Global energy consumption for desalination and wastewater treatment

An estimated 2 billion people across the globe lack access to a safe source of drinking water, while 3.6 billion people are not connected to safely managed sanitation. Expansion of technologies for drinking water and wastewater treatment is key to tackling global challenges in water supply and sanitation. Unconventional water resources, such as desalination and wastewater reuse, are also increasingly being adopted to alleviate water scarcity.

Modelling the current energy use of these technologies is essential to improve our understanding of the interdependencies between the water and energy sectors, and to prevent conflicts between mitigation of anthropogenic climate change, energy security and alleviation of global water scarcity. However, most research on energy-for-water has been conducted at local to regional scales, with inter-comparisons limited to a few cities or countries worldwide. Previous studies have also typically lacked spatial or temporal distribution, limiting their application in larger-scale assessments.

The aim of this research is to estimate global energy consumption for desalination and wastewater treatment at 5 arcmin resolution. Preliminary model results show that desalination required 0.74 – 1.04 EJ in 2015 to produce 29.8 km³ of freshwater, while 0.30 – 0.79 EJ were consumed in the same year to treat 186.4 km³ of wastewater. Large uncertainties in energy consumption for wastewater treatment are mostly caused by lack of data on advanced purification. The gridded output of our model may enable spatial representation of these processes in Integrated Assessment Models and Energy Supply Models, and the evaluation of future energy demands towards global clean water provision. Future work aims to shine light on global hotspots of energy consumption for clean water supply and the effects of unconventional water resources on the water-energy nexus.