Energy Production, Conversion, Transmission and Distribution, Policy, Planning, and Mitigation Processes – General Considerations

3.14 Energy Production, Conversion, Transmission and Distribution, Policy, Planning, and Mitigation Processes – General Considerations: Large Energy Projects, Efficiency, and Vulnerability ZN Vrontisi, National Technical University of Athens, Athens, Greece Ó 2013 Elsevier Inc. All rights reserved.

3.14.1 3.14.2 3.14.2.1 3.14.2.2 3.14.2.2.1 3.14.2.2.2 3.14.3 References

3.14.1

207 207 208 208 208 213 214 214

Introduction Vulnerability to Climate Variability Vulnerability of Energy Sector Vulnerability of Large Energy Projects Thermal Power Plants Solar Power Plants Conclusions

Introduction

Anthropogenic climate change has been an increasingly interesting issue of research during the last decades, primarily aiming at the identification of future-related threats and possible ways of alleviating the related harmful effects. Since anthropogenic climate change was acknowledged by the academic society, policies to combat climate change have partly been included in the decision-making agenda. Following the Stern review (2007), which recognized early action for decreasing greenhouse gas emissions as the most cost-efficient path for a successful climate policy, numerous policies have been introduced that aim at the mitigation of greenhouse gas emissions. One leading example is the launch of the Energy Package for 2020 (http://ec.europa.eu/clima/policies/package/ index_en.htm) by the European Commission which identifies the crucial role of the energy sector in taking action against climate variability. Nowadays, climate policy has already been incorporated in energy policy formulation, and the attempt to internalize the external societal costs of emissions has proved crucial for the formation of the future energy mix of the world. While a low-carbon power generation system and an overall ‘greener’ energy mix have been set as a priority in decision making, measures to adapt to a changing global environment have not gained much attention. Academic research on the vulnerability of the energy sector to climate variability has been limited so far and thus has not facilitated a thorough understanding of the impacts of climate variability to energy systems. Moreover, the location-specific impacts of climate variability in combination with the different energy mix of each location make the assessment of climate variability effects and of possible adaptation measures extremely case-specific and difficult to generalize. The prevailing uncertainty related to timing and intensity of climatic effects complicates the proper incorporation of adaptation parameters in future energy planning. Energy infrastructure in most regions of the world is soon to be reinforced, replanned, and rebuilt owing to increasing demand from developing countries and decreasing lifespan or revised environmental regulations in developed countries, thus bringing a period of large investment plants in the energy

Climate Vulnerability, Volume 3

sector. Climate vulnerability should be appropriately considered at all levels of energy infrastructure planning, especially because of the very long lifetime (40–80 years) of energy systems. An attempt is made in this chapter to specify the impacts of climate variability on large energy projects and propose possible climate-proof solutions for future energy projects. In this chapter, a brief review on the impacts of climatic variability on different forms of energy supply is given in order for the reader to understand the context in which large energy projects are under climate-related risks. The analysis then focuses on thermal power plants and in particular on nuclear plants and concentrated solar thermal plants, because both technologies are integrated only in a centralized and large-scale manner. An attempt is also made to provide a number of concrete adaptation measures and proposals to policy makers. The scope of this analysis is to raise awareness and provide some insights with regard to the vulnerability to climate change of large, centralized power plants; consequently, energy security can be enhanced along with prioritization of optimum win–win mitigation and adaptation plans.

3.14.2

Vulnerability to Climate Variability

As mentioned, there is still a high level of uncertainty as regards the various aspects of climate variability and the intensity of the related effects, while the future pace of climatic change shows the highest uncertainty levels. This article will be based on robust scientific and empirical climatic evidence that has been observed currently or is expected in the future. In brief, the main observed anthropogenic climate change according to the IPPC (http://www.ipcc.ch/) 2007 report includes the following: 1. An increase of the global average temperature and an increased rate of warming. 2. Snow, ice, and frozen ground are affected by increase melting, instability of permafrost, and reduced tropical glaciers.

http://dx.doi.org/10.1016/B978-0-12-384703-4.00323-3

207

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3. 4. 5. 6.

Increased or decreased runoff according to the location. Increased frequency of extreme events. More frequent heat waves, less cold days and nights. More frequent heavy precipitation events possibly leading to floods. 7. More frequent intense cyclone activity. 8. Sea level has risen an average of 18 cm since the nineteenth century. Projections for expected future climate variability are based on the above-mentioned observations and greatly depend on the time scale under analysis. Projected changes in surface temperature, wind patterns, solar radiation, sea level, permafrost, and rainfall along with extreme weather events are expected to occur depending on time and space. Certain weather variables of the long-term future climate projections deviate less than others; for example, average temperatures are more robust than the expected levels of precipitation. Anthropogenic climate change as described will affect all aspects of biological, economic, and social life. Assessment of the vulnerability of different sectors, countries, and societies to climate change is necessary in order to prepare against the identified threats. Science is expected to play a vital role in the conceptualization of a sustainable future, both by means of prevention (i.e., mitigation of greenhouse gases and other forms of pollution) and by means of adaptation to the changing conditions. The energy sector is expected to be widely affected by climate variability. At the same time, energy systems are considered central to mitigation policies and thus particular attention must be given to the synergies of mitigation and adaptation measures. Ebinger and Vergana (2011) in their report for the World Bank publications on the climate impacts on energy systems summarize all major impacts on energy resources and energy supply in Table 1. All different sources of energy are affected by climate variability at different levels of intensity. Large energy projects, namely large-scale installations of any form of energy supply, are the dominant feature of current energy systems. Climate vulnerability poses an additional factor of uncertainty which may increase investment costs, if impacts are assessed during the planning of the system, or increase operation costs, if no strategic adaptation measures are taken. Large energy projects generally constitute a significant factor of climate vulnerability for their respective energy systems. Centralized energy systems, that is, systems that feature large energy projects with central dispatching and no geographical dispersion, are found more susceptible to threats of climate variability because of the limited range of diversification and an inability of efficient adjustment. Additionally, energy systems are usually designed for relatively stable weather conditions and planners rarely take into account probable weather extremes. However, central planning and large-scale installations enable proper risk management and economies of scale with regard to the cost of adaptation measures. The parameters affecting the vulnerability of different types of large energy projects should be appropriately assessed. This assessment will facilitate the achievement of long-term energy security goals that are a prerequisite for economic activities and social welfare.

3.14.2.1

Vulnerability of Energy Sector

Recent research on the vulnerability of the energy sector to climate variability categorizes the impacts in two broad categories, namely impacts on resource endowments and impacts on energy supply. Impacts on factor endowments refer to increased fluctuations of energy inputs and unusual disturbances on supply of primary energy sources. Impacts on energy supply refer to vulnerabilities and inefficiencies of the transformation sector and in particular on the technologies that convert primary energy sources to energy services. Large energy projects are a central part of today’s energy systems and are found to be particularly vulnerable as compared with smaller and decentralized projects.

3.14.2.2 3.14.2.2.1

Vulnerability of Large Energy Projects Thermal Power Plants

Extreme weather conditions have been detrimental to the operation of thermal power plants in the past. For example, in the heat waves of 2003, 2006, and 2009 in Europe some nuclear plants had to cut output, triggering fears of blackouts. In 2003, the heat wave in France caused the cut of 4000 MW because of a forced reduction in capacity and/or the turning off of 17 nuclear reactors (IHT 2007). In 2006, the European heat wave caused disruption to the power systems of France, Spain, and Germany because nuclear plants had to cut output or were given special exemption licenses to discharge water above the permitted temperature into the rivers. In 2009, France again had to cut power and import electricity from the United Kingdom similar to 2003 (UCTE 2004). The economic implications of the described failure to adapt to the changing environment were significant, because power utilities had to purchase electricity from the power market in order to meet their contract obligations at prices even 10 times higher than the average seasonal price. In the following paragraphs, a description of the factors of vulnerability of thermal plants is given. Water Requirements for Cooling Purposes Thermoelectric generation requires large amounts of water for its operation. Water is required mainly for cooling purposes but also for water loss in boiler operation, flue gas desulfurization, and ash handling systems. According to statistics (Eureau 2009), it is estimated that 43% of water demand in Europe comes from cooling requirements in power plants. For specific European countries, the share of water demand for cooling in electricity production is even higher, for example in Hungary and Poland where the respective shares are 91 and 71%. As a result of the significant water dependence, considerations are already being made during the planning procedure of new power plants, for example the rejected permission of a new power plant in Arizona because of concerns about water withdrawal from the local aquifer, as noted in the USCCSP report (USCCSP 2008). In the USCCSP 2007 report, it is estimated that around 94.6 l of water are required for the production of each kilowatt hour by a steam cycle process. Feeley et al. (2008) provide a thorough description of freshwater withdrawal and consumption factors for different power technologies, indicating

Relevant climate impacts Item

General

Climate change impacts on resource endowment Hydropower Runoff

Wind power Biofuels

Wind field characteristics, changes in wind resource Crop response to climate change

Solar power

Atmospheric transmissivity

Wave and tidal energy

Ocean climate

Climate change impacts on energy supply Hydropower Water availability and seasonality Wind power

Alteration in wind speed frequency distribution

Biofuels

Reduced transformation efficiency Reduced solar cell efficiency

Solar power Thermal power plants

Generation cycle efficiency Cooling water availability

Specific

Additional

Impacts on the energy sector

Quantity (þ/) Seasonal flows high and low flows Extreme events Changes in density, wind speed Increased wind variability Crop yield Agro-ecological zones shift

Erosion Siltation

Reduced firm energy Increased variability Increased uncertainty Increased uncertainty

Water content Cloudiness Cloud characteristics Wind field characteristics No effect on tides Water resource variability Increased uncertainty of expected energy output Increased uncertainty of energy output

High temperatures reduced thermal generation efficiency Solar cell efficiency reduced by higher temperatures Reduced efficiency Increased water needs, for example during heat waves

Changes in vegetation (might change roughness and available wind) Pests Water demand Drought, frost, fires, storms

Increased uncertainty Increased frequency of extreme events Positive or negative impacts

Strong nonlinearity between wind speed and wave power

Increased uncertainty Increased frequency of extreme events

Impact on the grid Wasting excessive generation Extreme events Short life span reduces risk associated with climate change Extreme events Extreme events

Increased uncertainty Revision of system reliability Revision of transmission needs Increased uncertainty on energy output

Extreme events Extreme events

Reduced energy generated Increased uncertainty Reduced energy generated Increased uncertainty Reduced energy generated Increased uncertainty

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Table 1

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the significance of the choice of power technology type and also the diversification of plants as regards the actual consumption of water in relation to withdrawal. According to Feeley et al. (2008), values of withdrawal for US power plants range from 0.004 gal kWh1 for air-cooled natural gas combined-cycle plants to 27.113 gal kWh1 for coal plants with once-through cooling systems. As regards actual water consumption, factor values range from 0.002 gal kWh1 for natural gas combinedcycle plants with once-through cooling system to 0.804 gal kWh1 for coal plants with a cooling pond. Nuclear plants require substantially more water to cool or condense the coolant that is used to cool the reactor core by transferring heat from the core to the turbines. For example, a nuclear plant may require 2 billion cubic meters of water each year for cooling purposes. As a result, many scientists emphasize the contradiction between the positive role of nuclear energy in climate change mitigation efforts and the significant impacts of climate change to the operation of nuclear plants. By building new nuclear power plants to avoid an increase of greenhouse gas emissions, the energy system could become more vulnerable to increased ambient and water temperatures or even to extreme weather events like floods (e.g., the Fukushima accident in Japan was exacerbated by the floods in the installations caused by the tsunami). Because a certain level of anthropogenic climatic changes cannot be avoided, decision makers and future investors should consider this aspect of nuclear energy. The type of cooling technology of the power plant is an important factor for its water requirements and hence its vulnerability to climate changes. Three main types of cooling technologies can be found in most power plants, namely oncethrough cooling technology, once-through cooling with cooling tower, and closed circuit cooling. These can be seen in the figure by Koch and Vögele (2009). Once-through systems result in higher temperatures of the water body into which used water is being discharged because the water for cooling is discharged directly to the same water body after leaving the condenser. Excess temperature of the water body can be avoided by installing a cooling tower. The cooling tower uses an air stream in order to cool down the water before discharge, while a large share of the waste heat produced during the thermal cycle of the power plant is discharged through evaporation, thus leaving a lower quantity of water back to the water body.

Once-through cooling

Figure 1

Closed circuit systems recirculate the cooled water back to the condenser, thus decreasing water withdrawal and affecting the temperature of the water body in a minimum way. As Koch and Vögele (2009) state, however, closed circuit systems relate to lower plant efficiencies. Koch and Vögele (2009) conclude that power plants with closed circuit cooling systems are less vulnerable to fluctuations of temperature. In particular, they find that in a closed circuit system the increase in water demand is only 2% whereas plants with a once-through cooling system present an increase in water demand of 30%. In case water temperature is taken into consideration, power plants with closed circuit systems show a similar increase (Figure 1). As mentioned in the case of nuclear power technology, planning of a low-carbon power system should incorporate factors of vulnerability to irreversible future climate change. Carbon capture and storage (CCS) technology features similar problems because it can double the demand for water of a thermal power plant, mainly for two reasons. First, the operation of a CCS system requires large amounts of electricity thus increasing the water demand of the actual installation if this additional power is supplied by conventional thermal sources. Second, an additional cooling load is created caused by the heat generated by the amine CO2 absorption and the compressing of CO2. According to NETL (2009) and Moore (2010), by 2030 CCS technology can increase water consumption of the US power sector by 80%. Chandel et al. (2011) give lower estimations of the increase in water consumption caused by the integration of CCS technology. In their paper, they analyze the impacts of climate policy-driven future power systems on freshwater use. In their analysis, the power mix alters according to the value of the carbon price, and all new thermal power plants are assumed to use recirculating cooling systems. They find that in a carbonconstrained power system with increased renewable and nuclear penetration, freshwater withdrawals are 2–14% lower than in business-as-usual (BAU) scenario. Actual consumption of freshwater is found near BAU levels in all cases except when the carbon price exceeds US$50 ton1 CO2 and retrofitting of CCS is found cost-efficient. In Chandel et al. (2011), however, CCS technology contributes to a 15% increase in water consumption of the US power system. On the contrary, photovoltaic and wind technology contribute to a 20% reduction of water demand if renewables are substituted for coal plants.

Once-through cooling with cooling tower

Closed circuit cooling

Energy Production, Conversion, Transmission and Distribution, Policy, Planning, and Mitigation Processes

On a European level, Rubbelke and Vogele (2010) examine different scenarios to assess the impact of climatic changes to electricity exchange. They find that in a scenario with increased water scarcity, France will be obliged to reduce its electricity exports because of the large share of nuclear in the country’s power mix, which makes it vulnerable to climate variability. Spain and Switzerland will also have to limit nuclear production and subsequent exports. The power system in Germany, although prone to cooling problems, is found easier to adapt. Other countries, like Italy, are affected by reduced cheap imports from France, and so on and thus have to increase domestic supply or find alternative exporters. Adaptation measures include the consideration of efficient cooling systems and even the installation of water reuse systems, with appropriate treatment in order to protect equipment from increased saline levels. Moreover, once old power plants are to be decommissioned, they are expected to be replaced by more efficient ones that will require lesser amounts of water (and primary energy resources) for the production of 1 kW. Recirculating cooling systems or dry and hybrid air cooling are favorable in terms of water consumption. The latter, however, should not be installed in power plants located in regions expected to face high temperatures, as Chandel et al. (2011) note. An increase in ambient temperatures can also increase water temperatures and affect the plant’s cooling efficiency even in wet cooling systems by increasing the demand for water. Integrated gasification combined-cycle and oxyfuel plants are considered more efficient technologies in terms of water withdrawal and consumption, especially if CCS technology is to be used in order to minimize greenhouse gas emissions. The impact of CCS retrofit on water demand is reduced if amine systems are replaced with postcombustion capture technologies. Overall, research efforts are being made to develop technologies that are less water intensive. Feeley et al. (2008) emphasize the importance of R&D programs that aim at developing technologies that will enable improved water resource management practices in the power sector. Planning of maintenance shutdowns should take into consideration temperature and water supply parameters; maintenance could be scheduled during months of increased temperatures like July or August in order to avoid unexpected capacity cuts (Rubbelke and Vogele 2010). Moreover, the optimum location of new plants must consider expected long-term impacts of climate variability to the neighboring water body, such as river runoffs, and avoid water-stressed areas. Power companies that face difficulties related to water supply or legislation on permissible temperature of water discharges have respected their contractual agreements with their customers by purchasing electricity from other utilities. This highlights the importance of power mix diversification, especially in areas that are expected to be affected severely by climate variability. Different forms of power production are affected in a different manner by climate change and thus security of supply can be achieved only by a combination of production technologies. A region highly dependent on nuclear production or thermal power plants with CCS must consider a diversification of future power plant investments in order to avoid extended outages.

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For more information on the water dependence of power plants, see the special IEEE report http://spectrum.ieee.org/ static/special-report-water-vs-energy. Figure 2 comes from the analysis undertaken by IEEE in its report and shows the water and carbon intensity of power technologies. Impacts of Sea Level Rise and Intense Foods on Plant Operation and Security Nuclear reactors and other thermal plants are often located along the coasts because of their requirements for water aimed for cooling. A world map of the sites of nuclear plants, which has been created from the extensive database of the International Atomic Energy Agency (http://gcmd.nasa.gov/records/ GCMD_GNV181.html), shows that a considerable number of nuclear plants are located along coastlines. Nuclear power plants are given special consideration, owing to the dangerous consequences of possible damage to their equipment and installations. However, regular thermal power plants are also often located on coasts and may face similar difficulties to the ones described below. A look at past events can distinctly reveal the vulnerability of nuclear plants relating to their location. The catastrophic accident in Fukushima nuclear plant in Japan occurred mainly because of the tsunami wave that ensued after the earthquake, whereas floods (e.g., Missouri River in 2011), storms, and hurricanes (e.g., Katrina in 2005) have posed significant risks to nuclear plant operation on several occasions. Problems related to the events mentioned may include fatal malfunctions of the reactors, the fire-safety systems, or the security and/or communication systems, thus putting in danger the safe operation of the power plants. During past events it has been seen that it is crucial to maintain access to external provision of electric power in order to be able to cool the reactor’s cores. Moreover, extreme weather events may cause more floods and thus put in danger the plant’s operation by flooding installations, damaging equipment, and stopping communication between the plant and external operational systems. This was the case in the 1999 flooding event in Le Blayais nuclear plant in France and more moderately in 2003 again in France, where according to Kopytko and Perkins (2011), mud and debris in the water used for cooling purposes caused damage to the cooling system and led to the shutting down of nuclear plants in the affected area. Climatic change is expected to result in a rise of sea level, thus causing concerns for all infrastructure located on the coastlines. Although power plants are usually located a few meters or tens of meters above the sea and the mean sea level rise is not expected to reach that magnitude, sea level rise may in some cases interfere with the functionality of coastal installations (e.g., Committee on National Security Implications of Climate Change for US Naval Forces) through waves and risen sea level that is created from storms and hurricanes. The latter are actually expected to have a more severe impact on coastal installations through flooding and wind damage whereas mean sea level rise is expected to create coast erosion and inundation at reactor sites. Other impacts to nuclear production caused by climatic variability may include increased salt sprays that have a long-term effect of corrosion on the plant’s equipment. Measures to reduce the vulnerability of thermal plants to sea level rise and extreme weather events

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1.0

ONCETHROUGH COOLING*

Capacity factor** indicates how much energy a source actually produces as a percentage of what it would generate if it were operating at its peak output 24 h a day.

COOLING TOWER

COAL

CARBON (kg Kwh−1)

0.8

NUCLEAR

92%

COAL

80%

GEOTHERMAL

73%

SOLAR THERMAL 73%

0.6

NATURAL GAS

HYDROELECTRIC 42%

NATURAL GAS ONCETHROUGH COOLING*

0.4

COOLING TOWER

PHOTOVOLTAIC WIND 0

WIND

21%

PHOTOVOLTAIC

15%

Geothermal technology produces its carbon footprint from the carbon dioxide dissolved in the hot water that powers it.

Wind and photovoltaic power systems consume water and produce cardon only in the manufacturing of the equipment.

0.2

60%

ONCETHROUGH COOLING*

1

NUCLEAR COOLING TOWER

2

SOLAR THERMAL 3

Hydroelectric water GEOTHERMAL consumption is from evaporation of the reservoir HYDROELECTRIC behind the dam.

4

5

6

WATER CONSUMED (l kWh−1) *Once-through cooling dumps heat into surface water and returns the water to its source. Relatively little water is actually consumed by evaporation, but much more water must be available for the power plant to withdraw. **Circle size indicates capacity factor.

Figure 2

include careful siting for new investments and advanced weather monitoring systems for all new and existing plants that can enhance timeous reactions. As Kopytko and Perkins (2011) conclude in their research findings on the vulnerability of US coastal nuclear plants, most plants are found to have a high coastal vulnerability index mainly because of tides, storms, and increased sea level and less owing to erosion and waves. However, they conclude that coastal plants may face less severe consequences from climatic variability than inland plants especially if power demand is taken into consideration, because inland plants may have to force shutdown in periods of peak demand. On the other hand, costs related to adaptation measures or mere restructuring of damages is considerablely high. Consequently, they pose the important questions on whether nuclear energy can be a safe and economically efficient mitigation tool, especially because climate variability is limiting the sites suitable for building nuclear plants. Air Temperature Impacts on Plant Efficiency In addition to increased water demand for cooling purposes, increasing ambient air temperature can affect the plant’s

thermal efficiency in a direct manner. The impacts from increased ambient temperature are closely related to each other because the heat differential between the engine and the external environment is reduced; hence, the plant’s efficiency is reduced. In particular, ambient temperature affects the efficiency of the Brayton cycle, which in turn affects power output and fuel consumption by increasing the temperature of the airspecific volume of the compressor. Davcock et al. (2004) have examined the impacts of ambient temperature on gas turbine performance. Their results indicate that a 33  C increase in ambient temperature would decrease power output and heat rate of an open cycle gas turbine by 24 and 8.4%, respectively. Similar results are found by Kopac and Hilaci (2007) whereby under a 30  C increase the overall efficiency of the plant is reduced by 4%. The analysis also indicates that ambient temperature has significant impacts on the exergy efficiency and irreversibility rate of the plant’s boiler but lower effects on the outer components of the plant. Nevertheless, temperature increases caused by climate change are not expected to reach 30  C as examined by the studies mentioned; hence, impacts on thermal efficiency are expected to be low.

Energy Production, Conversion, Transmission and Distribution, Policy, Planning, and Mitigation Processes

Schaeffer et al. (2008) have examined the energy supply impacts of two main IPCC climate scenarios for Brazil. They find only 2% power output reduction for gas plants, thus conclude that impacts of increased temperature in Brazil’s electricity supply are of an insignificant magnitude. Lineraud et al. (2009) find that a 1  C temperature increase would affect thermal cooling and thus plant’s power output by 0.8% for nuclear and 0.6% for gas plants. Though the results of the research work described previously shows low percentage levels of efficiency loss caused by an increase in ambient temperature, the impact in absolute terms of power output is significant and would require either new investments or would undermine the systems’ security of supply.

3.14.2.2.2

Solar Power Plants

Renewable energy plants and in particular large power installations are susceptible to the impacts of climate change, similarly to thermal power plants discussed. Apart from resource vulnerability, which is directly related to climatic conditions owing to the intermittent nature of renewable sources, the installations can be vulnerable to external conditions. Concentrated solar thermal power (CSP) plants are a promising type of renewable energy. CSP plants collect and concentrate direct sunlight through mirrors (either flat or parabolic) and then focus sunlight to an absorber tube. The central receivers at the top of the absorber tower contain a heat transfer fluid that is heated by direct sunlight and then used to produce superheated steam for the steam turbine generator and produce electricity. A key feature of this technology is the ability of thermal storage which enables operation even in the absence of direct sunlight. On the other hand, CSP technology requires direct sunlight and thus is more susceptible to solar irradiation

Figure 3

213

conditions than PV plants. Because of the requirement of direct sunlight, arid areas are ideal for CSP installations, where solar irradiation is high, direct normal isolation is high, and weather is typically cloudless. CSP production is based on thermal power generation and thus is characterized by similar aspects of climate vulnerability especially regarding ambient temperature increase. CSP installations are mainly located in arid areas and thus are well prepared for high temperatures. However, climate variability is expected to have distinctive impacts in desert environments; therefore, CSP development must take these into consideration. In addition, because of the intermittency of the energy input and the remoteness of the installations, CSP plant vulnerability to climate change should be assessed before largescale development of this technology. Huge CSP plants are mentioned widely in the recent energy policy agenda. For example the Desertec project in North Africa is expected to supply clean and cost-efficient electricity to North Africa and Europe by 2050. In order to ensure higher levels of energy security for CSP energy systems, climate change vulnerability must be taken into consideration during planning procedures and the appropriate adaptation measures should be taken (Figure 3). Reduced Visibility Effects Sand storms are frequently found in deserts, for example, the Sahara, and are expected to be more frequent in the future because of climate variability; consequently sharp decreases of visibility in areas where CSP plants are installed may affect the plant’s generation. Because CSP generation is based on direct sunlight, sand storms may cause the plant’s shutdown or reduced operation according to storage options. Problems in

214

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operation or damages of CSP plants during sand storms can be reduced with proper action of the on-site personnel. Examples of good practices include turning the mirrors upside down or covering them in order to avoid damages from sand blasting and proper cleaning of the mirrors after sand storms. On-site personnel are expected to be familiar with similar actions for optimal maintenance and operation of CSP plants on a daily basis, because mirrors will require cleaning in particular hours of the day owing to regular desert winds. Another reason for reduced visibility and hence for reduced plant power output is increased and prolonged cloudiness. In particular, CSP plants rely on direct solar radiation and thus their operation ceases with diffused sunlight. For this reason, CSP plants are mainly developed in dry areas with short cloud coverage, but climate change may affect cloudiness owing to increased water precipitation, etc. Thermal storage capacity may reduce vulnerability to climatic conditions and substantially increase the plant’s efficiency but with a subsequent increase of capital costs. Proper geographical dispersion would also reduce vulnerability of energy systems with high shares of CSP generation. Temperature Increase Effects CSP plants are based on thermal generation of a steam turbine which is, as described above, vulnerable to increases of ambient air and water temperature. With regard to water cooling demand, the impacts on CSP plants are expected to be minimal because most CSP plants rely on dry cooling owing to their arid siting. However, ambient temperature determines the efficiency of dry cooling, and according to Patt et al. (2010) a temperature increase from 30 to 50  C will result in a 3–9% efficiency decrease. Because water cooling is not widely used in CSP plants, no plant outages are expected to be forced by plant operators owing to legislation that protects water temperature of rivers/ lakes as in the case of nuclear and other thermal plants. Research and development for new advanced technologies for parabolic or flat collectors, thermal storage, and dry cooling will determine CSP overall efficiency and vulnerability to climate change. Related considerations must be made prior to finalization of large investment plants that will determine the future energy systems of entire regions.

Awareness, as regards the specific impacts to each energy source, may result in the development of different adaptation responses. Awareness rising from all the different stakeholders is important in order to achieve synergies and incorporate climate risk assessment in all levels of decision making and operation. Scientists, consumers, plant personnel, policy makers, and investors should all cooperate and acknowledge the criticality of adaptation. Scientists relate to new and improved technologies in power generation, more resilient to key climatic impacts. Consumers relate to demand responses and the development of small-scale distributed generation. Plant personnel are responsible for emergency planning and appropriate maintenance of the plant (i.e., cleaning, on-site drainage, and runoff). Finally, policy makers and investors relate to technology and location choice, both critical parameters for energy system vulnerability. Technological responses relate to specialized research and development programs that will form the required knowledge capacity to achieve protection, better design, and new resilient, efficient, or even ‘climate-proof’ technologies. Some technological options in this direction are already available whereas others are in the development or demonstration stage. Technological measures include targeted retrofitting, for example, of dry cooling systems for thermal power plants instead of water cooling, or reinforcing of existing infrastructure and developing protective infrastructure such as increasing dam heights and enlarging floodgates. Adaptation actions include strategic assessment of investments, for example in terms of location choice, as well as changes in operation and maintenance of plants in order to incorporate best practices (e.g., regular cleaning of CSP mirrors) or even include improved meteorological forecasting tools. Moreover, the impacts of climate variability may be reduced by introducing different generation technologies in the energy system, in particular technologies with different facets of climate vulnerability, and/or by introducing geographical dispersion. Diversification of the energy mix is important for hedging climate-related risks and creating resilient energy systems. Decentralized generation will also enhance climate resilience of energy systems, owing to geographical dispersion and reduced probability of large-scale outages.

3.14.3

References

Conclusions

Energy systems have a key role in mitigating climate change but are also susceptible to climate changes. These two aspects should be central to determining energy policy and the energy systems of the future, along with cost-efficiency considerations and security of supply. Although the role of the energy sector in climate variability mitigation efforts is well understood and widely discussed, adaptation issues are not yet a high-priority policy agenda. It is important to build adaptive capacity that will ensure a secure energy system in spite of unavoidable climatic changes, thus research and development of new energy technologies must also focus on creating adaptive and resilient technologies. It is important to develop a basic knowledge capacity with regard to climate variability impacts on energy systems to avoid extremely vulnerable locations or types of technology.

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