Abstract

End-of-life management of copper indium gallium selenide (CIGS) thin-film solar photovoltaics (PV) panels is crucial due to the necessity of recycling valuable elements such as indium ($400/kg) and gallium ($618/kg), ensuring both economic viability and environmental sustainability. In this study, we analyze the private and external costs of end-of-life management for CIGS PV designed for mass-scale recycling. Our findings reveal that the private and external costs of end-of-life management range from ∼$3.5 to $4.5 and ∼$3.0 to $4.0 per m2, respectively. The chemicals utilized in the recycling process, particularly NaOH and HCl, significantly contribute to climate change, photochemical oxidant formation, particulate matter formation, and freshwater eutrophication impact categories, accounting for ∼50 % to 90 % of the impacts. Furthermore, we found the net cost of recycling by subtracting the economic benefit obtained from recovered materials from the sum of private and external costs, revealing values ranging between $4.3 and $5.7 per m2 of CIGS PV module. These findings suggest that there is room to reduce the net cost further by recovering more materials from the CIGS PV modules components.

Abstract 

Perovskite/silicon tandem solar cells (PSTs) have emerged as promising photovoltaic (PV) technology that can exceed the theoretical power conversion efficiency limit of single-junction solar cells. To determine the future potential benefits of PSTs, it is crucial to accurately assess their environmental impacts and recyclability. Here, we present the first complete life cycle toxicity assessment of the PST panels. For this, we evaluated the toxicity of material procurement, manufacturing, and use stages and compared them with the toxicity of crystalline silicon PVs and CdTe PVs, as well as other electricity sources. For the end-of-life (EoL) stage, we developed three variants of panel recycling processes and compared their toxicity impacts with those of procuring the materials required to manufacture a new panel. We found that the life cycle toxicity of PV sin general is mainly driven by metal emissions. PSTs in particular emit more metals (and these are more toxic) than other PVs, but less than conventional sources of energy. A lower silver content─or more sustainable silver procurement─would be the first step toward making PSTs more environmentally sustainable. Concerning the EoL analysis, all proposed variants are less impactful than materials procured from the market. Their largest benefits can be found in the recovery of the bottom glass and crystalline silicon subcell, the copper cables, and the top glass. 

Abstract

Perovskite solar cells (PSCs) hold significant promise over other photovoltaic (PV) technologies for meeting future energy demands. For PSCs to become a sustainable PV technology capable of replacing conventional PV systems, evaluating their end-of-life environmental impact is crucial. This study evaluates and compares the environmental impacts of five recently developed recycling approaches for PSCs using life cycle carbon analysis (LCCA). Our results indicate that the environmental impacts of a novel recycling approach using potassium iodide (KI) solution are significantly lower, while processes involving dimethylformamide (DMF) and butyl-amine (BA) have higher impacts. The findings of this study will help identify environmentally friendly recycling options feasible for industry-scale implementation. 

Abstract

Land use competition between agricultural activities and ground-mounted solar photovoltaic (PV) deployment has increased worldwide attention to hybrid agriculture, and PV systems known as agrivoltaic systems (AVS) in efforts to increase the efficiency of energy and food production and minimize the land use competition. However, little is known about AVS's economic feasibility and environmental tradeoffs. Here we aim to evaluate the techno-economic and environmental impacts of four AVS configurations (full density, half density, mono-axial tracking, and bi-axial tracking) and compare their performance against PV-only systems. We used the life cycle revenue generated from a hectare of land area ($/ha) as a functional unit of our analysis. We found that all AVS configurations outperformed PV-only systems in the economic feasibility assessment, where bi-axial tracking was the best-performing AVS. Further, we developed a case scenario for agricultural farmers to determine the minimum selling price of electricity required for AVS to compete with the economic performance of crop-only farms. We found that the AVS designs require additional incentives (2¢ - 6¢ per kWh of electricity generation) to be as competitive as the crop-only farms. The life cycle environmental assessment demonstrated that the AVS has better environmental performance than PV-only systems, with ∼15–55 % less environmental impacts per functional unit. On average, electricity generation accounts for ∼80 % of AVS environmental impacts, while food production and water demand account for ∼20 %. Additionally, a sensitivity analysis conducted on various uncertain parameters, such as crop yield, water demand, electricity selling price, crop selling prices, discount, and inflation rates, while varying these parameters across broader ranges, indicates that AVS designs become a more economically and environmentally sustainable alternative over PV-only systems in the majority (>66 %) of the data analyzed. 

Abstract

Perovskite solar cells (PSCs) have emerged as a promising option for solar energy generation. However, it is essential to consider the environmental impact of these innovative photovoltaic (PV) technologies as the industry moves towards commercialization. Researchers are currently exploring ways to recycle PSCs to recover valuable materials and reduce their environmental impact at the end of their life. To ensure the sustainability of PSCs, this study evaluates and compares the environmental impacts of five recently developed recycling approaches. The Tool for Reduction and Assessment of Chemicals (TRACI) method was utilized to measure environmental impacts in categories such as acidification (kg SO2-eq.), ecotoxicity (CTUe), eutrophication (kg Neq), GWP (kg CO2-eq), human toxicity (CTUh), cancer and non-cancer, human health particular air (kg PM2.5-eq), ozone depletion (kg CFC11eq), and smog (kg O3-eq). The results indicate a novel recycling approach using potassium iodide (KI) solution has lower environmental impacts. In contrast, processes involving butyl-amine (BA), chlorobenzene, and dimethylformamide (DMF) have significantly higher environmental impacts arising from 1 to 3 times higher than the reference method, except for ozone depletion, ~7 to 10 times higher than the reference. 

Abstract

While perovskite solar cells (PSC) have a high potential of achieving commercial-scale manufacturing, they still face some deficiencies regarding rapid degradation in the presence of moisture, oxygen, and high-temperature exposure. To address these challenges, recent research has identified lower dimensional (LD) materials as promising candidates to improve the stability and power conversion efficiency (PCE) of PCSs. The goal of this study is to analyze the environmental performance of LD material-based PSCs (ld-PSC) through a comprehensive life cycle assessment, comparing their environmental performance with reference PSC and commercial photovoltaics (PV) technologies including single-crystalline (c-Si), copper indium gallium diselenide (CIGS) and cadmium telluride (CdTe). To achieve this objective, we evaluated five LD materials such as graphene, reduced graphene oxide (rGO), graphene quantum dots (GQDs), molybdenum disulfide (MoS2), and black phosphorus (BP) that are commonly studied in experimental works, and two alternative (Alt) ld-PSC configurations such as Alt-1 and Alt-2, featuring LD materials with lower environmental and comparatively higher among those studied. A comparison of LD materials on a unit mass basis reveals that rGO, graphene, and MoS2 are the most environmentally friendly options. However, their environmental impact changes significantly when incorporated into ld-PSC configurations based on the type and amount of chemicals used for the dispersion which emphasizes the importance of carefully selecting the chemicals used for dispersion. Our results show that the Alt-1 configuration is ∼25% lower and the Alt-2 configuration has ∼15% higher average environmental impacts compared to reference PSCs. Further analyses show that at 20% benchmark PCE, ld-PSC has the potential to outperform the environmental performance of all conventional technologies, even with a lifetime up to 2.5 times shorter. Additionally, ld-PSC has a faster energy payback period compared to commercial PV technologies. 

Abstract

The intensification of agricultural practices in agroecosystems in the US since the 1950s has led to increased environmental impacts and greenhouse gas emissions. To address these concerns, global policies such as the United Nations Sustainable Development Goals (SDGs) are calling for Nature-based Climate Solutions that balance climate change mitigation with resource protection, sustainable energy transitions, and food security. Policymakers must therefore evaluate agroecosystems from both an anthropogenic and ecological perspective, leading to initiatives such as Natural Working Lands by the US Climate Alliance. However, climate mitigation may also have adverse effects, underscoring the importance of considering land management alongside indirect resource use and consumption and biophysical feedbacks. This chapter proposes linking geospatial land cover land use change (LCLUC) approaches with life cycle assessment (LCA) by land cover type. While environmental and climate data are available at higher spatiotemporal resolutions, reliable records of land management are limited to coarse resolution surveys conducted every 5 years and aggregated to state or county-level extents. To overcome this limitation, this work evaluates the intensity rates and ecological processes of cropland management within a 1 km extent and compares emissions scenarios from select inputs to predictions of land cover and carbon stock, testing a carbon offset approach. The results indicate that upstream processes have similar or larger emissions than onsite resource consumption. With land cover change prediction, it is found that carbon stocks may slightly decline by 2050, the year by which the SDGs aim for carbon neutrality. This study demonstrates the capacity to spatialize LCA with a functional unit of square area land managed and discusses aggregating socioecological processes for policymakers. 

Abstract

The transportation industry has led efforts to fight climate change and reduce air pollution. Autonomous electric vehicles (A-EVs) that use artificial intelligence, next-generation batteries, etc., are predicted to replace conventional internal combustion engine vehicles (ICEVs) and electric vehicles (EVs) in the coming years. In this study, we performed a life cycle assessment to analyze A-EVs and compare their impacts with those from EV and ICEV systems. The scope of the analysis consists of the manufacturing and use phases, and a functional unit of 150,000 miles·passenger was chosen for the assessment. Our results on the impacts from the manufacturing phase of the analyzed systems show that the A-EV systems have higher impacts than other transportation systems in the majority of the impacts categories analyzed (e.g., global warming potential, ozone depletion, human toxicity-cancer) and, on average, EV systems were found to be the slightly more environmentally friendly than ICEV systems. The high impacts in A-EV are due to additional components such as cameras, sonar, and radar. In comparing the impacts from the use phase, we also analyzed the impact of automation and found that the use phase impacts of A-EVs outperform EV and ICEV in many aspects, including global warming potential, acidification, and smog formation. To interpret the results better, we also investigated the impacts of electricity grids on the use phase impact of alternative transportation options for three representative countries with different combinations of renewable and conventional primary energy resources such as hydroelectric, nuclear, and coal. The results revealed that A-EVs used in regions that have hydropower-based electric mix become the most environmentally friendly transportation option than others. 

Abstract

A novel recycling method utilizing aqueous iodide solutions has shown promise at selectively dissolving lead perovskite and preserving the glass substrate of lead perovskite solar cells (PSCs). Perovskite compounds are notorious for degrading upon contact with moisture into lead iodide which can be capitalized upon for recycling. When iodide ions reach a critical concentration in aqueous solutions, the solubility of lead iodide begins to rapidly increase as several complex ions are formed. Iodide solutions selectively interact with the perovskite material which dissolves from the edge inwards, allowing for exfoliation of the back contact and retention of the glass substrate and electron transport layer. PbI2 solubility studies using KI, HI, and NH4I were conducted to determine an effective iodide source to develop a scalable recycling process. Retaining the coated glass substrate intact preserves the possibility to manufacture new solar cells from the same materials, by also omitting the use of organic solvents the costs as well as the human and environmental hazards of recycling PSCs can be minimized. 

Abstract

Perovskite photovoltaic (PV) cells have created a significant interest over the last few years due to their low-cost and high-power conversion efficiencies. While perovskite PVs are still under development, we analyze cost of alternative sustainable end-of-life management for perovskite PV cells; this allows to reuse economically valuable materials and prevent environmental contamination. Here, we studied the life cycle cost assessment of recovering metals such as lead, aluminum, gold, nickel, and silver and other valuable materials such as glass from waste perovskite PVs. We also developed a recycling scheme to optimize the material recovery and determine the economically feasible ways to separate the cells layer-by-layer. We assessed the cost and the net cost of the perovskite PV recycling processes. We found that the most feasible recycling technique’ cost is $10.70 and its net cost is $− 2.95 per 1 m2 module. These values could be further improved by optimizing and reusing chemicals involved in process. These results indicate that the cost of perovskite PV recycling is economically feasible and there is potentional to gain benefit from sustainable end-of-life management of perovskite PVs. 

Abstract

Integrated solar flow batteries (SFBs) are developed from a novel technology combining the functions of electricity generation and storage in one integrated device. Despite being in their infancy, their high efficiency, compact design, and reduced electronics are widely established. However, we know little about their environmental performance. Here, we present this lab-scale technology's first detailed life cycle assessment, specifically of one using a perovskite/silicon tandem photoelectrode. We also compared the environmental performance of the integrated SFB with an established competitor: a photovoltaic panel using the same tandem, coupled with a lithium manganese oxide battery. We found that, on average, ∼59% of the environmental impacts are from the electrolytes, 23% from the structure, and 18% from the PV component of the SFB. Our results showed that by replacing the Teflon and polyether ether ketone materials used in the structure of this SFB, we could reduce ozone depletion and global warming potential impacts by 85% and 36% respectively. Extending the lifetime of the electrolytes can further improve this SFB's environmental performance. 

Abstract

Solar photovoltaics (PV) has emerged as one of the world’s most promising power-generation technologies, and it is essential to assess its applications from the perspective of a material-energy-water (MEW) nexus. We performed a life cycle assessment of the cradle-to-grave MEW for single-crystalline silicon (s-Si) and CdTe PV technologies by assuming both PV systems are recycled at end of life. We found that the MEW network was dominated by energy flows (>95%), while only minor impacts of materials and water flows were observed. Also, these MEW flows have pyramid-like distributions between the three tiers (i.e., primary, secondary/sub-secondary, and tertiary levels), with greater flows at the primary and lower flows at the tertiary levels. A more detailed analysis of materials’ circularity showed that glass layers are the most impactful component of recycling due to their considerable weight in both technologies. Our analysis also emphasized the positive impacts that increased power-conversion efficiency and the use of recycled feedstock have on the PV industry’s circularity rates. We found that a 25% increase in power-conversion efficiency and the use of fully recycled materials in PV panel feedstocks resulted in 91% and 86% material circularity for CdTe and s-Si PV systems, respectively. 

Abstract

The rise of artificial intelligence (AI), blockchain (BC), and the internet of things (IoT) has had significant applications in the advancement of sustainability research. This review examines how these digital transformations drive natural and human systems, as well as which industry sectors have been applying them to advance sustainability. We adopted qualitative research methods, including a bibliometric analysis, in which we screened 960 publications to identify the leading sectors that apply AI/BC/IoT, and a content analysis to identify how each sector uses AI/BC/IoT to advance sustainability. We identified “smart city”, “energy system”, and “supply chain” as key leading sectors. Of these technologies, IoT received the most real-world applications in the “smart city” sector under the dimensions of “smart environment” and “smart mobility” and provided applications resolving energy consumption in the “energy system” sector. AI effectively resolved scheduling, prediction, and monitoring for both the “smart city” and “energy system” sectors. BC remained highly theoretical for “supply chain”, with limited applications. The technological integration of AI and IoT is a research trend for the “smart city” and “energy system” sectors, while BC and IoT is proposed for the “supply chain”. We observed a surge in AI/BC/IoT sustainability research since 2016 and a new research trend—technological integration—since 2020. Collectively, six of the United Nation’s seventeen sustainable development goals (i.e., 6, 7, 9, 11, 12, 13) have been the most widely involved with these technologies. 

Abstract

We evaluated the potential life cycle toxicity impacts of Pb, and five other metals found in perovskite solar panels-Al, Ag, Cu, In, and Sn. We focused on their use in integrated applications-urban, agrivoltaic, buildings, and floating solar, but also included their mining and recycling. Results indicated only the mining of silver is more ecotoxic than that of lead. During a catastrophic break, aluminum emissions in general and silver for floating photovoltaics, are more ecotoxic than those of lead. In all other cases, metals evaluated are potentially as toxic as lead. Finally, the use of virgin materials for the manufacture of the panel has similar impacts as recycling those materials. However, the recovery of the bottom glass and cell is environmentally beneficial due to its silver content. 

Abstract

Like many countries, Palestine suffers from water scarcity. Here, treated greywater is considered an essential nonconventional water resource. We aim to identify some wastewater reuse and disposal practices in rural areas and assess the acceptance level of different reuses of greywater. We conducted a survey analysis in four villages with a strong agricultural activity of the western Bethlehem Governorate. The level of acceptance of greywater reuse was generally independent of demographic variables like family size, income, or water bill, with a few exceptions regarding gender, age, and level of education. Centralized treatment was more valued than treatment at home, which presented similar acceptance levels than no treatment and might indicate a lack of trust in this alternative. The only reuse alternative trusted across treatments was bush irrigation (3.53-3.86 on a five-point Likert scale), but other options without clear, direct human contact like crop irrigation (3.14-3.62), stone cutting (3.19-3.36), and construction (3.12-3.42) also received considerable support. Reused perceived as having direct contact with humans was rejected, as it was the flushing of public toilets (2.59-2.7), aquaculture (1.98-2.37), olive pressing (1.85-1.94), and drinking (1.62-1.72). Relatively new reuse, car washing (2.95-3.17), was somewhere in between, partially because of its novelty. To increase this and other reuses, we strongly encourage local authorities to inform the population about the potentialities of greywater reuse. 

Abstract

With high efficiency and fast processing, metal halide perovskite (PK) solar cells promise a new paradigm for low-cost solar power. In addition to single junction device performance that is near the internal Shockley–Queisser limit, new tandem configurations promise even higher efficiencies. Efforts to commercialize PK-based modules are hindered by several factors including questions of cost and performance in the field. Long lifetimes are needed to achieve a low levelized cost of electricity (LCOE) and establish bankability. To understand the impact of device lifetime on LCOE we compared bottom-up cost and energy yield analyses for single-junction and tandem solar modules based on optical modeling of the device stacks, the device physics, and real-world advanced irradiance and temperature variation data. The degradation rate was taken to be a variable to examine the impact of stability on the LCOE. We show that both device and field lifetimes are critical to achieve a low LCOE for a solar power station. Additionally, for all PK device lifetimes, tandems constructed with higher-cost tandem partners will be economically disadvantaged in the market place. 

Abstract

Perovskite solar cells (PSCs) are emerging photovoltaic devices with great potential to become a terawatt-scale technology. To develop sustainable end-of-life strategies for PSCs, we performed a life cycle assessment on 13 PSC recycling techniques, focusing on the recovery of coated glass. We found that the ecotoxicity due to the consumption of materials is the major contributor to the environmental impact. All but one of the techniques generated more environmental impacts than the production of virgin coated glass. We also found that material reuse and recovery are the key to sustainable coated glass recycling. We can decrease the impact of these techniques between 56 and 68% by recovering the solvent, and further reductions are possible reusing solvents. Techniques with a thermal or a physical process would need to lower their electricity and material use in addition to solvent reuse and recovery to become an environmentally sustainable reality. 

Abstract

The intermittent nature of solar energy has made it necessary for photovoltaic (PV) systems to rely on external energy storage when deployed off-the-grid. In recent years, solar flow batteries (SFBs) have emerged as a potential alternative, which integrates energy production and storage in an integrated device. Here we performed an environmental assessment by highlighting potential hotspots that might hinder their acceptance, offering less pollutive alternatives. Specifically, we analyzed the environmental impacts of perovskite/silicon tandem based SFB. Our results show that the PV cell is responsible for three fourths of the impact of the device at lab scale, while the stack frame is responsible for the remaining impact. At this scale, the impact of the electrolytes is negligible. We expect the impact of the frame to reduce as the scale increases, while we anticipate an increase for the importance of the electrolytes as more energy is stored. For the future, the impact of the PV cell could be reduced by using a back electrode different than gold, and by substituting the perovskite/silicon tandem configuration with a perovskite/perovskite one. 

Abstract

To meet rising energy demands, power plant operations will expand, influencing the interactions between the water–energy nexus and society. However, a major challenge is integration of social dimensions within electricity generation. To address this, we generate a baseline dataset using US public data (2014–2019) from the Energy Information Administration and US Bureau of Labor Statistics. We identify the rate of energy consumed, CO2, SO2 and NOx emissions generated, and water used per MWh net electricity as well as employee wellbeing per unit MW capacity during electricity generation. Rates of energy consumption (MMBtu/MWh) decreased 4.9%, but water consumption and withdrawal (m3/MWh) both increased 0.93% and 0.31%, respectively. Emissions of CO2, SO2 and NOx decreased 22.64%, 75% and 25% MT/MWh, respectively. Thermoelectric cooling withdrawal and consumption is led by natural gas (50.07%, 38.31%), coal (29.61%, 25.07%), and nuclear energies (13.55%, 18.99%). Electric power generation contributes 0.06 injuries–illnesses/TWh and 0.001 fatalities/TWh, of which fossil fuels contributed 70% and 15%, respectively. Fossil fuels led in average annual employment (0.02 employees/MW) with low cost salaries (USD 0.09/MW) likely due to high collective capacity, which is declining. Estimated rates in this study and framework will aid power industry transition and operational decision makers. 

Abstract

The aim of this study was to estimate the socio-economic determinants of the residential water tariff system for Al-Bireh city, Palestine. Results confirmed that ~60% of respondents considered that the current water pricing as high in Al-Bireh. The majority (76.4%) of households would be willing to pay 1%–3% of their monthly income for possible new water tariff in return for services provided for them have arisen. More than 55% of families having greater than six family members showed to be more willing to pay higher percentages for water. This correlated to the increase of family members, households found the water pricing more reasonable (36.6%). Large households with higher income that have increased water consumption are more willing to pay larger amounts for their needs. Households with larger family members with limited income and education tend to think water pricing is high and their knowledge behind water pricing is mostly inadequate. 

Abstract

A promising technology for the future of solar energy is the highly efficient bifacial photovoltaic (PV) cell using perovskite as an absorbing layer. Here we report the environmental impact per energy generated from bifacial perovskite PV cells in single- and multi-junction configurations. To determine the environmental performance of the energy provided from bifacial perovskites and compare it with the analogous monofacial structures, we develop a realistic energy yield (EY) model. According to our model, the studied bifacial structures show between 9% and 26% EY increase compared with monofacial cells among all surfaces and locations studied. For the environmental impact analysis, we use normalized cradle-to-end-of-use impact from single-junction crystalline silicon (c-Si) solar cells as a reference point. Our results show that there are opportunities for all studied bifacial perovskite PV structures to become more environmentally friendly than c-Si cells. 

Abstract

There has been a substantial growth in the deployment of solar photovoltaic (PV) panels in the past couple decades. Solar PVs have a life span of about 25 years and much of the deployed PVs will soon reach their end of life (EoL). It is now timely to plan for the EoL of PVs to recover valuable materials and recycle PV modules sustainably. The goal of this study was to analyze the environmental impacts of different recycling methods for crystalline silicon (c-Si) and CdTe panels. A life cycle assessment (LCA) was performed for delamination and material separation phases of recycling solar panels. The LCA results showed that the recycling of c-Si and CdTe PVs contribute 13–25% and 3–4%, respectively to the entire PV lifecycle impacts. Also, for both c-Si and CdTe PVs, the thermal-based recycling methods resulted in lower environmental impacts than chemical and mechanical methods, except for pyrolysis. Nitric acid dissolution used for c-Si PV recycling had the highest impacts among all methods since the material consumption for this method has not been optimized for industrial use. Results from this study suggested that current techniques used in recycling of PVs, produce higher impacts than extraction of Al, Si and glass for c-Si and extraction of glass for CdTe. Lastly, this study identified which materials to prioritize for highest economic and environmentals benefits from recycling. These will be Ag, Al, Si, and glass in c-Si modules, and Te, Cu, and glass in CdTe modules. 

Abstract

The pressure on the energy, food, and water systems of our planet continues to become greater as the global population gets closer to eight billion people (Lee et al., 2016; Levis et al., 2013). Currently, the structure adapted around the world to produce energy relies on the burning of fossil fuels, releasing extreme amounts of greenhouse gasses into the atmosphere (International Energy Agency, 2018). This not only causes problems to human health, but also increases the number in extreme weather events, which affects the ability of farmers to produce consistently large yields of crops. The availability of clean water for human use continues to decrease along with the growing population (Barakoti et al., 2019; Celik et al., a, b, c, d). Along with food and shelter, water is a necessity for human survival, which is why it is important to find more ways to both conserve and reuse our water for the prosperity of future generations. 

Abstract

Emerging photovoltaic (PV) technologies have a potential to address the shortcomings of today’s energy market which heavily depends on the use of fossil fuels for electricity generation. We created inventories that offer insights into the environmental impacts and cost of all the materials used in emerging PV technologies, including perovskites, polymers, Cu2ZnSnS4 (CZTS), carbon nanotubes (CNT), and quantum dots. The results show that the CO2 emissions associated with the absorber layers are much less than the CO2 emissions associated with the contact and charge selective layers. The CdS (charge selective layer) and ITO (contact layer) have the highest environmental impacts compared to Al2O3, CuI, CuSCN, MoO3, NiO, poly (3-hexylthiophene-2,5-diyl (P3HT)), phenyl-C61-butyric acid methyl ester (PCBM), poly polystyrene sulfonate (PEDOT:PSS), SnO2, spiro-OMeTAD, and TiO2 (charge selective layers) and Al, Ag, Cu, FTO, Mo, ZnO:In, and ZnO/ZnO:Al (contact layers). The cost assessments show that the organic materials, such as polymer absorbers, CNT, P3HT and spiro-OMeTAD, are the most expensive materials. Inorganic materials would be more preferable to lower the cost of solar cells. All the remaining materials have a potential to be used in the commercial PV market. Finally, we analyzed the cost of PV materials based on their material intensity and CO2 emissions, and concluded that the perovskite absorber will be the most eco-efficient material that has the lowest cost and CO2 emissions. 

Abstract

This work provides economic and environmental analyses of transportation-related impacts of different photovoltaic (PV) module technologies at their end-of-life (EoL) phase. Our results show that crystalline silicon (c-Si) modules are the most economical PV technology (United States Dollars (USD) 2.3 per 1 m2 PV module (or 0.87 ¢/W) for transporting in the United States for 1000 km). Furthermore, we found that the financial costs of truck transportation for PV modules for 2000 km are only slightly more than for 1000 km. CO2-eq emissions associated with transport are a significant share of the EoL impacts, and those for copper indium gallium selenide (CIGS) PV modules are always higher than for c-Si and CdTe PV. Transportation associated CO2-eq emissions contribute 47%, 28%, and 40% of overall EoL impacts of c-Si, CdTe, and CIGS PV wastes, respectively. Overall, gasoline-fueled trucks have 65–95% more environmental impacts compared to alternative transportation options of the diesel and electric trains and ships. Finally, a hotspot analysis on the entire life cycle CO2-eq emissions of different PV technologies showed that the EoL phase-related emissions are more significant for thin-film PV modules compared to crystalline silicon PV technologies and, so, more environmentally friendly material recovery methods should be developed for thin film PV. 

Abstract

With solar photovoltaics (PV) playing an increasing role in our global energy market, it is now timely and critical to understand the end of life management of the solar panels. Recycling the panels can be an important pathway, possibly recovering a considerable amount of materials and adding economic benefits from currently installed solar panels. Yet, to date, the costs and benefits of recycling, especially when externality costs resulting from environmental pollution are considered, are largely unknown. In this study, we quantified the private and externality costs and benefits of recycling crystalline silicon (c-Si) PV panels. We found that the private cost of end-of-life (EoL) management of the c-Si PV module is USD 6.7/m2 and much of this cost is from transporting (USD 3.3/m2) and landfilling (USD 3.1/m2), while the actual recycling process (the cost of consumed materials, electricity or the investment for the recycling facilities) is very small (USD 0.3/m2). We found that the external cost of PV EoL management is very similar to the private cost (USD 5.2/m2). Unlike the breakdown of the private costs, much of the externality costs (USD 4.08/m2) come from the recycling process, which suggests that more environmentally friendly methods (e.g., recycling methods that involve fewer toxic chemicals, acids, etc.) should be preferred. We estimated that the total economic value of the recycled materials from c-Si PV waste is USD 13.6/m2. This means that when externality costs are not considered, the net benefit of recycling is USD 6.7; when the externality cost of recycling is considered, there is still a net benefit of USD 1.19 per m2.

Abstract

The objective of this study was to develop a social impact quantification framework for the resource extraction industry. The framework was developed to incorporate two approaches—scale-based and quantitative approaches. It aimed to be used for assessing upstream social impacts for products incorporating mined materials to produce a full social life cycle assessment (S-LCA). 

Abstract

Ecological network analysis (ENA) is emerging as a powerful tool for studying complex technological systems and can reveal information not captured by life cycle assessment (LCA). In this study, we developed an ENA based on the material, energy, and water life cycle inventory of CdTe photovoltaic (PV) modules. We defined one ecological (sun) and eight technological (manufacturing, construction, power grid, solar energy, fuel, water, recycling and waste treatment, and dissipation) network compartments. We studied the interactions of these compartments using throughflow analysis (TA), network utility analysis (NUA), network control analysis (NCA), and network stability analysis (NSA). The TA revealed that total throughflow of the system (TST), or quantified total size of the system is for producing 1 kWh of electricity from solar power is 604 kWh. The NUA assessed the symbiotic relationships within the system and revealed that both quantitative and qualitative beneficial relationships between compartments are prominent. Also, mutualism and synergism indexes were calculated as 2.4 and 7.0, respectively, indicating that most of the system compartments are gaining energy; thus, the system is flexible and preferable for industries when the system compartments are increasing their involvement and cycling within the system. The NCA results indicated that most of the compartments have control over the dissipation compartment, which suggested that large amounts of energy are lost in those compartments. Also, not surprisingly, almost all the compartments were dependent on fuel and water. Our NSA results showed that the current solar energy system lacks systematic diversity and resilience; it lacks the ability to return to the original state when the system is stressed. However, the main reason for these results is the low conversion efficiency of photonic energy to electricity. The same issue would apply to all other engineered power generation systems as well due to low fundamental limits of energy conversion. 

Abstract

Tandem photovoltaic (PV) cells with higher efficiency limits than current market dominated crystalline silicon PV devices are poised to be the next generation of solar cells. In this study we focus on analysis of perovskite/Cu(In x Ga 1-x )Se 2 tandem solar cells in the context of real-world conditions. Using material properties and the most recently updated atmospheric data we simulate the device energy yield for locations with different climate conditions. We use the resultant data in calculating module levelized cost and analyze the conditions under which using different forms of tracking become the cost-effective approach at each location. 

Abstract

Diversifying a system can reduce risk from- and increase resilience to perturbation. For this reason, the concept of diversity has been used in many different fields but its use in analyzing engineering infrastructure has been limited. In particular, the diversity of water sources and uses and the diversity of how sources are connected to uses (flow) have never been analyzed. In addition, the relationships between diversity and economic efficiency of water systems remain uncertain. In this study, we addressed these topics by conceptualizing and quantifying water source, use, and flow diversity in the USA. Water source and water use data were collected from the US Geological Survey for 2000, 2005, and 2010. Diversity was calculated with the Shannon Weaver Index. The overall mean water use diversity by state was 0.79 ± 0.31 (N = 150) and increased from 0.63 ± 0.31 in 2000 to 0.89 ± 0.28 by 2010, reflecting overall decreases in high-use categories, like thermonuclear power, and relative increases in already low domestic use. In contrast, source diversity showed no change over time, with an overall state mean of 0.82 ± 0.28 (N = 150) but varying between states largely due to differences in geographic and climatic factors influencing regional water sources. Water flow diversity also showed no change over time, averaging 1.00 ± 0.43 (N = 150), higher than both source and use diversity. The mean water use efficiency for all states over the study period was 52 ± 60 $/m3 of water and was positively and strongly related to both source and use diversity. Thus, the USA water system diversity is sensitive to factors logically expected to influence both source and use, and directly affects water use efficiency. 

Abstract

Urban agriculture has emerged as an alternative to conventional rural agriculture seeking to foster a sustainable circular economy in cities. When considering the feasibility of urban agriculture and planning for the future of food production and energy, it is important to understand the relationships between energy flows throughout the system, identify their strengths and weaknesses, and make suggestions to optimize the system. To address this need, we analyzed the energy flows for growing tomatoes at a rooftop greenhouse (RTG). We used life cycle assessment (LCA) to identify the flows within the supply chain. We further analyzed these flows using ecological network analysis (ENA), which allowed a comparison of the industrial system to natural systems. Going beyond LCA, ENA also allowed us to focus more on the relationships between components. Similar to existing ENA studies on urban metabolism, our results showed that the RTG does not mimic the perfect pyramidal structure found in natural ecosystems due to the system's dependency on fossil fuels throughout the supply chain and each industry's significant impact on wasted energy. However, it was discovered that the RTG has strong foundational relationships in its industries, demonstrating overall positive utility; this foundation can be improved by using more renewable energy and increasing the recycling rates throughout the supply chain, which will in turn improve the hierarchy of energy flows and overall energy consumption performance of the system. 

Abstract

Perovskite solar cells are promising to become one of the cheapest photovoltaic (PV) technologies due to low material utilization, easy manufacturing processes, and high power conversion efficiencies. In this work, we evaluate the manufacturing costs of perovskite PV modules fabricated using feasible low-cost materials and processes. Three types of perovskite cells based on single-junction and twoand fourterminal all-perovskite tandem configurations are analyzed. Our calculation shows the direct manufacturing costs are 28.7, 33.8, and 42.3 $/m 2 for single-junction, two-terminal tandem, and fourterminal tandem modules, respectively, corresponding to a minimum sustainable price (MSP) of 0.32, 0.34, and 0.37 $/Wp for the modules manufactured in the United States. We also discuss the potential for efficiency gains that could further lower the cost per watt for the tandem modules. 

Abstract

The potential release of toxic metals from damaged emerging photovoltaic (PV) cells has raised concerns about the safe use of these new types of PVs. In this study, this concern was addressed by analysing the life cycle toxicity of metals (cadmium, copper, lead, nickel, tin and zinc) that are commonly used in emerging PVs. In estimating the potential metal release, a new model that incorporates field conditions (crack size, time, and glass thickness) and physiochemical properties (diffusion coefficient and solubility product) was introduced. The results show that the use phase toxicity of copper and lead can be higher than the extraction phase toxicity. Thus, precautionary loss limits to manage toxic impacts from the use phase were proposed. Also, the toxicity from different layers of perovskite, copper zinc tin sulphide (CZTS), and quantum dot (QD) type of solar cells was compared. It was found that cadmium sulphide (compared to zinc oxide and tin oxide) and lead (II) sulphide (compared to lead (II) iodine and CZTS) were less toxic alternatives for the electron selective layer and light absorber, respectively. Finally, in comparing the toxic metal releases of the PVs to today's coal power plants, it was seen that the metal emissions from PVs are expected to be several times less than the emissions from coal. 

Abstract

The potential release of toxic metals from damaged emerging photovoltaic (PV) cells has raised concerns about the safe use of these new types of PVs. In this study, this concern was addressed by analysing the life cycle toxicity of metals (cadmium, copper, lead, nickel, tin and zinc) that are commonly used in emerging PVs. In estimating the potential metal release, a new model that incorporates field conditions (crack size, time, and glass thickness) and physiochemical properties (diffusion coefficient and solubility product) was introduced. The results show that the use phase toxicity of copper and lead can be higher than the extraction phase toxicity. Thus, precautionary loss limits to manage toxic impacts from the use phase were proposed. Also, the toxicity from different layers of perovskite, copper zinc tin sulphide (CZTS), and quantum dot (QD) type of solar cells was compared. It was found that cadmium sulphide (compared to zinc oxide and tin oxide) and lead (II) sulphide (compared to lead (II) iodine and CZTS) were less toxic alternatives for the electron selective layer and light absorber, respectively. Finally, in comparing the toxic metal releases of the PVs to today's coal power plants, it was seen that the metal emissions from PVs are expected to be several times less than the emissions from coal. 

Abstract

This dissertation explores the eco-design concepts for emerging PV cells. By conducting life cycle assessment (LCA) method, I addressed the following questions:(1) What is the environmental impact of a scalable perovskite PV cell?(2) How important are the metal emissions from the emerging thin film devices during the use phase?(3) What are the environmental impacts and costs of the materials used in emerging PVs? These questions are addressed in the analyses presented in the Chapters two, three and four, respectively.