We generate so much plastic waste today that it has become a serious environmental problem. Some of us do put aside our plastic bottles for recycling, but even that endeavour requires energy consumption just to get the plastic to a recycling centre. Even more energy is needed for the actual recycling. There is a better way to reuse the plastic, and 3D printing makes it possible.

Joshua M. Pearce of Michigan Technological University has published updates on the recycling project in a study called Life cycle analysis of distributed recycling of post-consumer high density polyethylene for 3-D printing filament, which demonstrates that making your own plastic 3D printer filament from milk jugs uses a lot less energy than conventional recycling, and it saves you the cost of filament, as well.

For the study, Pearce’s team used standard milk jugs made from HDPE plastic, which they clean and ran through an office shredder. They then used a RecycleBot to convert the shredded plastic into 3D printer filament that could be made into pencil cases or whatever else the plastic is suited for at home.

Recycled 3D printing

Joshua Pearce holds a DremelFuge chuck made from shredded plastic milk jugs.

Recycling one’s own plastic jug consumes 90 percent less energy than producing new ones from petroleum. But even when compared with other recycling, it offers savings that range from 3 percent, where collection and recycling is local, to as much as 80 percent for those of us who have transport the plastic first to be picked up for recycling, only to have it driven over yet again to get to the recycling center and a third time to a place where it will finally be shaped into something new.

I contacted Joshua and asked him a few questions about the ramifications of the study. In response to my question about the limits on the type of plastics that work for this type of recycling, as the study focuses on the type of plastic used in milk jugs.

He answered: “We only did the LCA on HDPE because we had the most experience with it, and HDPE represents such a large fraction of the waste stream. That said, all of the other recyclable polymers are also fair game for recycling in recyclebots or any of the commercialized versions (e.g. Filabot, FilaFab, etc.).”

Pearce said that he would expect comparable “energy/environmental advantages to home recycling,” for other plastics but conceded that the proof would have to be demonstrated in further studies. He added that to scale up to a “commercialized version,” additional factors will have to be taken into consideration for energy savings like “the amount of insulation” used.

When I suggested that the recycling benefit will grow larger in the future when there are more people doing 3D printing at home, Pearce agreed. For the conditions of the study commercial filament cost $35/kg, which is far more than the energy cost of recycling plastic at home, which amounts to just ten cents per kg. However, that benefit is limited at present to those with access to the equipment and designs for 3D printing at home.

In future, as a result of “the exponential rise in free and open source 3D printable designs and that kind of cost advantage,” we should see “the economic benefit” multiplied many times over. He offered the link to Life-Cycle Economic Analysis of Distributed Manufacturing with Open-Source 3-D Printers for detailed calculations about the projected growth for open-source 3D printing.

As on-the-spot recycling with 3D printings sounds so promising, I asked Pearce if there are any sponsored programs in place to encourage it. He answered in the affirmative: “Groups like Perpetual Plastic are pushing on the recycled filament educational front very hard. At the same time the Ethical Filament Foundation is working in India and elsewhere to lift ‘waste pickers’ out of poverty by enabling them to climb higher up the value chain from their recycling efforts.”  That would represent a dual benefit for the program, one for the environment and one for the economy.

Indeed, Pearce is very optimistic about what the study means for the future: “it is going to be much less costly both economically and environmentally to manufacture using 3D printers and recycle in your own home. This is the future and it is already here for a growing number of people.”

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