Multi-objective optimization of energy and greenhouse gas emissions in water pumping and treatment

Abstract

A large part of operating costs in urban water supply networks is usually due to energy use, mostly in the form of electricity consumption. There is growing pressure to reduce energy use to help save operational costs and reduce carbon emissions. However, in practice, reducing these costs has proved to be challenging because of the complexity of the systems. Indeed, many water utilities have concluded that they cannot practically achieve further energy savings in the operation of their water supply systems. This study shows how a hybrid linear and multi-objective optimization approach can be used to identify key energy consumption elements in a water supply system, and then evaluate the amount of investment needed to achieve significant operational gains at those points in the supply network. In application to the water supply system for the city of London, the method has shown that up to 18% savings in daily energy consumption are achievable. The optimal results are sensitive to discount rate and the financial value placed on greenhouse gas emissions. Valuation of greenhouse gas emissions is necessary to incentivise high levels of energy efficiency. The methodology can be used to inform planning and investment decisions, with specific focus on reducing energy consumption, for existing urban water supply systems.

Internalizing Sustainability into Research Practices of Higher Education Institutions: Case of a Research University in Taiwan

“…Moreover, multi-objective optimization theory [171] suggests optimal ways for the optimization of two or more conflicting objectives. Therefore, this theory is commonly used to resolve multi-objective optimization problems in macroeconomic policy decisions, such as energy use and emission reduction [172,173], and economic development and environment [169,170]. Thus, the government could consider multi-objective optimization when making rational decisions with respect to energy, the environment, and economic development channeled at setting a direction to enhance sustainability.…”

Water- and Energy-Efficient Appliances for Circular Water Economy: Conceptual Framework Development and Analysis of Greenhouse Gas Emissions and Water Consumption

“…Closing the loop on the circular water economy is accomplished through the recognition of all water as a resource rather than a waste product following its use. Although macroscale circular water economy has been addressed primarily as direct and indirect potable reuse and recovery of nutrients in cities and regions , and utility-scale improvements in water and energy efficiency, − microscale (i.e., residential household) circular water economy has not been adequately studied . In the United States (U.S.), the residential sector is the largest consumer of retail electricity; it uses 38% of the electricity produced by the electric power sector − and is one of the most energy-intensive water sectors because of heating water. , While demand-side energy–water nexus was analyzed based on the environmental abatement cost for upgrading baseline appliances to EnergyStar or WaterSense appliances certified by the U.S. government-sponsored programs, − the application to the concept of linear economy is limited because the analyses do not include advanced modular technologies implemented for household water reuse and recycling, the recycling of materials, or the heterogeneity of appliances driven by various policies and codes.…”

“…Furthermore, variations in the supply side of the energy–water nexus, − such as temporal and spatial changes in the emission factors of energy sources and energy mix, − the policies and regulations affecting water and energy utilities, and the use of renewable energy, can impact household GHG emissions and trade-offs with water consumption . Multiobjective optimization and trade-off analysis have been conducted on the production system; − however, in residential consumption, there is a trade-off between the choice of various household appliances and their impacts on GHG emissions and water consumption because of the differences in the capital and operational costs of each appliance, as well as different opportunities for water reuse and recycling. Thus, system optimization at the household scale can help choose energy- and water-efficient appliances, technologies, and scenarios to promote a circular water economy.…”

Design and performance analysis of a renewable pumping system for treated wastewater to reuse in the Moroccan desert

“…However, due to an increase in the price of oil in the international market, harmful emissions from burning of it, high maintenance cost, and short lifetime have been forced to find some alternative. Renewable energy has the potential to limit the use of fossil fuels, as researchers are shifting toward a solar-powered water pumping system (Singh et al 2017;Cardenes et al 2020;Verma et al 2020). As solar is available in large amounts and almost everywhere even in remote locations.…”

“…Journal of Water and Climate Change Vol 00 No 0, 72.5.2. Operating by thermal power stationsThe amount of fuel needed to generate 1 kWh is estimated at 206.3 g(Cardenes et al 2020). The estimated amount of CO 2 emitted from the pump station operation depends on the following equation: Emitted value of CO 2 ¼ Quantity of fuel  Emission factor(2)…”