Is there any technology trendier than 3-D printers? Applications real or planned include pizzas (prototype pizzeria printers use cartridges filled with food-like powder) and heart valves—which is convenient, because if you eat many of those printed pizzas, you’ll likely need that valve, stat.
Ease of manufacture isn’t the only perceived upside of this new technology. Because printing objects doesn’t require foundries, convection molding machines, lathes, and other adjuncts of heavy industry, the process just has to be greener, right?
Not always. According to a study by sustainable design strategist and Berkeley mechanical engineering Ph.D. candidate Jeremy Faludi, 3-D printers can exert impacts on the environment comparable to—or greater than—those of standard manufacturing. It all depends on what you’re making and the kind of printer you’re using to make it.
“We found there were a lot of assumptions about the environmental benefits of 3-D printing that simply turned out to be untrue,” says Faludi. “Transportation impacts were among them.”
Because 3-D printers extrude their products in situ, it is generally assumed they have small, dainty carbon footprints. But the size of the transportation-related carbon spoor has a lot to do with the mode of transport and the product, Faludi explains.
“Say you have something that’s cheap, plastic, and with the dimensions of an iPhone,” Faludi says. “Today’s freighters are enormous, and you can pack a tremendous number of things that size in one of them. Even though that ship is burning fuel as it transits the Pacific from China, the transportation-related carbon load for each unit is extremely small. In terms of the total environmental impact of the product, it’s infinitesimal.”
Nor is the 3-D printing process itself inherently eco-righteous. There are four basic types of 3-D printing—3D inkjet printing and three others with acronyms weirdly evocative of 1970s domestic terrorism groups: stereolithography (SLA), fused deposition modeling (FDM), selective laser sintering (SLS). All have their specific applications, and none is squeaky clean.
Take the inkjet process as an example. Actually 3-D inkjet printers aren’t really squirting ink: They’re squirting liquid polymer—plastic—which is then cured and hardened by UV light once the product is completed. Up to 40 percent of the polymer “ink” can be wasted when printing a gizmo.
“And that doesn’t even account for the support material that you sometimes need to hold a product upright while it’s being printed,” says Faludi. “That ends up as waste as well.”
Still, milling machines that make widgets by cutting them out of blocks and slabs of plastic are also wasteful—prodigiously so. Faludi acknowledges that milling machines can produce more polymer waste than 3-D printers. But printers, he emphasizes, can still have a worse impact on the environment.
“Three-D printers use a lot more power than conventional milling machines,” says Faludi. “Plus, many of the printers—particularly the inkjet printers—have to stay powered up even when they’re not in active use. The environmental impacts of all that energy consumption can be significant.”
So even if we can print out pizzas in the near future (hold the ersatz anchovies, please), there’s still no free lunch. Of course, 3-D printing won’t be stymied by environmental concerns. The technology has too many possibilities, too much buzz—too much momentum. And impacts can be minimized by identifying optimal applications, says Faludi. The best and highest use may be prototyping, not production: turning out limited runs of products to refine concept and design.
“The companies making these machines know their utilization specs, and they should be researched,” Faludi says. “One printer may be suitable for one project but not for another. And in many cases, conventional production methods might be best. You need to determine the right tool for each job.”