Solar powered recyclebot literature review

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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


Literature Review

Novel technique for improved power conversion efficiency in PV systems with battery back-up [1]

Abstract A novel technique for the improvement of power conversion efficiencies in photovoltaic (PV) systems with battery back-up is presented and analyzed, and applications for this parallel power conversion technique (PPCT) are suggested. The PPCT may increase the available energy in an existing PV system, using a polarity changing maximum power point tracker (MPPT), or a split battery system, without adding anything to the PV system. This is accomplished by rewiring the PV system, utilizing the PPCT. The PPCT may also be used to reduce the power rating of the PV array in new PV systems with battery back-up. This PPCT is also illustrated in a compound converter and a new topology for a MPPT is described. Experimental results using this PPCT are presented.

Photovoltaics: A review of cell and module technologies [2]

Abstract This review centers on the status, and future directions of the cell and module technologies, with emphasis on the research and development aspects. The framework is established with a consideration of the historical parameters of photovoltaics and each particular technology approach. The problems and strengths of the single-crystal, polycrystalline, and amorphous technologies are discussed, compared, and assessed. Single- and multiple junction or tandem cell configurations are evaluated for performance, processing, and engineering criteria. Thin-film technologies are highlighted as emerging, low-cost options for terrestrial applications and markets. Discussions focus on the fundamental building block for the photovoltaic system, the solar cell, but important module developments and issues are cited. Future research and technology directions are examined, including issues that are considered important for the development of the specific materials, cell, and module approaches. Novel technologies and new research areas are surveyed as potential photovoltaic options of the future.

An evaluation on the life cycle of photovoltaic energy system considering production energy of off-grade silicon [3]

Abstract In this study, single-crystalline silicon (c-Si) photovoltaic (PV) cells and residential PV systems using off-grade silicon supplied from semiconductor industries were evaluated from a life cycle point of view. Energy payback time (EPT) of the residential PV system with the c-Si PV cells made of the off-grade silicon was estimated at 15.5 years and indirect CO2 emission per unit electrical output was calculated at 91 g-C/kWh even in the worst case. These figures were more than those of the polycrystalline-Si and the amorphous-Si PV cells to be used in the near future, but the EPT was shorter than its lifetime and the indirect CO2 emissions were less than the recent average CO2 emissions per kWh from the utilities in Japan. The recycling of the c-Si PV cells should be discussed for the reason of the effective use of energy and silicon material.

  • evaluate the residential PV system with the c-Si PV cells made of the off-grade silicon from EPBT and carbon dioxide emission.

Materials for solar energy conversion: An overview [4]

Abstract We introduce the radiative properties of our natural surroundings and demonstrate how the characteristic features of thermal emission, solar irradiation, atmospheric absorption, and sensitivity of the human eye and of plant photosynthesis lead naturally to a set of solar energy materials with well-defined wavelength- and angular-dependent absorptance, emittance, reflectance, and transmittance. Specific discussions are given of antireflection through microstructuring and of overheating protection through thermotropism. The paper ends with a look in the crystal ball at some possible solar materials research in the future.

  • solar energy conversion: photovoltaic energy, photothermal energy, photochemical energy, photoelectric energy.

Energy viability of photovoltaic systems [5]

Abstract The energy balance of photovoltaic (PV) energy systems is analysed in order to evaluate the energy pay-back time and the CO2 emissions of grid-connected PV systems. After an short introduction of energy analysis methodology we discuss the energy requirements for production of solar cell modules based on crystalline silicon and on thin-film technology, as well as for the manufacturing of other system components. Assuming a medium–high irradiation of 1700 kWh/m2 yr the energy pay-back time was found to be 2.5–3 yr for present-day roof-top installations and almost 4 yr for multi-megawatt, ground-mounted systems. Prospects for improvement of the energy balance of PV systems are discussed and it is found that for future PV technology (in 2020) the energy pay-back time may be less than 1.5 yr for roof-top systems and less than 2 yr for ground-mounted systems (under the same irradiation). The specific CO2 emission of the roof-top systems was calculated as 50–60 g/kWh now and possibly around 20 g/kWh in the future. This leads to the conclusion that CO2 emissions of present PV systems are considerably lower than emissions from fossil-fuel power plants, but somewhat higher than for wind and biomass energy. No significant contribution to CO2 mitigation should be expected from PV technology in the year 2010. In the longer term, however, grid-connected PV systems do have a significant potential for CO2 mitigation.

  • investigate energy requirement of PV systems and evaluate the EPBT and carbon dioxide emission of grid-connected PV system.
  • evaluate EPBT of mc-Si and a-Si PV systems on roof and ground under different radiation of 2200 kWh/m2/yr, 1700 kWh/m2/yr, 1100 kWh/m2/yr.
  • compare carbon dioxide emission for grid-connected roof-top PV system with emission for other energy systems, and nuclear, biomass, wind energy system have less emission.

Photovoltaics: technology overview [6]

Abstract Solar electricity produced by photovoltaic solar cells is one of the most promising options yet identified for sustainably providing the world's future energy requirements. Although the technology has, in the past, been based on the same silicon wafers as used in microelectronics, a transition is in progress to a second generation of a potentially much lower-cost thin-film technology. Cost reductions from both increased manufacturing volume and such improved technology are expected to continue to drive down cell prices over the coming two decades to a level where the cells can provide competitively priced electricity on a large scale. The subsidised, urban residential rooftop application of photovoltaics is expected to provide the major application of the coming decade and to provide the market growth needed to reduce prices. Large centralised solar photovoltaic power stations able to provide low-cost electricity on a large scale would become increasingly attractive approaching 2020.

The viability of solar photovoltaics [7]

Abstract This paper summarises the contributions to a special issue of Energy Policy aiming to assess the viability of solar photovoltaics (PVs) as a mainstream electricity supply technology for the 21st Century. It highlights the complex nature of such an assessment in which technical, economic, environmental, social, institutional and policy questions all play a part. The authors summarise briefly the individual contributions to the special issue and draw out a number of common themes which emerge from them, for example: the vast physical potential of PVs, the environmental and resource advantages of some PV technologies, and the fluidity of the market. Most of the authors accept that the current high costs will fall substantially in the coming decade as a result of improved technologies, increased integration into building structures and economies of scale in production. In spite of such reassurances, energy policy-makers still respond to the dilemma of PVs with some hesitancy and prefer to leave its evolution mainly in the hands of the market. This paper highlights two clear dangers inherent in this approach: firstly, that short-term cost convergence may not serve long-term sustainability goals; and secondly, that laggards in the race to develop new energy systems may find themselves faced with long-term penalties.

  • assess the viability of PV in terms of technical, economic, environmental, social, institutional and policy questions, and most of researchers accept that the current high costs of PV will fall substantially in the future.

Empirical investigation of the energy payback time for photovoltaic modules [8]

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.

Development of high efficiency hybrid PV-thermal modules [9]

Abstract A hybrid system is described that combines the features of two solar technologies-photovoltaic conversion to electricity (PV), and thermal conversion to heat (T)-into a single high efficiency PV/T module for integrated building solar energy systems. The technical approach uses TerraSolar's low cost a-Si thin film solar cell modules, based on EPV technology, integrating them into hybrid flat plate PV/T modules. Initial measurements are described that demonstrates the concept of a hybrid system that uses a transparent PV module to replace the cover glass in a glazed thermal collector.

  • photovoltaic conversion and thermal conversion use different parts of the solar spectrum.
      • SPARK: PV conversion + thermal conversion power 3-D printing.

Economic analysis of hybrid photovoltaic/thermal solar systems and comparison with standard PV modules [10]

Abstract Most of the absorbed solar radiation by solar cells is not converted into electricity it increases their temperature, reducing their electrical efficiency. The PV temperature can be lowered by heat extraction with a proper natural or forced fluid circulation. An interesting alternative to plain PV modules is to use Hybrid Photovoltaic/Thermal (PV/T) systems, which consist of PV modules coupled to heat extraction devices, providing electricity and heat simultaneously. Hybrid PV/T systems are of higher cost than standard PV modules because of the addition of the thermal unit and therefore a cost/benefit analysis is needed to find out the limits of practical use of these. A couple of typical applications are selected in order to assess the benefits for the users of hybrid PV/T systems comparing the payback time with PV systems and Solar thermal ones, under the current support schemes and conditions in Greece. A spreadsheet was developed that calculates on an hourly basis the annual energy output of the different systems. Furthermore, the energy output and the estimated system costs per surface area are introduced in an economic analysis spreadsheet, where the payback time for each system is calculated.

Recent developments in photovoltaics [11]

Abstract The photovoltaic market is booming with over 30% per annum compounded growth over the last five years. The government-subsidised urban–residential use of photovoltaics, particularly in Germany and Japan, is driving this sustained growth. Most of the solar cells being supplied to this market are ‘first generation’ devices based on crystalline or multi-crystalline silicon wafers. ‘Second generation’ thin-film solar cells based on amorphous silicon/hydrogen alloys or polycrystalline compound semiconductors are starting to appear on the market in increasing volume. Australian contributions in this area are the thin-film polycrystalline silicon-on-glass technology developed by Pacific Solar and the dye sensitised nanocrystalline titanium cells developed by Sustainable Technologies International. In these thin-film approaches, the major material cost component is usually the glass sheet onto which the film is deposited. After reviewing the present state of development of both cell and application technologies, the likely future development of photovoltaics is outlined.

  • "first generation": cells are based on crystalline or multi-crystalline silicon wafers.
  • "second generation": thin film solar cells are based on amorphous silicon/hydrogen alloys or poly-crystalline compound semiconductors.

Temperature and wind speed impact on the efficiency of PV installations. Experience obtained from outdoor measurements in Greece [12]

Abstract Although efficiency of photovoltaic (PV) modules is usually specified under standard test conditions (STC), their operation under real field conditions is of great importance for obtaining accurate prediction of their efficiency and power output. The PV conversion process, on top of the instantaneous solar radiation, depends also on the modules' temperature. Module temperature is in turn influenced by climate conditions as well as by the technical characteristics of the PV panels. Taking into consideration the extended theoretical background in the field so far, the current study is focused on the investigation of the temperature variation effect on the operation of commercial PV applications based on in-situ measurements at varying weather conditions. Particularly, one year outdoor data for two existing commercial (m-Si) PV systems operated in South Greece, i.e. an unventilated building-integrated (81 kWp) one and an open rack mounted (150 kWp) one, were collected and evaluated. The examined PV systems were equipped with back surface temperature sensors in order to determine module and ambient temperatures, while real wind speed measurements were also obtained for assessing the dominant effect of local wind speed on the PVs' thermal loss mechanisms. According to the results obtained, the efficiency (or power) temperature coefficient has been found negative, taking absolute values between 0.30%/°C and 0.45%/°C, with the lower values corresponding to the ventilated free-standing frames.

Theoretical analysis of the optimum energy band gap of semiconductors for fabrication of solar cells for applications in higher latitudes locations [13]

Abstract In this work some results of theoretical analysis on the selection of optimum band gap semiconductor absorbers for application in either single or multijunction (up to five junctions) solar cells are presented. For calculations days have been taken characterized by various insolation and ambient temperature conditions defined in the draft of the IEC 61836 standard (Performance testing and energy rating of terrestrial photovoltaic modules) as a proposal of representative set of typical outdoor conditions that may influence performance of photovoltaic devices. Besides various irradiance and ambient temperature ranges, these days additionally differ significantly regarding spectral distribution of solar radiation incident onto horizontal surface. Taking these spectra into account optimum energy band gaps and maximum achievable efficiencies of single and multijunction solar cells made have been estimated. More detailed results of analysis performed for double junction cell are presented to show the effect of deviations in band gap values on the cell efficiency.

The real environmental impacts of crystalline silicon PV modules: an analysis based on up-to-date manufacturers data [14]

Abstract Together with a number of PV companies an extensive effort has been made to collect Life Cycle Inventory data that represents the current status of production technology for crystalline silicon modules. The new data covers all processes from silicon feed-stock production to cell and module manufacturing. All commercial wafer technologies are covered, that is multi- and mono-crystalline wafers as well as ribbon technology. The presented data should be representative for the technology status in 2004, although for mono-crystalline Si crystallisation further improvement of the data quality is recommended. On the basis of the new data it is shown that PV systems on the basis of c-Si technology are in a good position to compete with other energy technologies. Energy Pay-Back Times of 1.5-2.5 yr are found for South-European locations, while life-cycle CO2 emission is in the 25-40 g/kWh range. Clear perspectives exist for further improvements with roughly 25%.

Energy pay-back time of photovoltaic energy systems: present status and prospects [15]

Abstract In this paper we investigate the energy requirements of PV modules and systems and calculate the Energy Pay-Back Time for three major PV applications. Based on a review of past energy analysis studies we explain the main sources of differences and establish a "best estimate" for key system components. For present-day c-Si modules the main source of uncertainty is the preparation of silicon feedstock from semiconductor industry scrap. Therefore a low and a high estimate are presented for energy requirement of c-Si. The low estimates of 4200 respectively 6000 MJ (primary energy) per m2 module area are probably most representative for near-future, frameless mc-Si and sc-Si modules. For a-Si thin film modules we estimate energy requirements at 1200 MJ/m2 for present technology. Present-day and future energy requirements have also been estimated for the BOS in array field systems, rooftop systems and Solar Home Systems. The Energy Pay-Back Time of present-day array field and rooftop systems is estimated at 4-8 years (under 1700 kWh/m2 irradiation) and 1.2-2.4 for future systems. In Solar Home Systems the battery is the cause for a relatively high EPBT of more than 7 years, with little prospects for future improvements.

  • investigate the energy requirements of mc-Si, sc-Si and s-Si thin film modules and their systems, and calculate the energy payback time for them.
  • energy consuming process of mc-Si and sc-Si = silicon production + silicon purification + crystallization + wafering + cell process + module assembly.
  • energy consuming process of a-Si thin film = cell material + substrate material + cell processing + overhead operations + equipment manufacture.

Performance Results and Analysis of Large Scale PV System [16]

Abstract This paper presents performance result and analysis of large scale photovoltaic system (PV) supported by general dissemination & regional energy program in government polices for renewable energy sources in Korea. The total nominal capacity of PV systems installed at sincheon sewage disposal plant (SSDP) in Daegu City is 479 kW. The one of those, to evaluate and analyze performance of early installed 80 kW PV system, PV monitoring system is constructed and monitored performance results of PV system to observe the overall effect of environmental conditions on their operation characteristics. The PV system performance has been evaluated and analyzed for component perspective (PV array and power conditioning unit) and global perspective (system efficiency, capacity factor, and electrical power energy and power quality etc.) for six month monitoring periods.

Life cycle assessment and energy pay-back time of advanced photovoltaic modules: CdTe and CIS compared to poly-Si [17]

Abstract The paper is concerned with the results of a thorough energy and life cycle assessment (LIA) of CdTe and CIS photovoltaic modules. The analysis is based on actual production data, making it one of the very first of its kind to be presented to the scientific community, and therefore especially worthy of attention as a preliminary indication of the future environmental impact that the up-scaling of thin film module production may entail. The analysis is consistent with the recommendations provided by ISO norms 14040 and updates, and makes use of an in-house developed multi-method impact assessment method named SUMMA, which includes resource demand indicators, energy efficiency indicators, and “downstream” environmental impact indicators. A comparative framework is also provided, wherein electricity produced by thin film systems such as the ones under study is set up against electricity from poly-Si systems and the average European electricity mix. Results clearly show an overall very promising picture for thin film technologies, which are found to be characterised by favourable environmental impact indicators (with special reference to CdTe systems), in spite of their still comparatively lower efficiencies.

  • Cd and CIS are compared to Poly-Si on LCA and EPBT.
  • methods for environmental impact assessment:
  1. material flow accounting = abiotic material + water material
  2. embodied energy analysis = gross energy requirement(GER) + energy payback time(EPBT)
  3. emergy synthesis (transformity)
  4. CML 2 baseline 2000 = global warming potential(GWP) + acidification potential(AP) + freshwater aquatic ecotoxicity potential(EP)
  • CdTe and CIS have better environmental and thermodynamic performance.

Reduction of the environmental impacts in crystalline silicon module manufacturing [18]

Abstract In this paper we review the most important options to reduce environmental impacts of crystalline silicon modules. We investigate which are the main barriers for implementation of the measure. Finally we review which measures to reduce environmental impacts could also lead to a cost reduction. Reduction of silicon consumption is a measure which will significantly reduce environmental impacts and at the same time has a cost reduction potential. Silicon feedstock processes with lower energy consumption such as Fluidized Bed Reactor technology, also have a large impact reduction potential. Together these two options can reduce the Energy Pay-Back Time of a PV installation (in South-Europe) to values well below 1 year. Other improvement options are identified in crystal growing and cell and module manufacturing. A number of options is likely to be implemented as soon as technological barriers are overcome because they lead to cost advantages next to environmental impact reductions. In addition there are also several environmental improvement options that are not or less clearly linked to a cost reduction. In these cases it will depend on the policy of companies or on government ruling, whether such “best available technologies” will be implemented or not.

Effective efficiency of PV modules under field conditions [19]

Abstract The conversion efficiency of photovoltaic modules varies with irradiance and temperature in a predictable fashion, and hence the effective efficiency averaged over a year under field conditions can be reliably assessed. The suggested procedure is to define the efficiency versus irradiance and temperature for a specific module, collect the local irradiance and temperature data, and combine the two mathematically, resulting in effective efficiency. Reasonable approximations simplify the process. The module performance ratio is defined to be the ratio of effective efficiency to that under standard test conditions. Variations of the order of 10% in this factor among manufacturers, primarily the result of the differences in effective series resistance and leakage conductance, are not unusual. A focus on these parameters that control the effective efficiency should provide a path to PV modules with improved field performance.

Life cycle assessment of photovoltaic electricity generation [20]

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.

Industrial symbiosis of very large-scale photovoltaic manufacturing [21]

Abstract In order to stabilize the global climate, the world's governments must make significant commitments to drastically reduce global greenhouse gas (GHG) emissions. One of the most promising methods of curbing GHG emissions is a world transition from fossil fuels to renewable sources of energy. Solar photovoltaic (PV) cells offer a technically sustainable solution to the projected enormous future energy demands. This article explores utilizing industrial symbiosis to obtain economies of scale and increased manufacturing efficiencies for solar PV cells in order for solar electricity to compete economically with fossil fuel-fired electricity. The state of PV manufacturing, the market and the effects of scale on both are reviewed. Government policies necessary to construct a multi-gigaWatt PV factory and complementary policies to protect existing solar companies are outlined and the technical requirements for a symbiotic industrial system are explored to increase the manufacturing efficiency while improving the environmental impact of PV. The results of the analysis show that an eight-factory industrial symbiotic system can be viewed as a medium-term investment by any government, which will not only obtain direct financial return, but also an improved global environment. The technical concepts and policy limitations to this approach were analyzed and it was found that symbiotic growth will help to mitigate many of the limitations of PV and is likely to catalyze mass manufacturing of PV by transparently demonstrating that large-scale PV manufacturing is technically feasible and reaches an enormous untapped market for PV with low costs.

  • large scale mass manufacturing of PV can drive down production costs and reduce environmental compact when it is with government support.

Emissions from Photovoltaic Life Cycles [22]

Abstract Photovoltaic (PV) technologies have shown remarkable progress recently in terms of annual production capacity and life cycle environmental performances, which necessitate timely updates of environmental indicators. Based on PV production data of 2004–2006, this study presents the life-cycle greenhouse gas emissions, criteria pollutant emissions, and heavy metal emissions from four types of major commercial PV systems: multicrystalline silicon, monocrystalline silicon, ribbon silicon, and thin-film cadmium telluride. Life-cycle emissions were determined by employing average electricity mixtures in Europe and the United States during the materials and module production for each PV system. Among the current vintage of PV technologies, thin-film cadmium telluride (CdTe) PV emits the least amount of harmful air emissions as it requires the least amount of energy during the module production. However, the differences in the emissions between different PV technologies are very small in comparison to the emissions from conventional energy technologies that PV could displace. As a part of prospective analysis, the effect of PV breeder was investigated. Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid.

  • greenhouse gas emission, criteria pollutant emission, heavy metal emission during PV module production.
  • multi-crystalline silicon, mono-crystalline silicon, ribbon silicon, thin-film Cd-Te are compared.
  • greenhouse gas emission & pollutant emission were estimated on electricity mixture.
  • Ecoinvent for the European grid and Franklin for the U.S. grid mix, are commonly employed for the energy and emission factors.
  • Heavy metal emission: direct emission of Cd is during the mining, smelting ,and purification of the element and synthesis of CdTe; indirect emission of Cd is due to electricity generation.
  • Though CdTe thin film has lower electrical-conversion efficiency, it has lower emission annd less energy payback time.

Air Emissions Due To Wind And Solar Power [23]

Abstract Renewables portfolio standards (RPS) encourage large-scale deployment of wind and solar electric power. Their power output varies rapidly, even when several sites are added together. In many locations, natural gas generators are the lowest cost resource available to compensate for this variability, and must ramp up and down quickly to keep the grid stable, affecting their emissions of NOx and CO2. We model a wind or solar photovoltaic plus gas system using measured 1-min time-resolved emissions and heat rate data from two types of natural gas generators, and power data from four wind plants and one solar plant. Over a wide range of renewable penetration, we find CO2 emissions achieve ∼80% of the emissions reductions expected if the power fluctuations caused no additional emissions. Using steam injection, gas generators achieve only 30−50% of expected NOx emissions reductions, and with dry control NOx emissions increase substantially. We quantify the interaction between state RPSs and NOx constraints, finding that states with substantial RPSs could see significant upward pressure on NOx permit prices, if the gas turbines we modeled are representative of the plants used to mitigate wind and solar power variability.

  • analyze the emission of carbon dioxide and nitrous oxide for wind and solar electric power with natural gas compensating for the variability of the power.
  • When turbines are quickly ramped up and down, their fuel use may be larger than when they are operated at a steady power level.
  • Carbon dioxide emission reduce a lot from a wind or solar PV plus natural gas system.
  • Nitrous oxide emissions reduction depends strongly on the type of nitrous oxide control.

Improved photovoltaic energy output for cloudy conditions with a solar tracking system [24]

Abstract This work describes measurements of the solar irradiance made during cloudy periods in order to improve the amount of solar energy captured during such periods. It is well-known that 2-axis tracking, in which solar modules are pointed at the sun, improves the overall capture of solar energy by a given area of modules by 30–50% versus modules with a fixed tilt. On sunny days the direct sunshine accounts for up to 90% of the total solar energy, with the other 10% from diffuse (scattered) solar energy. However, during overcast conditions nearly all of the solar irradiance is diffuse radiation that is isotropically-distributed over the whole sky. An analysis of our data shows that during overcast conditions, tilting a solar module or sensor away from the zenith reduces the irradiance relative to a horizontal configuration, in which the sensor or module is pointed toward the zenith (horizontal module tilt), and thus receives the highest amount of this isotropically-distributed sky radiation. This observation led to an improved tracking algorithm in which a solar array would track the sun during cloud-free periods using 2-axis tracking, when the solar disk is visible, but go to a horizontal configuration when the sky becomes overcast. During cloudy periods we show that a horizontal module orientation increases the solar energy capture by nearly 50% compared to 2-axis solar tracking during the same period. Improving the harvesting of solar energy on cloudy days is important to using solar energy on a daily basis for fueling fuel-cell electric vehicles or charging extended-range electric vehicles because it improves the energy capture on the days with the lowest hydrogen generation, which in turn reduces the system size and cost.

LCA of renewable energy for electricity generation systems—A review [25]

Abstract Sustainable development requires methods and tools to measure and compare the environmental impacts of human activities for various products (goods and services). Providing society with goods and services contributes to a wide range of environmental impacts. Environmental impacts include emissions into the environment and the consumption of resources as well as other interventions such as land use, etc. Life cycle assessment (LCA) is a technique for assessing environmental loads of a product or a system. The aim of this paper is to review existing energy and CO2 life cycle analyses of renewable sources based electricity generation systems. The paper points out that carbon emission from renewable energy (RE) systems are not nil, as is generally assumed while evaluating carbon credits. Further the range of carbon emissions from RE systems have been found out from existing literature and compared with those from fossil fuel based systems, so as to assist in a rational choice of energy supply systems.

  • investigate some renewable electricity generation systems, such as wind, solar PV, biomass, solar thermal, hydro, and find out that hydro has the least carbon dioxide emission while the emission of solar PV is significant.

Dynamic Hybrid Life Cycle Assessment of Energy and Carbon of Multicrystalline Silicon Photovoltaic Systems [26]

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.

3-D Printing of Open Source Appropriate Technologies for Self-Directed Sustainable Development [27]

Abstract The technological evolution of the 3-D printer, widespread internet access and inexpensive computing has made a new means of open design capable of accelerating self-directed sustainable development. This study critically examines how open source 3-D printers, such as the RepRap and Fab@home, enable the use of designs in the public domain to fabricate open source appropriate technology (OSAT), which are easily and economically made from readily available resources by local communities to meet their needs. The current capabilities of open source 3-D printers is reviewed and a new classification scheme is proposed for OSATs that are technically feasible and economically viable for production. Then, a methodology for quantifying the properties of printed parts and a research trajectory is outlined to extend the existing technology to provide complete village-level fabrication of OSATs. Finally, conclusions are drawn on the potential for open source 3-D printers to assist in driving sustainable development.

  • review the present capabilities of the RepRap and the Rab@home with focus on their applicability on sustainable development.
  • key barriers need to be overcome:
  1. development of locally available materials for printing.
  2. the size of printed object and print speed need to be increased.
  3. an increased and improved material selection for 3-D printing is necessary.
  4. the development of a solar powered 3-D printer/computer for deployment in rural developing communities.

Life cycle assessment of solar PV based electricity generation systems: A review [28]

Abstract Sustainable development requires methods and tools to measure and compare the environmental impacts of human activities for various products viz. goods, services, etc. This paper presents a review of life cycle assessment (LCA) of solar PV based electricity generation systems. Mass and energy flow over the complete production process starting from silica extraction to the final panel assembling has been considered. Life cycle assessment of amorphous, mono-crystalline, poly-crystalline and most advanced and consolidate technologies for the solar panel production has been studied.

  • steps for fabrication of PV module = purification of silicon + growing silicon + silicon wafer to silicon solar cells + assembling module.
  • year, location, efficiency, power rating, life time, EPBT, GHG emission should be considered.

A review of solar photovoltaic technologies [29]

Abstract Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8 × 1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed.

  • light absorbing material: silicon(a-Si & c-Si), CdTe & CdS, organic and polymer cells, hybrid photovoltaic cells, thin film cells, others.
  • application: building integrated system, desalination plant, space, solar home system, pumps, PVT collector, others.

A review of the factors affecting operation and efficiency of photovoltaic based electricity generation systems [30]

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.

  • summary all factors affecting the efficiency and operation of the entire PV system.
  • factors: PV technology types, ambient conditions, system equipment(battery and charge control, inverters), power quality.

Solar photovoltaic electricity: Current status and future prospects [31]

Abstract We review the technical progress made in the past several years in the area of mono- and polycrystalline thin-film photovoltaic (PV) technologies based on Si, III–V, II–VI, and I–III–VI2 semiconductors, as well as nano-PV. PV electricity is one of the best options for sustainable future energy requirements of the world. At present, the PV market is growing rapidly at an annual rate of 35–40%, with PV production around 10.66 GW in 2009. Si and GaAs monocrystalline solar cell efficiencies are very close to the theoretically predicted maximum values. Mono- and polycrystalline wafer Si solar cells remain the predominant PV technology with module production cost around $1.50 per peak watt. Thin-film PV was developed as a means of substantially reducing the cost of solar cells. Remarkable progress has been achieved in this field in recent years. CdTe and Cu(In,Ga)Se2 thin-film solar cells demonstrated record efficiencies of 16.5% and almost 20%, respectively. These values are the highest achieved for thin-film solar cells. Production cost of CdTe thin-film modules is presently around $0.76 per peak watt.

Increasing the solar photovoltaic energy capture on sunny and cloudy days [32]

Abstract This report analyzes an extensive set of measurements of the solar irradiance made using four identical solar arrays and associated solar sensors (collectively referred to as solar collectors) with different tilt angles relative to the earth’s surface, and thus the position of the sun, in order to determine an optimal tracking algorithm for capturing solar radiation. The study included a variety of ambient conditions including different seasons and both cloudy and cloud-free conditions. One set of solar collectors was always approximately pointed directly toward the sun (DTS) for a period around solar noon. These solar collectors thus captured the direct beam component of the solar radiation that predominates on sunny days. We found that on sunny days, solar collectors with a DTS configuration captured more solar energy in accordance with the well-known cosine dependence for the response of a flat-surfaced solar collector to the angle of incidence with direct beam radiation. In particular, a DTS orientation was found to capture up to twice as much solar energy as a horizontal (H) orientation in which the array is tilted toward the zenith. Another set of solar collectors always had an H orientation, and this best captured the diffuse component of the solar radiation that predominates on cloudy days. The dependence of the H/DTS ratio on the solar-collector tilt angle was in approximate agreement with the Isotropic Diffuse Model derived for heavily overcast conditions. During cloudy periods, we found that an H configuration increased the solar energy capture by nearly 40% compared to a DTS configuration during the same period, and we estimate the solar energy increase of an H configuration over a system that tracks the obscured solar disk could reach 50% over a whole heavily-overcast day. On an annual basis the increase is predicted to be much less, typically only about 1%, because the contribution of cloudy days to the total annual solar energy captured by a photovoltaic system is small. These results are consistent with the solar tracking algorithm optimized for cloudy conditions that we proposed in an earlier report and that was based on a much smaller data set. Improving the harvesting of solar energy on cloudy days deserves wider attention due to increasing efforts to utilize renewable solar energy. In particular, increasing the output of distributed solar power systems on cloudy days is important to developing solar-powered home fueling and charging systems for hydrogen-powered fuel-cell electric and battery-powered vehicles, respectively, because it reduces the system size and cost for solar power systems that are designed to have sufficient energy output on the worst (cloudy) days.

Review of photovoltaic technologies [33]

Abstract This paper is a full review on the development of existing photovoltaic (PV) technology. It highlights the four major current types of PV: crystalline, thin film, compound and nanotechnology. The aim of continuous development of PV technology is not only to improve the efficiency of the cells but also to reduce production cost of the modules, hence make it more feasible for various applications. Moreover, such variety in technology is needed to enhance the deployment of solar energy for a greener and cleaner environment. Devices such as space PV cell technology were also described and the progress in this field is expanding. In addition, a quick overview of the application of PV installations is described.

A review of solar photovoltaic levelized cost of electricity [34]

Abstract As the solar photovoltaic (PV) matures, the economic feasibility of PV projects is increasingly being evaluated using the levelized cost of electricity (LCOE) generation in order to be compared to other electricity generation technologies. Unfortunately, there is lack of clarity of reporting assumptions, justifications and degree of completeness in LCOE calculations, which produces widely varying and contradictory results. This paper reviews the methodology of properly calculating the LCOE for solar PV, correcting the misconceptions made in the assumptions found throughout the literature. Then a template is provided for better reporting of LCOE results for PV needed to influence policy mandates or make invest decisions. A numerical example is provided with variable ranges to test sensitivity, allowing for conclusions to be drawn on the most important variables. Grid parity is considered when the LCOE of solar PV is comparable with grid electrical prices of conventional technologies and is the industry target for cost-effectiveness. Given the state of the art in the technology and favourable financing terms it is clear that PV has already obtained grid parity in specific locations and as installed costs continue to decline, grid electricity prices continue to escalate, and industry experience increases, PV will become an increasingly economically advantageous source of electricity over expanding geographical regions.

  • review the methodology of calculating the cost of electricity for PV.
  • As grid electricity prices continue to escalate and installed costs of PV continue to decline, PV has great potential.
  • A lower degradation rate means more energy output and thus a lower LCOE.

A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors [35]

Abstract 3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes (‘rapid prototyping’) before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term ‘carbomorph’ and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes.

Distributed Recycling of Post-Consumer Plastic Waste in Rural Areas [36]

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 [37]


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 [38]

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 [39]

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 [40]

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 [41]

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? [42]

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 [43]

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 [44]

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 [45]

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 [46]

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 [47]

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 [48]

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 [49]

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.


  • 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.


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