The general public has known about 3D printing only in this century, but it first developed in the 1980s. Hundreds of scholarly papers about it have appeared in the US alone over the course of the 21^st century. Most of them are not concerned with its environmental impact.

Yet it’s easy enough to find web sites that either assert or deny that it is eco-friendly. The environmental impact of widespread 3D printing depends on too many factors to be predicted with any simple generalizations.

Most products have parts made with different manufacturing techniques, including grinding, molding, casting, bending, stamping, extruding, and welding. The environmental impact of 3D printing varies according to which of these it replaces.

It also varies according to the materials it uses, how much energy it uses, how much waste it generates, and the emissions of the process. A full comparison of how eco-friendly 3D printing is compared to all these traditional technologies would fill a book.

This post will examine some issues not only of the environmental sustainability of 3D printing but also economic and social sustainability.

3D printing materials and techniques

Most often, we think of 3D printing and plastic.

It works with plastic, of course, but also metal powders, plaster, ceramics, food, living tissue, and more. In all, it can use more materials than are worth trying to list here.

Today, plastic is such a common material because it can be so easily made into almost any shape or form. Because it works with so much, 3D printing can conceivably take away this advantage.

Most plastic parts for consumer products are made with injection molding. And injection  molding has a lower environmental impact than any currently available printing technology for the industrial scale production runs. For small-scale production, however, 3D printing has the edge.

And even with plastic, sometimes bioplastics work better in 3D printing than thermoplastics. That should incentivize their development.

Each material requires a different kind of printer. For example, printing with thermoplastics requires machines that can melt and extrude the plastics. Printing with liquid epoxy materials requires UV light to harden them. Neither of those machines can print with metal or any of the other possible materials.

Some products of 3D printing require support materials to prevent the modeling materials from warping or collapsing. Sometimes it can use more support material than modeling material. The support material can be the same substance as the modeling material or something different.

In addition, some 3D printers can print more than one part at a time.

3D printing energy usage

Compared to traditional manufacturing, 3D printing may require 50 to 100 times as much electricity per finished piece according to some estimates. According to others, energy usage works out about the same. A lot depends on what is being compared and what is being measured.

What about the environmental impact of design? In traditional manufacturing, complexity of design costs more than either materials or energy. Efficiency in materials or energy, therefore, seems to matter less.

In 3D printing, complexity of design costs nothing. That ought to lead to complex designs that save materials.

Incentivizing energy savings is more difficult. For one thing, it takes more energy to produce metal powder for a 3D printer than ingots of the same metals for standard manufacturing methods.

There is some evidence that 3D printed solar cells are both less expensive to produce and more efficient compared to other solar cells. That, in turn may hasten the transition to solar energy.

3D printing waste

3D printing is an additive technique. That is, it builds objects by spraying materials. Some other manufacturing techniques, such as grinding, are subtractive.

Its boosters often claim that it eliminates waste. In some cases, that’s true. Machining a hollow part from a block of plastic or metal does indeed waste a lot of material, perhaps as much as 80%. While it might be possible to reuse  the waste material, it entails additional energy costs to make a new block with it.

Most hollow plastic parts for mass-produced products, however, come from injection molding, which results in very little waste. Some studies have estimated as much as 10% waste but others as little as 1%. And injection molding produces parts in seconds, where 3D printing takes much longer and uses much more energy per part.

Also, it eliminates waste only if the output requires no support material. The support material is often not recyclable and ends up in landfills. When a product requires more support material than modeling material, it is more than 50% waste. The only way to know it that’s a good or bad deal for the environment is to compare it to other ways to make the same part.

And support material doesn’t account for all the waste in 3D printing. Some types of printers inherently waste material. Poor design of a part or the process for making it can also waste material.

Failed prints also result in wasted plastic, which may or may not be recyclable.

3D printers can and do print with recycled plastics. Recycling the output of 3D printers presents all the same problems as any other recycling. Composites of various plastics—even those easily recyclable as separate materials—can’t be recycled with current technology.

3D printing emissions

Fine particle emissions from 3D printers are health hazards.

Liquid PolyJet model material is more toxic than the kinds of plastic used in standard injection molding. It presents a hazard to people working with or near it, although it is generally not considered toxic as a solid.

Using 3D printers in homes or offices that lack industrial safety measures exposes workers to toxic particulates. But some newer designs produce printers with sophisticated filters to capture them.

When it comes to greenhouse gas emissions, using 3D printing or not may not make much difference. Manufacturing in general accounts for about 29% of emissions globally. Breaking out the percentage of emissions attributable to any one manufacturing technique is difficult. And then its environmental impact would have to be compared with each one.

Printing 3D parts onsite instead of ordering them from an offsite vendor may reduce emissions from transportation.

Implications of 3D printing for economic sustainability

The costs and benefits of using 3D printing must be calculated separately for each technique. And, in fact, the difference between one 3D printer and another that does the same thing might be greater than the difference between either one of them and a traditional technique. That is, it depends on how well the printer is designed, made, and operated.

Will 3D printing move manufacturing from centralized factories to regional ones? And will that reduce transportation costs? Maybe, but probably not significantly.

Today’s 3D printers can’t print entire products unless they’re very simple. So it still involves transporting feedstock, then transporting parts to where the products will be assembled, and then all the usual transportation from factory to end user. Even where transportation savings are significant, manufacturing usually has a higher environmental impact than transportation.

But 3D printing may entail less complex supply chains.

Bioplastics

I have mentioned that bioplastics can work better than thermoplastics. Currently they are more expensive that regular plastics, largely because they are produced at a smaller scale. But labor costs often exceed material costs.

Since 3D printing doesn’t require skilled labor, it greatly reduces labor costs. It gives manufacturers the choice to use a more expensive material and still reduce overall manufacturing costs. Bioplastics are already the choice of many hobbyist printers.

And if the reason for the extra cost of bioplastic is low demand and therefore small production, higher demand and larger production should produce economies of scale to bring prices more in line with traditional plastics.

But speaking of economies of scale, 3D printing helps eliminate them in manufacturing. The economics of traditional manufacturing encourages mass use of a limited number of materials. Changing from one material to another requires expensive retooling.

With 3D printing, on the other hand, switching materials requires only using a different printer. Or perhaps even a different configuration of the same printer.

Encouraging repair rather than disposal

Here’s a consideration with both environmental and economic implications:

Currently, when something breaks, it’s easier to discard and replace it than fix it. When a single component breaks, there is no supply chain to replace the part.

Intellectual property rights present barriers to making new parts with 3D printing. Once these conflicts are worked out, the ability to fix rather than discard something that breaks should keep a lot of stuff out of landfills.

Implications of 3D printing for social sustainability

As far as social sustainability is concerned, 3D printing has both advantages and disadvantages.

It doesn’t require a skilled workforce. To the extent that it replaces traditional manufacturing, it costs skilled jobs, although it may also require creation of new skilled positions.

On the other hand, it can economically produce small to medium runs. Entrepreneurs will need less capital to start their  companies. Developing nations can do more of their own manufacturing and import less.

In other words, it’s too soon to tell the social costs and benefits of 3D printing. It has a tremendous potential upside, however.

So is it more eco-friendly and sustainable than traditional manufacturing? Often but not always.

It’s a fairly new manufacturing technique. Expect rapid innovation to combat the problems we see today. In that case, 3D printing will have a greater advantage over more traditional techniques than it has now. But probably not over everything.

Sources:

3D printing and its environmental implications [Chapter 5 of The next production revolution: implications for governments and business ]/ Jermy Faludi, Natasha Cline-Thomas, and Sardui Agrawala; OECD iLibrary. May 10, 2017
Is 3D printing more sustainable than traditional manufacturing? / Galina Spasova, IDC Europe. August 5, 2020
Sustainability of 3d printing: a critical review and recommendations / Zhichao Liu et al. Proceedings of the ASME 2016 International Manufacturing Science and Engineering Conference