An analysis of dynamic modelling of renewable energy sources for wastewater pumping stations in Cape Town

Abstract

This dissertation studies renewable energy sources of solar photovoltaic and wind turbines systems to attain self-sustainability for wastewater pumping within the wastewater treatment process as a potential green replacement to that of electric or diesel power systems currently in our city environment today. The data of wastewater pumping stations in Cape Town, South Africa are presented as case studies. In recent years, Cape Town has also encountered a severe drought lasting from 2015 until 2018. South Africa has for several decades experienced rolling blackouts as a result of total dependency on grid energy, with Cape Town not being exempted, placing a serious focus on these two critical resources, namely water and energy. There is consensus that the treatment of wastewater is estimated to account for 1% of the energy consumption of national grids around the world, however very few countries have undertaken this kind of study. It is also estimated that wastewater pumping accounts for 12 – 19% of the total energy expenditure within the treatment process. This dissertation looks to establish a benchmark for the energy intensity (kWh/m³) wastewater pumping stations in Cape Town by collating the daily energy consumption against effluent pumped and comparing this to other countries. This dissertation also analyses the dynamic modelling of renewable energy sources towards the application and feasibility of pumping at wastewater pumping stations located across Cape Town. Hybrid Optimisation of Multiple Energy Resources (HOMER) issued to carry out simulations based on the historic energy load profiles of these wastewater pumping stations. The results indicate that Cape Town has an average specific wastewater pumping energy intensity of 0.25 kWh/m³, furthermore, that wind and solar energy, as simulated, present viable opportunities for energy supplies of wastewater pumping station in Cape Town. The results could further imply that such technologies are implemented in the foreseeable future.