Water distribution system greenhouse gas emissions reduction by considering the use of time-dependent emissions factors

Due to the very large amount of options available during the design and operation of water distribution systems, optimisation algorithms have become a popular way to optimise the set of available options. However, as optimisation requires the WDS to be modelled, inaccuracies can be introduced. One of these inaccuracies is the use of static emissions factors, used to calculate the greenhouse gas emissions from the use of electricity. The emission intensity of electricity is dependent on the combination of generation types and is therefore time dependent. This paper introduces the use of a novel time-dependent emissions factor curve, which is used to estimate the time-dependent behaviour of emission intensities associated with electricity usage. Time-dependent emissions factors are compared against more conventional static emissions factors by using a case study. In order to compare the affect of using time-dependent emissions factors, two types of pump operational management are used: trigger levels and pump scheduling. Results suggest that while the tradeoffs between the costs and GHG emissions of optimal solutions are not changed by using time-dependent emissions factors, they may help with the further reduction of operational GHG emissions by identifying the use of high emissions intensity electricity usageChristopher S. Stokes, Holger R. Maier, Angus R. Simpso