Water-related Energy Use Research Articles

Modelling the system dynamics of household food, water, and energy nexus effects

The food-energy-water nexus (F-E-W) serves as a crucial resource for the sustainability of households, while the efficiency of resource use largely depends on our understanding and management of the nexus including all three factors. Limited research has been conducted on this topic thus far because of the increasing complexity of home technologies and data availability. This study develops an evidence-based system dynamics model for assessing the synergy and trade-offs of the household F-E-W. By applying the system dynamics (SD) methodology, the FEW consumption and generation originating from home appliances were modelled and simulated. The model was applied to an eco-house in Tokyo, and its efficacy was validated with one-year hour-based observations of a home energy management system (HEMS). The findings revealed that water-related and food-related energy use accounted for approximately 55% of the total energy use. In addition, water-related energy use showed high uncertainty, suggesting a management potential of approximately 24% for reduction, and was significantly correlated with household carbon emissions. Moreover, this result verified that the effective management of household energy consumption requires the adept manipulation of the diverse array of energy sources employed for air and water heating, while HEMSs could play a key role in implementation.

A quantitative study on the water-related energy use in the urban water system of Shenzhen

A comprehensive understanding of the nexus between urban water and energy is vital for economic development and human survival. Although extensive studies have been conducted on urban water–energy nexus, the nexus is site-specific and governed by many factors. Here, we analyzed water-related energy intensity for residential purpose based on statistical data and family surveys in Shenzhen, which is one of the world's fastest urbanizing megacities facing water and energy scarcity. Then household water and energy use and their main influencing factors were explored. Water-related energy intensity was calculated in kWh/m3 as follows: source water transfer (0.344), tap water production (0.217), tap water delivery (0.464), residential water use (7.43), wastewater treatment (0.20), and wastewater reuse (0.083). Results show that there's a strong nexus between water and energy in the urban water system. Household water use is mainly affected by family income (r = 0.202, p = 0.002), whereas household electricity use is mainly affected by education level (r = 0.191, p = 0.004). With the projected increases in family size, family income and education level, water and energy supply in Shenzhen are going to face severe challenges.

REGENERATIVE WATER MANAGEMENT ACROSS SCALES: A RETROFIT VISION FOR BIOSPHERE SUSTAINABILITY

There is a need for consistency in water management across scales and sectors, which motivated this paper to formulate a “proactive” retrofit vision seeking to integrate net-positive, sustainable and regenerative design concepts. Since the Planetary Boundaries framework is the key communication tool from scientific knowledge to political instruments (e.g., Sustainable Development Goals), water-related topics are revised accordingly. It is suggested that the role of water management in Climate Change is largely overlooked, which, in turn, is demonstrated to be the driver of change and, at the same time, impacted by these changes. Furthermore, it is demonstrated that the link between water-related carbon footprint and energy use presents the Climate Change community with a valuable opportunity to better manage two of the most valuable resources. A new approach is suggested by distinguishing water quality, quantity, and water state. So that beyond qualitative and quantitative goals, the physical state of water, which depends on hydrogen bonding, should help improve water management across scales. Understating water complexity shall facilitate communication raising awareness that every action creates a legacy. Overall, this study strengthens the idea that science-based strategies require better communication where biogeochemical science may serve a model to make knowledge more available to educators and policymakers.
 
 Keywords: water-related carbon footprint, molecular water structure, socio-ecological regeneration.

Investigating urban household water - energy nexus towards supporting sustainable and smart city policies: The case of Hanoi City, Vietnam

Sustainable and smart management of urban water and energy sectors is one of challenges facing by Vietnamese cities today. This study examined the water-energy nexus in urban households by analysing the “cause-and-effect” relationships among four major individual attributes (age, gender, education level, and family size) and three household behaviours (showering, cooking, and washing) with water and water related energy uses for the case of Hanoi City. The amount and component of water and water related energy uses with respect to those household behaviours and individual attributes were explored. The results showed that both water use and water related energy use had relationship with gender, education level, and family size. Specifically, people with more water and energy uses were female with age ≤ 30 years old, especially who have higher education level and live alone. The better understanding on how household behaviours and individual attributes influencing the household water and water related energy uses provided by this study could help the urban planners, policy makers, and relevant stakeholders to identify the opportunities for designing better and smart solutions for household water and energy management, towards achieving the goals of sustainable and smart cities.

The Transition to Improved Water-Related Energy Management: Enabling Contexts for Policy Innovation

We explored the potential for improved policy and regulation with a direct focus on household water-related energy (WRE) management in urban Victoria (Australia). Semi-structured interviews were employed to understand the perspectives of relevant actors within the existing institutional landscape. In this paper, questions about institutional and policy change are addressed through consideration of the literature on transitions management and institutional entrepreneurship. Key policy opportunities identified by the actors include consumer education and advocacy for behaviour change and technology adoption, and further development of residential building standards to improve the selection and layout of building services at the design phase. The work highlights medium-term opportunities to create an enabling environment for policy practitioners in Victoria to improve management of water-related energy use in households. The work provides an important new perspective on transitions theory in the field of integrated resources management.

China’s water-energy nexus: Assessment of water-related energy use

The water-related energy consumption is one of the core concepts in water-energy nexus, yet the classification and estimation values of its numerous branches have not been well documented in China. To address this gap, this paper sorted out water-related energy use processes after setting forth the implication and boundary of water activities, and then calculated their detailed energy flows. The results showed that the total energy consumed by China’s water sector was about 732 million GJ in 2015, accounting for 0.6% of the national energy consumption. The electricity power is the basic power source for water processes and the electricity consumed by water sector accounts for 3.4% of the total electricity consumption in China. From the perspective of different water activities: 54% of the energy consumption was attributed to raw freshwater collection, extraction and conveyance activities, 41% of the energy used in water treatment, distribution and wastewater treatment while the water resource construction activities occupied the remaining 5%. The analysis suggested that the energy consumption has not become a major restricting factor to water sector on national scale, while heavy energy burdens were likely to lower the current and future effectiveness of certain water projects or policies.

Developing a water-energy-GHG emissions modeling framework: Insights from an application to California's water system

Integrating processes of water and energy interdependence in water systems can improve the understanding of the tradeoffs between water and energy in management and policy. This study presents a development of an integrated water resources management model that includes water-related energy use and GHG emissions. We apply the model to a simplified representation of California's water system. Accounting for water demands from cities, agriculture, environment and the energy sector, and combining a surface water management model with a simple groundwater model, the model optimizes water use across sectors during shortages from an economic perspective, calculating the associated energy use and electricity generation for each water demand. The results of California's water system show that urban end-uses account for most GHG emissions of the entire water cycle, but large water conveyance produces significant peaks over the summer season. Different policy scenarios show the significant tradeoffs between water, energy, and GHG emissions.

Energy Consumption in the Municipal Water Supply Sector in the Kingdom of Bahrain

Water-energy nexus is an emerging issue that receives considerable attention in the world in general and in the Gulf Cooperation Council (GCC) countries in particular. The GCC countries depend mainly on energy generated from fossil fuels to produce drinking water. Yet, the amount of water-related energy use in Bahrain remains unexplored. This study aims to quantify the amount of energy used in the water supply cycle for the first time in Bahrain using quantitative methods. A bottom-up approach for data collection was adopted where data for the three main stages of the water supply in Bahrain: water production, water transmission, and water distribution were collected. Results show that the water production stage consumes about 97% of the total energy consumption in the water supply sector, followed by water transmission (2.9%) and water distribution (0.1%). Comparisons conducted with best practices in the world show that water desalination plants in Bahrain consume relatively high amounts of energy to produce water based on the desalination technology used. This study calls for focusing on the production stage in achieving energy efficiency since it is the largest consumer and where losses are occurring based on the benchmarking. This study also recommends investigating the share of electricity and thermal energy consumed in the water supply cycle in Bahrain in addition to the wastewater treatment sector. This is imperative to provide a holistic overview of the water-related energy use in Bahrain.

Energy implications of the millennium drought on urban water cycles in Southeast Australian cities

Abstract During the Millennium Drought in Australia, a wide range of supply-side and demand-side water management strategies were adopted in major southeast Australian cities. This study undertakes a time-series quantification (2001–2014) and comparative analysis of the energy use of the urban water supply systems and sewage systems in Melbourne and Sydney before, during and after the drought, and evaluates the energy implications of the drought and the implemented strategies. In addition, the energy implications of residential water use in Melbourne are estimated. The research highlights that large-scale adoption of water conservation strategies can have different impacts on energy use in different parts of the urban water cycle. In Melbourne, the per capita water-related energy use reduction in households related to showering and clothes-washing alone (46% reduction, 580 kWhth/p/yr) was far more substantial than that in the water supply system (32% reduction, 18 kWhth/p/yr). This historical case also demonstrates the importance of balancing supply- and demand-side strategies in managing long-term water security and related energy use. The significant energy saving in water supply systems and households from water conservation can offset the additional energy use from operating energy-intensive supply options such as inter-basin water transfers and seawater desalination during dry years.

Could smart growth lower the operational energy of water supply? A scenario analysis in Tampa, Florida, USA

Cities are coming under increasing pressure to minimize energy use and greenhouse gas emissions. Consequently, drinking water utilities must improve the efficiency of their management systems while guaranteeing a clean effluent that satisfies drinking water standards. One possible solution is via smart growth, an urban development paradigm with the goal of reducing the environmental impact of urbanization. Therefore, this study aims to determine the effect of smart growth on the operational energy of drinking water distribution. Projected water use in Tampa’s drinking water service area was estimated based on several urban growth projections. Then, each scenario’s associated projected water consumption is integrated in an EPANET simulation of Tampa’s water distribution system for the subsequent estimation of the operational energies of drinking water distribution. Results show that smart growth has no exclusive influence on the operational energy of water supply. However, location of added demand relative to the location of the water treatment plant has more of an influence on the operational energy. Also, smart growth in the City of Tampa Water Service Area is responsible for a decrease in per-capita residential water and energy use of about 6–10% and 0.5–6.2% respectively. In conclusion, smart growth in areas near the water treatment facility may minimize water-related energy use.

Understanding Australian household water-related energy use and identifying physical and human characteristics of major end uses

Residential resource use efficiency and management is a subject of interest to a number of fields spanning the physical and social sciences. Energy use for residential water heating in Australia is some five to eleven times more than the energy required to deliver urban water services. However, little is known about which activities within households contribute most significantly to water-related energy use (WRE). This work quantifies WRE use in individual households, and identifies household characteristics which contribute significantly to variation. Empirical data were collected through in-home audits, interviews and high-resolution end-use water flow meters for five households in Melbourne, and two in Brisbane, Australia. This was used to characterise 139 parameters describing household occupancy characteristics, behaviours, technologies, and structural and environmental aspects of influence. Mathematical material flow analysis (MMFA) modelling was conducted for individual water and energy use subsystems within each household. WRE use ranged from 7 to 21 kWh hh−1 d−1 (13–24% of total household energy use in Melbourne and 76–79% in Brisbane). Detailed end use analysis of the five Melbourne households showed that shower use (11–61% WRE), hot water system efficiency losses (8–31% WRE) and clothes washer usage (4–17% WRE) contributed most to differences in WRE between households. Findings highlighted shower use as a consistent influence on WRE across households, and suggest further investigation of shower programs as a potentially effective demand management measure for both water and energy in households. The work highlights the importance of consistent messaging for both water and energy efficiency, and suggests that a focus on both human and technical characteristics of households is needed for effective management of combined water and energy use.

Residential water and energy nexus for conservation and management: A case study of Tianjin

As an important part of energy use in the water end-use system, the energy consumption of urban household water use is typical to illustrate the nexus of water and energy. Considering its urban size and population, Tianjin is studied by questionnaires for residential water use and estimated energy intensity. This paper analyzes water-related energy use by studying water end-use data from 504 households and considering family-related impact and technical factors of water appliances. Results show that clothes washing and shower constitute the largest part of water end-use and water-related energy consumption, respectively. Overall simulation assesses the impact of technological improvements, behavioral modification and water-use decrease in household water-related energy use. It indicates that energy saving could reach to 1.69 * 1010 KWh per year which accounts for 24% of total energy consumption for non-production purposes, which indicate saving water could lead to saving energy. Correlation analysis are used to analyze the relative effects of factors on household water and energy use. The ratio of hand washing and frequency of shower have significant correlation respectively with water end-use and water-related energy consumption, particularly in the parched north. It is suggested to focus on considering the full cost about water resource, strengthening the development of water saving and energy-efficient water appliances, and enhancing the publicity of water saving in the next step. This paper demonstrates the linkage between water and energy in urban water end-use system, thus providing a decision-support tool for water conservation and management.

Quantifying and managing urban water-related energy use systemically: case study lessons from Australia

In this paper, three Australian case studies contribute to improved understanding of water-related energy quantification and management. A systems analysis of urban water in South East Queensland (Case Study 1) demonstrates the energy impact of water end use. In Melbourne (Case Study 2), water–energy interlinkages are explored within households. Finally, Case Study 3 in Sydney shows how abatement curves can help guide management action. Collectively, the case studies provide new information for least-cost solutions and simultaneous water and energy efficiency. The work highlights the need for frameworks to characterize and evaluate both the direct and indirect energy influences of urban water.

Quantifying water–energy links and related carbon emissions in cities

To date, key water–energy connections have not been systematically quantified. Nor has their potential for contributing to greenhouse gas mitigation been evaluated. Lack of knowledge of these links, particularly within cities, is viewed as a major limitation to energy-sensitive urban water management and integrated urban design. This paper fills part of this void. The key contribution is a new conceptual model coupled with a systematic review of the connections of influence. Drawing on Australian and international data, the results provide a structured estimate of water-related energy use and associated emissions in a hypothetical city of 1,000,000 people. This demonstrates that water-related energy use accounts for 13% of total electricity and 18% of the natural gas used by the population in the average case. This represents 9% of the total primary energy demand within Australia or 8% of total national territorial greenhouse gas emissions. Residential, industrial and commercial water-related energy use constitutes 86% of water-related greenhouse gas emissions. We conclude that urban water is a significant and overlooked lever that could significantly influence urban energy consumption.

Xxive Journées franco-suisses de médecine et santé au travail. Fribourg, 16–17 juin 2011. Résumés des communications

Residential resource use efficiency and management is a subject of interest to a number of fields spanning the physical and social sciences. Energy use for residential water heating in Australia is some five to eleven times more than the energy required to deliver urban water services. However, little is known about which activities within households contribute most significantly to water-related energy use (WRE). This work quantifies WRE use in individual households, and identifies household characteristics which contribute significantly to variation. Empirical data were collected through in-home audits, interviews and high-resolution end-use water flow meters for five households in Melbourne, and two in Brisbane, Australia. This was used to characterise 139 parameters describing household occupancy characteristics, behaviours, technologies, and structural and environmental aspects of influence. Mathematical material flow analysis (MMFA) modelling was conducted for individual water and energy use subsystems within each household. WRE use ranged from 7 to 21 kWh hh−1 d−1 (13–24% of total household energy use in Melbourne and 76–79% in Brisbane). Detailed end use analysis of the five Melbourne households showed that shower use (11–61% WRE), hot water system efficiency losses (8–31% WRE) and clothes washer usage (4–17% WRE) contributed most to differences in WRE between households. Findings highlighted shower use as a consistent influence on WRE across households, and suggest further investigation of shower programs as a potentially effective demand management measure for both water and energy in households. The work highlights the importance of consistent messaging for both water and energy efficiency, and suggests that a focus on both human and technical characteristics of households is needed for effective management of combined water and energy use.

Integrated Policy and Planning for Water and Energy

We are faced with chronic water and energy vulnerabilities. Some argue that we will face two crises in the 21st century: a water crisis and an energy crisis (Brown 1998, 2003, Flavin 1999, Feffer 2008). Water will become increasingly scarce as water tables drop due to over-consumption and water quality will continue to deteriorate as a result of excessive contamination. Further, the present energy regime’s dependence on non-renewable sources has added considerable stress to the environment, including the prospect of climate change (Intergovernmental Panel on Climate Change 2007). We are amidst a situation where we could be easily blamed for compromising the ability of future generations to meet their needs. This paper first briefly describes a need for understanding the integrated considerations of water and energy in resource planning, especially during droughts. After introducing a conceptual framework of the water-energy integration, this paper reviews the results of a national survey of energy and water departments to see how these synergic benefits are explored at the state level. Lessons learned from our case studies serve as useful guidelines for state water-energy planning and program development. Finally, as an example case of the water-energy nexus, the concept of desalination is introduced with its implication on energy demand.