Carbon footprint of water conveyance versus desalination as alternatives to expand water supply

This research compares the cost and the carbon footprint of two potential water supply options: seawater desalination and water conveyance from remote locations. System dynamic modeling is used to simulate the water system and future water needs of the arid Las Vegas Valley (LVV), located in Nevada, US as an example case. Since, LVV is not a coastal city, the seawater desalination supply option is actually a paper-transfer agreement between Nevada and California or Mexico in which Nevada will build a desalination plant in the Pacific Ocean of California or Mexico and in turn withdraw an equivalent amount of Colorado River water from Lake Mead. The conveyance option involves pumping water from a remote location, located 421 km away. The analysis showed that the energy requirement for the seawater desalination (0.53 million MW h/year) is 96% higher as compared to the water conveyance (0.27 million MW h/year). Similarly, associated CO2 emissions for seawater desalination (0.25 million metric tons/year) is 47.5% higher than that for water conveyance (0.17 million metric tons/year). However, the unit cost of water for seawater desalination is lower ($0.56/m3) compared to the water conveyance ($0.68/m3).

► Desalination and conveyance from long distances compared as options for water supply.
► Carbon footprint of desalination similar to that of water conveyance for special cases.
► Carbon footprint of water is smaller when fuels used generate less greenhouse gasses.