Environmental impact is an increasingly important factor for many companies and individuals, especially in light of rising political focus on climate change and carbon emissions. As companies seek to make their products more “green,” their approach to manufacturing is clearly one of the easiest and most effective ways to impact their emissions. As a relatively new method of manufacturing, there have been very few dedicated studies on how 3D printing’s direct emissions and energy usage compares to other existing manufacturing methods such as injection molding. Additive manufacturing has several specific advantages and disadvantages that are important to consider depending on the application. I will explore these arguments, to provide a qualitative overview on how green is 3D printing.
A key advantage that 3D printing has over standard manufacturing methods is that it is additive, meaning that material is added to create the product, resulting in less waste during production of each part. This is especially important for more complex parts with details that would normally have to be milled or cut away from the stock piece through traditional methods. This may seem insignificant, but drilling holes and rounding corners does produce significant waste, which extends manufacturing time and increases the amount of raw material used to produce the parts. In the case of plastics, manufacturing the material itself can be a major source of emissions, so every bit that is saved is crucial. Of course, these advantages are only applicable to specific production cases, as is any argument for or against 3D printing. For lightweight parts requiring little infill or support material, 3D printing is an obvious choice to cut back on material usage. Unlike injection molding or more robust fabrication, the user can select how much material they wish to use to control the density and weight of the part, meaning that the same object can be made effectively with about 10% of the material used in other processes. In theory, manufacturers can make decisions on part creation that can balance the interaction of part density and weight against material usage. For solid parts that need to be densely filled, however, the case for better material efficiency decreases, reducing the case for 3D printing as a “green technology.”
Power usage appears to be a bigger issue with 3D printing, especially because the process is far from the most power efficient manufacturing method, and print times tend to run long. The biggest issue is keeping the bed and hot end of the printer at the correct temperature for hours on end. Due to basic laws of thermodynamics, additive manufacturing requires a fair amount of energy to maintain necessary temperatures, which could potentially offset the advantage provided by producing less waste. This does depend, of course, on the printer and materials used. Printers without enclosures are subject to more heat loss, thus requiring more energy to maintain operating temperatures than those with insulated enclosures. Certain materials, such as nylon or metal-based filaments, also require higher bed and nozzle temperatures, while also lengthening the time to reach the necessary temperatures, especially for the bed. Another aspect to consider is the volume of objects being made. Larger size prints will obviously consume more power than smaller ones because of the extended run time. Additionally, printing multiple parts in an automated process may not be the best option, either, again due to the extended print time. However, it is far more beneficial to use an automated process that does not require re-heating between jobs.
One of the most important factors to consider in terms of overall emissions isn’t in the manufacturing process itself, but rather the shipping and transport of manufactured products. As an example, let’s consider a company shipping a product from Los Angeles, California, to Boston, Massachusetts, a distance of ~2590 miles by air or ~3015 by road. In order to ship the same load of 200,000 lbs. of product via both methods, it would take ~1618 gallons of fuel via air (at 1.6 mpg, 1 trip) or ~1277 gallons via road (at 5.9 mpg, 3 18-wheeler trucks). The burning of just one gallon of gasoline creates roughly 19.6 lbs. of CO2 emissions, so the emissions created from just transportation are quite substantial. The advantage of having an electronic file that can be distributed and manufactured on-site is that these transportation emissions are completely eliminated once the client has access to a 3D printer. This is especially important to consider for long-distance clients, as well as international ones, and the obvious, yet extreme case of clients working on manufacturing in space, such as the ISS. Of course, this solution is applicable mainly to contractors, who are not necessarily on-site to implement their products. Example industries that could take advantage of this are space travel, military, and research vessels out at sea.
3D printing has massive potential to be an important green technology, but only when used in the correct context. For many small-scale operations where 3D printing has seemed to establish its niche, the environmental impact is lessened, giving it another advantage over other traditional solutions. The numerous factors and lack of concrete research at this time make this decision tricky, but it’s important to consider the specific use of the machine and its planned application to properly evaluate how green is 3D printing.