Evaluating options for Balancing the Water-Electricity Nexus in California: Part 1 – Securing Water Availability

Evaluating options for balancing the water–electricity nexus in California: Part 2—Greenhouse gas and renewable energy utilization impacts

Integrated concepts in water reuse: managing global water needs

The world's supply of fresh water is finite and is threatened by pollution. Rising demands for water to supply agriculture, industry and cities are leading to competition over the allocation of limited fresh water resources. This paper examines how water reuse increases the available supply of water and enables human needs to be met with less fresh water. The paper is illustrated with water reuse case studies in agriculture, urban areas, industry and water resource supplementation in Australia and other countries. The links between water reuse and sustainable water management are examined. Water conservation and water reuse produce substantial environmental benefits, arising from reductions in water diversions, and reductions in the impacts of wastewater discharges on environmental water quality. Some examples are presented demonstrating the environmental benefits in quantitative terms. The paper also describes the economic and environmental benefits identified in a number of recent integrated water cycle planning studies in Australia.

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.

Parts of the USA are facing impending shortages of freshwater. One proposed solution is the construction of desalination plants to turn seawater into freshwater. Although seawater desalination plants are widely used in the Middle East, especially Saudi Arabia, there are few desalination plants in the USA. In 2003, Tampa Bay Water built the largest desalination plant in North America. Persistent operating problems and escalating costs have caused the utility to re-evaluate its reliance on the seawater desalination plant as part of a long-term regional water supply strategy. In addition, environmental effects of the plant are uncertain. Advances in reverse osmosis technology have significantly reduced desalination costs. However, desalination of seawater is still more expensive than other freshwater supply sources and demand management measures. With time and research, seawater desalination may prove to be a sustainable, cost-effective source of new freshwater supplies, especially if plants are coupled with renewable energy sources. Until then, the development of small-scale groundwater desalination plants, the re-use of water, water conservation, and a more efficient allocation of water through higher prices and rising block rates will be important strategies in meeting growing water demand. Moreover, it is important to improve the coordination between water supply planning and land use planning as populations continue to increase.

In August 2002, North Carolina passed the Central Coastal Plain Capacity Use Area (CCPCUA) Rule to regulate groundwater withdrawal from the Cretaceous aquifers in order to minimize serious water level declines and salt water intrusion that have been progressively worsening in these aquifers. The major groundwater impacts are being observed in two principal aquifers, the Black Creek and Upper Cape Fear, which have been desirable sources of high-quality, low-cost drinking water throughout this 15-County region. The regulations require groundwater withdrawals from the most affected portions of the region to be limited to 1997 withdrawal rates and may be further reduced by up to 75% over a 16-year period ending in 2018. The regulations are meant to avoid permanent damage to the aquifers and to help support economic growth in the region by having a sustainable water supply through development of alternative water supplies and by promoting water conservation and reuse. The North Carolina Rural Center undertook a study to determine the effects of the CCPCUA Rule, evaluate current and future water supply needs and sources, identify water supply alternatives, and estimate the costs of compliance for 122 public water supply systems affected by this Rule. If fully implemented, the CCPCUA Rule will directly impact over 40 public water systems and will result in the elimination of 38 million gallons per day (mgd) of existing groundwater sources. Replacement of these sources and development of alternative water supplies to meet future 2020 water demand is estimated to cost more than $250 million. Alternative water sources identified by the study include: 1) development of alternate groundwater supplies from underutilized aquifers; 2) development of surface water sources; 3) regionalization of water systems to allow more efficient use of existing water supplies; 4) water conservation, demand reduction, and water reuse; and 5) non-traditional sources such as brackish water, mine dewatering supplies, horizontal collector wells, and aquifer storage and recovery. Regional cooperation will be an important opportunity, allowing economy of scale in addressing aggregate demand, cost sharing, uniform rates, and bond-issuing authority.

Water conservation and reuse in poultry processing plant—A case study

Urban communities, farms, businesses, and natural ecosystems depend upon adequate, reliable, and affordable supplies of clean water. As populations and economies grow and as climatic changes alter both water supply and demand, traditional options for meeting freshwater needs are becoming less available, reliable, and effective. As we approach peak water constraints on traditional water supplies, more efforts needed to reduce water demands through a wide range of conservation and efficiency technologies and policies, and to develop alternative, non-traditional water sources. A key factor in the adoption of these strategies is their economic feasibility; yet, only limited and often confusing data are available on their relative costs. To fill this gap, this analysis evaluates the costs of four groups of alternatives for urban supply and demand based on data and analysis in the California context: stormwater capture; water recycling and reuse; brackish and seawater desalination; and a range of water conservation and efficiency measures. We also describe some important co-benefits or avoided costs, such as reducing water withdrawals from surface water bodies or polluted runoff in coastal waterways. While difficult to quantify, such benefits are economically relevant, and we highlight areas where further research and analysis are needed to improve estimates presented here. All of the water-use efficiency options are far less costly than traditional or alternative supply systems with the exception of some of the most expensive landscape water reduction options. The water treatment and reuse systems and the urban stormwater capture projects are more costly per unit of water produced but still less expensive than seawater desalination—the most expensive option evaluated.

Urban resilience and water resilience are both increasingly relying on urban non-potable water reuse under the context of the Climate Emergency, but sound risk assessment is lacking. Compared to the state of art, the proposed framework for health risk assessment and management of urban non-potable water reuse includes (i) an additional step for establishing the context and (ii) the risk identification step being extended to introduce a description of the activities from which the hazard exposure scenarios may be built. This novel scenario-building process allows for a clear and comprehensive risk description, assessment, and treatment. The model of risk management is structured around three primary components: the decision-makers, i.e., the municipal services and the population at risk (users and workers); data elements relevant for the risk management process (reclaimed water quality, hazards, hazardous events, sites where exposure can happen, exposure routes, and activities developed by the population at risk and their vulnerabilities); and the links between the decision-makers and these elements and between the elements themselves. Its application in a representative case study shows that the framework comprehensively guides decision-making and communication to relevant stakeholders. From this practical exercise, the main recommendations were derived for risk mitigation by the municipal risk manager and the park users.

SummaryWater conservation is of particular importance for arid regions, including many Muslim-majority countries. With the added pressures of human population growth and expansion and global climate change, water conservation efforts are imperative to extending the life of current water supplies as well as to sourcing water treatment methods that are religiously congruent. We review Qur’anic verses that address water usage and conservation. We searched the English translations of the King Fahd Complex for the Printing of the Holy Qur’an and the King Saud University Electronic Moshaf Project for Qur’anic scripture related to water and water conservation. A total of 25 verses were found that related to creation, water usage for agriculture and food provision/production and as a common resource for humanity. Qur’anic scripture encourages gratitude for water and wise stewardship of this resource. Specific prohibitions against the reuse of water (e.g., treated water) were not found, and recent Islamic literature supports the use of cleansed greywater. Treated greywater may thus be an additional source for agricultural needs, thus reducing the stress placed on already limited water supplies. Water conservation falls within Qur’anic scripture.

Water reuse with Advanced Water Treatment (AWT) is increasingly appealing for urban areas seeking water supply reliability. In cities facing water scarcity, how can large-scale reuse support reliability and how do reuse operations affect water quality, energy use, and water conservation? This paper presents a systems analysis of metropolitan-scale water reuse and its effects on water supply and quality. For the case study of Los Angeles County, California, USA, hydroeconomic modeling is used to evaluate reuse as a contributor to water supply given urban water conservation, drought-induced water scarcity, and costs and benefits for supply and demand. Results indicate that AWT can be a viable source of supply especially when coupled with conservation. Across modeled scenarios, reuse provides as much as 30% of regional supplies. New water reuse with AWT becomes viable when imported water availability is 50% or less of historic values. Existing indirect potable reuse operations in the county remain important. Systemwide energy intensity of operations increases with greater reuse in the absence of water conservation. Modeled influent flow rates to wastewater treatment plants resemble historical values, but extreme flow events could pose risks. The paper offers a holistic framework to evaluate water reuse as a component of urban water management.

Blueprint for a greener city: growth need not costthe earth

In 2004, there were no industry-wide concentrate management performance standards for the types of desalination and water reuse technologies identified in the recently completed "Desalination and Water Purification Technology Roadmap". Additionally, brackish and seawater desalination and concentrate management regulations vary significantly from state-to-state, region-to-region, and internationally, in terms of both field testing and monitoring requirements. For example, the best management practices recommended for concentrate disposal in one state may not be allowed in an adjoining state. In other cases, receiving water quality criteria either do not exist, or may require a concentrate stream's quality to be significantly better than the quality of the receiving water. As desalination and water reuse become an increasingly larger part of our water supply and water use portfolio, improved guidance and standards on environmentally, ecologically, and economically sound management practices for desalination and water reuse concentrate are needed. In 2005, several organizations including the American Water Works Association, Ground Water Protection Council, Water Reuse Foundation, and the Environmental Protection Agency agreed to work cooperatively through an American Society of Civil Engineers-Environmental and Water Resources Institute task committee to develop a consensus-based assessment and provide recommendations and guidance on sound and commonly acceptable concentrate management practices for new and existing desalination and water reuse facilities of all sizes. The ASCE/EWRI task committee has worked to establish appropriate activities for 2006–2007, and this paper provides an overview of the goals, objectives, schedule, and progress to date of these efforts.

Public Attitude towards Water and Water Reuse

Energy Implications of Water Management in Cities