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Open Access Publications from the University of California

Scholarly Works (5 results)

  • Thesis
  • Peer Reviewed
UC Irvine Electronic Theses and Dissertations (2024)

To combat air pollution and mitigate the release of carbon, two primary pathways have emerged: (1) decarbonizing electricity generation by integrating renewable energy into the electric grid, (2) electrifying various end uses including the adoption of zero-emission vehicles (ZEVs) such as plug-in electric vehicles (PEVs) and the transition to all-electric residence. However, the diurnal and intermittent nature of solar and wind power, coupled with the mismatch between the generation of renewable power and the consumption of electricity, necessitates large-scale energy storage to support a highly renewable electric grid. Bidirectional energy flow systems, including Vehicle-to-Load (V2L), Vehicle-to-Home (V2H), and Vehicle-to-Grid (V2G), present promising solutions by empowering PEVs to act as energy sources. Among these, discharging energy at a residence represents an immediate application and opportunity.To identify the benefits and technical barriers associated with implementing bidirectional energy flow systems in residential settings, this dissertation employed a combination of simulation-based research and experimental testing. A home energy management system cost-optimization model (HEMSopt) was developed to evaluate the potential of V2H technology in achieving zero net energy homes, reducing utility costs, and enhancing resilience during grid outages. Laboratory tests were conducted to examine the functionality of V2L from the perspective of PEV owners, aiming to provide insights and raise awareness of bidirectional applications. Furthermore, laboratory and field experiments were conducted to assess the efficiency and dynamics of prototype V2H systems, emphasizing the importance of compatibility testing and interoperability enhancements. Additionally, a comprehensive test procedure is proposed to evaluate bidirectional product performance and compatibility with other distributed energy resources such as PV and home battery systems, serving as a benchmark for future testing protocols. Overall, this dissertation contributes to advancing the theoretical understanding of bidirectional power flow technologies and provides practical insights for effective implementation in residential applications.

    • Thesis
    • Peer Reviewed
    UC Irvine Electronic Theses and Dissertations (2020)

    While energy storage systems (ESS) are required to integrate and manage renewable resources on the electric grid, ESS can result in life cycle environmental impacts associated with (1) the production of the system, (2) the use of the system, and (3) the end-of-life of the system. As more energy storage capacity is deployed, the grid benefits and associated life cycle environmental impacts may not scale the same. For example, thresholds of energy and power capacity may exist beyond which additional energy storage results in a negative environmental impact. To explore this question, this study addressed the use-phase environmental impacts of three flow-battery energy storage systems. Dynamic electric grid modeling tools were used to establish the use-phase environmental benefits and impacts on Global Warming Potential (GWP), Particulate Matter (PM) emissions, Acidification Potential (AP), and Fossil Fuel Cumulative Energy Demand (CED) as the aggregate ESS power and energy capacity installed on the electric grid is increased. For an electric grid with a high percentage of renewable resources, the results reveal that (1) the use-phase impact can be as, or more significant than, the production - phase depending on the grid composition, (2) the combined power and energy capacities for flow battery systems where the net environmental benefits are a maximum, and (3) that power and energy capacities must be limited to certain thresholds in order to ensure that flow-battery storage provides net environmental benefits.

      Cover page: Environmental Benefit-Detriment Thresholds for Flow Battery Energy Storage Systems
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2022)
      Batteries are important for promoting renewable energy, but, like most engineered products, they contain multiple hazardous materials. The purpose of this study is to evaluate industrial-scale batteries using GreenScreen® for Safer Chemicals, an established chemical hazard assessment (CHA) framework, and to develop a systematic, transparent methodology to quantify the CHA results, harmonize them, and aggregate them into single-value hazard scores, which can facilitate quantitative comparison and a robust evaluation of data gaps, inconsistencies, and uncertainty through the implementation of carefully selected scenarios and stochastic multicriteria acceptability analysis (SMAA). Using multiple authoritative toxicity data sources, six battery products are evaluated: three lithium-ion batteries (lithium iron phosphate, lithium nickel cobalt manganese hydroxide, and lithium manganese oxide), and three redox flow batteries (vanadium redox, zinc-bromine, and all-iron). The CHA results indicate that many materials in these batteries, including reagents and intermediates, inherently exhibit high hazard; therefore, safer materials should be identified and considered in future designs. The scenario analysis and SMAA, combined, provide a quantitative evaluation framework to support the decision-making needed to compare alternative technologies. Thus, this study highlights specific strategies to reduce the use of hazardous materials in complex engineered products before they are widely used in this rapidly-expanding industry sector.
        Cover page: Advancing chemical hazard assessment with decision analysis: A case study on lithium-ion and redox flow batteries used for energy storage.
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2020)
        Energy storage systems, such as flow batteries, are essential for integrating variable renewable energy sources into the electricity grid. While a primary goal of increased renewable energy use on the grid is to mitigate environmental impact, the production of enabling technologies like energy storage systems causes environmental impact. Thus, understanding the impact of producing energy storage systems is crucial for determining the overall environmental performance of renewable energy from a systems perspective. In this study, the environmental impact associated with the production of emerging flow battery technologies is evaluated in an effort to inform materials selection and component design decisions. The production of three commercially available flow battery technologies is evaluated and compared on the basis of eight environmental impact categories, using primary data collected from battery manufacturers on the battery production phase including raw materials extraction, materials processing, manufacturing and assembly. In the baseline scenario, production of all-iron flow batteries led to the lowest impact scores in six of the eight impact categories such as global warming potential, 73 kg CO2 eq/kWh; and cumulative energy demand, 1090 MJ/kWh. While the production of vanadium redox flow batteries led to the highest impact values for six categories including global warming potential, 184 kg CO2 eq/kWh; and cumulative energy demand, 5200 MJ/kWh. Production of zinc-bromine flow batteries had the lowest values for ozone depletion, and freshwater ecotoxicity, and the highest value for abiotic resource depletion. The analysis highlight that the relative environmental impact of producing the three flow battery technologies varies with different system designs and materials selection choices. For example, harmonization of the battery system boundary led to freshwater eutrophication and freshwater ecotoxicity values for vanadium redox flow batteries lower than the values for zinc-bromine flow batteries. Regarding alternative material use strategies, we conclude that vanadium redox flow batteries exhibit the lowest potential in four of the eight impact categories including global warming potential at 61 kg CO2 eq/kWh. In zinc-bromine flow batteries, the titanium-based bipolar plate contributes higher environmental impact compared to carbon-based materials, and the polymer resins used in all-iron flow batteries could be replaced with material with lower potential for ecotoxicity. Overall, the analysis reveals the sources of potential environmental impact, due to the production of flow battery materials, components and systems. The findings from this study are urgently needed before these batteries become widely deployed in the renewable energy sector. Furthermore, our results indicate that materials options change the relative environmental impact of producing the three flow batteries and provide the potential to significantly reduce the environmental impact associated with flow battery production and deployment.
          Cover page: Flow battery production: Materials selection and environmental impact
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2021)
          Energy storage systems are critical for enabling the environmental benefits associated with capturing renewable energy to displace fossil fuel-based generation, yet producing these systems also contributes to environmental impacts through their materials use and manufacturing. As energy storage capacity is scaled up to support increasingly renewable grids, the environmental benefits from their use may scale at different rates than the environmental impacts from their production. This implies the existence of capacity thresholds beyond which installing additional storage capacity may be environmentally detrimental. Identifying such thresholds are important for ensuring that energy storage capacity selection in future grids are consistent with net emissions reduction goals, but such thresholds have not been studied in the present literature. To identify such thresholds, here we combine electric grid dispatch modeling with life cycle analysis to compare how the emissions reductions from deploying three different flow battery energy storage types on a future California grid (>80% wind and solar) compare with emissions contributions from producing such batteries as total battery capacity installed on the grid increases. Depending on the type of battery and environmental impact indicator (greenhouse gas or particulate matter emissions), we find that the marginal environmental benefits of storage begin to diminish at deployed capacities of 38–76% of the mean daily renewable generation (256–512 GWh in our California scenarios) and reach zero at 105–284% of mean daily renewable generation (700–1810 GWh). Such storage capacities are conceivable, but upstream impacts of storage must be assessed in evaluating the environmental benefits of large-scale storage deployment, or they could negate the environmental benefits of regional electricity system decarbonization.
            Cover page: Environmental benefit-detriment thresholds for flow battery energy storage systems: A case study in California
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