In the first part in our series on the possible role of 3D printing in a degrowth society, we explored some of the more sustainable aspects of the technology and its potential use for more sustainable production. Here we take a more realistic look at AM.

The Less Sustainable Side of 3D Printing

Less Material Waste

Though 3D printing uses less material than subtractive techniques, it still requires more material inputs than simply avoiding the production a new product item. Metal powder bed fusion (PBF) technology, one of the most widely used AM process for manufacturing end use parts, is a good example.

An aircraft bracket that was used as the subject of the EOS/Airbus study. Image courtesy of EOS.

In 2014, PBF system manufacturer EOS performed an environmental lifecycle analysis study with Airbus regarding the environmental lifecycle benefits of DMLS as compared to rapid investment casting. Compared to casting, AM used 25 percent less material, which is still significant.

More Energy Use

In the EOS/Airbus study, the research determined that, while both technologies used about the same amount of energy, AM produced 40 percent less CO2 emissions due to a 10-kilogram weight reduction in the 3D-printed part, due to optimized design geometry. The study, however, did not consider the carbon economics of scale.

Due to the low throughput of additive technologies, the amount of energy used to make a batch of parts with AM and a traditional mass manufacturing technology like injection molding may be the same, but the total number of parts that can be produced at once differs vastly. A 2008 study by Loughborough University and industry partners found that the energy it takes to make 1,000 parts using a process like injection molding would only make 100 parts with AM.

This was considered to be offset in part by the amount of weight reduction it could bring to high-emitting aircraft. The LEAP fuel nozzle 3D-printed by GE Additive and Safran is thought to reduce aircraft carbon emissions by 15 percent and NOx emissions by 50 percent.

Recycling Plastic

In an ideal scenario, we could develop a perfectly circular method of production in which disused items were recycled into feedstock for brand new parts. That is still a worthy goal to pursue, but we are currently far from it.

As discussed in the last installment, Joshua Pearce’s lab at Michigan Tech is doing outstanding work to “tightening” the loop of a circular economy. However, even if the lab’s RecycleBot system can decrease the embodied energy of plastic filament by 90 percent, the degradation that results from recycling and heating the material allows for only about five recycling cycles before the material is no longer usable.

A Gigabot X 3D printer modified with a 3D-printed hopper. Image courtesy of Michigan Tech.

The lab is attempting to improve the overall quality of recycled feedstock by replacing the use of plastic filament for direct printing of shredded, recycled plastic. Rather than shred plastic parts and then extruding the chopped pieces into new filament, the researchers modified an open source 3D printer to print using a hopper instead of a filament extruder. They then printed pellets made of recycled materials. While recycled PLA was 2.5 percent weaker in terms of tensile strength than virgin PLA, the study suggested that recycled ABS, PET and PP were on par with traditional virgin filament 3D printing.

Outside of these issues, our recycling systems have sufficient ground to cover before they are anywhere near capable of maintaining truly circular product lifecycles. In the U.S., 3D printing’s most “sustainable” plastic, PLA, is not recyclable by most industrial facilities. Worth noting is the fact that, as it is currently made, the growing of corn to produce PLA feedstock relies on low-cost fertilizers that result in nitrous oxide emissions during their manufacture. N2O is 310 times as potent as CO2 in terms of its impact on the atmosphere.

Industrial Hurdles

As exciting as it would be to achieve 100 percent closed-loop, sustainable production and implement a distributed manufacturing supply chain, we can’t rely on existing industrial actors to ensure this outcome. Some of the largest companies in the 3D printing industry are themselves heavily invested in the oil and gas, aerospace and weapons industries, all of which contribute to the greenhouse gas (GHG) emissions responsible for current climate emergency.

Less obvious is the role that the existing intellectual property regime plays in the rapid development of sustainable technologies. Michigan Tech’s Joshua Pearce pointed out in one paper:

“A series of careful scientific studies have found weak or no evidence that IP increases innovation and, in fact, often retards it. These conclusions are explained by the following inefficiencies: i) higher transaction costs for information exchange slows technical progress, ii) patenting of building block technologies holds back downstream research and development, and iii) the flexible ‘non-obvious’ requirement of patents locks away common-sense approaches to solving problems, and basic, obvious algorithms for creating innovations. Finally, many patents are not used, but only prevent others from following lines of inquiry.”

In order to execute any of the visions that Pearce’s lab is working on, a complete change in the IP regime of industrialized nations is required. Just as the open source movement allowed for a rapid deployment of new low-cost 3D printing technologies, we might expect rapid improvements related to the technologies necessary for creating a closed-loop production system.

“The Sustainable Development Index measures the ecological efficiency of human development, recognizing that development must be achieved within planetary boundaries… The SDI starts with each nation’s human development score (life expectancy, education and income) and divides it by their ecological overshoot: the extent to which consumption-based CO2 emissions and material footprint exceed per-capita shares of planetary boundaries. Countries that achieve relatively high human development while remaining within or near planetary boundaries rise to the top.” Image courtesy of the Sustainable Development Index.

This is especially true if environmental justice is to be implemented, with countries in the Global South able to pursue their own growth strategies while those in the Global North are required to shrink their production and consumption patterns. For poor nations who are not responsible for our ecological collapse to improve standards of living while maintaining a limited ecological footprint, it will be necessary that technological transfers are made at as little cost as possible, which will necessitate foregoing standard IP protections for companies and governments in the Global North.

Returning to Degrowth

The UN Intergovernmental Panel on Climate Change has given us less than 10 years to cut GHG emissions by 45 percent and less than 30 to become completely carbon neutral (without considering tipping points in the climate system). In order to meet these goals, it will be necessary not just to develop the technologies necessary to make such a transition, but to avoid assuming the eventual existence of solutions that will address all of our ecological problems. This means that, while we might like to envision a future of carbon capture technologies that will allow us to maintain our existing carbon-intensive (and globally unjust) lifestyles, we cannot rely on such solutions to address today’s problems.

With that in mind, 3D printing could be integrated into a broad sustainable manufacturing strategy in the long-term as technological obstacles are overcome, it might only play a limited role in an immediate shift to degrowth. Even the most optimistic renewable energy engineers have told this author that wealthier countries, particularly the U.S., will need to reduce the amount they produce and consume in order to mitigate ecological collapse. The world’s richest 10 percent account for half of global emissions, according to Oxfam.

At first this may seem like a form of austerity directed at the financially well-off, but degrowth advocates choose to frame this idea as a form of “radical abundance”. This is because degrowth would entail reducing labor and frivolous material consumption in favor of more leisure time to spend with one’s loved ones and community.