Energy Consumption of Distributed Manufactured Goods
Via Tessel Renzenbrink:
"A study from Michigan Technology University shows 3D printed products require 41% to 74% less energy than large-scale manufactured goods.
Since the First Industrial Revolution manufacturing has gone through stages of increasing centralization. But with the emergence of affordable open source 3D printers the pendulum may swing back to decentralized home-based production.
Megan Kreiger and Joshua M. Pearce of Michigan Technology University did a comparative study [PDF] of energy demand and greenhouse gas emissions of centralized and distributed manufactured goods. The scope of the study is small plastic products because they are perfectly suited for 3D printed home production.
Currently, plastics are mostly mass-manufactured in low-cost labor countries and shipped across the globe. In terms of energy consumption, home-based 3D printing has the obvious advantage of avoiding international transportation costs. Another important factor is the improved material efficiency of additive manufacturing.
The conventional method to create plastic components is to inject heated thermoplastics into a mold. Injection molding leaves little room for material manipulation, the parts are always solid plastic. Kreiger and Pearce found that for most 3D prints a fill percentage of 25% or less was enough to maintain the structural integrity of the product. Moreover, 3D printing allows for creating complex forms in a single session such as moving parts and hollow structures, saving energy on drilling and assembly machinery.
To compare distributed and conventional manufacturing Kreiger and Pearce, did a Life Cycle Analysis of three products: a citrus juicer, a children’s building block and a water spout. For each product they calculated the total Cumulative Energy Demand from cradle-to-gate. The conventional LCA includes raw material extraction in the country of production, mass-production and international transportation to a warehouse in the US. The distributed LCA includes raw material extraction in the US, domestic transportation and home-based production.
The researchers also experimented with solar powered 3D printers. Here they achieved the best result, saving 74% energy compared to conventional manufacturing. For non-renewable sourced electricity the best result was 64%." (http://www.techthefuture.com/technology/3d-printing-beats-mass-production-in-energy-efficiency/)
But no ?
Melba Kurman, and Hod Lipson:
"The reality today is that the technology is not there yet. Despite the potential of additive manufacturing to promote cleaner manufacturing, 3D-printing technologies aren't yet eco-friendly. A 3D printer — no matter what sort of raw material it's working with — is an energy hog. [The 10 Best 3D Printers of 2013]
Research at Loughborough University in the United Kingdom (in a study called the Atkins Project) revealed that the 3D-printing process consumes a frightening amount of electrical energy. Researchers compared industrial-grade printers to injection molding machines. They learned that 3D printers that use heat or a laser to melt plastic consumed an estimated 50 to 100 times more electrical energy than injection molding to make an object of the same weight.
A scourge of plastics: Energy consumption during the manufacturing process aside, another not-so-ideal environmental impact of 3D printed manufacturing is its heavy reliance on plastics. Plastic is rarely good news when it comes to the environment, regardless of what sort of manufacturing technique is involved. However, odd as it may sound, injection molding (the traditional method used to manufacture plastic objects) is actually quite clean in that it leaves behind very few unused plastic pieces.
In contrast, industrial-grade-plastic 3D printers that use powdered or molten polymers leave behind a substantial amount of unused raw material in the print bed. Plastic byproduct left behind in a print job can sometimes be reused, but more typically, its material properties are corrupted and therefore no longer suitable. A glimmer of hope is offered by a corn-based printing plastic called PLA that's biodegradable (although its biodegrading process takes many years).
Secondhand fumes: It took years to prove that secondhand smoke was hazardous for your health. Recent groundbreaking research led by Brent Stephens suggests that secondhand printing fumes contain toxic byproducts given off when plastic is heated to high temperatures. For years, printing aficionados have remarked on the fact that certain 3D-printing plastics give off a nice, cozy smell, similar to burning corn kernels. To see whether the burning plastic smell was harmful to living things, Steele measured the air quality inside an air-conditioned office where five desktop 3D printers fabricated small plastic objects (using both ABS and PLA plastics) over the course of two and a half hours.
Air quality analysis revealed that 3D printers could be characterized as "high emitters" of what are known as "ultra fine particles," or UFPs. According to a report from the Heath Effects Institute (HFI), in animal and human studies, observed effects of UFPs included "lung function changes, airway inflammation, enhanced allergic responses, vascular thrombogenic effects, altered endothelial function, altered heart rate and heart rate variability, accelerated atherosclerosis, and increased markers of brain inflammation."The good news about the UFPs emitted by the few 3D printers in Steele’s study was their levels were about the same as cooking indoors. The bad news is that more research is needed on what UFPs, exactly, are emitted by home-scale plastic printers and the impact of UFP emissions in industrial-scale 3D printing environments. In the shorter term, it might be wise to not let your child leave the printer running overnight in her bedroom. And if you're printing plastic at home or in your office, open a window and use a fan to keep the air fresh.
3D printing might someday encourage a new kind of pollution: rapid garbage generation. Engineers being trained to respect their raw materials are taught "Think twice, cut once." When people get ahold of easy production tools, however, it’s easy to not heed that wise old adage. Like printing draft after draft of a term paper during its painful revision process, designers and tinkerers might find themselves rapidly printing out a series of incremental variations of a design, an environmentally costly process. [Video - 3D Printing: Doodads to Prosthetic Hands]
To unleash 3D printing's potential as a greener manufacturing technology, the key will be to create unique, greener product life cycles. Perhaps one of 3D printing's most promising environmental benefits will be the fact that computer-generated designs help improve a product's form, function, performance and durability. For example, a 3D- printed metal airplane made of computer-designed, lightweight parts would consume less fuel during its lifetime of use.
3D-printed manufacturing could also change the product life cycle by shortening global supply chains, reducing the amount of fuel that's consumed to ship products from place to place. On-the-spot 3D-printed manufacturing would also reduce the environmental costs of maintaining a climate-controlled warehouse to store inventory. Your family doctor could print out a custom hearing aid for you when you need it. Your local car mechanic could print out new parts for your car without having to order them from a supplier far, far away.
Renewable energy is key to greener manufacturing. However, most renewable energy sources today can't yet provide (at a reasonable price) the incessant, reliable stream of power needed to fuel mass-manufacturing operations.
What if small bursts of renewable energy could be applied to small bursts of manufacturing activity? Computer scientists call the transmission of electrical signals of vastly differing sizes "bursty communication." Why not a future in which "bursty energy" would be applied to "bursty 3D-printed manufacturing?"
Despite improvements in storage technologies and smart-energy grids, renewable energy may always be more prone to fits and starts than burning gas or coal. However, a 3D printer is a versatile beast and can turn on a dime, production-wise. A small manufacturing facility of the future could run several 3D printers, each making a wide variety of different products. This facility could be powered with set amounts of stored renewable energy that would fuel scheduled start-and-stop 3D-printed production runs. Someday, it would be great to see agile 3D-printing facilities that would rapidly adjust fabrication rates to the level of available renewable power, instead of the other way around.
As Earth staggers under the weight of pollution, humanity needs to better balance the health of the environment against a global consumer economy that grows larger each year. Despite its promise as a manufacturing technology, there's nothing innately green about 3D printing." (http://www.livescience.com/38323-is-3d-printing-eco-friendly.html)