Energy Payback Time of a Solar Photovoltaic Powered Waste Plastic Recyclebot System/Environmental Life Cycle Analysis of Distributed Three-Dimensional Printing and Conventional Manufacturing of Polymer Products

This literature review supported: Shan Zhong, Pratiksha Rakhe and Joshua M. Pearce. Energy Payback Time of a Solar Photovoltaic Powered Waste Plastic Recyclebot System. Recycling 2017, 2(2), 10; doi: 10.3390/recycling2020010 open access

Environmental Life Cycle Analysis of Distributed Three-Dimensional Printing and Conventional Manufacturing of Polymer Products^[1][edit | edit source]

Abstract With the recent development of the RepRap, an open-source self-replicating rapid prototyper, low-cost three-dimensional (3D) printing is now a technically viable form of distributed manufacturing of polymer-based products. However, the aggregate environmental benefits of distributed manufacturing are not clear due to scale reductions and the potential for increases in embodied energy. To quantify the environmental impact of distributed manufacturing using 3D printers, a life cycle analysis was performed on three plastic products. The embodied energy and emissions from conventional large-scale production in low-labor cost countries and shipping are compared to experimental measurements on a RepRap with and without solar photovoltaic (PV) power fabricating products with acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). The results indicate that the cumulative energy demand of manufacturing polymer products can be reduced by 41–64% (55–74% with PV) and concomitant emission reductions using distributed manufacturing with existing low-cost open-source 3D printers when using <25% fill PLA. Less pronounced positive environmental results are observed with ABS, which demands higher temperatures for the print bed and extruder. Overall, the results indicate that distributed manufacturing using open-source 3D printers has the potential to have a lower environmental impact than conventional manufacturing for a variety of products.

• Naef building block, water spout, juicer.
• distributed manufactured PLA product requires less cumulative energy and create less emission than conventional manufacturing except for 100% fill, and these benefits extend with PV system.
• Because of higher heated build platform temperature for ABS, distributed manufacturing need to be combined with PV system to save more cumulative energy and emission than conventional manufacturing.
• 3-D printing can manipulate internal structure, and less fill percentage save more cumulative energy and emission.

Life cycle analysis of distributed recycling of post-consumer high density polyethylene for 3-D printing filament^[2][edit | edit source]

Abstract The growth of desktop 3-D printers is driving an interest in recycled 3-D printer filament to reduce costs of distributed production. Life cycle analysis studies were performed on the recycling of high density polyethylene into filament suitable for additive layer manufacturing with 3-D printers. The conventional centralized recycling system for high population density and low population density rural locations was compared to the proposed in home, distributed recycling system. This system would involve shredding and then producing filament with an open-source plastic extruder from post-consumer plastics and then printing the extruded filament into usable, value-added parts and products with 3-D printers such as the open-source self replicating rapid prototyper, or RepRap. The embodied energy and carbon dioxide emissions were calculated for high density polyethylene recycling using SimaPro 7.2 and the database EcoInvent v2.0. The results showed that distributed recycling uses less embodied energy than the best-case scenario used for centralized recycling. For centralized recycling in a low-density population case study involving substantial embodied energy use for transportation and collection these savings for distributed recycling were found to extend to over 80%. If the distributed process is applied to the U.S. high density polyethylene currently recycled, more than 100 million MJ of energy could be conserved per annum along with the concomitant significant reductions in greenhouse gas emissions. It is concluded that with the open-source 3-D printing network expanding rapidly the potential for widespread adoption of in-home recycling of post-consumer plastic represents a novel path to a future of distributed manufacturing appropriate for both the developed and developing world with lower environmental impacts than the current system.

• Comparisons on embodied energy and greenhouse gas emission between distributed recycling of HDPE and centralized recycling( high density population & low density population )
• Distribute recycling saves a substantial amount of energy and emits less greenhouse gas than centralized recycling in low density population area, but the advantage compared with centralized recycling in high density population area is very small.
• It will be better if elongating the period for centralized recycling in low density population area.
• Uses the SimaPro 7.2 and the database EcoInvent v2.0.

Evaluation of Potential Fair Trade Standards for an Ethical 3-D Printing Filament^[3][edit | edit source]

Abstract Following the rapid rise of distributed additive manufacturing with 3-D printing has come the technical development of filament extruders and recyclebots, which can turn both virgin polymer pellets and post-consumer shredded plastic into 3-D filament. Similar to the solutions proposed for other forms of ethical manufacturing, it is possible to consider a form of ethical 3-D printer filament distribution being developed. There is a market opportunity for producing this ethical 3-D printer filament, which is addressed in this paper by developing an "ethical product standard" for 3-D filament based upon a combination of existing fair-trade standards and technical and life cycle analysis of recycled filament production and 3-D printing manufacturing. These standards apply to businesses that can enable the economic development of waste pickers and include i) minimum pricing, ii) fair trade premium, iii) labor standards, iv) environmental and technical standards, v) health and safety standards, and vi) social standards including those that cover discrimination, harassment, freedom of association, collective bargaining and discipline.

• recycling & 3-D printing, create job opportunities, make waste pickers earn more money and make their life better.
• recycling & 3-D printing, reduce environmental impact (save raw materials, reduce transportation; need to improve thermal efficiency and reduce water use).

Exergetic life cycle assessment of a grid-connected, polycrystalline silicon photovoltaic system^[4][edit | edit source]

Abstract Purpose: Nowadays, the intensive use of natural resources in order to satisfy the increasing energy demand suggests a threat to the implementation of the principles of sustainable development. The present study attempts to approach thermodynamically the depletion of natural resources in the methodological framework and the principles of life cycle assessment (LCA). Methods: An environmental decision support tool is studied, the exergetic life cycle assessment (ELCA). It arises from the convergence of the LCA and exergy analysis (EA) methodologies and attempts to identify the exergetic parameters that are related to the life cycle of the examined system or process. The ELCA methodology, beside the fact that it locates the system parts which involve greater exergy losses, examines the depletion of natural resources (biotic and abiotic) and the sustainable prospective of the examined system or process, under the scope of exergy. In order to obtain concrete results, the ELCA methodology is applied to a large-scale, grid-connected, photovoltaic (PV) system with energy storage that is designed to entirely electrify the Greek island of Nisyros. Results and discussion: Four discerned cases were studied that reflect the present state and the future development of the PV technology. The exergy flows and balance for the life cycle of the PV system, as they were formed in the ELCA study, showed that the incoming exergy (solar radiation, energy sources, and materials) is not efficiently utilized. The greater exergy losses appear at the stage of the operation of the PV installation. Due to the fact that contribution of the renewable exergy (solar radiation) to the formation of the total incoming exergy of Life Cycle is significant, it emerges that satisfaction of electric power needs with a PV system appears to be exergetic sustainable. The increase of the Life Cycle exergetic efficiency supported by the future technological scenario in contrast to present scenarios emerges from the increased electricity output of the PV system. Consequently, the increased exergetic efficiency involves decreased irreversibility (exergy losses) of the PV system's life cycle. Conclusions: The application of ELCA in electricity production technologies exceeds the proven sustainable prospective of the PV systems; however, it aims to show the essence of the application of ELCA methodology in the environmental decision making process. ELCA can be a useful tool for the support and formation of the environmental decision making that can illustrate in terms of exergetic sustainability the examined energy system or process.

FabLabs, 3D-printing and degrowth – Democratisation and deceleration of production or a new consumptive boom producing more waste?^[5][edit | edit source]

Abstract This Stirring Paper addresses the question to what extent small-scale additive manufacturing can contribute to peer production, collaborative and open source economy. The environmental risks and chances of these technologies as well as their relation to consumerism will equally be discussed.

• FabLabs & 3-D printing, economic perspectives or a new way of producing things: decentralised production, sharing, commons and open source.

Mobile Open-Source Solar-Powered 3-D Printers for Distributed Manufacturing in Off-Grid Communities^[6][edit | edit source]

Abstract Manufacturing in areas of the developing world that lack electricity severely restricts the technical sophistication of what is produced. More than a billion people with no access to electricity still have access to some imported higher-technologies; however, these often lack customization and often appropriateness for their community. Open source appropriate tech­nology (OSAT) can over­come this challenge, but one of the key impediments to the more rapid development and distri­bution of OSAT is the lack of means of production beyond a specific technical complexity. This study designs and demonstrates the technical viability of two open-source mobile digital manufacturing facilities powered with solar photovoltaics, and capable of printing customizable OSAT in any com­munity with access to sunlight. The first, designed for com­munity use, such as in schools or maker­spaces, is semi-mobile and capable of nearly continuous 3-D printing using RepRap technology, while also powering multiple computers. The second design, which can be completely packed into a standard suitcase, allows for specialist travel from community to community to provide the ability to custom manufacture OSAT as needed, anywhere. These designs not only bring the possibility of complex manufacturing and replacement part fabrication to isolated rural communities lacking access to the electric grid, but they also offer the opportunity to leap-frog the entire conventional manufacturing supply chain, while radically reducing both the cost and the environmental impact of products for developing communities.

• two types of solar-powered 3-D printers are compared: mobile community-scale & ultra-portable scale.
• three designs were printed for testing:

1. Avocado Pit Germination Holder;
2. Cross-Tweezers;
3. Battery Terminal Separator.

And change in state of charge in percent and print time are recorded for comparing.

• Solar powered 3-D printer has the ability to complete complex manufacturing and replacement part fabrication to isolated rural communities lacking access to electric grid. But the cost should be reduced further.
• Solar powered 3-D printer also can reduce environmental impact.

Reversing the Trend of Large Scale and Centralization in Manufacturing: The Case of Distributed Manufacturing of Customizable 3-D-Printable Self-Adjustable Glasses^[7][edit | edit source]

Abstract Although the trend in manufacturing has been towards centralization to leverage economies of scale, the recent rapid technical development of open-source 3-D printers enables low-cost distributed bespoke production. This paper explores the potential advantages of a distributed manufacturing model of high-value products by investigating the application of 3-D printing to self-refraction eyeglasses. A series of parametric 3-D printable designs is developed, fabricated and tested to overcome limitations identified with mass-manufactured self-correcting eyeglasses designed for the developing world's poor. By utilizing 3-D printable self-adjustable glasses, communities not only gain access to far more diversity in product design, as the glasses can be customized for the individual, but 3-D printing also offers the potential for significant cost reductions. The results show that distributed manufacturing with open-source 3-D printing can empower developing world communities through the ability to print less expensive and customized self-adjusting eyeglasses. This offers the potential to displace both centrally manufactured conventional and self-adjusting glasses while completely eliminating the costs of the conventional optics correction experience, including those of highly-trained optometrists and ophthalmologists and their associated equipment. Although, this study only analyzed a single product, it is clear that other products would benefit from the same approach in isolated regions of the developing world.

• Distributed manufacturing using 3-D printing has potential to solve the problem that lots of products, such as glasses, are lacking in remote areas of the developing countries.
• deployed Adspecs have four challenges:

1. fragile;
2. expensive;
3. inappropriate size;
4. not look good.

• Open source 3-D printing can solve problems above by using appropriate materials and designing product by customer themselves.
• advantages: reduce costs and environmental impact and design by themselves.

Applications of Open Source 3-D Printing on Small Farms^[8][edit | edit source]

Abstract There is growing evidence that low-cost open-source 3-D printers can reduce costs by enablingdistributed manufacturing of substitutes for both specialty equipment and conventional mass-manufacturedproducts. The rate of 3-D printable designs under open licenses is growing exponentially and there arealready hundreds of designs applicable to small-scale organic farming. It has also been hypothesized thatthis technology could assist sustainable development in rural communities that rely on small-scale organicagriculture. To gauge the present utility of open-source 3-D printers in this organic farm context both inthe developed and developing world, this paper reviews the current open-source designs available andevaluates the ability of low-cost 3-D printers to be effective at reducing the economic costs of farming.This study limits the evaluation of open-source 3-D printers to only the most-developed fused filament fab-rication of the bioplastic polylactic acid (PLA). PLA is a strong biodegradable and recyclable thermoplasticappropriate for a range of representative products, which are grouped into five categories of prints: handtools, food processing, animal management, water management and hydroponics. The advantages andshortcomings of applying 3-D printing to each technology are evaluated. The results show a generalizabletechnical viability and economic benefit to adopting open-source 3-D printing for any of the technologies,although the individual economic impact is highly dependent on needs and frequency of use on a specificfarm. Capital costs of a 3-D printer may be saved from on-farm printing of a single advanced analyticalinstrument in a day or replacing hundreds of inexpensive products over a year. In order for the full potentialof open-source 3-D printing to be realized to assist organic farm economic resiliency and self-sufficiency,future work is outlined in five core areas: designs of 3-D printable objects, 3-D printing materials, 3-Dprinters, software and 3-D printable repositories.

• test several printable tools for farm using: hand tools, food processing, animal management, water management, hydroponic.
• application of 3-D printing on small farm is viable because of technical viability and economic benefit.
• future work: designs of 3-D printable objects, 3-D printing materials, 3-D printers, software and 3-D printable repositories.

Polymer recycling codes for distributed manufacturing with 3-D printers^[9][edit | edit source]

Abstrasct With the aggressive cost reductions for 3-D printing made available by the open-source self-replicating rapid prototypers (RepRaps) the economic advantage of custom distributed manufacturing has become substantial. In addition, the number of free designs is growing exponentially and the development and commercialization of the recyclebot (plastic extruders that fabricate 3-D printing filament from recycled or virgin materials) have greatly improved the material selection available for prosumer 3-D printer operators. These trends indicate that more individuals will manufacturer their own polymer products, however, there is a risk that an even larger fraction of polymer waste will not be recycled because it has not been coded. The current limited resin identification code available in the U.S. similarly restricts closing the loop on less popular polymers, which could hamper the environmental impact benefits of distributed manufacturing. This paper provides a solution for this challenge by (1) developing a recycling code model based off of the resin identification codes developed in China that is capable of expansion as more complex 3-D printing materials are introduced, (2) creating OpenSCAD scripts based on (1) to be used to print resin identification codes into products, (3) demonstrating the use of this functionality in a selection of products and polymer materials, and (4) outlining the software and policy tools necessary to make this application possible for widespread adoption. Overall the results showed that a far larger resin code identification system can be adopted in the U.S. to expand distributed recycling of polymers and manufacturing of plastic-based 3-D printed products.

• Recycling symbol makes it easier to identify and recycle plastic using these distributed methods, so it is economical and beneficial to environment.
• Embedding recycling symbol into plastic product should be mandatory.
• uses OpenSCAD to design recycling symbol.

Prototyping the Environmental Impacts of 3D Printing:
Claims and Realities of Additive Manufacturing^[10][edit | edit source]

Abstract 3D printing has the potential to become a disruptive technology by cutting down on the environmental and time costs associated with traditional manufacturing processes. For example, supply chains and product storage could essentially be eliminated if product design became entirely digital. Although 3D printing is potentially highly beneficial for the environment, awareness of 3D printing's impact on the environment is essential for healthy development and should be addressed before the technology is used on an industrial scale. The purpose of this research is to discuss the environmental aspects of additive manufacturing. By objectively examining 3D printing sustainability claims and case studies, an understanding of 3D printings' environmental effect on society will be made. The research takes an interdisciplinary approach, analyzing economic risks, carbon and ecological footprints, and how the field is currently regulated, in addition to how it may be regulated in the future. By using historical and market data, a clear understanding of the 3D printing market can be established. I will examine the various methods used to formulate the industry's environmental impacts. By examining case studies, 3D printing's environmental impact will be evaluated. Focusing on what current laws and regulations apply to 3D printing and what laws could be applied in the future, the research aims to understand how environmental costs are and should be minimized.

Distributed manufacturing with 3-D printing: a case study of recreational vehicle solar photovoltaic mounting systems^[11][edit | edit source]

Abstract For the first time, low-cost open-source 3-D printing provides the potential for distributed manufacturing at the household scale of customized, high-value, and complex products. To explore the potential of this type of ultra-distributed manufacturing, which has been shown to reduce environmental impact compared to conventional manufacturing, this paper presents a case study of a 3-D printable parametric design for recreational vehicle (RV) solar photovoltaic (PV) racking systems. The design is a four-corner mounting device with the ability to customize the tilt angle and height of the standoff. This enables performance optimization of the PV system for a given latitude, which is variable as RVs are geographically mobile. The open-source 3-D printable designs are fabricated and analyzed for print time, print electricity consumption, mechanical properties, and economic costs. The preliminary results show distributed manufacturing of the case study product results in an order of magnitude reduction in economic cost for equivalent products. In addition, these cost savings are maintained while improving the functionality of the racking system. The additional electrical output for a case study RV PV system with improved tilt angle functionality in three representative locations in the U.S. was found to be on average over 20% higher than that for conventional mass-manufactured racking systems. The preliminary results make it clear that distributed manufacturing - even at the household level - with open-source 3-D printers is technically viable and economically beneficial. Further research is needed to expand the results of this preliminary study to other types of products.

• design and fabricate Z-mounting bracket and standoff using 3-D printer, and compare 3-D printable mounting bracket with Al bracket.
• PV system in this study has a higher electrical output because mounting bracket can be designed with an optimal tilt angle.
• 3-D printing can manufacture products customizing prosumer's need, reduce cost and environmental impact.

High-Efficiency Solar-Powered 3-D Printers for Sustainable Development^[12][edit | edit source]

Abstract The release of the open source 3-D printer known as the RepRap (a self-Replicating Rapid prototyper) resulted in the potential for distributed manufacturing of products for significantly lower costs than conventional manufacturing. This development, coupled with open source-appropriate technology (OSAT), has enabled the opportunity for 3-D printers to be used for sustainable development. In this context, OSAT provides the opportunity to modify and improve the physical designs of their printers and desired digitally-shared objects. However, these 3-D printers require electricity while more than a billion people still lack electricity. To enable the utilization of RepRaps in off-grid communities, solar photovoltaic (PV)-powered mobile systems have been developed, but recent improvements in novel delta-style 3-D printer designs allows for reduced costs and improved performance. This study builds on these innovations to develop and experimentally validate a mobile solar-PV-powered delta 3-D printer system. It is designed to run the RepRap 3-D printer regardless of solar flux. The electrical system design is tested outdoors for operating conditions: (1) PV charging battery and running 3-D printer; (2) printing under low insolation; (3) battery powering the 3-D printer alone; (4) PV charging the battery only; and (5) battery fully charged with PV-powered 3-D printing. The results show the system performed as required under all conditions providing feasibility for adoption in off-grid rural communities. 3-D printers powered by affordable mobile PV solar systems have a great potential to reduce poverty through employment creation, as well as ensuring a constant supply of scarce products for isolated communities.

• "PV + battery" power the 3-D printer.
• under 5 conditions:

1. PV modules charging the battery and driving the 3-D printer.
2. System working under low insolation.
3. Battery powering the 3-D printer (no PV).
4. PV modules charging the battery only (no printing).
5. Battery fully charged and the PV modules power the 3-D printer.

• Condition(1)(2) show the current change of printer, battery, panels with time. Condition(3)(4) show the SOC change of battery with time, and SOC did not change in condition(5).
• Printer's maximum voltage variation being of less than 2.5%. And 3-D printer's voltage variation should be small.

Terms[edit | edit source]

• Life cycle analysis (LCA) is the systematic approach of looking at a product's complete life cycle, from raw materials to final disposal of the product. It offers a "cradle to grave" look at a product or process, considering environmental aspects and potential impacts.
• Embodied energy is the energy consumed by all of the processes associated with the production of a building, from the mining and processing of natural resources to manufacturing, transport and product delivery.
• SimaPro is the professional tool to collect, analyse and monitor the sustainability performance data of company's products and services. The software can be used for life cycle assessment and a variety of other applications, such as sustainability reporting, carbon and water footprinting, product design, generating environmental product declarations and determining key performance indicators.
• EcoInvent is the LCA database which contains international industrial life cycle inventory data on energy supply, resource extraction, material supply, chemicals, metals, agriculture, waste management services and transport services that can be imported easily in open LCA.
• Ethical Filament Foundation believes that there is an opportunity to create an environmentally friendly and ethically produced filament alternative to meet the needs of the rapidly growing 3D Printing market, and also believe that by doing this we could potentially open up a new market for value added products that can be produced by waste picker groups in low income countries.
• Fab lab (fabrication laboratory) is a small-scale workshop offering (personal) digital fabrication, and is generally equipped with an array of flexible computer controlled tools that cover several different length scales and various materials, with the aim to make "almost anything".
• Additive manufacturing is a procedure in which an object is formed successively from layers of material following computer model. 3-D printing is the most prominent example of it.
• OpenSCAD is a free software application for creating solid 3D CAD objects.
• Thingiverse is a website dedicated to the sharing of user-created digital design files.
• Hybrid LCA is an extended method that combines bottom-up process-sum and top-down economic input-output(EIO)methods.
• Economic input-output life-cycle assessment, or EIO-LCA involves the use of aggregate sector-level data to quantify the amount of environmental impact that can be directly attributed to each sector of the economy and how much each sector purchases from other sectors in producing its output.
• State of charge (SOC) is the equivalent of a fuel gauge for the battery pack.The units of SOC are percentage points (0% = empty; 100% = full). SOC is normally used when discussing the current state of a battery in use.
• Buck converter is a voltage step down and current step up converter.
• Start-up time is defined as the time passed between start-up and initial extrusion. During this time, the barrel must heat up and plastic remaining from previous extrusions must re-melt.
• Extrusion time is defined as the average time required to produce a meter of filament as timed with a digital watch.
• Solar cell efficiency is the ratio of the electrical output of a solar cell to the incident energy in the form of sunlight. The energy conversion efficiency of a solar cell is the percentage of the solar energy to which the cell is exposed that is converted into electrical energy.
• Energy payback time is the time it takes for a photovoltaic(PV) system to generate an amount of energy equal to that used in its production.
• Levelized cost of electricity (LCOE) represents the per-kilowatt hour cost (in real dollars) of building and operating a power plant over an assumed financial life and duty cycle.
• Grid parity refers to the lifetime generation cost of the electricity from PV being comparable with the electricity prices for conventional sources on the grid.
• grid-connected PV system is an electricity generating solar PV system that is connected to the utility grid. A grid-connected PV system consists of solar panels, one or several inverters, a power conditioning unit and grid connection equipment. They range from small residential and commercial rooftop systems to large utility-scale solar power stations.
• Sustainable development (SD) is a process for meeting human development goals while maintaining the ability of natural systems to continue to provide the natural resources and ecosystem services upon which the economy and society depend.
• charge controller, limits the rate at which electric current is added to or drawn from electric batteries. It prevents overcharging and may protect against overvoltage, which can reduce battery performance or lifespan, and may pose a safety risk. It may also prevent completely draining ("deep discharging") a battery, or perform controlled discharges, depending on the battery technology, to protect battery life.
• solid-state relay (SSR) is an electronic switching device that switches on or off when a small external voltage is applied across its control terminals. SSRs consist of a sensor which responds to an appropriate input (control signal), a solid-state electronic switching device which switches power to the load circuitry, and a coupling mechanism to enable the control signal to activate this switch without mechanical parts.

Reference[edit | edit source]