The cost–greenhouse gas emission nexus for water distribution systems including the consideration of energy generating infrastructure: an integrated conceptual optimization framework and review of literature

Abstract

The increased release of greenhouse-gas (GHG) emissions associated with human activities causing climate change is one of the most significant problems faced by human-kind. Water distribution systems (WDS), whilst providing an essential service to society, are responsible for the generation of significant amounts of GHGs. In response, the minimization of GHG emissions associated with WDSs has become a research focus. In this paper, a critical review of previous research is provided, summarizing research progress and highlighting research needs in this emergent and important area. This is done within the context of the water distribution system cost-emissions nexus (WCEN) conceptual framework, which is a novel conceptual framework that considers the interaction between all components required to accurately evaluate the costs and greenhouse gas (GHG) emissions associated with water distribution systems (WDSs) in an integrated fashion. Key findings from this review indicate that future research should (1) include the use of time-dependent emissions factors (EFs), which would allow the scheduling of pumps at times of lower emissions intense energy to be considered; (2) include the modeling of seasonally variable water demands; (3) include greater consideration of the hydraulic simulation process, such as using seasonal extended period simulations; (4) include greater consideration of the management of pumping operations at the design stage, instead of solely focusing on changes in infrastructure design to reduce costs and GHG emissions; (5) include consideration of the effects that external policies, such as carbon taxes and present value discounting, have on the trade-offs between costs and GHG emissions.

Improved genetic algorithm optimization of water distribution system design by incorporating domain knowledge

“…One application area where this is the case of is the design of water distribution systems (WDSs) (Marchi et al, 2014a,b;Stokes et al, 2014). Over the past two decades, a variety of EAs have been applied to this problem, as detailed in Zheng et al (2013a).…”

“…Zhang et al, 2013;Housh et al, 2013) and nonoptimization based WDS design approaches (e.g. Sitzenfrei et al, 2013).…”

Comparison of Pumping Regimes for Water Distribution Systems to Minimize Cost and Greenhouse Gases

“…Objectives of pumping electricity cost and GHG emissions are considered separately and the characteristics of the optimal operating strategies for the objectives are compared. Multi-objective optimization of cost and GHG emissions for WDSs has been extensively covered in Wu et al (2010a); Wu et al (2010b); Wu et al (2011); Stokes et al (2012b); Stokes et al (2012c); Wu et al (2012a); Wu et al (2012b); Wu et al, (2013);and Stokes et al (2014). This research is different in that it considers the effect of the different pump operating regimes on each objective individually.…”

Framework for the optimization of operation and design of systems with different alternative water sources

“…A discount rate for costs or GHG emissions may be set in the government policy sub-component [G] which will impact the ongoing costs and emissions in a life-cycle analysis. The discount rate may be informed by economists, such as the Stern review which recommends low discount rates for projects that lead to the production of GHG emissions (Stern 2006). Information about the performance of each potential solution in relation to the objectives and constraints is provided to the optimization algorithm in order to find the best solutions.…”

“…When selecting discount rates, consideration should be given to whether both economic costs and GHG emissions are discounted, if they have the same discount rate, and if intergenerational equity is taken into account using social discount rates. Various social discount rates have been proposed for discounting ongoing costs; the Intergovernmental Panel on Climate Change (IPCC) adopted a zero discount rate over a period of 100 years, after which no consideration for future costs or benefits is given (Fearnside 2002), other suggestions include 1.4% (Stern 2006) for projects that are impacted by climate change, 2-4% (Weitzman 2007) and a time declining rate (Gollier and Weitzman 2010). Wu et al (2010b) gave an example of a sensitivity analysis of discount rates in the optimization of WDS design for minimization of costs and GHG emissions.…”