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Key Economic Sectors and Services Chapter 10
d
ischarge restrictions, and occasional exemptions might be an institutional
adaptation (Eisenack and Stecker, 2012). Though it is easier to plan for
changing climatic conditions and select the site and the conforming
cost-efficient cooling technology for new builds, response options are
more limited for existing power plants, especially for those toward the
end of their economic lifetime.
Climate change impacts on thermal efficiency and cooling water
availability affect nuclear power plants as well but the safety regulations
are stricter than for fossil-fired plants (Williams and Toth, 2013). A range
of alternative cooling options are available to deal with water deficiency,
ranging from re-using wastewater and recovering evaporated water
(Feeley III et al., 2008) to installing dry cooling (EPA, 2001).
The implications of EWEs for nuclear plants can be severe if not properly
addressed. Reliable interconnection (on-site power and instrumentation
connections) of intact key components (reactor vessel, cooling equipment,
control instruments, back-up generators) is indispensable for the safe
operation and/or shutdown of a nuclear reactor. For most of the existing
global nuclear fleet, a reliable connection to the grid for power to run
cooling systems and control instruments in emergency situations is
another crucial item (IAEA, 2011). Several EWEs can damage the
components or disrupt their interconnections. Preventive and protective
measures include technical and engineering solutions (circuit insulation,
shielding, flood protection) and adjusting operation to extreme conditions
(reduced capacity, shutdown) (Williams and Toth, 2013).
Hydropower is by far the largest of renewable energy sources in the
current electricity mix. It is projected to remain important in the future,
irrespective of the climate change mitigation targets in many countries
(IEA, 2010a,b). The resource base of hydropower is the hydrologic cycle
driven by prevailing climate and topology. The former makes the
resource base and hence hydropower generation highly dependent on
future changes in climate and related changes in extreme weather
events (Ebinger and Vergara, 2011; Mukheibir, 2013).
Assessing the impacts of climate change on hydropower generation is
highly complex. A series of nonlinear and region-specific changes in
mean annual and seasonal precipitation and temperatures, the resulting
evapotranspiration losses, shifts in the share of precipitation falling as
snow and the timing of its release from high elevation, and the climate
response of glaciers make resource estimates difficult (see Chapters 2
and 3) while regional changes in water demand due to changes in
population and economic activities (especially irrigation demand for
agriculture) present competition for water resources that are hard to
project (see Section 10.3). Further complications stem from the possibly
increasing need to combine hydropower generation with changing flood
control and ecological (minimum dependable flow) objectives induced
by changing climate regimes. For hydropower locations, adaption to
climate change to maintain output has been reported; in Ethiopia, Block
and Strzepek (2012) report that capital expenditures through 2050 may
either decrease by approximately 3% under extreme wet scenarios or
increase by up to 4% under a severe dry scenario. In the Zambezi river
basin, hydropower may fall by 10% by 2030, and by 35% by 2050 under
the driest scenario (Strzepek et al., 2012). Lower generation is likely in
the upstream power stations of the Zambezi basin and increases are
likely downstream (Fant et al., 2013).
F
ocusing on the possible impacts of climate change on hydroelectricity
and the adaptation options in the sector in response to the changes in
the amount, the seasonal and interannual variations of available water,
and in other demands, the conclusion from the literature is that the
overall impacts of climate change and EWEs on hydropower generation
by 2050 is expected to be slightly positive in most regions (e.g., in Asia,
by 0.27%) and negative in some (e.g., in Europe, by –0.16%), with
diverging patterns across regions, watersheds within regions, and even
river basins within watersheds (IPCC, 2011). Adaptation responses and
planning tools for long-term hydrogeneration may need to be enhanced
to cope with slow but persistent shifts in water availability. Short-term
management models may need to be enhanced to deal with the impacts
of EWEs. A series of hard (raising dam walls, adding bypass channels)
and soft (adjusting water release) measures are available to protect the
related infrastructure (dams, channels, turbines, etc.) and optimize incomes
by timing generation when electricity prices are high (Mukheibir, 2013).
Solar energy is expected to increase from its currently small share in
the global energy balance across a wide range of mitigation scenarios
(IEA, 2008, 2009, 2010a,b). The three main types of technologies for
harnessing energy from insolation include thermal heating (TH; by flat
plate, evacuated tube, and unglazed collectors), photovoltaic (PV) cells
(crystalline silicon and thin film technologies), and concentrating solar
power (CSP; power tower and power trough producing heat to drive a
steam turbine for generating electricity). The increasing body of literature
exploring the vulnerability and adaptation options of solar technologies
to climate change and EWEs is reviewed by Patt et al. (2013).
All types of solar energy are sensitive to changes in climatic attributes
that directly or indirectly influence the amount of insolation reaching
them. If cloudiness increases under climate change (WGI AR5 Chapters
11, 12), the intensity of solar radiation and hence the output of heat or
electricity would be reduced. Efficiency losses in cloudy conditions are
less for technologies that can operate with diffuse light (evacuated tube
collectors for TH, PV collectors with rough surface). Since diffuse light
cannot be concentrated, CSP output would cease under cloudy conditions
but the easy and relatively inexpensive possibility to store heat reduces
this vulnerability if sufficient volume of heat storage is installed (Khosla,
2008; Richter et al., 2009).
The exposure of sensitive material to harsh weather conditions is another
source of vulnerability for all types of solar technologies. Windstorms
can damage the mounting structures directly and the conversion units
by flying debris, whereby technologies with smaller surface areas are
less vulnerable. Hail can also cause material damage and thus reduced
output and increased need for repair. Depending on regional conditions,
strong wind can deposit sand and dust on the collector’s surface, reducing
efficiency and increasing the need for cleaning.
Climate change and EWE hazards per se do not pose any particular
constraints for the future deployment of solar technologies. Technological
development continues in all three solar technologies toward new
designs, models, and materials. An objective of these development efforts
is to make the next generation of solar technologies less vulnerable to
existing physical challenges, changing climatic conditions, and the
impacts of EWEs. Technological development also results in a diverse
portfolio of models to choose from according to the climatic and