Climate Change Implications For US Energy Supply And Use - Climate Change and Energy Supply and Use - page 24

BOX 2
Four Major Assessment Reports in Late 2011 Examined Water Use for
Electricity Generation, Related to Concerns about Climate Change

• Water Use for Electricity Generation and
Other Sectors; Recent Changes (1985-
2005) and Future Projections (2005-2030).
EPRI Technical Report, November 2011
• Freshwater Use by U.S. Power Plants:
Electricity's Thirst for a Precious
Resource, Energy and Water in a
Warming World Initiative (EW3), Union
of Concerned Scientists, November 2011

• Water for Energy: Future Water Needs
for Electricity in the Intermountain West,
Paciic Institute, November 2011
• Efects of Climate Change on Federal
Hydropower, Oak Ridge National Labo-
ratory for DOE, draft July 2011, inal
forthcoming

Studies conducted during 2011 indicate that there is a high likelihood that water
shortages will limit power plant electricity production in many regions (See Box 2 ) ,
pointing to growing regional water constraints, particularly in the Southwest, Southeast,
as a result of chronic or seasonal drought, growing populations, and increasing demand
for water for various uses, at least seasonally (UCS, 2011).
More speciically, the EPRI technical report includes scenario-based projections of
water demand for 2030, related to drivers of demand rather than of supply. It inds that
one-quarter of existing power generation facilities, or roughly 240,000 MW of genera-
tion capacity nationwide, are in counties associated with some type of water sustain-
ability concern. The most signiicant future water stresses are in the South, Southwest,
and Great Plains regions, with water use for electricity generation growing especially
rapidly in the east (Figure 8 ), although water sustainability concerns are seen in many
regions (Figure 9 ) .
The report by the Union of Concerned Scientists starts with a number of cases where
droughts and/or heat waves since 2006 have required reductions in electricity genera-
tion, with Texas as a current case in 2011 (Figure 10 ) . It notes that droughts and heat
waves are projected to be more frequent and more severe with climate change, which
is a reason for concern not only in the U.S. west but also in a number of locations in the
east (Figure 11 ) . The report also notes that (a) water intensity varies regionally, along
with water availability, and (b) low-carbon electricity technologies are not necessarily
low-water in their input requirements. Finally, the report includes a host of ideas about
how to reduce risks and threatsOne efort to compare operational water consumption
for diferent sources of electricity is Figure 12 (SRREN, 2011).

Effects of rising ambient air and water temperatures
In addition to the problem of water availability, there are issues related to an increase
in water temperature. Use of warmer water reduces the eiciency of thermal power