Energy Payback Time of a Solar Photovoltaic Powered Waste Plastic Recyclebot System/Literature review

Literature Review

Dynamic Hybrid Life Cycle Assessment of Energy and Carbon of Multicrystalline Silicon Photovoltaic Systems ^[1]

Abstract This paper advances the life cycle assessment (LCA) of photovoltaic systems by expanding the boundary of the included processes using hybrid LCA and accounting for the technology-driven dynamics of embodied energy and carbon emissions. Hybrid LCA is an extended method that combines bottom-up process-sum and top-down economic input−output (EIO) methods. In 2007, the embodied energy was 4354 MJ/m2 and the energy payback time (EPBT) was 2.2 years for a multicrystalline silicon PV system under 1700 kWh/m2/yr of solar radiation. These results are higher than those of process-sum LCA by approximately 60%, indicating that processes excluded in process-sum LCA, such as transportation, are significant. Even though PV is a low-carbon technology, the difference between hybrid and process-sum results for 10% penetration of PV in the U.S. electrical grid is 0.13% of total current grid emissions. Extending LCA from the process-sum to hybrid analysis makes a significant difference. Dynamics are characterized through a retrospective analysis and future outlook for PV manufacturing from 2001 to 2011. During this decade, the embodied carbon fell substantially, from 60 g CO2/kWh in 2001 to 21 g/kWh in 2011, indicating that technological progress is realizing reductions in embodied environmental impacts as well as lower module price.

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

Distributed Recycling of Post-Consumer Plastic Waste in Rural Areas ^[2]

Abstract Although the environmental benefits of recycling plastics are well established and most geographic locations within the U.S. offer some plastic recycling, recycling rates are often low. Low recycling rates are often observed in conventional centralized recycling plants due to the challenge of collection and transportation for high-volume low-weight polymers. The recycling rates decline further when low population density, rural and relatively isolated communities are investigated because of the distance to recycling centers makes recycling difficult and both economically and energetically inefficient. The recent development of a class of open source hardware tools (e.g. RecycleBots) able to convert post-consumer plastic waste to polymer filament for 3-D printing offer a means to increase recycling rates by enabling distributed recycling. In addition, to reducing the amount of plastic disposed of in landfills, distributed recycling may also provide low-income families a means to supplement their income with domestic production of small plastic goods. This study investigates the environmental impacts of polymer recycling. A life-cycle analysis (LCA) for centralized plastic recycling is compared to the implementation of distributed recycling in rural areas. Environmental impact of both recycling scenarios is quantified in terms of energy use per unit mass of recycled plastic. A sensitivity analysis is used to determine the environmental impacts of both systems as a function of distance to recycling centers. The results of this LCA study indicate that distributed recycling of HDPE for rural regions is energetically favorable to either using virgin resin or conventional recycling processes. This study indicates that the technical progress in solar photovoltaic devices, open-source 3-D printing and polymer filament extrusion have made distributed polymer recycling and upcycling technically viable.

• Distributed recycling of HDPE using Recyclebot saves a large amount of energy than centralized recycling in rural areas.
• Distributed recycling using Recyclebot create job opportunities and increase income for low-income families.

Environmental Life Cycle Analysis of Distributed Three-Dimensional Printing and Conventional Manufacturing of Polymer Products ^[3]

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 ^[4]

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 ^[5]

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).

FabLabs, 3D-printing and degrowth – Democratisation and deceleration of production or a new consumptive boom producing more waste? ^[6]

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.

Polymer recycling codes for distributed manufacturing with 3-D printers ^[7]

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.

High-Efficiency Solar-Powered 3-D Printers for Sustainable Development ^[8]

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

• 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.

Reference