Understanding the Impact of Spot Market Electricity Price on Wastewater Asset Management Strategy

Abstract

Development of an advanced pumping control scheme is one of the useful methods that can be applied in operational optimisation of wastewater pumps. Optimisation of pumping control can benefit the utility by overall cost saving using different electricity pricing schemes from the energy market. As electricity prices can be varied based on the spot market in some countries such as Australia, the consideration of operating the pumps at the most favourable electricity price, when managed correctly, can offer remarkable savings. This paper provides understanding on the electricity spot price behaviour of South Australia in the National Electricity Market (NEM). Half-hourly electricity spot price data of over 22 years from January 1999 to June 2021 were analysed to investigate the key characteristics of spot prices, including seasonality (intraday, intraweek and seasonal price patterns), spiky behaviour and occurrences of negative prices. In addition, the possible impacts of other factors on electricity spot prices such as electricity demand and weather conditions on pump control were examined. Results indicate a strong relationship between electricity demand and spot price with the Pearson correlation coefficient up to R = 0.95, and extreme high spot prices tended to occur on scorching days with the maximum temperature above 35 °C when air-conditioner usage was high. This paper also explains the importance of electricity spot prices in the wastewater pump on/off operations and analyses opportunities for cost savings by including electricity spot price forecasts as an input of the smart controller to enhance the efficiency of the real-time pumping control.