DUBLIN, Ireland — The Hewlett-Packard printer cartridges spinning down an assembly line in a Dublin-area factory (with a lawn heavily populated by hopping brown rabbits) go on a long, strange trip to sustainability. And clothes hangers play a starring role.

bunnies in a field next to HP in Ireland

The HP campus is a rabbit paradise. (Photo: Jim Motavalli)

If you send in your used cartridges, or recycle them via the local Staples or OfficeMax, they could get their passports stamped in several countries. But according to a report commissioned by HP, recycling a cartridge has just 33 percent the lifecycle carbon impact (and 54 percent the fossil fuel use) of making a new one.

The company now makes 75 percent of its inkjet cartridges with “closed loop” recycled plastic, and that means not only the aforementioned hangers (made out of just the right kind of polypropylene plastic) but also used cartridge casings, which are ground down into plastic pellets half a world away in Montreal.

Orange end caps on the printer cartridge assembly line.

Orange end caps on the assembly line. (Photo: Jim Motavalli)

HP’s PET plastic cartridges take in a more familiar raw material — water bottles. The company’s toner cartridges are on a similar path, though it’s going to take longer. Today, 24 percent of them are made with recycled plastic.

automated printer cartridge recycling line

Two cartridges per pallet. The line is totally automated. (Photo: Jim Motavalli)

You may wonder, as I did, if it wouldn’t be easier to simply refill the collected cartridges with ink, the same way glass Coke bottles were once repurposed. HP tells me it wouldn’t work, that it’s a onetime process —  performance would suffer and nozzles would clog.  

Obviously, HP is not the only company to recycle printer cartridges. Canon lets you drop your empties at FedEx stores. Brother takes back its spent laser jet cartridges. Epson takes back printer hardware, and cartridges, too (though it’s up to you to mail them back). Some private companies will buy old ink.

But HP is really into recycling. I love seeing things made, and the company's cartridge line in Dublin was quite cool. The recycled plastic pellets from Montreal are sent into a clean room where they’re melted and molded into basic black #364 bodies in an injection process, then spit out into bins. The two machines on the line run 24/7 and process 130,000 cartridge bodies per day. Here's video showing that process in action:

From there, the bodies move down a mostly automated assembly line where relentless robots insert such familiar parts as the wick, the lid, the internal foam block and the ship cap. And the ink, of course, in shades of magenta, yellow, cyan and black. Other robots package the cartridges (the internal word is “pens”) for shipment to Germany, where they’re prepared for their final destinations at international markets.

According to Shelley Zimmer, HP’s worldwide environmental leadership program manager, reviving ink cartridge plastic as part of what it calls the “circular economy” has kept 566 million used cartridges out of the landfill since 1991. Together, they’d weigh as much as 47,075 orca whales, or, laid end to end, would cover 24 Tour de France routes.

Finished cartridges

Finished cartridges ready for shipping to Germany. (Photo: Jim Motavalli)

Some 2.5 billion post-consumer plastic bottles have been used in making HP cartridges since 2005, and 1.1 million pounds of recycled hangers since the polypropylene process started in 2013. The cartridges have between 50 and 70 percent recycled content, depending on type.

Adding cartridge labels on the printer cartridge recycling line

Adding cartridge labels. (Photo: Jim Motavalli)

HP calls its reuse of plastic hangers “upcycling,” because it turns them into a more valuable form of commercial material. The cartridges are, obviously, returned empty, but there’s still some residual ink in them. HP doesn’t have a recycling process for ink yet, so it goes to waste-to-energy processes. “We’re working on a solution for our waste ink,” said Zimmer.

All recycling processes are works in progress. Not long ago, we were throwing our printer cartridges in the garbage can. But now they’re out of the landfill and on a global journey to sustainability.

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