Geoscience Reference
In-Depth Information
BOX 3
Implications of Climate Change for Hydropower Supply
IPCC's Fourth Assessment Report and SAP 4.5
note that projected efects of climate change on
regional rain and snowfall, both in terms of long-
term changes in totals and changes in seasonal
variability, are virtually certain to have implica-
tions for hydropower production in some US re-
gions. Since 2008, most of the new research on
energy/water connections has focused on con-
sumptive uses of water by thermal power plants
(see section III B) rather than water resource avail-
ability for hydropower, but ongoing research at
ORNL for a draft report on federal hydropower
(see Box
1
for reference), based on CMIP 3 ensem-
bles of SRES scenarios, suggests several regional
trends - varying seasonally, spatially, and tempo-
rally, with large uncertainty bounds.
In very general terms, this research indicates
higher annual runof in the US northwest to 2040,
mainly in the spring, but a possibility of slightly
decreasing hydropower generation in the longer
term. It shows considerable variation across the
west and southwest, with an overall slightly de-
creasing overall trend but with dry water years
more frequent. In the southeast, it inds that dry
years will occur signiicantly more often, while
normal and wet years will decrease somewhat, as-
sociated with an overall slight decrease in hydro-
power generation but an increase in annual and
seasonal variability in generation. The northern
Great Plains region is the only US region project-
ed to become weter, with a potential to increase
hydropower generation.
rely on river low series that are derived by downscaled GCM model data assessing pre-
cipitation and temperature under various emission scenarios again relecting the need
for beter down scaled data sets (also see Box
4
).
As noted in earlier assessments, it is anticipated that extreme events, air temperature,
and atmospheric conditions will directly impact the eiciency, performance, and eco-
nomics of all renewable energy technologies (SAP 4.5, 2008). At the same time, increased
peak demand for cooling during the day and late afternoon may in some cases make
utility scale PV and CSP more atractive and economic in particular regions. The body of
research on these impacts continues to grow, generally indicating a variety of impacts -
positive and negative - on potentials at a ine-grained (local) scale but very litle impact
on aggregate potentials at the national scale. In other words, reduced potentials in some
areas are likely to be balanced by increased potentials in others; the main Impact on
renewable energy potentials is likely to be a shift in national/regional paterns of poten-
tials. But there is still a gap in the availability of very localized forecasts that can inform
how speciic sites or regions may be afected.
Over the past ive years, industry, utilities, and governments have also received more
practical exposure to the challenges that environmental changes can bring to energy se-
curity and reliability and the relative unpredictability of these impacts on renewable en-
ergy supply. These speciic examples have provided more case studies and insights for
the research community to beter understand the potential 'relationship between climate
