The advent of advanced metering technologies combined with machine learning creates an opportunit... more The advent of advanced metering technologies combined with machine learning creates an opportunity to form digital multi-utility service providers. These service providers can concurrently collect a customers' water, electricity and gas demand data and provide phone and web applications to disseminate this information back to utility professionals and customers. Service companies that can provide inexpensive integrated systems will derive benefits such as operational synergies and access to mass markets not bounded by historical city, state or country limits. This article provides a vision of an integrated multi-utility service provider covering the system architecture, barriers and strategies, and opportunities and benefits. The focus of paper is to demonstrate the data modelling processes and informatics opportunities for contemporaneously collected water, electricity and gas demand data. Moreover, a transformative R&D framework is provided to realize this digital multi-utility future.
As rooftop solar photovoltaic (PV) adoption in Australia is exponentially growing in the past dec... more As rooftop solar photovoltaic (PV) adoption in Australia is exponentially growing in the past decade, there is a need to promote effective product stewardship for PV panels reaching their end-of-life (EoL). This paper presents the development of a System Dynamics (SD) model for managing EoL rooftop PV panels based on the circular economy concept. Four stages of the SD modelling process include problem scoping and variable identification, model conceptualisation, SD model development, and scenario analysis. Stakeholder engagement is central to this research as the system under study is underpinned by high uncertainties and limited data availability. Four socio-technical transition pathways examined in this study include market-driven growth, conservative development, shared responsibility, and disruptive change. The simulation results indicated an improvement of collection and recovery performance when a stringent product stewardship scheme is enabled and improvement of installers' participation in the collection program. This study argued that a system of shared responsibility will be capable of balancing techno-economic motivations of stakeholders across the supply chain to participate in the recovery scheme, while being less disruptive to PV adoption. Under this scenario, a gradual change in regulatory requirements (e.g. recovery target and material recovery rate requirements) is introduced to allow a period of industry and market development.
Water utility companies in urban areas face two major challenges: ensuring there is enough water ... more Water utility companies in urban areas face two major challenges: ensuring there is enough water for everyone during prolonged drought and maintaining adequate water pressure during the hours of peak demand. These issues can be overcome by applying data analytics and machine learning to the data gathered from digital water meters. For water conservation and demand management strategies to be effective, utility companies need to gain a better understanding of consumer behaviours, habits and routines. To accomplish this goal, we adapted a clustering approach to reveal residential water consumption patterns within metered data. In the experiment, we used two data sets (engineered features data set as well as the times of use and weighted probabilities of use data set) based on the data collected over 10 months from 306 households in Melbourne, Australia. For the engineered features data set, first, we identified the number of optimal clusters. We then performed extensive experiments to find the best clustering approach in terms of performance evaluation and clustering quality. We chose the hierarchical agglomerative clustering technique based on the nature of the data and the objective of the study. We observed that for the engineered features data set, k-means is the best performing clustering technique after considering performance metrics. For the other data set, we found that the number of clusters varies based on the type of water-consumption event, type of day (i.e., weekday or weekend), profiling interval and probability of use. In addition, we observed that insight into tap-water usage could be used to determine the population's adaptation of hygiene practices in an unprecedented time, such as the COVID-19 pandemic. Finally, we recommend that future clustering studies also employ aligned socio-demographic data and other key features.
The green bond market is emerging as an impactful financing mechanism in climate change mitigatio... more The green bond market is emerging as an impactful financing mechanism in climate change mitigation efforts. Studies investigating this market have revealed the notion of a 'green premium' or 'greenium' within green bond pricing, including insights into influential characteristics and drivers that govern it. However, methodological heterogeneity among these studies has resulted in general ambiguity regarding a consensus over the existence of the green premium. This research addresses this gap through a systematic literature review with the aim of establishing a consensus on the existence, or nonexistence, of a green premium in the green bond market. The review examines studies published between 2007 and 2019. A ranking of the green bond characteristics most likely to exhibit a green premium is organised, including a framework of driving factors. The findings confirm a consensus on the existence of a green premium within 56% of primary and 70% of secondary market studies, particularly for those green bonds that are government issued, investment grade, and that follow defined green bond governance and reporting procedures. The green premium varies widely for the primary market; however, an average greenium of -1 to -9 basis points on the secondary market is observed. Overall, our findings highlight the crucial role of strengthening environmental preferences amongst bond market participants; including implications for bond pricing theory, by suggesting that future bond pricing should consider noneconomic motives of investors, such as environmental preferences; and, for future growth implications as a catalyst towards the financing of climate change mitigation efforts globally.
Renewable & Sustainable Energy Reviews, Dec 1, 2020
Understanding the complexities around managing the end-of-life (EoL) residential solar photovolta... more Understanding the complexities around managing the end-of-life (EoL) residential solar photovoltaic (PV) and battery energy storage systems (BESS) is a precursor to a better decision-making process that mitigates unintended product life-cycle impacts. In this paper, a participatory Systems Thinking approach was utilised to build a causal loop diagram (CLD) for this system based on the collective knowledge of stakeholders. The developed CLD was categorised into three sub-systems: (1) waste flows; (2) regulatory aspects; and (3) industry strategies and government incentives. Two main system archetypes were identified in a reflection to the CLD, namely fixes that fail and drifting goals. The identified feedback loops indicate the need to introduce a comprehensive national product stewardship scheme, complimentary landfill restrictions, and provide sufficient incentives to industries for promoting recovery activities within residential PV panels and BESS sectors. An effective waste management system for these renewable energy technologies is most effective if industries are required to participate through regulation which also specifies certain targets, such as product and material recovery rates and establishes a sustainable funding model to meet operational requirements and future needs. The increasingly prohibitive overseas waste export market will require local industries and governments to collaboratively improve domestic recycling capability and capacity. In this light, the failure to build an effective EoL management system for residential PV and BESS will result in valuable and hazardous materials in both technologies to be disposed of in the landfill, stockpiled or illegally dumped; consequently, reinforcing unintended and adverse environmental impacts. Causal loop diagram mapped the complexity of EoL management system of PV and BESS.
Collaboration between government agencies and communities for sustainable water governance in rem... more Collaboration between government agencies and communities for sustainable water governance in remote Indigenous communities is espoused as a means to contribute to more equitable, robust, and long-term decision-making and to ensure that water services contribute to broader considerations of physical, social, and economic prosperity. In Australia, the uptake of collaborative water governance in remote Aboriginal and Torres Strait Island contexts has been slow and few examples exist from which to inform policy and practice. This study identifies barriers to uptake of collaborative sustainable water governance, drawing from qualitative interviews with water practitioners working in remote Indigenous Australia and analysis of key project documentation. Thematic analysis revealed discrete barriers across five key categories: (1) governance arrangements, (2) economic and financial, (3) capacity and skills, (4) data and information, and (5) cultural values and norms, with many barriers identified, unique to the remote Indigenous Australian context. The paper provides insights into how to address these barriers strategically to create transformative and sustainable change for Indigenous communities. The results contribute to the greater body of knowledge on sustainable and collaborative water governance, and they are of relevance for broader water management, policy, and research.
Distributed solar photovoltaic (PV) systems are a low-cost form of renewable energy technology th... more Distributed solar photovoltaic (PV) systems are a low-cost form of renewable energy technology that has had an exponential rate of uptake globally in the last decade. However, little attention has been paid to the potential environmental and human health related impacts associated with PV systems, if not managed properly at the end-of-life (EoL). Rare materials such as ruthenium, gallium, indium, and tellurium are essential components in PV panels, while battery energy storage systems (BESS) are composed of various chemistries (i.e. lithium-ion, lead acid, nickel cadmium, salt water, and flow batteries). An appropriate EoL management strategy for solar photovoltaic systems (i.e. PV modules, BESS) is necessary, not only to prevent and/or mitigate future environmental problems but also to reduce demand on rare earth materials. Drawn from a portfolio of 191 papers collected from Scopus and Web of Science databases between 2000 and 2018 (by 30 June 2018), a systematic quantitative literature review on solar energy systems EoL studies was conducted to examine the temporal trend of current research as well as methodological and geographical distributions of the published articles. Research has been concentrated within Europe, some parts of Asia, and North America, with experimental and modelling/simulation methods being mostly applied. The focus of this study was to compile and synthesise reported drivers, barriers, and enablers to EoL management of PV panels and BESS in the context of the circular economy. A conceptual framework is proposed to facilitate the transition of current PV system material flows and supply chain management practices to circular economy concepts. This paper also presents a future research agenda.
We investigate the notion of capitalizing on investments in energy, water and gas efficiency with... more We investigate the notion of capitalizing on investments in energy, water and gas efficiency within the context of affordable rental housing subsidy schemes; how associated utility savings offer a means to deliver policy designed to mitigate for issues of split-incentives. An Australian case study representing a typical affordable housing development is analyzed for two scenarios -a 'Business as usual' and 'Green-certified' case. Over a 10-year rental tenancy, operational utility efficiencies, achieved through green building principles are modelled to reduce total housing costs by 1.7-3.8% (AUD $5-18 per week), for one-and four-person households, respectively. Over the building lifecycle, the net present value of improvements are forecasted to be positive, signalling favourable support for policy interventions. The findings provide evidence to support a broader notion of 'housing assistance' to one that includes improved standards on residential utility efficiency. We present three policy options on how to deliver these benefits to stakeholders.
Achieving a thorough understanding of the determinants of household water consumption is crucial ... more Achieving a thorough understanding of the determinants of household water consumption is crucial to support demand management strategies. Yet, existing research on household water consumption determinants is often limited to specific case studies, with findings that are difficult to generalize and not conclusive. Here, we first contribute an updated framework for review, classification, and analysis of the literature on the determinants of household water consumption. Our framework allows trade-off analysis of different criteria that account for the representation of a potential water consumption determinant in the literature, its impact across heterogeneous case studies, and the effort required to collect information on it. We then review a comprehensive set of 48 publications with our proposed framework. The results of our trade-off analysis show that distinct groups of determinants exist, allowing for the formulation of recommendations for practitioners and researchers on which determinants to consider in practice and prioritize in future research.
Understanding elements of non-revenue water (NRW) has become more critical in an era where urban ... more Understanding elements of non-revenue water (NRW) has become more critical in an era where urban water has a rapidly increasing value. Meter under-and over-registration of flows has received considerable research attention over the years, but there has been limited focus on non-registration, particularly for domestic water meters over their life cycle. This paper presents empirical estimates on nonregistration for typically installed domestic water meters and emphasises that both under-and non-registration should be considered for any meter replacement assessments and associated policies. Economic modelling showed that domestic water meters should be replaced at lower throughput volumes when considering both of these meter inaccuracy categories. The key value of the paper is that it provides a methodology for determining nonregistration for a fleet of domestic meters.
Wide Bay Water Corporation is in the process of implementing automated meter reading technology i... more Wide Bay Water Corporation is in the process of implementing automated meter reading technology in their water network. This technology allows the remote measurement and evaluation of water consumption at a residential and commercial level using a FIREFLY ® data logger and Commstar software. By using the FIREFLY ® , water usage patterns can be recorded each hour and stored for collection via a drive-by system. This paper presents the findings from a pilot study in Hervey Bay Queensland that Wide Bay Water Corporation has undertaken in conjunction with Griffith University. The objective was to identify household water leakage in residential properties located within a selected district metered area (DMA). Research outcomes include a water use profile of the metered residential properties, the types of leaks encountered and the cost of leak repairs. At the commencement of the program it was found that 2% of the meters accounted for 24% of the night time consumption. This study provides evidence that automated meter reading technology can quantify water leakage beyond the meter.
The advent of advanced metering technologies combined with machine learning creates an opportunit... more The advent of advanced metering technologies combined with machine learning creates an opportunity to form digital multi-utility service providers. These service providers can concurrently collect a customers' water, electricity and gas demand data and provide phone and web applications to disseminate this information back to utility professionals and customers. Service companies that can provide inexpensive integrated systems will derive benefits such as operational synergies and access to mass markets not bounded by historical city, state or country limits. This article provides a vision of an integrated multi-utility service provider covering the system architecture, barriers and strategies, and opportunities and benefits. The focus of paper is to demonstrate the data modelling processes and informatics opportunities for contemporaneously collected water, electricity and gas demand data. Moreover, a transformative R&D framework is provided to realize this digital multi-utility future.
As rooftop solar photovoltaic (PV) adoption in Australia is exponentially growing in the past dec... more As rooftop solar photovoltaic (PV) adoption in Australia is exponentially growing in the past decade, there is a need to promote effective product stewardship for PV panels reaching their end-of-life (EoL). This paper presents the development of a System Dynamics (SD) model for managing EoL rooftop PV panels based on the circular economy concept. Four stages of the SD modelling process include problem scoping and variable identification, model conceptualisation, SD model development, and scenario analysis. Stakeholder engagement is central to this research as the system under study is underpinned by high uncertainties and limited data availability. Four socio-technical transition pathways examined in this study include market-driven growth, conservative development, shared responsibility, and disruptive change. The simulation results indicated an improvement of collection and recovery performance when a stringent product stewardship scheme is enabled and improvement of installers' participation in the collection program. This study argued that a system of shared responsibility will be capable of balancing techno-economic motivations of stakeholders across the supply chain to participate in the recovery scheme, while being less disruptive to PV adoption. Under this scenario, a gradual change in regulatory requirements (e.g. recovery target and material recovery rate requirements) is introduced to allow a period of industry and market development.
Water utility companies in urban areas face two major challenges: ensuring there is enough water ... more Water utility companies in urban areas face two major challenges: ensuring there is enough water for everyone during prolonged drought and maintaining adequate water pressure during the hours of peak demand. These issues can be overcome by applying data analytics and machine learning to the data gathered from digital water meters. For water conservation and demand management strategies to be effective, utility companies need to gain a better understanding of consumer behaviours, habits and routines. To accomplish this goal, we adapted a clustering approach to reveal residential water consumption patterns within metered data. In the experiment, we used two data sets (engineered features data set as well as the times of use and weighted probabilities of use data set) based on the data collected over 10 months from 306 households in Melbourne, Australia. For the engineered features data set, first, we identified the number of optimal clusters. We then performed extensive experiments to find the best clustering approach in terms of performance evaluation and clustering quality. We chose the hierarchical agglomerative clustering technique based on the nature of the data and the objective of the study. We observed that for the engineered features data set, k-means is the best performing clustering technique after considering performance metrics. For the other data set, we found that the number of clusters varies based on the type of water-consumption event, type of day (i.e., weekday or weekend), profiling interval and probability of use. In addition, we observed that insight into tap-water usage could be used to determine the population's adaptation of hygiene practices in an unprecedented time, such as the COVID-19 pandemic. Finally, we recommend that future clustering studies also employ aligned socio-demographic data and other key features.
The green bond market is emerging as an impactful financing mechanism in climate change mitigatio... more The green bond market is emerging as an impactful financing mechanism in climate change mitigation efforts. Studies investigating this market have revealed the notion of a 'green premium' or 'greenium' within green bond pricing, including insights into influential characteristics and drivers that govern it. However, methodological heterogeneity among these studies has resulted in general ambiguity regarding a consensus over the existence of the green premium. This research addresses this gap through a systematic literature review with the aim of establishing a consensus on the existence, or nonexistence, of a green premium in the green bond market. The review examines studies published between 2007 and 2019. A ranking of the green bond characteristics most likely to exhibit a green premium is organised, including a framework of driving factors. The findings confirm a consensus on the existence of a green premium within 56% of primary and 70% of secondary market studies, particularly for those green bonds that are government issued, investment grade, and that follow defined green bond governance and reporting procedures. The green premium varies widely for the primary market; however, an average greenium of -1 to -9 basis points on the secondary market is observed. Overall, our findings highlight the crucial role of strengthening environmental preferences amongst bond market participants; including implications for bond pricing theory, by suggesting that future bond pricing should consider noneconomic motives of investors, such as environmental preferences; and, for future growth implications as a catalyst towards the financing of climate change mitigation efforts globally.
Renewable & Sustainable Energy Reviews, Dec 1, 2020
Understanding the complexities around managing the end-of-life (EoL) residential solar photovolta... more Understanding the complexities around managing the end-of-life (EoL) residential solar photovoltaic (PV) and battery energy storage systems (BESS) is a precursor to a better decision-making process that mitigates unintended product life-cycle impacts. In this paper, a participatory Systems Thinking approach was utilised to build a causal loop diagram (CLD) for this system based on the collective knowledge of stakeholders. The developed CLD was categorised into three sub-systems: (1) waste flows; (2) regulatory aspects; and (3) industry strategies and government incentives. Two main system archetypes were identified in a reflection to the CLD, namely fixes that fail and drifting goals. The identified feedback loops indicate the need to introduce a comprehensive national product stewardship scheme, complimentary landfill restrictions, and provide sufficient incentives to industries for promoting recovery activities within residential PV panels and BESS sectors. An effective waste management system for these renewable energy technologies is most effective if industries are required to participate through regulation which also specifies certain targets, such as product and material recovery rates and establishes a sustainable funding model to meet operational requirements and future needs. The increasingly prohibitive overseas waste export market will require local industries and governments to collaboratively improve domestic recycling capability and capacity. In this light, the failure to build an effective EoL management system for residential PV and BESS will result in valuable and hazardous materials in both technologies to be disposed of in the landfill, stockpiled or illegally dumped; consequently, reinforcing unintended and adverse environmental impacts. Causal loop diagram mapped the complexity of EoL management system of PV and BESS.
Collaboration between government agencies and communities for sustainable water governance in rem... more Collaboration between government agencies and communities for sustainable water governance in remote Indigenous communities is espoused as a means to contribute to more equitable, robust, and long-term decision-making and to ensure that water services contribute to broader considerations of physical, social, and economic prosperity. In Australia, the uptake of collaborative water governance in remote Aboriginal and Torres Strait Island contexts has been slow and few examples exist from which to inform policy and practice. This study identifies barriers to uptake of collaborative sustainable water governance, drawing from qualitative interviews with water practitioners working in remote Indigenous Australia and analysis of key project documentation. Thematic analysis revealed discrete barriers across five key categories: (1) governance arrangements, (2) economic and financial, (3) capacity and skills, (4) data and information, and (5) cultural values and norms, with many barriers identified, unique to the remote Indigenous Australian context. The paper provides insights into how to address these barriers strategically to create transformative and sustainable change for Indigenous communities. The results contribute to the greater body of knowledge on sustainable and collaborative water governance, and they are of relevance for broader water management, policy, and research.
Distributed solar photovoltaic (PV) systems are a low-cost form of renewable energy technology th... more Distributed solar photovoltaic (PV) systems are a low-cost form of renewable energy technology that has had an exponential rate of uptake globally in the last decade. However, little attention has been paid to the potential environmental and human health related impacts associated with PV systems, if not managed properly at the end-of-life (EoL). Rare materials such as ruthenium, gallium, indium, and tellurium are essential components in PV panels, while battery energy storage systems (BESS) are composed of various chemistries (i.e. lithium-ion, lead acid, nickel cadmium, salt water, and flow batteries). An appropriate EoL management strategy for solar photovoltaic systems (i.e. PV modules, BESS) is necessary, not only to prevent and/or mitigate future environmental problems but also to reduce demand on rare earth materials. Drawn from a portfolio of 191 papers collected from Scopus and Web of Science databases between 2000 and 2018 (by 30 June 2018), a systematic quantitative literature review on solar energy systems EoL studies was conducted to examine the temporal trend of current research as well as methodological and geographical distributions of the published articles. Research has been concentrated within Europe, some parts of Asia, and North America, with experimental and modelling/simulation methods being mostly applied. The focus of this study was to compile and synthesise reported drivers, barriers, and enablers to EoL management of PV panels and BESS in the context of the circular economy. A conceptual framework is proposed to facilitate the transition of current PV system material flows and supply chain management practices to circular economy concepts. This paper also presents a future research agenda.
We investigate the notion of capitalizing on investments in energy, water and gas efficiency with... more We investigate the notion of capitalizing on investments in energy, water and gas efficiency within the context of affordable rental housing subsidy schemes; how associated utility savings offer a means to deliver policy designed to mitigate for issues of split-incentives. An Australian case study representing a typical affordable housing development is analyzed for two scenarios -a 'Business as usual' and 'Green-certified' case. Over a 10-year rental tenancy, operational utility efficiencies, achieved through green building principles are modelled to reduce total housing costs by 1.7-3.8% (AUD $5-18 per week), for one-and four-person households, respectively. Over the building lifecycle, the net present value of improvements are forecasted to be positive, signalling favourable support for policy interventions. The findings provide evidence to support a broader notion of 'housing assistance' to one that includes improved standards on residential utility efficiency. We present three policy options on how to deliver these benefits to stakeholders.
Achieving a thorough understanding of the determinants of household water consumption is crucial ... more Achieving a thorough understanding of the determinants of household water consumption is crucial to support demand management strategies. Yet, existing research on household water consumption determinants is often limited to specific case studies, with findings that are difficult to generalize and not conclusive. Here, we first contribute an updated framework for review, classification, and analysis of the literature on the determinants of household water consumption. Our framework allows trade-off analysis of different criteria that account for the representation of a potential water consumption determinant in the literature, its impact across heterogeneous case studies, and the effort required to collect information on it. We then review a comprehensive set of 48 publications with our proposed framework. The results of our trade-off analysis show that distinct groups of determinants exist, allowing for the formulation of recommendations for practitioners and researchers on which determinants to consider in practice and prioritize in future research.
Understanding elements of non-revenue water (NRW) has become more critical in an era where urban ... more Understanding elements of non-revenue water (NRW) has become more critical in an era where urban water has a rapidly increasing value. Meter under-and over-registration of flows has received considerable research attention over the years, but there has been limited focus on non-registration, particularly for domestic water meters over their life cycle. This paper presents empirical estimates on nonregistration for typically installed domestic water meters and emphasises that both under-and non-registration should be considered for any meter replacement assessments and associated policies. Economic modelling showed that domestic water meters should be replaced at lower throughput volumes when considering both of these meter inaccuracy categories. The key value of the paper is that it provides a methodology for determining nonregistration for a fleet of domestic meters.
Wide Bay Water Corporation is in the process of implementing automated meter reading technology i... more Wide Bay Water Corporation is in the process of implementing automated meter reading technology in their water network. This technology allows the remote measurement and evaluation of water consumption at a residential and commercial level using a FIREFLY ® data logger and Commstar software. By using the FIREFLY ® , water usage patterns can be recorded each hour and stored for collection via a drive-by system. This paper presents the findings from a pilot study in Hervey Bay Queensland that Wide Bay Water Corporation has undertaken in conjunction with Griffith University. The objective was to identify household water leakage in residential properties located within a selected district metered area (DMA). Research outcomes include a water use profile of the metered residential properties, the types of leaks encountered and the cost of leak repairs. At the commencement of the program it was found that 2% of the meters accounted for 24% of the night time consumption. This study provides evidence that automated meter reading technology can quantify water leakage beyond the meter.
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Papers by Rodney Stewart