Geoffrey M. Lewis

Application of life-cycle energy analysis to photovoltaic module design

This paper highlights results from a collaborative life-cycle design project between the University of Michigan, the US Environment Protection Agency and United Solar Systems Corporation. Energy analysis is a critical planning and design tool for photovoltaic (PV) modules. A set of model equations for evaluating the life-cycle energy performance of PV systems and other electricity-generating systems are presented. The total PV life-cycle, encompassing material production, manufacturing and assembly, use and end-of-life management, was investigated. Three metrics—energy payback time, electricity production eAciency and lifecycle conversion eAciency—were defined for PV modules with and without balanceof-system (BOS) components. These metrics were evaluated for a United Solar UPM-880 amorphous silicon PV module based on average insolation in Detroit, Boulder and Phoenix. Based on these metrics, a minimum condition for assessing the sustainability of electricity-generating systems was proposed and discussed. The life-cycle energy analysis indicated that the aluminum frame is responsible for a significant fraction of the energy invested in the UPM-880 module. #1997 John Wiley & Sons, Ltd.

Modeling the life cycle energy and environmental performance of amorphous silicon BIPV roofing in the US

Building integrated photovoltaics (BIPV) perform traditional architectural functions of walls and roofs while also generating electricity. The displacement of utility generated electricity and conventional building materials can conserve fossil fuels and have environmental benefits. A life cycle inventory model is presented that characterizes the energy and environmental performance of BIPV systems relative to the conventional grid and displaced building materials. The model is applied to an amorphous silicon PV roofing shingle in different regions across the US. The electricity production efficiency (electricity output/total primary energy input excluding insolation) for a reference BIPV system (2kWp PV shingle system with a 6% conversion efficiency and 20 year life) ranged from 3.6 in Portland OR to 5.9 in Phoenix, AZ indicating a significant return on energy investment. The reference system had the greatest air pollution prevention benefits in cities with conventional electricity generation mixes dominated by coal and natural gas, not necessarily in cities where the insolation and displaced conventional electricity were greatest.

Amorphous silicon photovoltaic modules: a life cycle design case study

The life cycle design framework was applied to photovoltaic module design. Two metrics were used to assess life cycle energy performance of a PV module: energy payback time; and electricity production efficiency. These metrics are based on material production, manufacturing, and transportation energies, and were evaluated for several geographic locations. An aluminum frame was responsible for a significant fraction of the total energy invested in the studied module. Design options to reduce the energy impact of this and other components are discussed.

Defining The Pattern Of The Sustainable Urban Region

To date, the debate on the sustainability of human settlements has focused on the urban portion of the land use pattern. Since urban areas rely on suburban, rural, and other less densely settled areas for their existence, these areas must be included in any sustainability assessment. This need for a regional view has resulted in a typology of regional form, which allows comparisons of relative sustainability between various regional land use patterns. Based on resource efficiency, this regional analysis includes measurements related to water, agricultural land, habitat, energy use, and transportation and identifies primary indicators for each category. Existing methods employed to assess urban sustainability are reviewed and compared with two new methods, introduced here, that take a more holistic regional view: population density zones and regional characteristic curves. Future work to fully evaluate the properties of these new methods by applying them to a variety of regional form types is described.

Integrating a Triple Bottom-Line Approach into the Management System: A Framework for Institutions and Businesses Alike

Organizations are increasingly transitioning to a more sustainable management approach as a result of drivers related to corporate reputation, operational efficiency, and regulatory compliance. Accordingly, organizations that are proving resilient to this trend are gaining a competitive edge. This paper draws from the field of industrial ecology in terms of material flow analysis to set a foundation for organizations that wish to integrate sustainability principles into the management system. Though research has linked industrial ecology to sustainable business operations, there is a void on the practical level in terms of implementation and maintenance strategies, leaving businesses unequipped to adapt to a more sustainable approach, now commonly known as triple bottom line. In response, the framework of this paper uses the concept of material flow analysis, to guide a detailed process for achieving more sustainable business operations.

Environmental Impacts of Abdominal Imaging: A Pilot Investigation

PURPOSE Clinical decision making regarding the use of imaging is appropriately centered on diagnostic efficacy and individual patient factors. However, health policy and imaging guidelines may incorporate other inputs, such as cost-effectiveness and patient preference. In the context of climate change and resource scarcity, the environmental impacts of imaging modalities including ultrasound, CT, and MRI will also become relevant. The purpose of this study was to estimate the environmental impacts of various abdominal imaging examinations. METHODS Using commercially available software (SimaPro) and data from user manuals and field experts, a streamlined life cycle assessment was performed to estimate multifactorial environmental impacts of the production and use of ultrasound, CT, and MRI per abdominal imaging examination. RESULTS Ultrasound consumed less energy in both production and use phases (7.8 and 10.3 MJ/examination, respectively) than CT (58.9 and 41.1 MJ/examination) or MRI (93.2 and 216 MJ/examination). Ultrasound emitted fewer CO2 equivalents in production and use phases (0.5 and 0.65 kg/examination) than CT (4.0 and 2.61 kg/examination) or MRI (6.0 and 13.72 kg/examination). Potential human health effects from pollutant emissions were found to be smallest with ultrasound in both production and use phases. CONCLUSIONS Among the three imaging modalities, ultrasound was found to have the least environmental impact, by one or more orders of magnitude in various domains. This analysis provides an initial framework for comparing environmental impacts across imaging modalities, which may provide useful inputs for cost-effectiveness analyses and policymaking.