Scenarios for Low Carbon and Low Water Electric Power Plant Operations: Implications for Upstream Water Use

Electric
sector water use, in particular for thermoelectric operations,
is a critical component of the water-energy nexus. On a life cycle
basis per unit of electricity generated, operational (e.g., cooling
system) water use is substantially higher than water demands for the
fuel cycle (e.g., natural gas and coal) and power plant manufacturing
(e.g., equipment and construction). However, could shifting toward
low carbon and low water electric power operations create trade-offs
across the electricity life cycle? We compare business-as-usual with
scenarios of carbon reductions and water constraints using the MARKet
ALlocation (MARKAL) energy system model. Our scenarios show that,
for water withdrawals, the trade-offs are minimal: operational water
use accounts for over 95% of life cycle withdrawals. For water consumption,
however, this analysis identifies potential trade-offs under some
scenarios. Nationally, water use for the fuel cycle and power plant
manufacturing can reach up to 26% of the total life cycle consumption.
In the western United States, nonoperational consumption can even
exceed operational demands. In particular, water use for biomass feedstock
irrigation and manufacturing/construction of solar power facilities
could increase with high deployment. As the United States moves toward
lower carbon electric power operations, consideration of shifting
water demands can help avoid unintended consequences.