc-style bag, poured in roughly 8 pounds of grounds (it could have held more), sealed the bag, and closed the box with a self-adhesive strip. With a click in the Mill app, I notified the U.S. Postal Service that I had a pick up — who knew you could request that? — and by the next evening the box was gone.

The trial was over. Now the $30 a month question: Will I subscribe on my own dime?

No, I won’t.

The Mill experience accomplished much of what the startup aims for — it was pleasant and hassle-free to dispose of food waste in a very planet friendly manner.

But there was no getting around the bin’s size. You could stick it in the basement or garage, but then you’re losing the convenience factor. I also wondered if that $400 a year could go toward another climate cause that could have comparable impact. And the truth is, my family is used to the routine of dumping food scraps into the yard waste bin, even if it gets gross and buggy.

For the majority of households that don’t have curbside food waste pick up — only about 10% of utilities offer it — or that find it too unpleasant to actually use, Mill could be a great fit. That said, there are other options, such as buying a countertop food composter for $350-$500, or even starting a worm bin.

Alternatives aside, Tannenbaum said demand is growing and the company is hustling to catch up on subscription requests.

“There are lots of different solutions out there, and there’s no silver bullet,” he said. “When we’re talking about keeping food out of landfills or keeping fruit flies out of kitchens, we need as much ammunition as we can to fight that.”

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