Troy R. Hawkins

Life Cycle Environmental Assessment of Lithium-Ion and Nickel Metal Hydride Batteries for Plug-In Hybrid and Battery Electric Vehicles

This study presents the life cycle assessment (LCA) of three batteries for plug-in hybrid and full performance battery electric vehicles. A transparent life cycle inventory (LCI) was compiled in a component-wise manner for nickel metal hydride (NiMH), nickel cobalt manganese lithium-ion (NCM), and iron phosphate lithium-ion (LFP) batteries. The battery systems were investigated with a functional unit based on energy storage, and environmental impacts were analyzed using midpoint indicators. On a per-storage basis, the NiMH technology was found to have the highest environmental impact, followed by NCM and then LFP, for all categories considered except ozone depletion potential. We found higher life cycle global warming emissions than have been previously reported. Detailed contribution and structural path analyses allowed for the identification of the different processes and value-chains most directly responsible for these emissions. This article contributes a public and detailed inventory, which can be easily be adapted to any powertrain, along with readily usable environmental performance assessments.

Exiopol - Development And Illustrative Analyses Of A Detailed Global Mr Ee Sut/Iot

EXIOPOL (A New Environmental Accounting Framework Using Externality Data and Input–Output Tools for Policy Analysis) was a European Union (EU)-funded project creating a detailed, global, multiregional environmentally extended Supply and Use table (MR EE SUT) of 43 countries, 129 sectors, 80 resources, and 40 emissions. We sourced primary SUT and input–output tables from Eurostat and non-EU statistical offices. We harmonized and detailed them using auxiliary national accounts data and co-efficient matrices. Imports were allocated to countries of exports using United Nations Commodity Trade Statistics Database trade shares. Optimization procedures removed imbalances in these detailing and trade linking steps. Environmental extensions were added from various sources. We calculated the EU footprint of final consumption with resulting MR EE SUT. EU policies focus mainly on energy and carbon footprints. We show that the EU land, water, and material footprint abroad is much more relevant, and should be prioritized in the EUs environmental product and trade policies.

Hybrid Framework for Managing Uncertainty in Life Cycle Inventories

Life cycle assessment (LCA) is increasingly being used to inform decisions related to environmental technologies and polices, such as carbon footprinting and labeling, national emission inventories, and appliance standards. However, LCA studies of the same product or service often yield very different results, affecting the perception of LCA as a reliable decision tool. This does not imply that LCA is intrinsically unreliable; we argue instead that future development of LCA requires that much more attention be paid to assessing and managing uncertainties. In this article we review past efforts to manage uncertainty and propose a hybrid approach combining process and economic inputoutput (I-O) approaches to uncertainty analysis of life cycle inventories (LCI). Different categories of uncertainty are sometimes not tractable to analysis within a given model framework but can be estimated from another perspective. For instance, cutoff or truncation error induced by some processes not being included in a bottom-up process model can be estimated via a top-down approach such as the economic I-O model. A categorization of uncertainty types is presented (data, cutoff, aggregation, temporal, geographic) with a quantitative discussion of methods for evaluation, particularly for assessing temporal uncertainty. A long-term vision for LCI is proposed in which hybrid methods are employed to quantitatively estimate different uncertainty types, which are then reduced through an iterative refinement of the hybrid LCI method.

Life Cycle Assessment of Diesel and Electric Public Transportation Buses

The Clean Air Act in the United States identifies diesel‐powered motor vehicles, including transit buses, as significant sources of several criteria pollutants that contribute to ground‐level ozone formation or smog. The effects of air pollution in urban areas are often more significant due to congestion and can lead to respiratory and cardiovascular health impacts. Life cycle assessment (LCA) has been utilized in the literature to compare conventional gasoline‐powered passenger cars with various types of electric and hybrid‐powered alternatives, however, no similarly detailed studies exist for mass transit buses. LCA results from this study indicate that the use phase, consisting of diesel production/combustion for the conventional bus and electricity generation for the electric bus, dominates most impact categories; however, the effects of battery production are significant for global warming, carcinogens, ozone depletion, and eco‐toxicity. There is a clear connection between the mix of power‐generation technologies and the preference for the diesel or electric bus. With the existing U.S. average grid, there is a strong preference for the conventional diesel bus over the electric bus when considering global warming impacts alone. Policy makers must consider regional variations in the electricity grid prior to recommending the use of battery electric buses to reduce carbon dioxide (CO) emissions. This study found that the electric bus was preferable in only eight states, including Washington and Oregon. Improvements in battery technology reduce the life cycle impacts from the electric bus, but the electricity grid makeup is the dominant variable.

Harmonising National Input-Output Tables For Consumption-Based Accounting - Experiences From Exiopol

Environmentally extended, multi-regional, input–output (MRIO) databases have emerged to fulfil the need for mapping the impacts of globalisation, following resource-intensive supply chains crossing country borders. EXIOBASE is one such data set designed for use in analysis relevant to resource use and European Union policy. It provides the most detailed harmonised sector classification in any MRIO and integrates data from a wide range of sources. We review the necessary steps in order to harmonise source data in MRIO databases, and describe methods to increase the product and industry detail of aggregate supply and use tables (SUTs) in order to provide a homogenous classification across countries that allows resource-specific modelling. We cover mathematical programming approaches used to reconcile data sets, and investigate some implications of reverse engineering symmetric input–output tables and disaggregating the SUTs. We focus particularly on the footprint multiplier at the product level, where policy formation is targeted.

Critical insights for a sustainability framework to address integrated community water services: Technical metrics and approaches.

Planning for sustainable community water systems requires a comprehensive understanding and assessment of the integrated source-drinking-wastewater systems over their life-cycles. Although traditional life cycle assessment and similar tools (e.g. footprints and emergy) have been applied to elements of these water services (i.e. water resources, drinking water, stormwater or wastewater treatment alone), we argue for the importance of developing and combining the system-based tools and metrics in order to holistically evaluate the complete water service system based on the concept of integrated resource management. We analyzed the strengths and weaknesses of key system-based tools and metrics, and discuss future directions to identify more sustainable municipal water services. Such efforts may include the need for novel metrics that address system adaptability to future changes and infrastructure robustness. Caution is also necessary when coupling fundamentally different tools so to avoid misunderstanding and consequently misleading decision-making.

Life Cycle Assessment of Domestic and Agricultural Rainwater Harvesting Systems

To further understanding of the environmental implications of rainwater harvesting and its water savings potential relative to conventional U.S. water delivery infrastructure, we present a method to perform life cycle assessment of domestic rainwater harvesting (DRWH) and agricultural rainwater harvesting (ARWH) systems. We also summarize the design aspects of DRWH and ARWH systems adapted to the Back Creek watershed, Virginia. The baseline design reveals that the pump and pumping electricity are the main components of DRWH and ARWH impacts. For nonpotable uses, the minimal design of DRWH (with shortened distribution distance and no pump) outperforms municipal drinking water in all environmental impact categories except ecotoxicity. The minimal design of ARWH outperforms well water in all impact categories. In terms of watershed sustainability, the two minimal designs reduced environmental impacts, from 58% to 78% energy use and 67% to 88% human health criteria pollutants, as well as avoiding up to 20% blue water (surface/groundwater) losses, compared to municipal drinking water and well water. We address potential environmental and human health impacts of urban and rural RWH systems in the region. The Building for Environmental and Economic Sustainability (BEES) model-based life cycle inventory data were used for this study.

Comparative Human Health Risk Analysis of Coastal Community Water and Waste Service Options

As a pilot approach to describe adverse human health effects from alternative decentralized community water systems compared to conventional centralized services (business-as-usual [BAU]), selected chemical and microbial hazards were assessed using disability adjusted life years (DALYs) as the common metric. The alternatives included: (1) composting toilets with septic system, (2) urine-diverting toilets with septic system, (3) low flush toilets with blackwater pressure sewer and on-site greywater collection and treatment for nonpotable reuse, and (4) alternative 3 with on-site rainwater treatment and use. Various pathogens (viral, bacterial, and protozoan) and chemicals (disinfection byproducts [DBPs]) were used as reference hazards. The exposure pathways for BAU included accidental ingestion of contaminated recreational water, ingestion of cross-connected sewage to drinking water, and shower exposures to DBPs. The alternative systems included ingestion of treated greywater from garden irrigation, toilet flushing, and crop consumption; and ingestion of treated rainwater while showering. The pathways with the highest health impact included the ingestion of cross-connected drinking water and ingestion of recreational water contaminated by septic seepage. These were also among the most uncertain when characterizing input parameters, particularly the scale of the cross-connection event, and the removal of pathogens during groundwater transport of septic seepage. A comparison of the health burdens indicated potential health benefits by switching from BAU to decentralized water and wastewater systems.

Life cycle assessment of electricity transmission and distribution—part 1: power lines and cables

PurposeThe purpose of this study is to provide life cycle inventory data and results for components of electrical grids to the larger community of life cycle assessment practitioners. This article is the first in a series of two, each focusing on different components of power grids. In part 1, the objects under scope are power lines and cables. Systems for overhead, underground, and subsea transmission are modeled here, including HVDC systems used in long-distance transmission.MethodsWe use process-based life cycle assessment based on information provided by companies and in reports, Ecoinvent v2.2 as a background dataset and ReCiPe Midpoint Hierarchist perspective v1.0 as the impact assessment method. The average European power mix is used to model the electrical energy required to compensate power losses in the equipment.Results and discussionUnder the assumption of European power mix, power losses are the dominant process for impacts of lines and cables in all impact categories, contributing with up to 99% to climate change impacts. An exception is the category of metal depletion, for which the production of metal parts is the most relevant process.ConclusionsAfter power losses, processes generating the most impacts for overhead lines are the production of metals for masts and conductors; production of foundations comes third. Recycling of metal parts shows benefits in all impact categories. For cables, infrastructure impacts are dominated by cable production, and recycling of cable materials does not always compensate for the other impacts generated at the end of life.

Life cycle assessment of electricity transmission and distribution—part 2: transformers and substation equipment

PurposeThe purpose of this paper is to characterize the environmental impacts of equipment used in power transmission and distribution. This study is divided in two parts, each addressing different main components of the electrical grid system. This part is concerned with the impacts of transformers and substation equipment while in part 1 a similar analysis is presented for power lines and cables.MethodsThe method used here is process-based life cycle assessment. Ecoinvent v 2.2 is used as a background dataset, and the results are obtained with the impact assessment method ReCiPe Midpoint Hierarchist perspective (v1.0). The average European power mix is used to model the electrical energy required to compensate power losses in the electrical equipment.Results and discussionAssuming a European power mix, results for transformers indicate that power losses are by far the most dominant process for almost all impact categories evaluated here, contributing at least 96% to climate change impacts. An exception is the category of metal depletion, for which production of raw materials is the most relevant process. Within infrastructure-related impacts, the production of raw materials is the most important process. Recycling shows benefits for most impact categories. For some substation equipment using sulfur hexafluoride (SF6), climate change impacts due to SF6 leakages surpass impacts due to losses.ConclusionsThe results suggest that improvements in component efficiency—reduction of power losses and reduction of SF6 gas leakages in gas-insulated equipment—would significantly contribute to decreases in overall component impacts.