Jun-Ki Choi

Integrated Sustainable Life Cycle Design: A Review

Product design is one of the most important sectors influencing global sustainability, as almost all the products consumed by people are outputs of the product development process. In particular, early design decisions can have a very significant impact on sustainability. These decisions not only relate to material and manufacturing choices but have a far-reaching effect on the product’s entire life cycle, including transportation, distribution, and end-of-life logistics. However, key challenges have to be overcome to enable eco-design methods to be applicable in early design stages. Lack of information models, semantic interoperability, methods to influence eco-design thinking in early stages, measurement science and uncertainty models in eco-decisions, and ability to balance business decisions and eco-design methodology are serious impediments to realizing sustainable products and services. Therefore, integrating downstream life cycle data into eco-design tools is essential to achieving true sustainable product development. Our review gives an overview of related research and positions early eco-design tools and decision support as a key strategy for the future. By merging sustainable thinking into traditional design methods, this review provides a framework for ongoing research, as well as encourages research collaborations among the various communities interested in sustainable product realization.

Life Cycle Greenhouse Gas Emissions of Crystalline Silicon Photovoltaic Electricity Generation

Published scientific literature contains many studies estimating life cycle greenhouse gas (GHG) emissions of residential and utility‐scale solar photovoltaics (PVs). Despite the volume of published work, variability in results hinders generalized conclusions. Most variance between studies can be attributed to differences in methods and assumptions. To clarify the published results for use in decision making and other analyses, we conduct a meta‐analysis of existing studies, harmonizing key performance characteristics to produce more comparable and consistently derived results. Screening 397 life cycle assessments (LCAs) relevant to PVs yielded 13 studies on crystalline silicon (c‐Si) that met minimum standards of quality, transparency, and relevance. Prior to harmonization, the median of 42 estimates of life cycle GHG emissions from those 13 LCAs was 57 grams carbon dioxide equivalent per kilowatt‐hour (g CO‐eq/kWh), with an interquartile range (IQR) of 44 to 73. After harmonizing key performance characteristics (irradiation of 1,700 kilowatt‐hours per square meter per year (kWh/m2/yr); system lifetime of 30 years; module efficiency of 13.2% or 14.0%, depending on module type; and a performance ratio of 0.75 or 0.80, depending on installation, the median estimate decreased to 45 and the IQR tightened to 39 to 49. The median estimate and variability were reduced compared to published estimates mainly because of higher average assumptions for irradiation and system lifetime. For the sample of studies evaluated, harmonization effectively reduced variability, providing a clearer synopsis of the life cycle GHG emissions from c‐Si PVs. The literature used in this harmonization neither covers all possible c‐Si installations nor represents the distribution of deployed or manufactured c‐Si PVs.

Life Cycle Greenhouse Gas Emissions of Thin‐Film Photovoltaic Electricity Generation

We present the process and the results of harmonization of greenhouse gas (GHG) emissions during the life cycle of commercial thin‐film photovoltaics (PVs), that is, amorphous silicon (a‐Si), cadmium telluride (CdTe), and copper indium gallium diselenide (CIGS). We reviewed 109 studies and harmonized the estimates of GHG emissions by aligning the assumptions, parameters, and system boundaries. During the initial screening we eliminated abstracts, short conference papers, presentations without supporting documentation, and unrelated analyses; 91 studies passed this initial screening. In the primary screening we applied rigorous criteria for completeness of reporting, validity of analysis methods, and modern relevance of the PV system studied. Additionally, we examined whether the product is a commercial one, whether the production line still exists, and whether the studys core data are original or secondary. These screenings produced five studies as the best representations of the carbon footprint of modern thin‐film PV technologies. These were harmonized through alignment of efficiency, irradiation, performance ratio, balance of system, and lifetime. The resulting estimates for carbon footprints are 20, 14, and 26 grams carbon dioxide equivalent per kilowatt‐hour (g CO‐eq/kWh), respectively, for a‐Si, CdTe, and CIGS, for ground‐mount application under southwestern United States (US‐SW) irradiation of 2,400 kilowatt‐hours per square meter per year (kWh/m2/yr), a performance ratio of 0.8, and a lifetime of 30 years. Harmonization for the rooftop PV systems with a performance ratio of 0.75 and the same irradiation resulted in carbon footprint estimates of 21, 14, and 27 g CO‐eq/kWh, respectively, for the three technologies. This screening and harmonization rectifies previous incomplete or outdated assessments and clarifies variations in carbon footprints across studies and amongst thin‐film technologies.

A framework for the integration of environmental and business aspects toward sustainable product development

Growing environmental concerns, coupled with public pressure and stricter regulations, are fundamentally impacting the way companies design and launch new products across the world. Companies are recognising that implementing design for environment (DfE) in their product development process provides opportunities both for improving environmental aspects of a product and for enhancing the product competitiveness. Therefore, integrating environmental and business aspects for decision-making during DfE consideration are crucial in the product design process. The environmental aspect of the product is captured by the lifecycle assessment, and the result is directly introduced to the selection of DfE strategies followed by the multi-criteria decision-making process, in order to integrate business aspects. The proposed method may help the company systematically develop appropriate and profitable design for environment strategies for their product systems.

Economic Feasibility of Recycling Photovoltaic Modules

The market for photovoltaic (PV) electricity generation has boomed over the last decade, and its expansion is expected to continue with the development of new technologies. Taking into consideration the usage of valuable resources and the generation of emissions in the life cycle of photovoltaic technologies dictates proactive planning for a sound PV recycling infrastructure to ensure its sustainability. PV is expected to be a green technology, and properly planning for recycling will offer the opportunity to make it a double-green technology - that is, enhancing life cycle environmental quality. In addition, economic feasibility and a sufficient level of value-added opportunity must be ensured, to stimulate a recycling industry. In this article, we survey mathematical models of the infrastructure of recycling processes of other products and identify the challenges for setting up an efficient one for PV. Then we present an operational model for an actual recycling process of a thin-film PV technology. We found that for the case examined with our model, some of the scenarios indicate profitable recycling, whereas in other scenarios it is unprofitable. Scenario SC4, which represents the most favorable scenario by considering the lower bounds of all costs and the upper bound of all revenues, produces a monthly profit of

An automotive bulk recycling planning model

107,000, whereas the least favorable scenario incurs a monthly loss of

Design and Optimization of Photovoltaics Recycling Infrastructure

151,000. Our intent is to extend the model as a foundation for developing a framework for building a generalized model for current-PV and future-PV technologies.

Prioritizing Design for Environment Strategies Using a Stochastic Analytic Hierarchy Process

The automotive recycling infrastructure successfully recovers 75% of the material weight in end-of-life vehicles primarily through ferrous metal separation. However, this industry faces significant challenges as automotive manufacturers increase the use of nonferrous and nonmetallic materials. As the nonferrous content in end-of-life vehicles rises, automotive shredders need to evaluate to what extent to separate nonferrous metals. We propose a recycling planning model for automotive shredders to make short-term tactical decisions regarding to what extent to process and to reprocess materials through multiple passes. In addition, the mixed integer programming model determines whether to combine materials for shipment. In a case study for automotive shredding decisions for the current composition and more polymer-intensive end-of-life vehicles, we use our model to show the sensitivity of the decision to reprocess light nonferrous metal to low and high metal prices. Contrary to observations in practice to mix light and heavy nonferrous metals for shipment, we show multiple scenarios where the model chooses to reprocess and ship separated light and heavy nonferrous metals.

The Potential of Wind for Energy Production and Water Pumping in Iran, Saravan County

With the growing production and installation of photovoltaics (PV) around the world constrained by the limited availability of resources, end-of-life management of PV is becoming very important. A few major PV manufacturers currently are operating several PV recycling technologies at the process level. The management of the total recycling infrastructure, including reverse-logistics planning, is being started in Europe. In this paper, we overview the current status of photovoltaics recycling planning and discuss our mathematic modeling of the economic feasibility and the environmental viability of several PV recycling infrastructure scenarios in Germany; our findings suggest the optimum locations of the anticipated PV take-back centers. Short-term 5-10 year planning for PV manufacturing scraps is the focus of this article. Although we discuss the German situation, we expect the generic model will be applicable to any region, such as the whole of Europe and the United States.

Product Node Architecture: A Systematic Approach to Provide Structured Flexibility in Distributed Product Development

This paper describes a framework for applying design for environment (DfE) within an industry setting. Our aim is to couple implicit design knowledge such as redesign/process constraints with quantitative measures of environmental performance to enable informed decision making. We do so by integrating life cycle assessment (LCA) and multicriteria decision analysis (MCDA). Specifically, the analytic hierarchy process (AHP) is used for prioritizing various levels of DfE strategies. The AHP network is formulated so as to improve the environmental performance of a product while considering business-related performance. Moreover, in a realistic industry setting, the onus of decision making often rests with a group, rather than an individual decision maker (DM). While conducting independent evaluations, experts often do not perfectly agree and no individual expert can be considered representative of the ground truth. Hence, we integrate a stochastic simulation module within the MCDA for assessing the variability in preferences among DMs. This variability in judgments is used as a metric for quantifying judgment reliability. A sensitivity analysis is also incorporated to explore the dependence of decisions on specific input preferences. Finally, the paper discusses the results of applying the proposed framework in a real-world case. [DOI: 10.1115/1.4025701]