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Life cycle analysis of distributed recycling of post-consumer high density polyethylene for 3-D printing filament ^[1]

Abstract

The growth of desktop 3-D printer 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.

Notes

• Calculation of waste energy and material resources from not Recycling HDPE.
• Estimating the Energy use and the CO2 emission during the use of a RECYCLEBOT.
• Estimating the time required for the filament extrusion.

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.

Notes

• Explaining the benefits of recycling plastics and its difference on the environment.
• Development of tools for the same recycling process.
• Eonomic effect of this recycling technique.

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

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.

Notes

• A necessary change of Power Source in developing world.
• Introduction of mobile designs based on solar photovoltaics.

Distributed manufacturing with 3-D printing: a case study of recreational vehicle solar photovoltaic mounting systems.^[4]

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.

Polymer recycling codes for distributed manufacturing with 3-D printers.^[5]

Abstract

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.

Notes

• Resin Identification OpenSCAD codes introduced in product designing
• Need of Recycling Code models in market
• Worldwide expansion of these ideas

Distributed recycling of waste polymer into RepRap feedstock^[6]

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.

Evaluation of Potential Fair Trade Standards for an Ethical 3-D Printing Filament^[7]

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.

FabLabs, 3D-printing and degrowth – Democratisation and deceleration of production or a new consumptive boom producing more waste? ^[8]

Abstract

FabLabs are open high-tech workshops where individuals have the opportunity to develop and produce custom-made things which are not accessible by conventional industrial scale technologies . FabLabs are strongly connected to activities in social networks and the exchange of knowledge.The equipment of a FabLab typically consists of a 3D-printer, a laser cutter and a milling machine.for developing countries 3D printing holds a high potential to overcome the poor availability of spare parts, high-tech and customized objects.3 Thus the FabLab-movement affects one of the main ideas of sustainable development: balancing human welfare, fairness and participation on a global scale.

Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers ^[9]

Abstract

The recent development of open-source 3-D printers makes scaling of distributed additive-based manufacturing of high-value objects technically feasible and offers the potential for widespread proliferation of mechatronics education and participation. These self-replicating rapid prototypers (RepRaps) can manufacture approximately half of their own parts from sequential fused deposition of polymer feedstocks. RepRaps have been demonstrated for conventional prototyping and engineering, customizing scientific equipment, and appropriate technology-related manufacturing for sustainable development. However, in order for this technology to proliferate like 2-D electronic printers have, it must be economically viable for a typical household. This study reports on the life-cycle economic analysis (LCEA) of RepRap technology for an average US household. A new low-cost RepRap is described and the costs of materials and time to construct it are quantified. The economic costs of a selection of 20 open-source printable designs (representing less than 0.02% of those available), are typical of products that a household might purchase, are quantified for print time, energy, and filament consumption and compared to low and high Internet market prices for similar products without shipping costs. The results show that even making the extremely conservative assumption that the household would only use the printer to make the selected 20 products a year the avoided purchase cost savings would range from about $300 to $2000/year. Assuming the 25 h of necessary printing for the selected products is evenly distributed throughout the year these savings provide a simple payback time for the RepRap in 4 months to 2 years and provide an ROI between >200% and >40%. As both upgrades and the components that are most likely to wear out in the RepRap can be printed and thus the lifetime of the distributing manufacturing can be substantially increased the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average US household already. It appears clear that as RepRaps improve in reliability, continue to decline in cost and both the number and assumed utility of open-source designs continues growing exponentially, open-source 3-D printers will become a mass-market mechatronic device.

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

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.

Applications of Open Source 3-D Printing on Small Farms ^[11]

Abstract

There is growing evidence that low-cost open-source 3-D printers can reduce costs by enabling distributed manufacturing of substitutes for both specialty equipment and conventional mass-manufactured products. 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 that this technology could assist sustainable development in rural communities that rely on small-scale organic agriculture. To gauge the present utility of open-source 3-D printers in this organic farm context both in the developed and developing world, this paper reviews the current open-source designs available and evaluates 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 fabrication of the bioplastic polylactic acid (PLA). PLA is a strong biodegradable and recyclable thermoplastic appropriate 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 and shortcomings of applying 3-D printing to each technology are evaluated. The results show a general izabletechnical 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 specific farm. Capital costs of a 3-D printer may be saved from on-farm printing of a single advanced analytical instrument in a day or replacing hundreds of inexpensive products over a year. In order for the full potential of 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.

Environmental Life Cycle Analysis of Distributed Three-Dimensional Printing and Conventional Manufacturing of Polymer Products ^[12]

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.

The effects of PLA color on material properties of 3-D printed components ^[13]

Abstract

As the number of prosumer printers has expanded rapidly, they now make up the majority of the 3-D printer market and of these printers those in the open-source lineage of the RepRap also have expanded to dominate. Although still primarily used for prototyping or hobbyist production of low-value products, the RepRap has the capacity to be used for high-value distributed manufacturing. A recent study found that RepRap printed parts printed in realistic environmental conditions can match and even out perform commercial 3-D printers using proprietary FDM in terms of tensile strength with the same polymers. However, tensile strengths of the large sample set of RepRap prints fluctuated. In order to explain that fluctuation and better inform designers on RepRap print properties this study determines the effect of color and processing temperature on material properties of Lulzbot TAZ deposited PLA in various colors. Five colors (white, black, blue, gray, and natural) of commercially available filament processed from 4043D PLA is tested for crystallinity with XRD, tensile strength following ASTM D638 and the microstructure is evaluated with environmental scanning electron microscope. Results are presented showing a strong relationship between tensile strength and percent crystallinity of a 3-D printed sample and a strong relationship between percent crystallinity and the extruder temperature. Conclusions are drawn about the effects of color and processing temperature on the material properties of 3-D printed PLA to promote the open-source development of RepRap 3-D printing.

High-Efficiency Solar-Powered 3-D Printers for Sustainable Development ^[14]

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.

A novel approach to obviousness: An algorithm for identifying prior art concerning 3-D printing materials ^[15]

Abstract

With the development and commercialization of the recyclebot (plastic extruders that fabricate 3-D printing filament from recycled or virgin materials) and various syringe pump designs for self-replicating rapid prototypers (RepRaps), the material selection available for consumers who produce products using 3-D printers is expanding rapidly. This paper provides an open-source algorithm for identifying prior art for 3-D printing materials. Specifically this paper provides a new approach for determining obviousness in this technology area. The potential ramifications on both innovation and patent law in the 3-D printing technological space are discussed.

The case for open source appropriate technology ^[16]

Abstract

Much of the widespread poverty, environmental desecration, and waste of human life seen around the globe could be prevented by known (to humanity as a whole) technologies, many of which are simply not available to those that need it. This lack of access to critical information for sustainable development is directly responsible for a morally and ethically unacceptable level of human suffering and death. A solution to this general problem is the concept of open source appropriate technology or OSAT, which refers to technologies that provide for sustainable development while being designed in the same fashion as free and open source software. OSAT is made up of technologies that are easily and economically utilized from readily available resources by local communities to meet their needs and must meet the boundary conditions set by environmental, cultural, economic, and educational resource constraints of the local community. This paper explores both the open source and appropriate technology aspects of OSAT to create a paradigm, in which anyone can both learn how to make and use needed technologies free of intellectual property concerns. At the same time, anyone can also add to the collective open source knowledge ecosystem or knowledge commons by contributing ideas, designs, observations, experimental data, deployment logs, etc. It is argued that if OSAT continues to grow and takes hold globally creating a vibrant virtual community to share technology plans and experiences, a new technological revolution built on a dispersed network of innovators working together to create a just sustainable world is possible.

Open-source, self-replicating 3-D printer factory for small-business manufacturing ^[17]

Abstract

Additive manufacturing with 3-D printers may be a key technology enabler for entrepreneurs seeking to use disruptive innovations such as business models utilizing distributed manufacturing. Unlike centralized manufacturing, distributed manufacturing makes the parts and products (the prints) at (or closer to) the source of the demand, cutting out much of the traditional supply chain. Although many expect 3-D printing to take off at the household level and previous work has shown significant returns for those choosing to do so, there are still significant barriers to entry for typical consumers. Our analysis demonstrates that for an individual to make an abnormally high return on their investments in 3-D printers, they must serve others to achieve high utilization rates. The impetus to do so is created by a service that can undercut traditionally manufactured products due to affordability and customizability. Low-cost, open-source 3-D printers are now priced within range of individual entrepreneurs who can take advantage of the long tail of consumers with highly varied interests. The margin advantage, net present value, and return on investment (ROI) analysis provided herein could form the basis of thousands of new small-business ventures in the coming years

Combined low-cost, high-efficient inverter, peak power tracker and regulator for PV applications ^[18]

Abstract

A novel compound power converter that serves as a DC-to-AC inverter, maximum power point tracker (MPPT), and battery charger for stand-alone photovoltaic (PV) power systems is introduced. A theoretical analysis of the proposed converter is performed, and the results are compared with experimental results obtained from a 1.5 kW prototype. The overall cost of PV systems can thus be reduced by using load management control and efficiency-optimization techniques. Power flow through the converter is controlled by means of a combination of duty cycle and output frequency control. With load management, large domestic loads, such as single phase induction motors for water pumping, hold-over refrigerators, and freezers, can be driven by day at a much higher energy efficiency. This is due to the high efficiency of the inverter with high insolation, and because the inverter uses the energy directly from the solar array. The battery loss component is thus reduced.

Open-source development of solar photovoltaic technology ^[19]

Abstract

The rise of solar photovoltaic (PV) technology as a driver of rural electrification in the developing world and a contributor to climate change mitigation suggests that innovations enhancing PV efficiency and scalability could make considerable strides in reducing both poverty and greenhouse gas emissions. The nearly global access to the solar resource coupled to innovation-driven decreases in the costs of PV provides a path for a renewable energy source to accelerate sustainable development. Open-source software development has proven to produce reliable and innovative computer code at lower costs than proprietary software through sharing development responsibility with a large community of invested individuals. Concepts of open-source design have been applied to other fields in an attempt to reap the same benefits realized within software development; however, applying open-source strategies to solar PV research is uncommon. This paper reviews and examines how open-source design can be utilized to catalyze rapid innovation in the PV industry. The results show how successful open design and development methods can be created and utilized by identifying business models that provide PV researchers, turnkey suppliers and solar PV module manufacturers with the opportunity to utilize open-source design principles to accelerate innovation

Photovoltaic projects for decentralized power supply in India: A financial evaluation ^[20]

Abstract

The present study concentrates on photovoltaic (PV) projects for providing decentralized power supply in remote locations in India. Results of a techno-economic evaluation are presented. Some PV projects in the capacity range 1–110 kWp, that have either been implemented or are under implementation, have been considered. An analysis of the capital cost of the PV projects and sub-systems has been undertaken. Levelized unit cost of electricity (LUCE) has been estimated for eighteen select locations situated in different geographical regions of the country. The LUCE is found to vary in the range of Rs. 28.31–59.16/kW h (US$ 0.65–1.35/k Wh) for PV projects in the capacity range 1–25 kWp. In view of high unit cost of electricity from PV projects, need for financial incentives has been examined from the perspective of users. A sensitivity analysis has also been undertaken.

A review of the factors affecting operation and efficiency of photovoltaic based electricity generation systems ^[21]

Abstract

One of the most popular techniques of renewable energy generation is the installation of photovoltaic (PV) systems using sunlight to generate electrical power. There are many factors that affecting the operation and efficiency of the PV based electricity generation systems, such as PV cell technology, ambient conditions and selection of required equipment. There is no much study that presents all factors affecting efficiency and operation of the entire PV system, in the literature. This paper provides a detailed review of these factors and also includes suggestions for the design of more efficient systems. The presented detailed overview will be useful to people working on theory, design and/or application of photovoltaic based electricity generation systems.

Empirical investigation of the energy payback time for photovoltaic modules ^[22]

Abstract

Energy payback time is the energy analog to financial payback, defined as the time necessary for a photovoltaic panel to generate the energy equivalent to that used to produce it. This research contributes to the growing literature on net benefits of renewable energy systems by conducting an empirical investigation of as-manufactured photovoltaic modules, evaluating both established and emerging products. Crystalline silicon modules achieve an energy break-even in 3 to 4 years. At the current R&D pilot production rate (8% of capacity) the energy payback time for thin film copper indium diselenide modules is between 9 and 12 years, and in full production is ∼2 years. Over their lifetime, these solar panels generate 7 to 14 times the energy required to produce them. Energy content findings for the major materials and process steps are presented, and important implications for current research efforts and future prospects are discussed.

Life cycle assessment of photovoltaic electricity generation ^[23]

Abstract

The paper presents the results of a life cycle assessment (LCA) of the electric generation by means of photovoltaic panels. It considers mass and energy flows over the whole production process starting from silica extraction to the final panel assembling, considering the most advanced and consolidate technologies for polycrystalline silicon panel production. Some considerations about the production cycle are reported; the most critical phases are the transformation of metallic silicon into solar silicon and the panel assembling. The former process is characterised by a great electricity consumption, even if the most efficient conversion technology is considered, the latter by the use of aluminium frame and glass roofing, which are very energy-intensive materials. Moreover, the energy pay back time (EPBT) and the potential for CO2 mitigation have been evaluated, considering different geographic collocations of the photovoltaic plant with different values of solar radiation, latitude, altitude and national energetic mix for electricity production.

REFERENCES