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
MOST group articles on waste plastic extrusion[edit | edit source]
- Dennis J. Byard, Aubrey L. Woern, Robert B. Oakley, Matthew J. Fiedler, Samantha L. Snabes, and Joshua M. Pearce. Green Fab Lab Applications of Large-Area Waste Polymer-based Additive Manufacturing. Additive Manufacturing 27, (2019), pp. 515-525. https://doi.org/10.1016/j.addma.2019.03.006 open access
- David Shonnard, Emily Tipaldo, Vicki Thompson, Joshua Pearce, Gerard Caneba, Robert Handler. Systems Analysis for PET and Olefin Polymers in a Circular Economy. 26th CIRP Life Cycle Engineering Conference. Procedia CIRP 80, (2019), 602-606. https://doi.org/10.1016/j.procir.2019.01.072 open access
- Aubrey L. Woern, Joseph R. McCaslin, Adam M. Pringle, and Joshua M. Pearce. RepRapable Recyclebot: Open Source 3-D Printable Extruder for Converting Plastic to 3-D Printing Filament. HardwareX 4C (2018) e00026 doi: https://doi.org/10.1016/j.ohx.2018.e00026 open access
- Aubrey L. Woern and Joshua M. Pearce. 3-D Printable Polymer Pelletizer Chopper for Fused Granular Fabrication-Based Additive Manufacturing. Inventions 2018, 3(4), 78; https://doi.org/10.3390/inventions3040078 open access
- Woern, A.L.; Byard, D.J.; Oakley, R.B.; Fiedler, M.J.; Snabes, S.L.; Pearce, J.M. Fused Particle Fabrication 3-D Printing: Recycled Materials' Optimization and Mechanical Properties. Materials 2018, 11, 1413. doi: https://doi.org/10.3390/ma11081413 open access
- Adam M. Pringle, Mark Rudnicki, and Joshua Pearce (2017) Wood Furniture Waste-Based Recycled 3-D Printing Filament. Forest Products Journal 2018, Vol. 68, No. 1, pp. 86-95. https://doi.org/10.13073/FPJ-D-17-00042 open access
- Debbie L. King, Adegboyega Babasola, Joseph Rozario, and Joshua M. Pearce, "Mobile Open-Source Solar-Powered 3-D Printers for Distributed Manufacturing in Off-Grid Communities," Challenges in Sustainability 2(1), 18-27 (2014). open access
- Shan Zhong & Joshua M. Pearce. Tightening the loop on the circular economy: Coupled distributed recycling and manufacturing with recyclebot and RepRap 3-D printing,Resources, Conservation and Recycling 128, (2018), pp. 48–58. doi: 10.1016/j.resconrec.2017.09.023 open access
- M.A. Kreiger, M.L. Mulder, A.G. Glover, J. M. Pearce, Life Cycle Analysis of Distributed Recycling of Post-consumer High Density Polyethylene for 3-D Printing Filament, Journal of Cleaner Production, 70, pp. 90–96 (2014). DOI:http://dx.doi.org/10.1016/j.jclepro.2014.02.009. open access
- 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
- Feeley, S. R., Wijnen, B., & Pearce, J. M. (2014). Evaluation of Potential Fair Trade Standards for an Ethical 3-D Printing Filament. Journal of Sustainable Development, 7(5), 1-12. DOI: 10.5539/jsd.v7n5p1 open access
- M. Kreiger, G. C. Anzalone, M. L. Mulder, A. Glover and J. M Pearce (2013). Distributed Recycling of Post-Consumer Plastic Waste in Rural Areas. MRS Online Proceedings Library, 1492, mrsf12-1492-g04-06 doi:10.1557/opl.2013.258. open access
- Christian Baechler, Matthew DeVuono, and Joshua M. Pearce, "Distributed Recycling of Waste Polymer into RepRap Feedstock" Rapid Prototyping Journal, 19(2), pp. 118-125 (2013). open access
Literature Review[edit | edit source]
Novel technique for improved power conversion efficiency in PV systems with battery back-up[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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:
- material flow accounting = abiotic material + water material
- embodied energy analysis = gross energy requirement(GER) + energy payback time(EPBT)
- emergy synthesis (transformity)
- 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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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[edit | edit source]
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.
- ↑ Snyman, Danie B., and Johan HR Enslin. "Novel technique for improved power conversion efficiency in PV systems with battery back-up." In Telecommunications Energy Conference, 1991. INTELEC'91., 13th International, pp. 86-91. IEEE, 1991.
- ↑ Kazmerski, Lawrence L. "Photovoltaics: a review of cell and module technologies." Renewable and sustainable energy reviews 1, no. 1 (1997): 71-170.
- ↑ Kato, Kazuhiko, Akinobu Murata, and Koichi Sakuta. "An evaluation on the life cycle of photovoltaic energy system considering production energy of off-grade silicon." Solar Energy Materials and Solar Cells 47, no. 1 (1997): 95-100.
- ↑ Granqvist, Claes G., and Volker Wittwer. "Materials for solar energy conversion: An overview." Solar Energy Materials and solar cells 54, no. 1 (1998): 39-48.
- ↑ Alsema, Erik A., and E. Nieuwlaar. "Energy viability of photovoltaic systems." Energy policy 28, no. 14 (2000): 999-1010.
- ↑ Green, Martin A. "Photovoltaics: technology overview." Energy Policy 28, no. 14 (2000): 989-998.
- ↑ Jackson, Tim, and Mark Oliver. "The viability of solar photovoltaics." Energy policy 28, no. 14 (2000): 983-988.
- ↑ Knapp, K., and T. Jester. "Empirical investigation of the energy payback time for photovoltaic modules." Solar Energy 71, no. 3 (2001): 165-172.
- ↑ Staebler, David L., Natko B. Urli, and Zoltan J. Kiss. "Development of high efficiency hybrid PV-thermal modules." In Photovoltaic Specialists Conference, 2002. Conference Record of the Twenty-Ninth IEEE, pp. 1660-1663. IEEE, 2002.
- ↑ Tselepis, S., and Y. Tripanagnostopoulos. "Economic analysis of hybrid photovoltaic/thermal solar systems and comparison with standard PV modules." In Proceedings of the international conference PV in Europe, pp. 7-11. 2002.
- ↑ Green, M. A. "Recent developments in photovoltaics." Solar energy 76, no. 1 (2004): 3-8.
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