  Thermoelectric power production at risk, owing to current and projected water
scarcity and rising stream temperatures, is assessed for the contiguous United
States at decadal scales. Regional water scarcity is driven by climate
variability and change, as well as by multi-sector water demand. While a
planning horizon of zero to about thirty years is occasionally prescribed by
stakeholders, the challenges to risk assessment at these scales include the
difficulty in delineating decadal climate trends from intrinsic natural or
multiple model variability. Current generation global climate or earth system
models are not credible at the spatial resolutions of power plants, especially
for surface water quantity and stream temperatures, which further exacerbates
the assessment challenge. Population changes, which are difficult to project,
cannot serve as adequate proxies for changes in the water demand across
sectors. The hypothesis that robust assessments of power production at risk are
possible, despite the uncertainties, has been examined as a proof of concept.
An approach is presented for delineating water scarcity and temperature from
climate models, observations and population storylines, as well as for
assessing power production at risk by examining geospatial correlations of
power plant locations within regions where the usable water supply for energy
production happens to be scarcer and warmer. Our analyses showed that in the
near term, more than 200 counties are likely to be exposed to water scarcity in
the next three decades. Further, we noticed that stream gauges in more than
five counties in the 2030s and ten counties in the 2040s showed a significant
increase in water temperature, which exceeded the power plant effluent
temperature threshold set by the EPA. Power plants in South Carolina,
Louisiana, and Texas are likely to be vulnerable owing to climate-driven water
stresses.
