Quantification of the water-use reduction associated with the transition from coal to natural gas in the US electricity sector

The transition from coal to natural gas and renewables in the electricity sector and the rise of unconventional shale gas extraction are likely to affect water usage throughout the US. While new natural-gas power plants use less water than coal-fired power plants, shale gas extraction through hydraulic fracturing has increased water utilization and intensity. We integrated water and energy use data to quantify the intensity of water use in the US throughout the electricity's lifecycle. We show that in spite of the rise of water use for hydraulic fracturing, during 2013-2016 the overall annual water withdrawal (8.74 × 10¹⁰ m³) and consumption (1.75 × 10⁹ m³) for coal were larger than those of natural gas (4.55 × 10¹⁰ m³, and 1.07 × 10⁹ m³, respectively). We find that during this period, for every MWh of electricity that has been generated with natural gas instead of coal, there has been a reduction of ∼1 m³ in water consumption and ∼40 m³ in water withdrawal. Examining plant locations spatially, we find that only a small proportion of net electricity generation takes place in water stressed areas, while a large proportion of both coal (37%) and natural gas (50%) are extracted in water stressed areas. We also show that the growing contribution of renewable energy technologies such as wind and solar will reduce water consumption at an even greater magnitude than the transition from coal to natural gas, eliminating much of water withdrawals and consumption for electricity generation in the US.