Water System Modifications for the Optimal Integrated Energy-Water Systems Design Considering the Energy-Water-Carbon Nexus

One of the biggest challenges to global stability and economic growth is climate change. Numerous research has been carried out considering the nexus between energy and carbon emissions in an integrated energy-water system. The water sector and its resultant carbon emissions are mostly neglected even though the amount of carbon discharge from water systems contributes significantly to global warming. The carbon footprint from various water sources should also be assessed to establish optimal integrated systems with minimal environmental impact. This paper aims to study the effects of carbon emissions from the water sector on the design of integrated energy-water systems. A framework consisting of the Water Pinch Planning Diagram (WPPD) technique is proposed to calculate the carbon emission from the processing of two water sources i.e., freshwater, and treated water in an integrated energy-water system. Design modifications on the water processes are proposed to achieve the desired carbon emissions target for the integrated system. The results from the case study show that freshwater supply and use in the manufacturing process emits 86% more carbon as compared to treated water because its supply volume to fulfill the water demand is higher by 66%. Water sources supply volume was adjusted accordingly, and a 5% carbon emissions reduction has been achieved. Considering carbon emissions from the water sources and the carbon discharge from the energy system can provide more realistic targets for energy, water, and carbon emission for the optimal design of an integrated energy-water system.