Energy Intensity of Water: Literature Suggests Increasing Interest Despite Limited and Inconsistent Data

Author(s):  
Kathleen C. Hallett

Water agencies use energy to pump, treat, and distribute potable water. Wastewater treatment plants use energy to collect, treat, and discharge wastewater. The energy intensity of water—the energy embedded in a unit of water delivered—varies considerably depending on the water source, the location and size of the agency’s service area, and the treatment technology employed. The frequency at which agencies collect energy use data also varies, as does the degree to which those data are available. Available estimates of the energy intensity of water also vary greatly. There is a growing recognition within the water and energy communities that new water supplies will likely be increasingly energy intensive and that water conservation efforts will thus result in energy savings. As a result, there is increasing interest in understanding baseline energy use, projected energy use, and opportunities for reducing energy consumption by water and wastewater agencies. The collection of additional, more consistent and more granular data is essential to gaining this understanding.”

2013 ◽  
Author(s):  
Jill B. Kjellsson ◽  
David Greene ◽  
Raj Bhattarai ◽  
Michael E. Webber

Nationally, 4% of electricity usage goes towards moving and treating water and wastewater. The energy intensity of the water and wastewater utility sector is affected by many factors including water source, water quality, and the distance and elevation that water must be transported. Furthermore, energy accounts for 10% or more of a utility’s total operating cost, suggesting that energy savings can account for significant cost savings. Better knowledge of where and when energy is used could support strategic energy interventions and reveal opportunities for efficiency. Accordingly, this investigation quantifies energy intensity by process and type, including electricity and natural gas, and explores the time-varying nature of electric energy consumption for potable water distribution using the Austin Water Utility (AWU) in Austin, Texas as a case study. This research found that most of energy consumed by the AWU is for pumping throughout the distribution network (57%) and at lift stations (10%) while potable water treatment accounts for the least (5%). Though the focus is site specific, the methodology shown herein can be applied to other utilities with sufficient data.


Author(s):  
Kelly M. Twomey ◽  
Michael E. Webber

Previous analyses have concluded that the United State’s water sector uses over 3% of national electricity consumption for the production, conveyance, and treatment of water and wastewater and as much as 10% when considering the energy required for on-site heating, cooling, pumping, and softening of water for end-use. The energy intensity of water is influenced by factors such as source water quality, its proximity to a water treatment facility and end-use, its intended end-use and sanitation level, as well as its conveyance to and treatment at a wastewater treatment facility. Since these requirements differ by geographic location, climate, season, and local water quality standards, the energy consumption of regional water systems vary significantly. While national studies have aggregated averages for the energy use and energy intensity of various stages of the of the US water system, these estimates do not capture the wide disparity between regional water systems. For instance, 19 percent of California’s total electricity generation is used to withdraw, collect, convey, treat, distribute, and prepare water for end-use, nearly doubling the national average. Much of this electricity is used to move water over high elevations and across long distances from water-rich to water-stressed regions of the state. Potable water received by users in Southern California has typically been pumped as far as 450 miles, and lifted nearly 2000ft over the system’s highest point in the Tehachapi Mountains. Consequently, the energy intensity of San Diego County’s water is approximately 11,000 kWh per million gallons for pumping treatment and distribution, as compared to the US average which is estimated to be in the vicinity of 1,500–2,000 kWh per million gallons. With added pressures on the state’s long-haul transfer systems from population growth and growing interest in energy-intensive desalination, this margin will likely increase. This manuscript consists of a first-order analysis to quantify the energy embedded in the US public water supply, which is the primary water source to residential, commercial, and municipal users. Our analysis finds that energy use associated with the public water supply is 4.7% of the nation’s annual primary energy and 6.1% of national electricity consumption, respectively. Public water and wastewater pumping, treatment, and distribution, as well as commercial and residential water-heating were considered in this preliminary work. End-use energy requirements associated with water for municipal, industrial, and self-supplied sectors (i.e. agriculture, thermoelectric, mining, etc.) were not included in this analysis.


Author(s):  
Aman Majid ◽  
Iliana Cardenes ◽  
Conrad Zorn ◽  
Tom Russell ◽  
Keith Colquhoun ◽  
...  

The water and wastewater sectors are energy-intensive, and so a growing number of utility companies are seeking to identify opportunities to reduce energy use. Though England’s water sector is of international interest, in particular due to the early experience with privatisation, for the time being very little published data on energy usage exists. We analyse telemetry data from Thames Water Utilities Ltd. (TWUL), which is the largest water and wastewater company in the UK and serves one of the largest mega-cities in the world, London. In our analysis, we (1) break down sectoral energy use into their components, (2) present a statistical method to analyse the long-term trends in use, as well as the seasonality and irregular effects in the data, (3) derive energy-intensity (kWh m3) figures for the system, and (4) compare the energy-intensity of the network against other regions in the world. Our results show that electricity use grew during the period 2009 to 2014 due to capacity expansions to deal with growing water demand and storm water flooding. The energy-intensity of the system is within the range of reported figures for systems in other OECD countries. Plans to improve the efficiency of the system could yield benefits in lower the energy-intensity, but the overall energy saving would be temporary as external pressures from population and climate change are driving up water and energy use.


Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 225 ◽  
Author(s):  
Aman Majid ◽  
Iliana Cardenes ◽  
Conrad Zorn ◽  
Tom Russell ◽  
Keith Colquhoun ◽  
...  

The water and wastewater sectors of England and Wales (E&W) are energy-intensive. Although E&W’s water sector is of international interest, in particular due to the early experience with privatisation, for the time being, few published data on energy usage exist. We analysed telemetry energy-use data from Thames Water Utilities Ltd. (TWUL), the largest water and wastewater company in the UK, which serves one of the largest mega-cities in the world, London. In our analysis, we: (1) break down energy use into their components; (2) present a statistical approach to handling seasonal and random cycles in data; and (3) derive energy-intensity (kWh m−3) metrics and compare them with other regions in the world. We show that electricity use in the sector grew by around 10.8 ± 0.4% year−1 as the utility coped with growing demands and stormwater flooding. The energy-intensity of water services in each of the utility’s service zone was measured in the range 0.46–0.92 kWh m−3. Plans to improve the efficiency of the system could yield benefits in lower energy-intensity, but the overall energy saving would be temporary as external pressures from population and climate change are driving up water and energy use.


Author(s):  
Xiaobo Xue Romeiko

Energy shortage and climate change call for sustainable water and wastewater infrastructure capable of simultaneously recovering energy, mitigating greenhouse gas emissions, and protecting public health. Although energy and greenhouse gas emissions of water and wastewater infrastructure are extensively studied, the human health impacts of innovative infrastructure designed under the principles of decentralization and resource recovery are not fully understood. In order to fill this knowledge gap, this study assesses and compares the health impacts of three representative systems by integrating life cycle and microbial risk assessment approaches. This study found that the decentralized system options, such as on-site septic tank and composting or urine diverting toilets, presented much lower life cycle cancer and noncancer impacts than the centralized system. The microbial risks of decentralized systems options were also lower than those of the centralized system. Moreover, life cycle cancer and noncancer impacts contributed to approximately 95% of total health impacts, while microbial risks were associated with the remaining 5%. Additionally, the variability and sensitivity assessment indicated that reducing energy use of wastewater treatment and water distribution is effective in mitigating total health damages of the centralized system, while reducing energy use of water treatment is effective in mitigating total health damages of the decentralized systems.


2018 ◽  
Vol 6 (3) ◽  
Author(s):  
Arie Herlambang

Clean water to poor communities who live in crowded municipal area is stillexpensive and a luxury. This condition is evidenced by the number of people whouse ground water for their daily water, because water taps still seems expensivefor them. Diarrheal disease is still relatively high for Indonesia, where nearly 16thousand people suffer from diarrhea due to poor sanitation. To help the poor inthe city, there are several alternative technologies that can be applied to publicaccess to clean water and adequate low-cost, including ground water treatmenttechnology with a filter system equipped with an ultraviolet sterilizer, or ozonegenerators, or using ultrafiltration, if possible can also use the reverse osmosismembrane that for fresh water. Arsinum is the best alternative should be chosenfor fulfilled potable water in slump area.Keywords : Sanitation, water treatment technology, portable water, low-cost, slump area


1982 ◽  
Vol 14 (1-2) ◽  
pp. 121-133
Author(s):  
C Forsberg ◽  
B Hawerman ◽  
B Hultman

Experience from advanced municipal wastewater treatment plants and recovery of polluted waters are described for the last ten years in Sweden. Except in municipalities with large recipients, the urban population is served by treatment plants with combined biological and chemical treatment. Most of these plants are post-precipitation plants. Several modified operational modes have been developed in order to improve the removal efficiencies of pollutants and to reduce the costs. Results are presented on the recovery of specially investigated lakes with a lowered supply of total phosphorus and organic matter.


Author(s):  
Elias Marvinney ◽  
Alissa Kendall

Abstract Purpose California’s Central Valley produces more than 75% of global commercial almond supply, making the life cycle performance of almond production in California of global interest. This article describes the life cycle assessment of California almond production using a Scalable, Process-based, Agronomically Responsive Cropping System Life Cycle Assessment (SPARCS-LCA) model that includes crop responses to orchard management and modeling of California’s water supply and biomass energy infrastructure. Methods A spatially and temporally resolved LCA model was developed to reflect the regional climate, resource, and agronomic conditions across California’s Central Valley by hydrologic subregion (San Joaquin Valley, Sacramento Valley, and Tulare Lake regions). The model couples a LCA framework with region-specific data, including water supply infrastructure and economics, crop productivity response models, and dynamic co-product markets, to characterize the environmental performance of California almonds. Previous LCAs of California almond found that irrigation and management of co-products were most influential in determining life cycle CO2eq emissions and energy intensity of California almond production, and both have experienced extensive changes since previous studies due to drought and changing regulatory conditions, making them a focus of sensitivity and scenario analysis. Results and discussion Results using economic allocation show that 1 kg of hulled, brown-skin almond kernel at post-harvest facility gate causes 1.92 kg CO2eq (GWP100), 50.9 MJ energy use, and 4820 L freshwater use, with regional ranges of 2.0–2.69 kg CO2eq, 42.7–59.4 MJ, and 4540–5150 L, respectively. With a substitution approach for co-product allocation, 1 kg almond kernel results in 1.23 kg CO2eq, 18.05 MJ energy use, and 4804 L freshwater use, with regional ranges of 0.51–1.95 kg CO2eq, 3.68–36.5 MJ, and 4521–5140 L, respectively. Almond freshwater use is comparable with other nut crops in California and globally. Results showed significant variability across subregions. While the San Joaquin Valley performed best in most impact categories, the Tulare Lake region produced the lowest eutrophication impacts. Conclusion While CO2eq and energy intensity of almond production increased over previous estimates, so too did credits to the system for displacement of dairy feed. These changes result from a more comprehensive model scope and improved assumptions, as well as drought-related increases in groundwater depth and associated energy demand, and decreased utilization of biomass residues for energy recovery due to closure of bioenergy plants in California. The variation among different impact categories between subregions and over time highlight the need for spatially and temporally resolved agricultural LCA.


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