Quantification of renewable electricity generation in the Australian water industry

Abstract

Water and wastewater utilities have increasingly invested in on-site renewable electricity generation to address rising energy costs, reduce greenhouse gas emissions and meet renewable energy targets. Yet, the extent to which renewable electricity sources are currently adopted by these utilities is unknown. This work quantifies the current level of renewable electricity generated by Australian water and wastewater utilities, the renewable electricity sources adopted, and their overall contribution to the total water industry electricity generation. In 2018, the Australian water industry generated 18% (279 GWh/y) of its electricity demand from on-site renewable electricity sources. Biogas from anaerobic digestion of wastewater and sewage sludge accounted for 67% (187 GWh/y) of the electricity generated, followed by hydropower (30%, 84 GWh/y), biogas from co-digestion and waste-to-energy through anaerobic digestion of organic feedstock (2%, 5.5 GWh/y), and solar photovoltaic (1%, 2.2 GWh/y). Further recovery of biogas from wastewater and sewage sludge might be limited by the economies of scale. However, hydropower could still be an untapped resource. Solar photovoltaic did not contribute significantly to the electricity generation of the industry, and space requirements to install large systems might limit its future development to a more significant level of electricity generation. To increase electricity generation and achieve the renewable energy targets, external energy sources will need to be imported, such as organic feedstock in co-digestion systems or waste-to-energy through anaerobic digestion facilities.