Global Warming Impacts of Residential Electricity Consumption: Agent-Based Modeling of Rooftop Solar Panel Adoption in Los Angeles County, California.

Solar photovoltaics (PV) are a renewable electricity technology with lower carbon dioxide equivalent (CO2 e) impacts compared to fossil electricity, making it a technology of interest with respect to combatting global climate change. This paper combines agent-based modeling (ABM) with life cycle assessment (LCA) to simulate rooftop solar PV adoption in Los Angeles (LA) County from 2018-2050 and generate CO2 e impact data at the societal level to compare PV and grid electricity. With respect to solar PV panels, consumer adoption is the "pull" that moves the system and corresponding life cycle CO2 e impacts forward. ABM is used to evaluate the impact of policies and evolutions in technology regarding the adoption of solar PV. Life cycle assessment is used to quantify the life cycle CO2 e impacts of solar PV (including raw materials, manufacturing, and use). The results show that scenarios that increase PV adoption also increase the CO2 e impacts from solar PV use in the short term, due to the raw materials and manufacturing portions of the life cycle. Yet, in the long term, adoption of solar PV may provide CO2 e impact savings from offsetting grid electricity (although this is dependent on the carbon intensity of the electricity sources). The CO2 e impacts of solar panels are dominated by the raw materials and manufacturing phases on a product level basis, but the use phase contributes to the majority of environmental impact savings from an adoption and societal-level perspective. Future work may apply the methodology to other locations in the United States to evaluate if solar panels are an advantageous electricity source compared to the environmental impacts of the electricity grid. Integr Environ Assess Manag 2020;16:1008-1018. © 2020 SETAC.

Maintenance and Expansion: Modeling Material Stocks and Flows for Residential Buildings and Transportation Networks in the EU25.

Material stocks are an important part of the social metabolism. Owing to long service lifetimes of stocks, they not only shape resource flows during construction, but also during use, maintenance, and at the end of their useful lifetime. This makes them an important topic for sustainable development. In this work, a model of stocks and flows for nonmetallic minerals in residential buildings, roads, and railways in the EU25, from 2004 to 2009 is presented. The changing material composition of the stock is modeled using a typology of 72 residential buildings, four road and two railway types, throughout the EU25. This allows for estimating the amounts of materials in in-use stocks of residential buildings and transportation networks, as well as input and output flows. We compare the magnitude of material demands for expansion versus those for maintenance of existing stock. Then, recycling potentials are quantitatively explored by comparing the magnitude of estimated input, waste, and recycling flows from 2004 to 2009 and in a business-as-usual scenario for 2020. Thereby, we assess the potential impacts of the European Waste Framework Directive, which strives for a significant increase in recycling. We find that in the EU25, consisting of highly industrialized countries, a large share of material inputs are directed at maintaining existing stocks. Proper management of existing transportation networks and residential buildings is therefore crucial for the future size of flows of nonmetallic minerals.

Resource Use in Small Island States: Material Flows in Iceland and Trinidad and Tobago, 1961-2008.

Iceland and Trinidad and Tobago are small open, high-income island economies with very specific resource-use patterns. This article presents a material flow analysis (MFA) for the two countries covering a time period of nearly five decades. Both countries have a narrow domestic resource base, their economy being largely based on the exploitation of one or two key resources for export production. In the case of Trinidad and Tobago, the physical economy is dominated by oil and natural gas extraction and petrochemical industries, whereas Iceland's economy for centuries has been based on fisheries. More recently, abundant hydropower and geothermal heat were the basis for the establishment of large export-oriented metal processing industries, which fully depend on imported raw materials and make use of domestic renewable electricity. Both countries are highly dependent on these natural resources and vulnerable to overexploitation and price developments. We show how the export-oriented industries lead to high and growing levels of per capita material and energy use and carbon dioxide emissions resulting from large amounts of processing wastes and energy consumption in production processes. The example of small open economies with an industrial production system focused on few, but abundant, key resources and of comparatively low complexity provides interesting insights of how resource endowment paired with availability or absence of infrastructure and specific institutional arrangements drives domestic resource-use patterns. This also contributes to a better understanding and interpretation of MFA indicators, such as domestic material consumption.

The Physical Economy of the United States of America.

The United States is not only the world's largest economy, but it is also one of the world's largest consumers of natural resources. The country, which is inhabited by some 5% of the world's population, uses roughly one-fifth of the global primary energy supply and 15% of all extracted materials. This article explores long-term trends and patterns of material use in the United States. Based on a material flow account (MFA) that is fully consistent with current standards of economy-wide MFAs and covers domestic extraction, imports, and exports of materials for a 135-year period, we investigated the evolution of the U.S. industrial metabolism. This process was characterized by an 18-fold increase in material consumption, a multiplication of material use per capita, and a shift from renewable biomass toward mineral and fossil resources. In spite of considerable improvements in material intensity, no dematerialization has happened so far; in contrast to other high-income countries, material use has not stabilized since the 1970s, but has continued to grow. This article compares patterns and trends of material use in the United States with those in Japan and the United Kingdom and discusses the factors underlying the disproportionately high level of U.S. per capita resource consumption.