Energy Payback Time of a Solar Photovoltaic Powered Waste Plastic Recyclebot System/Literature review: Difference between revisions

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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.

• hybrid LCA (additive hybrid) = process-sum LCA + EIO LCA.
• Hybrid LCA expand the boundary of the included process, and find that embodied energy, carbon emission and energy payback time are higher than the results of process-sum LCA by approximately 60%.
• Technological progress reduces the environmental impacts of photovoltaic modules.

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.

Distributed recycling of waste polymer into RepRap feedstock ^[3]

Abstract

Purpose: A low‐cost, open source, self‐replicating rapid prototyper (RepRap) has been developed, which greatly expands the potential user base of rapid prototypers. The operating cost of the RepRap can be further reduced using waste polymers as feedstock. Centralized recycling of polymers is often uneconomic and energy intensive due to transportation embodied energy. The purpose of this paper is to provide a proof of concept for high‐value recycling of waste polymers at distributed creation sites.

Design/methodology/approach: Previous designs of waste plastic extruders (also known as RecycleBots) were evaluated using a weighted evaluation matrix. An updated design was completed and the description and analysis of the design is presented including component summary, testing procedures, a basic life cycle analysis and extrusion results. The filament was tested for consistency of density and diameter while quantifying electricity consumption.

Findings: Filament was successfully extruded at an average rate of 90 mm/min and used to print parts. The filament averaged 2.805 mm diameter with 87 per cent of samples between 2.540 mm and 3.081 mm. The average mass was 0.564 g/100 mm length. Energy use was 0.06 kWh/m.

Practical implications: The success of the RecycleBot further reduces RepRap operating costs, which enables distributed in‐home, value added, plastic recycling. This has implications for municipal waste management programs, as in‐home recycling could reduce cost and greenhouse gas emissions associated with waste collection and transportation, as well as the environmental impact of manufacturing custom plastic parts.

Originality/value: This paper reports on the first technical evaluation of a feedstock filament for the RepRap from waste plastic material made in a distributed recycling device.

• The extruder prototype was tested the HDPE in following metrics:(1)resultant filament consistency; (2)energy use per unit length of filament; (3)process time.
• There are 87% of filaments whose size satisfy the requirement of 3-D printer feedstock. It is necessary to make the extrusion rate more consistent.
• Constant rate is necessary to support a steady extrusion rate and high quality prints.
• reduce embodied energy, cost and greenhouse gas emissions.

Environmental Life Cycle Analysis of Distributed Three-Dimensional Printing and Conventional Manufacturing of Polymer Products ^[4]

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 ^[5]

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 ^[6]

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? ^[7]

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 ^[8]

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: Avocado Pit Germination Holder; Cross-Tweezers; 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 ^[9]

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.

Polymer recycling codes for distributed manufacturing with 3-D printers ^[10]

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 ^[11]

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.
• 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.

Reference