3D Printing – a Chance for a Sustainable Future?
04 Mai 2021
From prototype production through to ecological house building – 3D printing technology is no longer only used in industrial production. In future it will open up new opportunities for medical applications, food manufacturing and the re-use of recycled raw materials. This article looks into the fields of application for 3D printing that are gaining in significance and asks to what extent they can contribute to a more sustainable future.
Additive processes – commonly referred to as 3D printing – were first used in the 80s to make prototypes for the automotive industry. Since then, they have made constant advances in terms of quality, precision and speed. They have also become increasingly affordable, making additive manufacturing one of today’s most important technical innovations. According to a study by Learnbonds, the 3D printing market could grow from a good 16 to 40.8 billion dollars by 2024, because – due to its excellent customisation capability – 3D printing is being used in an ever more diverse range of applications. However, it would first be useful to understand the technology behind 3D printing.
How does 3D printing work?
Additive manufacturing means production of a three-dimensional object designed with the aid of a CAD program. Various processes can be used for this purpose:
- Powder-based processes: Here powder, e.g. made of plastic or metal, is chemically bonded or melted into a specified form with a laser.
- Extrusion process: In the physical extrusion process, thermoplastics are melted, extruded and deposited. In the chemical alternative, liquid substances are transformed into a solid state by a chemical reaction.
- PP process (photopolymerisation): Liquid photopolymers, that is to say light-sensitive artificial resins, are hardened one point or one layer at a time by UV light.
Areas of application
At the moment, 3D printing is mainly used for product development (rapid prototyping), production (rapid tooling), model building and medical applications. The rest of this article focuses on those areas of application in which 3D printing can contribute to positive ecological or social developments.
Recycling and circular economy
There is a wide variety of ways in which waste can be recycled with the aid of 3D printing. In Amsterdam, for example, seats for public spaces are printed using plastic waste. Wheat or coffee waste can be converted in bio-plastics and used for 3D filaments. A further exciting project is the production of bio-degradable printing resin from used cooking oil.
Flexible, decentralised production is a great benefit, especially when producing small quantities. 3D printing enables the individual production of spare parts and therefore the rapid repair of defective equipment, thereby extending its life cycle and preventing early disposal. Since the corona crisis, it has become even more important to reduce reliance on global supply chains and escape the effects of delivery bottlenecks.
Additive processes usually produce less waste material than subtractive processes, i.e. machining processes like milling or drilling. However, in the field of powder-based printing in particular, there is still a need for improvement with 50% of the input material going used. But work is in progress on solutions for powder recycling.
In future, 3D printers could also find their way into private households. Theoretically, the “open source” availability of templates on the internet already makes it possible to flexibly produce a wide variety of products at home whenever they are needed – whether a pipe wrench or a matching tie for a suit. This reduces the need for large stocks in businesses and the associated transports. It also reduces CO2 emissions. At the same time, thanks to 3D printing, the user is given infinite design options and doesn’t have to rely on conventional products or sizes. Beginner’s models of the printers are now available to consumers starting at €100.
The popularity of meat alternatives has also reached the 3D printing industry: various start-ups are working on the development of meat substitutes with the aid of additive processes, using stem cells or vegetable proteins, for example. In this way, further alternatives could be created to meat consumption, thereby reducing its ecological impact. The consumption of one kilogram of beef alone generates around 12 kilograms of CO2. The structure of a steak printed on a 3D printer could also help to further reduce meat consumption, because 3D printers can imitate the fibre structure of real meat better than existing substitute products, thereby creating an almost equivalent alternative.
Besides the production of meat substitutes, there are many other possible applications for food printing. For example, confectionery businesses can make chocolate or marzipan in unusual shapes, while fast food chains can plan the production of printed hamburgers – and the longer shelf life would reduce food waste. Furthermore, mashed food can be given an appealing shape with the aid of 3D printing and even supplemented with individual nutrients, which can be a great benefit for people with certain illnesses.
Due to its tremendous customisation capability, 3D printing enables the manufacture of precisely fitting prosthetic limbs and implants for patients. Even people in developing countries and war zones can be provided with printed prosthetic limbs thanks to the relatively low costs, short production time and independence from medical infrastructures. Furthermore, enterprises are already working on methods of producing human organs and skin using additive processes.
The way we build could also change in future. Several projects have already proved that 3D printed houses are possible. One particularly interesting aspect here is the construction method using locally available materials as demonstrated by WASP’s ecological village. Here a huge 3D printer uses a material consisting of earth, straw and water and deposits it layer by layer until a finished house is constructed. This not only saves on conventional building materials and their transportation but also cuts costs and energy consumption. This could give people in developing countries a sustainable alternative for building a house. The pilot project, which goes by the name of Shamballa, also considers the aspect of self-sufficiency, whereby household items, furniture and medical products can be printed locally.
These diverse examples of possible applications clearly illustrate the major benefits of 3D printing:
- Resource efficiency, use of recycled materials
- Decentralisation of production, less transportation and no need to rely on global supply chains
- Customisation and adaptation to needs instead of mass and over-production
- Fast, low-cost production of spare parts: repair extends product lifetimes
Despite their many benefits, new technologies, of course, always involve risks. To begin with, there is still too little regulation regarding 3D printers – so they could also be used for not entirely positive purposes. For example, printing templates for weapons have already been made openly available on the internet. Furthermore, there are fears that environmental standards could be circumvented as a result of decentralised production, which makes regulation more difficult. Although 3D printing opens up opportunities in terms of sustainability, it could also lead to negative ecological developments: on the one hand, because the simple, spontaneous production of all kinds of products could lead to wasteful consumption and further promote a “throw-away society”. On the other hand, because there will be a general increase in consumption due to the new range of products, thus fuelling a greater demand for energy and resources.
The critical point for life cycle assessment is the materials used. If ever scarcer metals or conventional plastics are used instead of biological or recycled alternatives, this will further exacerbate existing environmental issues. Nor should the direct ecological impact of 3D printing be underestimated, the main problem being the high energy requirement – with the added possibility of pollution from fine particulate matter and nano-particles. The impact strongly depends on the process used, the energy source and utilisation of the device’s capacity.
Wide-ranging options for applications and customisation as well as decentralised and cost-efficient production make 3D printing a promising future technology. However, it is important that sustainable materials are used and that the items produced have a long useful lifetime. A scenario must be prevented in which – regardless of the actual demand – new (disposable) articles are constantly being produced. This is essential if the use 3D printers is to be exploited as a means of achieving more sustainability – for enterprises as well as for every household.