Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Contents lists available at ScienceDirect

Renewable and Sustainable Energy Reviews

journal homepage: www.elsevier.com/locate/rser

A comprehensive review of state-of-the-art concentrating (CSP) technologies: Current status and research trends T ⁎ ⁎ Md Tasbirul Islama, , Nazmul Hudaa, , A.B. Abdullahb, R. Saidurc,d a School of Engineering, Macquarie University, NSW 2109, Australia b School of Mechanical Engineering, University Science Malaysia (USM), Engineering Campus, 14300 Nibong Tebal, Penang, Malaysia c Research Centre for Nano-Materials and Energy Technology (RCNMET), School of Science and Technology, Sunway University, No. 5, Jalan Universiti, Bandar Sunway, Petaling Jaya 47500, Selangor Darul Ehsan, Malaysia d American University of Ras Al Khaimah, Ras Al Khaimah, United Arab Emirates

ARTICLE INFO ABSTRACT

Keywords: Concentrating solar power (CSP) has received significant attention among researchers, power-producing com- Concentrating solar power (CSP) panies and state policymakers for its bulk electricity generation capability, overcoming the intermittency of solar resources. The parabolic trough collector (PTC) and (SPT) are the two dominant CSP systems Solar thermal power plant that are either operational or in the construction stage. The USA and Spain are global leaders in CSP electricity Solar thermal electricity generation, whereas developing countries such as China and India are emerging by aggressive investment. Each year, hundreds of articles have been published on CSP. However, there is a need to observe the overall research Direct steam generation development of this field which is missing in the current body of literature. To bridge this gap, this study 1) provides a most up-to-date overview of the CSP technologies implemented across the globe, 2) reviews pre- viously published review articles on this issue to highlight major findings and 3) analyzes future research trends in the CSP research. Text mining approach is utilized to analyze and visualize the scientific landscape of the research. , solar collector and policy-level analysis are found as core topics of discussion in the previous studies. With a holistic analysis, it is found that direct steam generation (DSG) is a promising innovation which is reviewed in this study. This paper provides a comprehensive outlook on the CSP technol- ogies and its research which offers practical help to the future researchers who start to research on this topic.

1. Introduction Moreover, fossil-fuel energy sources are responsible for an increasing pace of climate change, and developing countries especially should seek Global energy and electricity consumption is increasing rapidly due alternative energy sources for their respective power sectors to mitigate to the growth in population, industrialization, and urbanization. As carbon emissions in the near future [9]. major conventional energy sources are depleting in nature and emit To eradicate such catastrophic scenario, global renewable-energy harmful emissions, the world is experiencing severe challenges in pro- initiatives show that, with the existing development of the renewable- viding a clean and sustainable to mass populations [1,2]. energy infrastructure, renewables will contribute to an overall CO2 Compared to global population growth, energy consumption is growing reduction of 30% by 2050, compared to the year 2012 [11]. From such much faster and, within the next 15–20 years’ time, electricity con- perspectives, the development, adoption, and dissemination of low- sumption will double [3,4]. The energy-consumption pattern of various carbon technologies, particularly of renewable-energy-harvesting energy sources, both conventional and renewable, will play the most technologies, has become the highest priority, to satisfy the energy important role in sustainable development, as this pattern is one of the requirement of society and contribute to a greater CO2 reduction effort critical indicators of resource use and environmental impact [5,6].At [12]. present, 80% of the global primary energy supply comes from fossil Due to the features of being green, low-cost and renewable, solar fuels (e.g. coal, liquid petroleum and natural gas), which are now being energy is widely recognized as one of the most competitive alternatives considered a depleting energy source, and are responsible for emitting among all the renewables [13]. Using the energy source, concentrating major -gas (GHG) emissions such as CO2 [1,7,8]. Fig. 1 solar power (CSP) or solar thermal electricity (STE) is a technology that shows global energy-related CO2 emissions from different fuel types. is capable of producing utility-scale electricity, offering firm capacity

⁎ Corresponding authors. E-mail addresses: [email protected], [email protected] (M.T. Islam), [email protected] (N. Huda). https://doi.org/10.1016/j.rser.2018.04.097 Received 22 November 2017; Received in revised form 11 April 2018; Accepted 15 April 2018 1364-0321/ © 2018 Elsevier Ltd. All rights reserved. M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Abbreviation TES thermal energy storage TIR total internal reflection CSP concentrating solar power USC ultra super critical CCS carbon capture and storage CF capacity factor Symbol DNI direct normal irradiance

DSG direct steam generation CO2 carbon dioxide EU European Union °C degrees celsius EPCMs encapsulated phase change materials GW gigawatt FiT feed-in tariff kW h kilowatt hour GHGs greenhouse gases kW h/m2/yr kilowatt hour per square meter per year

HRSG heat recovery steam generator kWe kilowatt hours of electricity HTF heat transfer fluid kW h/m2/day kilowatt hours per square meter per day LOCE levelized cost of electricity/ levelized cost of energy kW h/m2 kilowatt hours per square meter LSS large-scale solar kg/TJ kilograms per terajoule LFR linear Fresnel reflectors Mtoe million tonnes of oil equivalent LHSS latent heat storage system MW megawatt MENA Middle East and North m2 square meter MH metal hydride m meter NEM net energy metering mm millimeter O&M operational and maintenance MW h/m2/yr megawatt hours per square meter per year OECD Organisation for Economic Co-operation and MW h/yr megawatt hours per year Development m2/kW square meters per kilowatt

PV solar photovoltaic MWe megawatts of electricity PTC parabolic trough collectors m3/MW h cubic meters per megawatt hour PCM phase change material m2/MW h/year square meters per megawatt hour per year RETs renewable energy technologies MJ/m2/day megajoules per square meter per day RE renewable energy MJ/m2 megajoules per square meter

RSER renewable and sustainable energy reviews NOx nitrogen oxide STE solar thermal electricity SO2 sulphur dioxide SPD solar parabolic dishes TW h terawatt hours SPT solar power tower US$ United States dollar SMS simultaneous multiple surface µm micrometer

and dispatchable power on demand by integrating thermal energy [17]. Fig. 2 shows the potential of the annual CO2 reduction and the storage or in hybrid operation [14]. Considering the high energy saving number of jobs will be created under market projections of the current and high energy efficiency, CSP plants are predicted to produce a global policy, and moderate and aggressive development scenarios, in the CSP electricity contribution of 7% by the year 2030 and 25% by the year sector. According to the Solar thermal electricity Global outlook 2016 2050 [15]. It is envisioned that, with high levels of energy efficiency [14], 5% and 12% of the global electricity demand will be meet in the and advanced industry development, CSP could meet up 6% of the moderate scenario and the advanced scenario, respectively, by the year world's power demand by 2030 and 12% by 2050 [16]. Apart from the 2050. production of electricity, CSP also has tremendous potential in em- Potential locations for CSP plants around the world are generally ployment generation and reducing CO2 emissions on a global scale being identified by using the global distribution of Direct Normal Irradiance (DNI) [18]. North Africa, the Middle East, the Mediterra- nean, and vast areas in the United States including California, Arizona, Nevada, New Mexico are known as the “Sun Belt” where greater solar radiation is available from the sun. Geographically, the Belt is suitable for CSP plants, as there are massive land areas with extraordinary solar irradiation, well suited to install a large number of solar-energy har- vesting systems. By 2020, CSP is expected to be an economically competitive source of bulk power generation for peak and intermediate loads, and by 2025–2030 for base-load power [19,20]. Commercially viable CSP plants should maintain a DNI of at least 2000–2800 kW h/ m2/yr. Present commercial CSP plants are being developed based on this level of irradiance [18]. However, it is also argued that a DNI value > 1800 kW h/m2/yr is suitable for CSP plant development [21]. In the period 1984–1991, the first commercial CSP plant was con- structed in the Mojave Desert, California, the USA by Luz International Ltd. However, due to a drop in the oil price at that time, the regulatory initiatives that supported the progress of CSP collapsed. In 2006, CSP plant development initiatives were pursued in Spain and in the United Fig. 1. Global energy-related CO2 emissions [10].

988 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 2. (a) Projected number of employment and (b) CO2 savings under different policy approaches from 2015 to 2050 [14].

States. The policy in regard to solar power generation was amended in regions, and will reach 342 GW by 2050; this expected power genera- those countries, and feed-in tariffs were introduced in Spain [20].Asof tion will be coming from the Middle East (55%) and Northern Africa March 2014, the California Energy Commission approved licenses for (30%), and the remaining 15% will be from European countries, as- five CSP plants with a total installed capacity of 2284 MW [22]. In the suming a modest growth of CSP technology [15]. As of 2016, in Spain, United States, it has been assessed that CSP plants with a total capacity the total installed capacity of the operational CSP plants is 2304 MW of 118 GW could be installed by 2030, and by 2050 the capacity could [25], outperforming the estimate in the Spanish Renewable Energy Plan be increased further to 1504 GW [23]. As of 2015, the total installed made for the time frame of 2005–2010 [15]. capacity of CSP plants in Europe reached 5 GW, from 0.5 GW in the year In the coming decades, it is expected that CSP will show prospects of 2006 [14]. exporting electricity generated from the desert regions of the Middle With the present development policy on CSP technology, six East and North Africa (MENA) to Europe. Moreover, it is found that the European Union (EU) countries, Cyprus, France, , Italy, Portugal electricity demand of all Europe can be met by harvesting from only and Spain, envision producing electricity of 20 TW h by the year 2020 0.4% of the Sahara desert. Indeed, by using only 2% of the earth's total [24]. By 2030, a total of 83 GW could be installed in the sunniest land surface, the global electricity demand can be entirely fulfilled [7]. By 2020, the annual electricity production from CSP plants is expected to reach 85 TW h, which will meet 2% of Europe's electricity produc- tion, and by 2030 the installed capacity will double, reaching 60 GW, and producing 70 TW h of electricity per annum [26]. Fig. 3 shows the growth of global CSP capacity. Universities and major research institutions are producing high- quality research output that is contributing to CSP technology devel- opment and its dissemination all over the world. With a search term “concentrating solar power” in the SCOPUS database, a total of 15,998 patent documents was found. Fig. 4 shows the yearly number of patents in between 1981 and 2017 on CSP, which depicts the tremendous progress in the technology. With the pace of patent documents, publications on CSP have grown dramatically over recent years. Previous review articles analyzed in- dividual research themes independently or focused on specific issues. However, an overall perspective in CSP research needs to be developed. Therefore, the purpose of this review is to provide a holistic overview on CSP by (1) analyzing the present global status of CSP technology implementation, (2) identifying major research findings of previous Fig. 3. Global CSP capacity growth [27]. review articles, (3) discovering the historical development and recent

989 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 4. Number of CSP technology-related patents.

Fig. 5. Various CSP technologies along with their installed ratios [30].

trends on CSP research. The rest of the paper is organized in the fol- 2. Overview of CSP technology lowing order: after this introduction, Section 2 gives an overview of the CSP technologies, Section 3 presents the status of global CSP projects, In CSP power plants, electrical energy is generated by concentrating Section 4 reviews previous review articles on CSP, Section 5 presents a solar radiation. Generally, CSP plants consist of several components text-mining based bibliometric analysis, Section 6 presents major re- such as solar concentrators, receiver, steam turbine and electrical search findings of the analysis, and finally, Section 7 ends with con- generator. Until today, four different kinds of CSP power generation clusion and future work. plants are found; those are 1) solar parabolic dishes (SPD), 2) parabolic

990 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 6. Main parts of a CSP plant and their components [34]. trough collectors (PTC), 3) solar power tower (SPT), and 4) linear electric conversion efficiencies of all the solar technologies [39]. The Fresnel reflectors (LFR) [3,28,29]. Fig. 5 shows the various CSP tech- reason such behind efficiency is that the curved mirrors used in the nologies and their installed ratios in the technology mix, where the PTC system always point directly to the sun, whereas other technologies represents the highest establishment, globally. such as the PTC and SPT suffer from cosine losses (the projected area Depending upon their current power generation capacity, the plants will experience a reduction) [7,45,46]. SPD has 50–100% higher solar- are further classified into operational, under construction and under to-electric efficiencies than SPTs and PTCs, respectively, on an development. The CSP power generation systems use concentrators to equivalent basis of the systems [47]. Unlike other CSP technologies, one focus sunlight onto a receiver that carries a working fluid which is of the unique advantages of the SPD is that the system does not need heated up to a high temperature, and this heated fluid goes to a con- completely level ground and is readily applicable in remote and small ventional steam turbine that is attached to a generator, thus electricity isolated grids [48]. Fig. 7 shows a set of four 25 kWe units that can be is produced [3,31]. Thermal energy storage (i.e. heat stored in a tank) is used for a typical village power system. To provide a more reliable an integrated part of a CSP plant, where stored heat can be used for source of power, SPD systems can also be combined with a fossil-fuel continuous operation of the CSP plant during the night, and on cloudy driven power plant. days. However, storage capabilities might not be present in all CSP According to Solar Power And Chemical Energy Systems plants. For instance, only 50 plants (around 40% of all plants) have the (SolarPACES) [25] two parabolic-dish CSP plants have been con- storage capacity in Spain [32]. In addition, other conventional fuels structed so far, one being operational and the other having stopped its such as gas/oil are used as supplementary sources of energy [3,12,33]. electricity production. At present, the only commercial and operational Fig. 6 shows the major parts of a CSP plant. Table 1 details the major SPD plant is at the Tooele Army Depot which is located at Tooele, Utah characteristics of all CSP technologies. in the United States. The plant has a capacity of 1.5 MW and consists of 429 solar dishes with a Stirling engine. 2.1. Solar parabolic-dish (SPD) system The working fluid of the plant is helium with a closed-loop cooling system. The primary target of the plant is to supply 30% of the elec- In the SPD-CSP system, a parabolic point-focus concentrator in the tricity requirements of the Tooele US Army facility. On the other hand, form of a dish is used in a system that reflects solar radiation onto a the currently non-operational parabolic-dish plant, the Maricopa Solar receiver at the focal point. The concentrators are placed in an assembly Project (Maricopa), had a capacity of 1.5 MW and is located at Peoria, with a two-axis tracking system that follows the sun. At the focal point, Arizona, United States. The technical characteristics of both plants are for efficient power conversion, a Stirling/Brayton engine is placed with given in Table 2. an electrical generator to utilize the concentrated heat on the receiver [39]. With a concentration ratio of approximately 2000 at the focal 2.2. Parabolic-trough collector (PTC) point of the SPDes, the temperature and pressure of the working fluid generally reaches around 700–750 °C and 200 bar, respectively In the PTC-CSP system, large mirrors shaped like a giant U are used [7,12,33,40–42]. Generally, the diameter of the SPDes varies from 5 to to reflect the solar radiation on to a receiver. The collector field com- 10 m and the surface area is 40–120 m2. The shiny surface of the SPD is prises several hundred troughs that are placed in parallel rows aligned constructed of silver or aluminum which is coated on glass or plastic. on a north-south axis. This configuration enables the single-axis troughs However, higher performance can be attained when glass is used with a to track the sun from east to west throughout the day, ensuring that the surface of silver having a thickness of 1 µm. In addition, to improve the solar radiation is continuously focused on the receiver pipes [25]. When reflection of the surface, a certain percentage of iron is used in the glass. the sun's heat is reflected off the mirror, the curved shapes send most of In such a combination, the solar reflectance can reach 90–94%. A single that reflected heat on to a receiver. The receiver or absorption tube is parabolic-dish CSP system can have a power generation capacity colored in order to achieve maximum absorption of the solar irradiation varying from 0.01 to 0.5 MW [43,44]. and a reduction in heat losses. The receiver tube is filled with the fluid; To operate a Stirling engine, the is collected in the form it could be oil, molten salt, or something that holds the heat well. of heat that flows from a hot source to a cold sink. The output of the Different percentages of sodium nitrate, potassium, potassium nitrate Stirling cycle is then used to run the generator, thus electrical power is are used for the molten salt. A high absorption coefficient of the ab- generated. The efficiency of the SPD system with Stirling engine varies sorption tube and its position in the focal point of the trough are the between 25% and 30% [40,43,44], which is one of the highest solar-to- two important issues that need to be ensured for efficient heating of the

991 ..Ilme al. et Islam M.T.

Table 1 Characteristics of CSP technologies [3,7,21,34–37].

PTC LFR SPT SPD

Capacity (MWe) 10–200 10–200 10–150 0.01–0.4 Concentration ratio 25–100 70–80 300–1000 1000–3000 Solar efficiency max. 20% (expected) 21% (demonstrated) 20% (demonstrated) 35% (expected) 29% (demonstrated) Annual solar-to-electric efficiency 15% 8–10% 20–35% (concepts) 20–35% Optical efficiency Medium Low Medium High Collector concentration 70–80 suns > 60 suns (depends on secondary reflector) > 1000 suns > 1300 suns Receiver/absorber Absorber attached to collector, moves with collector, Fixed absorber, no evacuation, secondary reflector External surface or cavity receiver, Absorber attached to collector, complex design fixed moves with collector Area requirement (m²/MWh) 4–66–88–12 30–40 Thermal efficiency (%) 30–40 – 30–40 30–40 Plant peak efficiency (%) 14–20 ∼ 18 23–35 ∼ 30 Capital cost (US$/kW) 3972 – 4000+ 12,578 3770 Solar field < $75/m2; receiver and HTF(HTF) < $150/kW; power block < $1200/kW; thermal energy storage (TES) < $15/kW hb Capital cost (US$/m2) 424 234 476 – Operation and maintenance cost (US 0.012 − 0.02 low 0.034 0.21 $/kW h) Basic plant cost (US$/W) 3.22 – 3.62 2.65 Levelized cost of electricity (LCOE)a 0.26–0.37 (no TES) and 0.22–0.34 (with TES) 0.17–0.37 (6 h TES) 0.2–0.29 (6–7.5 h TES) and 0.17–0.24 – (USD/kW h) (12–15 h TES) 0.06b Land use (m2/MW h/year) 6–84–68–12 8–12 2

992 Specific power (W/m ) 300 – 300 200 Site solar characteristics/solar Generally sites with annual sum of DNI larger than 1800 kWh/m2 radiation required Land requirement Large Medium Medium Small Typical shape of solar plant Rectangular Rectangular Sector of a circle/rectangular Rectangular Water requirement (m3/MW h) 3 (wet cooling), 0.3 (dry cooling) and 0.4–1.7 (hybrid) 3 (wet cooling) and 0.2 (dry cooling) 2–3 (wet cooling), 0.25 (dry cooling) 0.05–0.1 (mirror washing) and 0.3–1 (hybrid) Water cooling (L/MW h) 3 000 or dry 3 000 or dry 2 000 or dry – Suitability for air cooling Low to good Low Good Best Storage with molten salt Commercially available Possible, but not proven Commercially available Possible, but not proven Operating temperature of solar field 290–550 250–390, possible up to 560° C 250–650 800 Renewa (°C) Annual CF (%) 25–28 (no TES), 29–43 (7 h TES) 22–24 55 (10 h TES) 25–28

Grid stability Medium to high (TES or hybridization) Medium (back-up firing possible) High (large TES) Low ble andSustainableEnergyReviews91(2018)987–1018 Power block cycle and fluid Superheated steam Rankine, steam @380 °C/100 bar Saturated steam Rankine (steam @ 270 °C/55 bar), Superheated steam Rankine, steam @ Stirling/Brayton conditions superheated steam Rankine (steam @ 380 °C/50 bar) 540 °C/100–160 bar Supercritical steam Rankine, supercritical CO2 Brayton cycle (600 °C/200 bar), air Brayton cycle Possible backup/hybrid mode Yes Yes Yes Yes, but in limited cases Storage possibility Yes, but not yet with direct steam generation (DSG) Yes, but not yet with DSG Depends on plant configuration Depends on plant configuration Storage system indirect 2-tank molten salt at 380 °C (ΔT = 100 °C) or Short-term pressurized steam storage (< 10 min) Direct 2-tank molten salt at 550 °C (ΔT No storage, chemical storage under Direct 2-tank molten salt at 550 °C (ΔT = 300 °C) = 300 °C) development 14 h TESb (continued on next page) M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018 SPD Air, hydrogen, helium

Fig. 7. Parabolic dish for village power application [39]. cant Through mass production fi working fluid. Depending on the concentration ratio, solar intensity, working fluid flow rate and other parameters, the temperature of the working fluid can reach 400 °C [52]. As the solar energy is concentrated Water/steam, molten salt, air SPT (demonstration) Torresol, Solarreserve 70–100 times in the system, the operating temperature reaches 350–550 °C. The solar-to-electric efficiency is 15% for the system [53]. If a parabolic-trough system is integrated with a steam-turbine power plant then it is called direct steam generation technology. The super-hot liquid heats water through a heat exchanger, the water turns into steam, that steam is used to rotate a turbine, and from there it works like a conventional power plant where a steam turbine turns the gen- erator and electricity is produced. Once the fluid transfers its heat to water it is recycled and used again in the process, and the steam is also cooled, condensed and recycled again to repeat the process [20,54]. One of the big advantages of the trough system is that the heated fluid can be stored and used later to generate electricity when sunlight is absent. Among the various solar harvesting technologies, this system

b – 2 cant Very signi ensures the best land use [3,7,12,40 43,55]. Some parabolic-trough fi plants use fossil fuel to supplement energy production during low solar Water/steam LFR Austra, MAN Ferrostaal , eSolar, Sener, BrightSource, radiation, and often the trough system can be integrated with conven- tional natural-gas-fired or coal-fired plants [25]. Compared to other CSP technologies, the parabolic-trough system is more advanced [43]. Fig. 8 shows some of the PTC plants in the world. The parabolic-trough system is the most widely used CSP tech- nology. The first parabolic-trough system was developed in 1912 in Cairo, Egypt [7]. At present, globally, there are 77 operational para- bolic-trough power plants and most of them are located in Spain and

[38] . the United States. Two plants are located in , 2 in Italy, 2 in South Africa, 1 in Canada, 3 plants in India, 1 in Algeria, 1 in Egypt, 1 in the United Arab Emirates and 1 plant in Thailand. Table 3 shows technical characteristics of the plants. In Spain, there are 39 parabolic-trough power plants, where the net turbine capacity varies from 22.5 MW to 50 MW. The first parabolic- trough system was installed in 2008 near Granada, named Andasol-1 (AS-1) and with a capacity of 49.9 MW. The solar resource per year for the plant was estimated to be 2136 kW h/m2. The planned electricity Molten salt with lower melting points, air, steam, supercritical CO Synthetic oil, water/steam (DSG),(demonstration), molten air salt (demonstration) NoLimited Signi No Yes Yes 380 to 540/100Most provenLowSener, Solar Millennium, Abengoa, ACS-Cobra,Solel Acciona, 260/50 Demonstration Medium Mature 540/100 to 160 Medium Not applicable Demonstration Medium PTC generation is 158,000 MW h/year [25]. Helios I and Helios II are the two largest parabolic-trough plants in Spain, representing the largest land area used, 2,600,000 m2 each. The total installed capacity of the operational parabolic-trough plants in Spain reached 1871.9 MW up until 2016. Table 4 summarizes the details of PTC plants in Spain. On the other hand, in the United States, until 2016, the total in-

) stalled capacity of parabolic-trough CSP plants reached a capacity of uid fl 1255.8 MW. The Genesis Solar Energy Project, and Solana Generating Station are three CSP plants that have 250 MW of continued ( capacity, each representing the highest capacity using the technology in and exergetic e ffi ciency greater than 95% by the year 2020 t

SunShot Initiative is launched in 2011 by the United States Department of Energy that targets levelized cost of CSP-generated electricity to be less than USD 0.06/kW h with cost of thermal storage less than USD 15/ the world. Solar Electric Generating Station I (SEGS I), established in Net present value of the unit cost of electricity over the lifetime of a generating asset is known as LCOE. a b Solar fuels Outlook for improvement Development status Technology development risk Technology providers Steam conditions (°C/bar) Heat Transfer 1984 with a capacity of 13.8 MW, is the first PTC CSP plant in the kW h Table 1

993 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Table 2 Technical characteristics of parabolic-dish CSP plants [25,49].

Name Maricopa solar project (Maricopa) Tooele army depot

Image source [50] Image source [51] Start year 2010 2013 Location Peoria, Arizona, United States Tooele, Utah, United States Latitude/longitude 33°33′ 31.0″ North, 112°13′ 7.0″ West 40°30′ 4.0″ North, 112°22′ 25.0″ West (location) Capacity 1.5 MW 1.5 MW Land area 15 acres 17 acres # of dishes 60 429 Output type Stirling Stirling Dish Aperture Area – 35 m2 Cooling Method Does not use water for electricity generation or cooling cycles. Minimal Closed-loop cooling system Description water is used for site operations and washing its mirrors. Heat-Transfer Fluid Type Hydrogen Helium Annual Solar-to- 26% – Electricity Efficiency (Gross) Storage Type None None Project type Demonstration Commercial Status Currently Non-Operational Operational

United States. Installed in the year 2013, the Solana Generating Station centrally located tower [58]. The materials for the receiver are gen- was the most expensive project so far undertaken in the United States erally ceramics or metals that are stable at relatively elevated tem- based on this technology, with a cost of US$ 2 billion. The planned peratures. The average solar flux impinging on the receiver varies from electricity generation is estimated to be 944,000 MW h/year. For the 200 kW/m2 to 1000 kW/m2, providing an opportunity to achieve a high Saguaro power plant, the net specific land area, at 64.7497 m2/kW, is working temperature [46]. In the receiver the temperature of the the highest among all the present operational plants in the United working fluid becomes high enough to produce steam, which eventually States. Table 5 shows some characteristics of the parabolic-trough spins a conventional turbine to generate electricity. Water/steam, plants in the United States. Using the RETscreen International's clean- molten salt, liquid sodium or air can be utilized as the working fluid in energy project analysis software, it is estimated that the cities where the the system for large plants with capacity of 100–200 MW [59,60].In CSP plants are located have had an average annual daily solar irra- the 1980s and 1990s, the United States Department of Energy Projects diance of 5.13–4.63 kW h/m2/day for Spain and 4.8–5.78 kW h/m2/day in California demonstrated that a SPT could collect and store heat, to for the United States. At present, there are 4 parabolic-trough plants generate utility-scale electricity all day round, 24 h a day. Today SPTs (50 MW, 100 MW, 25 MW and 100 MW) being constructed in India, 2 continue to help build a clean energy economy. In 2009, the Sierra Sun (100 MW and 100 MW) plants in South Africa, 1 (43 MW) in Saudi Tower, a modular two-tower system in the Mojave Desert, powered Arabia, 1 (200 MW) in Morocco, and 1 (12 MW) in Mexico. China is more than 5000 homes, and in 2010 construction began of the 392 MW investing heavily in this technology and 6 parabolic-trough plants are three-tower system of the Ivanpah Solar Electric Generating System now under development, with a capacity of 414 MW. Under the present located in California, USA. In this plant there are about 175,000 mir- development plan, Chile is going to construct the largest parabolic- rors. This California plant has created more than 1000 jobs and powers trough plant, at Maria Elena in the Antofagasta region, with a capacity more than 350,000 homes [61]. Thousands of mirrors called of 360 MW. The estimated cost of the project will be 2610 million US$. reflect sunlight onto a receiver on top of a tower. Fig. 9 shows the Some other countries such as Israel, South Africa and Kuwait are also 10 MW PS-10 SPT CSP plant located at Seville, Spain. The heliostats are planning to build parabolic-trough plants with capacities ranging from the major capital investment in a power-tower CSP plant [35]. These 50 MW to 110 MW. computer-controlled mirrors move to maintain a focus from dawn to dusk. In the Sierra Sun Tower plant water is used as the working fluid, 2.3. Solar power-tower (SPT)/central receiver whereas at present molten salt nitrate is widely used at power plants in the United States, as the fluid is not flammable, is non-toxic, and has SPTs are the CSP power generation system that employ large flat better heat storage capacity than water. In the Jülich Solar Tower plant mirrors to reflect sunlight on to a solar receiver at the top of the in Germany, the working fluid used in the plant is air.

994 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 8. (a) 354 MW solar energy generating system (SEGS), USA [56], (b) 150 MW Andasol solar power plant, Spain [56], (c) 5 MW Thai solar energy 1, Thailand [57].

In a steam SPT, water is impelled to the receiver where concentrated power plant. Unlike other CSP plants, power-tower plants require a solar radiation heats the water to over 537 °C. A fraction of the super- considerable water supply and the largest land area. The efficiency of hot steam is stored (in a heat storage tank) while the majority of the the plant varies, depending on number of criteria such as the optical steam is sent to the power block for later use, as with a parabolic-trough characteristics of the heliostats, the accuracy of the mirror's tracking system. After that, high-pressure steam spins the turbine to produce system and the cleanliness of the mirror. SPTs must be large in size to be electricity. If cloud covers the sunlight, the steam that was stored pre- economically viable and profitable. Generally, economic viability and viously in the tank is used to produce electricity for up to an hour. On profitability can be achieved when the plant is capable of producing the other hand, in a SPT where molten salt is used as the working fluid, power of 50–100 MW [3,65]. relatively cold molten salt at 290 °C is pumped to the receiver where it To reduce the financial risk and to lower the cost of electricity is heated up to 565 °C, and then flows to the storage tank of hot molten production, often power-tower CSP plants (i.e. commercial plants with salt. The hot salt then flows through a heat exchanger from where heat a capacity of > 30 MW) are advised to hybridize with natural gas is transferred to water, producing steam that spins a conventional combined-cycle, coal-fired or oil-fired Rankine plants [65,66]. Due to Rankine-cycle turbine/generator system. The exhausted steam derived low cost of solar PV, many of the investors in CSP technology were from the turbine is condensed and afterwards the condensate is pumped moving towards the technology, however, there is a potential for in- into the heat exchanger system. Here the molten salt that has been tegrating a SPT CSP with solar PV (Fig. 11). cooled again is heated by the solar receiver and the process repeats At present, the total operational gross installed capacity of SPT-CSP itself continuously [3,7,12,41,42,62–64]. Finally, the molten salt then plants has reached 618.42 MW worldwide and is expanding rapidly. In flows back to the cold storage tank. The stored hot salt can produce 2007, the first commercial power-tower plant was established in Spain, steam and generate electricity efficiently for hours. For continuous named Planta Solar 10, with a capacity of 11.02 MW. The total land output from a turbine, storage tanks can be designed in a way that can area of the plant is 55 ha and planned electricity generation is assessed supply sufficient heat as an energy source for up to 13 h [65]. Today as 23,400 MW h/year. As mentioned earlier, the largest plant using innovation continues to drive down costs and boost efficiency so that a such technology was established in 2014 and it is located in the United

SPT can supply utility-scale power (ranging from 30 to 400 MWe) States, named the Ivanpah Solar Electric Generating System, with a providing dependable clean electricity to homes, businesses and com- gross turbine capacity of 392 MW. This commercial plant spreads over munities. The annual solar-to-electric efficiency for this type of power one of the largest land areas, of 3500 acres, and electricity generation plant varies from 20% to 35% [59,60]. Fig. 10 depicts the schematic from the plant is projected as 1,079,232 MW h/year. Among the op- diagram of the primary flow paths in a molten-salt driven power-tower erational plants, the Greenway CSP Mersin Tower Plant in and CSP plant and hybridization scope with a conventional combined-cycle the Dahan Power Plant in China are the two smallest plants, with a

995 ..Ilme al. et Islam M.T.

Table 3 Technical characteristics of the operational parabolic-trough plants worldwide, except Spain and the United States [25].

Sl no. Project Country Net Start year Average daily Solar resource Electricity Location of the Land area Project type Cost Specific land Working/heat Thermal Thermal turbine solar radiation (kW h/m2/yr) generation climate data (m2) (approximately) area – net transfer fluid storage storage capacity over a year – (MW h/yr) point (m2/kW) capacity description (MW) horizontal (h) (kW h/m2/day)

1 Airlight Morocco 3 2014 5.55 2200 2390 Agadir/ 240,000 Pilot plant - 80 Air at ambient 5 Packed-bed Energy Ait- Inezgane pressure of rocks Baha Pilot Plant 2 ISCC Ain Morocco 20 2010 - - 55,000 - - Commercial - Therminol VP-1 - None Beni Mathar 3 Archimede Italy 4.72 2010 – 1936 9200 – 80,000 –– 16.95 Molten salts 8 Molten salts 4 ASE Demo Italy – 2013 3.75 1527 275 Perugia 30,000 Demonstration – Molten salt – Molten salt Plant 5 Bokpoort South 50 2016 ––230,000 – 1,000,000 Commercial US$ 565 million 20 Dowtherm A 9.30 Molten salts Africa

996 6 KaXu Solar South 100 2015 ––330,000 ––Commercial US$ 860 million Thermal oil 2.50 Molten salts One Africa 7 City of Canada 1.1 2014 4.04 – 1500 Medicine Hat – Demonstration US$ 9 million 0 Xceltherm®SST – None Medicine Hat Airport ISCC Project 8 Godawari India 50 2013 ––118,000 – 1500,000 Commercial 30 Dowtherm A – None Solar Project 9 Megha Solar India 50 2014 5.34 – 110,000 Anantapur 2,420,000 Commercial Rs 848 Crore 48.40 Xceltherm®MK1 – None Plant 10 National India 1 2012 –––––Demonstration – Therminol VP-1 – None Solar Renewa Thermal Power

Facility ble andSustainableEnergyReviews91(2018)987–1018 11 ISCC Hassi Algeria 20 2011 ––––640,000 Commercial Euros 315 32 Thermal oil – None R'mel million 12 ISCC Egypt 20 2011 5.31 2431 34,000 Cairo H.Q. – Commercial – Therminol VP-1 – None Kuraymat 13 Shams 1 United 100 2013 – 1934 210,000 – 2,500,000 Commercial US$ 600 million 25 Therminol VP-1 – None Arab Emirates 14 Thai Solar Thailand 5 2012 4.88 – 8000 Kanchanaburi 1,100,000 Commercial – 220 Water/Steam – None Energy 1 (TSE1) ..Ilme al. et Islam M.T.

Table 4 Details of PTC CSP plants in Spain [25].

Turbine Capacity (MW)

Project Start year Net Gross Electricity generation Land area Project type Cost Specific land area Working fluid Thermal storage Thermal storage (MW h/yr) (m2) (million Euro) – net (m2/kW) capacity (h) description

Andasol-1 (AS-1) 2008 49.9 50 158,000 2,000,000 Commercial – 40.08 Thermal Oil 7.5 Molten salts Andasol-2 (AS-2) 2009 49.9 50 158,000 2,000,000 Commercial 40.08 Dowtherm A 7.5 Molten salt Andasol-3 (AS-3) 2011 50 50 175,000 2,000,000 – 315 40 Thermal Oil 7.5 Molten salts Arcosol 50 (Valle 1) 2011 49.9 49.9 175,000 2,300,000 – 270 46.09 Diphenyl/Diphenyl Oxide 7.5 Molten salts Arenales 2013 50 50 166,000 2,200,000 Commercial – 44 Diphenyl 7 Molten salts Aste 1A 2012 50 50 170,000 1,800,000 Commercial – 36 Dowtherm A 8 Molten salts Aste 1B 2012 50 50 170,000 1,800,000 Commercial 36 Dowtherm A 8 Molten salts Astexol II 2012 50 50 170,000 1,600,000 Commercial – 32 Thermal Oil 8 Molten salts Borges Termosolar 2012 22.5 25 98,000 960,000 Commercial 153 42.67 Thermal Oil – None Casablanca 2013 50 50 160,000 2,000,000 Commercial – 40 Diphenyl/Biphenyl oxide 7.5 Molten salts Enerstar 2013 50 50 100,000 2,140,000 Commercial – 42.8 Thermal Oil – None Extresol-1 2010 0 50 158,000 2,000,000 Commercial – Diphenyl/Biphenyl oxide 7.5 Molten salts Extresol-2 2010 49.9 49.9 158,000 2,000,000 Commercial – 40.08 Diphenyl/Biphenyl oxide 7.5 Molten salts Extresol-3 2012 50 50 158,000 2,000,000 Commercial – 40 Diphenyl/Biphenyl oxide 7.5 Molten salts Guzmán 2012 50 50 104,000 2,000,000 Commercial – 40 Dowtherm A – None Helioenergy 1 2011 50 50 95,000 1,100,000 Commercial – 22 Thermal Oil – None

997 Helioenergy 2 2012 50 50 95,000 1,100,000 Commercial – 22 Thermal Oil – None Helios I 2012 50 50 97,000 2,600,000 Commercial – 52 Thermal Oil – None Helios II 2012 50 50 97,000 2,600,000 Commercial – 52 Xceltherm®MK1 – None Ibersol Ciudad Real 2009 50 50 103,000 1,500,000 – 200 30 Diphenyl/Biphenyl oxide - – None (Puertollano) Dowtherm A La Africana 2012 50 50 170,000 2,520,000 Commercial 387 50.4 – 7.5 Molten salts La Dehesa 2011 49.9 49.9 175,000 2,000,000 –– 40.08 Diphenyl/Biphenyl oxide 7.5 Molten salts La Florida 2010 50 50 175,000 2,000,000 –– 40 Diphenyl/Diphenyl oxide 7.5 Molten salts La Risca 2009 50 50 105,200 1,350,000 –– 27 Biphenyl/Diphenyl oxide – None Lebrija 1 2011 50 50 120,000 1,880,000 –– 37.6 Therminol VP1 – None Majadas I 2010 50 50 104,500 1,350,000 –– 27 Biphenyl/Diphenyl oxide – None Renewa Manchasol-1 2011 49.9 49.9 – 2,000,000 Commercial – 40.08 Diphenyl/Diphenyl oxide 7.5 Molten salts Manchasol-2 2011 50 50 2208 2,000,000 Commercial – 40 Diphenyl/Diphenyl oxide 7.5 Molten salts

Morón 2012 50 50 100,000 1,600,000 Commercial 295 32 Thermal Oil – None ble andSustainableEnergyReviews91(2018)987–1018 Olivenza 1 2012 50 50 100,000 1,600,000 Commercial 284 32 Thermal Oil – None Orellana 2012 50 50 118,000 1,860,000 Commercial 240 37.2 Thermal Oil – None Palma del Río I 2011 50 50 114,500 1,350,000 –– 27 Biphenyl/Diphenyl oxide – None Palma del Río II 2010 50 50 114,500 1,350,000 –– 27 Biphenyl/Diphenyl oxide – None Solaben 1 2013 50 50 100,000 1,100,000 Commercial – 22 Thermal Oil – None Solaben 2 2012 50 50 100,000 1,100,000 Commercial – 22 Thermal Oil – None Solaben 3 2012 50 50 100,000 1,100,000 Commercial – 22 Thermal Oil – None Solaben 6 2013 50 50 100,000 1,100,000 Commercial – 22 Thermal Oil – None Solacor 1 2012 50 50 100,000 1,100,000 Commercial – 22 Thermal Oil – None Solacor 2 2012 50 50 100,000 1,100,000 Commercial – 22 Thermal Oil – None Termesol 50 (Valle 2) 2011 49.9 2,300,000 – 270 46.09 Diphenyl/Diphenyl Oxide 7.5 Molten salt Termosol 1 2013 50 2,000,000 Commercial – 40 Thermal Oil 9 Molten salt Termosol 2 2013 50 2,000,000 Commercial – 40 Thermal Oil 9 Molten salt ..Ilme al. et Islam M.T.

Table 5 Operational PTC plants in the United States [25].

Project Net turbine capacity Start year Land area (m2) Cost in millions US$ Specific land area – net Solar resource Electricity generation (MW) (approximately) (m2/kW) (kW h/m2/yr) (MW h/year)

Genesis Solar Energy Project 250 2014 7,891,370 31.57 – 580,000 Holaniku at Keahole Point 2 2009 12,140.60 – 6.07 4030 Martin Next Generation Solar Energy Center 75 2010 2,023,430 476.3 26.98 – 155,000 Mojave Solar Project 250 2014 7,142,702 1600 28.57 – 600,000 72 2007 4,000,000 266 55.56 2606 134,000 Saguaro Power Plant 1 2006 64,749.70 6 64.75 2636 2000 Solana Generating Station 250 2013 7,800,000 2000 31.20 – 944,000 Solar Electric Generating Station I (SEGS I) 13.8 1984 –– 0 2725 – Solar Electric Generating Station II (SEGS II) 30 1985 –– 0 2725 – Solar Electric Generating Station III (SEGS III) 30 1985 –– 0 2725 – 998 Solar Electric Generating Station IV (SEGS IV) 30 1989 –– 0 2725 – Solar Electric Generating Station V (SEGS V) 30 1989 –– 0 2725 – Solar Electric Generating Station VI (SEGS VI) 30 1989 –– 0 2725 – Solar Electric Generating Station VII (SEGS VII) 30 1989 –– 0 2725 – Solar Electric Generating Station VIII (SEGS VIII) 80 1989 –– 0 2725 – Solar Electric Generating Station IX (SEGS IX) 80 1990 –– 0 2725 – Stillwater GeoSolar Hybrid Plant 2 2015 84,984 – 42.49 – 3000 Renewa ble andSustainableEnergyReviews91(2018)987–1018 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018 capacity of 1 MW each; established for demonstration and experimental Besides this, the Kimberlina Solar Thermal Power Plant in the United purposes. The average daily solar radiation in a year in the city/region States (5 MW), and the Rende-CSP Plant, Italy (1 MW) are the two in China and Turkey where the plants were established is 3.73 kW h/ linear Fresnel-reflector based CSP plants that were built for demon- m2/day and 4.78 kW h/m2/day, respectively. The latest operational stration, whereas the Liddell , Australia (9 MW) and the power-tower plant named Khi Solar One, and located in South Africa, 2 Thermosolar Power Plant, Spain (30 MW) were built was established in 2016; it has a capacity of 50 MW and the expected for commercial production in 2012. Alba Nova 1, France (12 MW) and electricity generation will be 180,000 MW h/year [25]. IRESEN, a 1 MWe CSP-ORC pilot project, Morocco (1 MW) are plants The SPT is one of the fastest growing CSP technologies. At present, currently under construction. In China, there are four linear Fresnel- there are 6 plants under construction, with a total installed capacity of reflector CSP plants under development whose capacity will be 50 MW 632.5 MW and of which the Golmud project located in China is ex- each [25]. Table 7 summarizes characteristics of the Fresnel plants. pected to contribute 200 MW starting from 2018. The solar resource calculated for the project is 2158 kW h/m2/year and the estimated electricity generation will be 1,120,000 MW h/year. In the near future, 3. Status of CSP projects plants under development based on power-tower technology will reach around 995 MW and most of the plant will be located in China [25]. It was identified that, even though the first CSP plant was installed Table 6 shows the operational, under-construction and under-devel- in the USA in 1982, this technology is expanding rapidly worldwide opment power-tower plants worldwide. and, as a result, there are currently 98 active CSP plants, while 18 are under construction and 24 plants are under development. Table 8 2.4. Linear Fresnel-reflector (LFR) shows the total number of CSP plants that are installed, under con- struction and under development, worldwide. LFR-CSP plants consist of an array of linear mirror strips as re- CSP technology is expected to grow rapidly all over the world, flectors, with receivers, tracking system, process and instrumentation especially in Asia, the MENA and South American countries. Fig. 13 system, steam turbine and generator. The reflectors are the most im- shows the capacity of the CSP plants in different countries of the world, portant components in the system and the mechanism of the reflectors out of which 4749 MW, 1187 MW, 4177 MW are operational, under is the same as that of the Fresnel lens. The sun's rays are reflected by the construction and under development, respectively. Fresnel lens and focused at one point, generally on to a permanent Daily solar availability, sufficient land area and a source of water for receiver on a linear tower. In the daytime, the Fresnel reflectors are cooling and cleaning of the reflectors, are crucial for the development directed automatically toward the sun, and from there the reflected of CSP plants [73]. A range of costs including capital cost, basic cost solar irradiation carries on to the linear tower where a receiver shaped and operation and maintenance cost, efficiencies, land and water re- like a long cylinder contains a number of tubes filled with water. With quirements, and others are compared. For all the technologies, the solar the high solar radiation the water evaporates and under pressure runs radiation, land and water requirement was found to be 1800 kW h/m2, into the steam turbine that spins a generator that generates electricity 5–7 acres/MW and 4 m3/MW h, respectively. Another research by Pitz- [3,69–71]. Fig. 12 shows the major components of a LFR plant, and the Paal [74] indicated that parabolic-trough and Fresnel plants require less 1.4 MW Puerto Errado 1 Thermosolar Power Plant. A LFR is made up of area than the other two CSP technologies, especially a SPD with the a number of linear mirror strips. This type of reflector can also resemble same capacity. However, from installed CSP plant experience, it is the dismantled reflector of a parabolic-trough system. Using Fresnel found that SPTs require the largest area. But again the area depends on reflector design, the capital cost of the reflectors becomes lower, the presence of heat storage facilities. If heat storage is not being however the efficiency is less than with parabolic-trough reflectors considered, the land area requirement will be 25 m2/kW for the PTC [46,54]. The capacities of the LFR CSP plants vary from 10 to 200 MW and 45 m2/kW for the SPT [75]. and the yearly solar-to-electric efficiency is estimated to be 8–10% PTC and LFR systems are suitable for power generation capacities [59]. In 1999, the largest LFR CSP plant was built by the Belgian from 10 MW to 200 MW, for SPT 10–150 MW, and finally, the capacity company Solarmundo on a prototype basis, with a collector width of of the SPD varies from 0.01 MW to 0.4 MW, which is suitable for small 24 m and 2500 m2 reflector area [60]. In 2014, the largest operational and off-grid generation. However, parabolic-trough technology is the linear Fresnel-reflector CSP plant was installed in India, with a capacity most proven, SPT is mature, and both SPDes and LFRs are in the de- of 125 MW and a planned electricity generation of 280,000 MW h/year. monstration stage. Unlike the low capacity, SPDes have the highest concentration ratio, ranging from 1000 to 3000, one of the highest among all other CSP technologies; the PTC and LFR being low, and the SPT in the intermediate range. Due to the high concentration ratio, the SPD system can reach very high temperatures (800 °C) and thereby achieve high efficiency. SPTs and SPDes are regarded as the most effi- cient CSP plants, expected to have a 50% better efficiency than the trough and the Fresnel plants. The annual solar-to-electric conversion efficiency is higher for SPDes and LFRs than for the PTC and SPT. As demonstrated, SPDes and LFRs have efficiencies of 29% and 21%, re- spectively. On the other hand, research by Ummadisingu and Soni [7] found that SPDes and LFRs have solar-to-electric efficiency of 25–30%. Even though SPDes have the highest efficiency, the basic plant cost, the operation and maintenance cost, and the capital costs are the highest among the plants, with the LFR being the lowest. For both SPD and SPT, the land use is found to be 8–12 m2/MWh/year, with 6–8m2/MW h/ year for the PTC and 4–6m2/MW h/year for the LFR [35].

Fig. 9. 10 MW PS-10 solar power tower at Seville, Spain.

999 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 10. (a) Schematic diagram of molten-salt driven solar power-tower CSP plant [65] and (b) solar power-tower hybridized with combined-cycle plant [67].

Fig. 11. Hybridization of solar power tower CSP with solar PV [68].

4. Previous reviews on CSP process we used the following functions of the software (1) importation of publication information (2) creating co-occurrence map by text data, This holistic historical development and current progress in the CSP (3) retrieving data for citation analysis by analyzing co-citation re- technology have been achieved through intense research and develop- porting and (4) clustering and visualizing keywords by co-occurrence in ment by global research organizations and universities. Even though network and overlay form. This is one of the most automated and previous review articles produced on the topic discussed many tech- systematic approaches by which a large body of literature can con- nological advancements and issues related to CSP, there is a need to veniently be analyzed. understand the overall research progress by reviewing them. Table 9 summarizes the main body of review articles published on CSP. 5.1. Publication collection

5. Text-mining based bibliometric analysis on CSP research For this study, the Thomson Reuters’ Web of Science (WoS) biblio- graphic database (Web of Science Core Collection) was selected to ex- Since CSP research is expanding dramatically, it is challenging to tract publication information on CSP studies. The following search conduct holistic reviews manually. Instead, we have taken advantage of terms were utilized to collect the maximum number of related papers bibliographical data, keywords and citations, and utilized free text- on CSP articles by acknowledging that the word “concentrated” is a mining software, VOSviewer, to generate bibliometric maps of scientific synonym of the word “concentrating” in the title of the articles: “con- research fields [123–125]. Publications in international peer-reviewed centrating solar power*” OR “concentrating solar thermal*” OR “con- journals using the software can be found at this source [126]. For the centrating solar collectors” OR “concentrating solar energy” OR

1000 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Table 6 Operational, under-construction and under-development SPT plants [25].

Project Start year Country Net turbine capacity (MW) Gross turbine capacity (MW) Status

ACME Solar Tower 2011 India 2.50 2.50 Operational Crescent Dunes Solar Energy Project (Tonopah) 2015 United States 110 110 Operational Dahan Power Plant 2012 China 1 1 Operational Gemasolar Thermosolar Plant 2011 Spain 19.90 19.90 Operational Greenway CSP Mersin Tower Plant 2012 Turkey 1 1.40 Operational Ivanpah Solar Electric Generating System 2014 United States 377 392 Operational Jemalong Solar Thermal Station 2016 Australia – 1.10 Operational Jülich Solar Tower 2008 Germany 1.50 1.50 Operational Khi Solar One 2016 South Africa 50 50 Operational Lake Cargelligo 2011 Australia 3 3 Operational Planta Solar 10 2007 Spain 11 11.02 Operational Planta Solar 20 2009 Spain 20 20 Operational Sierra SunTower 2009 United States 5 5 Operational Ashalim Plot B 2017 Israel 121 121 Under Construction Atacama-1 2018 Chile 110 110 Under Construction Golmud 2018 China 200 200 Under Construction NOOR III 2017 Morocco 150 150 Under Construction Sundrop CSP Project 2016 Australia 1.50 1.50 Under Construction Supcon Solar Project 2010 China 50 50 Under Construction Copiapó 2019 Chile 260 260 Under Development Delingha Qinghai 135 MW DSG Tower CSP Project 2017 China 135 135 Under Development Dunhuang 100 MW Molten Salt CSP Project – China 100 100 Under Development Golden Tower 100 MW Molten Salt project 2016 China 100 100 Under Development Hami 50 MW CSP Project – China 50 50 Under Development Qinghai Gonghe 50 MW CSP Plant 2016 China 50 50 Under Development Redstone Solar Thermal Power Plant 2018 South Africa 100 100 Under Development Shangyi 50 MW DSG Tower CSP project – China 50 50 Under Development Yumen 100 MW Molten Salt Tower CSP project – China 100 100 Under Development Yumen 50 MW Molten Salt Tower CSP project – China 50 50 Under Development

Fig. 12. (a) Schematic diagram of CSP plant with Fresnel reflector [3] and 1.4 MW Puerto Errado 1 Thermosolar Power Plant (PE1) at Calasparra, Spain [72].

“concentrated solar power*” OR “concentrated solar thermal*” OR under the scope of the solar and renewable energy field. The first “Concentrated solar energy”. By using these search terms, the pub- method is a keyword analysis in which the software considers keywords lication information was downloaded, for example, title, abstract, year that are generally located within the title and abstract. Keyword ana- of publication, source of journals etc. as a tab-delimited text file, re- lysis results in scientific landscapes with which we follow the devel- commended for subsequent processing in the VOSviewer software. By opment of CSP topics as well as recent research issues that future re- this process, a total of 976 research articles on CSP published from 1981 searchers can work with. In the second method, we analyzed citations to January 2018 were collected. Documents were analyzed according to of highly cited articles that are working as the knowledge base in the their general pattern and the frequency of publications over the years, field of CSP research. These the methods are described below. journal source, geographical distribution and finally, an in-depth pub- lication analysis by keyword and citation that provides a comprehen- 5.3. Keyword analysis sive understanding of the past trends, new developments and future prospects of the CSP research area. For the selection of keywords in a scientific landscape, all the key- words were extracted using the title and abstract of the selected pub- 5.2. Publication analysis lications. Initially, 18,288 terms were found in the publication collec- tions that were extracted from title and abstract, later they were filtered In this study two analysis techniques were employed to generate a with a minimum number of occurrence 10. Finally, filtered words were preliminary result on the progress and future trend of CSP research extracted by means of a built-in text-mining based function of

1001 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Table 8 Number of CSP plants in the world [25].

Type of CSP Operational Under construction Under development plants Commercial

PTCs 77 10 10 SPT 13 6 10 SPDes 10 0

Land area Project type 12 acres– Demonstration LFRs 72 4 Total 98 18 24 Electricity generation (MW h/yr) 280,000 13,550 /yr) 2 (kW h/m – – –– Start year Solar resource –––––––– – – – – –– –– ––

Fig. 13. Total capacity of the operational, under-construction and under-de- velopment CSP plants [25].

VOSviewer [123]. Some of the unrelated words such as abbreviations and generic terms and merged related words (i.e. singular and plural Gross turbine capacity (MW) 1.4 2009 2100 2000 5 ha Prototype forms of a word) were eliminated by developing a thesaurus file. With the keywords list VOSviewer generated the co-occurrence map where keywords were clustered based on their co-occurrences. In a single document, if the words appear then the words are defined as co- occurred. Furthermore, the names of the clustered keywords are manually labelled based on the observed keywords in a cluster. In this manner, finally a scientific landscape of the CSP research is generated. Turbine Capacity Net turbine capacity (MW) – Here, the size and color of the cluster represents the frequency of the co- occurrence of the keywords and their distinct keyword type, respec- tively. Finally, if the distance between the keywords is short, that in- dicates that keywords co-occur more frequently with each other, whereas the largest distance means they do not co-occur.

5.4. Citation analysis

According to Rubin [127], citation analysis is a widely accepted method that can establish links and relationships to other works or Country Status China Under development 50 50 researchers by examining the citations of frequency, patterns and gra- phical representations in article and books. To investigate which works are the most influential in CSP research, we developed a co-citation map using the bibliographic information of the whole collection of publications. This is also done with the VOSviewer. A total of 19,598 cited references found in the collection and a minimum of 20 citations of a cited reference are selected for the analysis. .

[25] 6. Results

6.1. Overview of the publications Fresnel project By implementing the methodology described in the previous sec- Project Augustin Fresnel 1DhursarLiddell Power StationPuerto Errado 1 Thermosolar Power Plant Spain France Operational Australia Operational India Operational 0.25 Operational 9 125 0.25 9 125 2012 2012 2014 Kimberlina Solar Thermal Power PlantPuerto Errado 2 United Thermosolar StatesRende-CSP Power Plant Plant OperationalAlba Nova 1 SpainIRESEN 1 MWe CSP-ORCDacheng pilot Dunhuang project 50 MW Molten Salt 5 Operational Morocco Under 30 construction Italy 5 France Operational Under construction 30 12 2008 2012 12 2095 2015 49,000 1800 70 ha 25,000 Commercial 23 ha Demonstration Urat 50 MW Fresnel CSPZhangbei project 50 MW CSG FresnelZhangjiakou CSP 50 project MW CSG Fresnel project China China China Under development 50 Under development Under development 50 50 50 50 fi 50 Table 7 LFR CSP plants tion, we identi ed a total of 976 articles for CSP. Fig. 14 shows the

1002 ..Ilme al. et Islam M.T. Table 9 Previous review articles published in CSP research.

Ref Year of Topic Components in the CSP Name of the journal Major findings and/or future research direction publication system

[76] 2008 Prospects of CSP in China – Renewable and sustainable • CSP technologies can be conveniently adopted in the northern and western part energy reviews (RSER) of China • government support and strategies are required for large-scale and commercial CSP technologies implementation [77] 2009 China's effort in CSP deployment – RSER • GHG mitigation can be efficiently performed by implementing CSP technology for China's power generation and heat supply targeting buildings and industry sectors in China • scaling up CSP requires institutional and energy pricing reform is required to eradicate financing barriers [78] 2009 Reviewing and mathematical model development for Solar field RSER • Design optimization opportunity is present in the area of reflective-material transmission of concentrated solar energy via optical fibres usage in receiver, selection of length of fibre-optic bundle (FOB). (TCSEvOF) for SPD technology [79] 2011 Fresnel lenses Solar field RSER • non-imaging LFR systems have potential for large-scale commercial power generation. [7] 2011 Potential of CSP in India – RSER • Rajasthan and Gujarat in India have the potential for widespread application of CSP in India • feed-in tariffs as incentive, government policy and industry-university collaborations have a crucial role in deploying CSP application for electricity generation [33] 2011 CSP potential in Turkey – RSER • Abundant solar radiation and the presence of large wasteland make the southern and south eastern part of Turkey potential locations for CSP application. • Government support and strategies are required for commercial application. 1003 [80] 2012 Thermochemical fuel production and technological Thermal energy storage Energy & Environmental • production of solar hydrogen, syngas, and liquid hydrocarbon fuels from H2O advancement of CSP Science and CO2 via 2-step redox cycles has tremendous opportunity for large-scale demonstration. [3] 2012 Description and working principles of CSP technologies and – RSER • PTC, SPD and LFR power plants were found suitable for Serbia potential implementation in Serbia • isolated community in rural areas can use SPD CSP power plant which can work independently regardless of the grid connection [81] 2012 Life cycle assessment (LCA) for PTC and SPT CSP technology – Journal of Industrial Ecology • full-scale LCA study needs to be conducted for individual new CSP power plant project to unleash the GHG emissions phenomenon with a comparison of conventional fossil-fuel power plants [82] 2012 Development Issues and futuristic view for 2050 – Journal of Solar Energy • EU and national-level research funding should be given in the area: high- Engineering temperature materials, optical coatings, radiative heat-transfer modeling, solar Renewa collectors, heat transfer fluids, thermodynamic cycles, new storage media and designs of thermal storage system • Simulation studies of Stochastic power system models for different renewable ble andSustainableEnergyReviews91(2018)987–1018 energy resources at EU, MENA, and EU–MENA levels in the light of power system integration • in the MENA region, Co-funding and co-financing options should be developed by the EU for large-scale CSP plant commercialization • national and international research collaboration among universities and companies [83] 2012 Development and distribution of CSP technology in China – RSER • Promotion of Stirling engine with integrated energy storage and stand-alone parabolic reflector with low-cost micro-facet solar concentrator are required for rural isolated areas of China for industrial and building applications [34] 2013 Thermal-energy storage system design methodologies Thermal-energy storage Progress in Energy and • Research opportunities in thermal performance and economics of storage unit Combustion Science medias for TES • impact of different types of TES systems (in combination) could reduce cost and increase CSP plant efficiency [71] 2013 CSP technologies and SPT design methodology Solar field RSER • power yield of a CSP plant can be assessed by annual, monthly and daily levels of direct (beam) solar irradiation • technical improvements by design optimization for SPT type power plant (continued on next page) ..Ilme al. et Islam M.T. Table 9 (continued)

Ref Year of Topic Components in the CSP Name of the journal Major findings and/or future research direction publication system

[84] 2013 Hybrid integration of CSP plant with conventional gas and Hybridization Renewable Energy Based on hybridization scenarios with existing built/under-construction CSP plant, coal-fired Rankine-cycle power plants and its application the assessment study found that • LFR systems are suitable for preheating feedwater, < 450 °C steam boost applications and cold reheat steam • at steam temperatures < 380 °C, PTCs using thermal oil rank second • with steam temperatures above 450 °C with direct steam generation, SPT can perform better using molten salt • for high-pressure steam delivery at and above 580 °C, SPD is the only alternative for hybridization scenario [85] 2013 Technological evolution and applicability of CSP technologies – RSER • Concentrating optical components, absorber tubes, thermal storage material or in West African countries heat transfer fluids should take advantage of new materials and design concepts to reduce cost and environmental impacts, at the same time increasing performance • Thermal energy storage or heat-transfer oils still have opportunities to improve • There is a need to assess solar resources for the solar-belt countries. Furthermore, in terms of scale or materials and equipment, CSP technologies are not well adapted to these countries • European countries have the opportunities for developing companies for CSP process improvement and component development • CSP is a great opportunity for a West African country like Burkina Faso [86] 2014 SPT designs with high-temperature power cycles Solar field RSER • for liquid and gaseous working fluids, tubular receivers utilized in the SPT has potential for improvement • Further investigation is required for selecting working fluid at SPT plant according to their storage capabilities (number of hours). 1004 • Opportunities lie in the area of receiver design for SPT plant [87] 2014 Applicability of high-efficiency thermodynamic cycles in CSP Power block RSER • steam Rankine system can elevate temperature to about 600 °C with higher power plants thermal efficiency • Above 600 °C, CO2 recompression Brayton cycle possesses high thermal efficiency • specific nature of the thermodynamic cycle configuration has to be considered in case of determining maximum receiver operating temperature (under various Carnot assumptions) [88] 2014 TES systems with metal hydrides Thermal storage unit RSER • Metal-hydride (MH) based material modification and heat transfer system improvement need further attention for cost-effective TES system. [89] 2014 Properties and applications of high-temperature HTFs Solar field and thermal AIMS Energy • thermal and transport properties of eutectic salts: NaCl-KCl-AlCl3 and NaCl-

storage unit KCl-ZnCl2 need further investigation Renewa • chemical corrosion of different salts to metals of pipes and containers requires research in the future [90] 2014 Liquid metals as HTF Solar field and thermal AIMS Energy • Liquid metal is a promising solution for central receiver as high-temperature ble andSustainableEnergyReviews91(2018)987–1018 storage unit HTF and it contributes to lowering LCOE • Transfer of knowledge of liquid metal from other fields (glass production or electronics cooling) to CSP application is necessary [91] 2014 CSP-related technology transfer to north African countries for – RSER • North African enterprises have the opportunity in manufacturing CSP plant- employment creation process related components through horizontal technology transfer [92] 2015 HTFs Solar field and thermal Applied Energy • corrosion characteristics of molten salts to metal alloys needs to be discussed storage unit further for wide-spread commercial application. • molten-salts based HTF will be used to achieve higher operating temperature (800 °C) • carbonate or chloride-based salts are being proposed but need further investigation [93] 2015 PCM's application for thermal energy storage Thermal energy unit Applied Energy • The size of the storage tank can be significantly reduced by using PCM as latent thermal storage and sensible heat storage (continued on next page) ..Ilme al. et Islam M.T. Table 9 (continued)

Ref Year of Topic Components in the CSP Name of the journal Major findings and/or future research direction publication system

[94] 2015 Historical development of CSP technologies – RSER • if cosine effect is reduced LFR type CSP can work more efficiently than globally commercialized PTC technology. • if the cost of heliostats and receiver are decreased, SPT CSP plant can be a great competitor of PTC • despite having the highest solar-to-electricity conversion efficiency and no water consumption, the cost of SPD technology prohibits commercial application [95] 2015 Overall CSP technology development and its implementation – Chemical Reviews • system-level investigation is required for SPD, SPT and LFR CSP plants. • at component level concentrator, receiver, HTF, thermal storage and heat engine have potential for improvement to overcome plant level challenges • reliability, cost and performance are the major optimization parameters • technical and innovative perspectives of component manufacturing methods and their materials for commercialization of CSP plants is an open research and discussion avenue [96] 2015 Fresnel lens Solar field RSER • Simultaneous Multiple Surface (SMS) and Total Internal Reflection (TIR) are the two emerging technologies in the Fresnel lens which need to be investigated further for CSP application. [97] 2015 CSP hybridization with biogas production system in Spain – RSER • Hybridization increases the plant operating hours to produce electricity with minimum cost in comparison with molten-salt TESs • Hybridization ensures shorter recovery of investment period, larger profitability and financial resource acquisition [98] 2015 Transformation of global energy source, CSP as a technology – RSER • electricity transition is a political and economic issue rather than technical and the role of China [99] 2015 Electricity generation and future CSP economics in Egypt – RSER • Specialized sub-authority should be created for CSP promotion • DNI measurement, identify specific sites (land acquisition) for CSP power plants 1005 and conduct feasibility studies (technical support, business partners etc.) are some of the essential work that needs to be done at national level [36] 2016 Development trends in high-temperature TES Thermal storage unit RSER • corrosion in molten salts has the incentive to investigate further from chemistry, metallurgy and thermodynamics points of view. • thermal cycling and mechanical loading in presence of PCM system requires more research to have safe and economic TES system [100] 2016 Technology review of Thermochemical energy storage Thermal storage unit RSER • reactivation cycle needs to be designed at research plant level for calcium carbonate for further evaluating the potential in CSP's thermal-heat storage system • manganese oxide cycle is suitable for desert climate but still needs to be

developed Renewa [101] 2016 Development trend of geometrical configurations for thermal Thermal storage unit RSER • Packed-bed encapsulated PCMs use in the TES is a continuous research area to energy storage system explore [102] 2016 CSP potential in Tunisia and European interconnection – RSER • Simulation results show that CSP project can be economically viable when ble andSustainableEnergyReviews91(2018)987–1018 collector structure and supports, the mirrors and the storage system are manufactured locally [30] 2016 Problems and prospects of CSP in desert regions – RSER • dry cooling or CSP-desalination cogeneration technologies are suitable against water scarcity problems in the CSP plant in desert areas • Latent-heat storage system (LHSS) will be dominant in future [103] 2016 Exergetic and environmental life-cycle assessment analysis – RSER • PTC plant possesses superiority over other CSP technologies where DNI is high regardless of the land usage (shoreline of Libya, for example) • First, solar field and then storage system showed the highest contribution under environmental impact categories as steel and synthetic oil are used, respectively • Solar field represented the highest cost due to initial investment • The cost can be minimized by increasing plant operation time which generally involves no fossil-fuel use and zero CO2 tax (continued on next page) ..Ilme al. et Islam M.T. Table 9 (continued)

Ref Year of Topic Components in the CSP Name of the journal Major findings and/or future research direction publication system

[104] 2016 CSP in India – RSER • Lack of technological data, financial barriers, and complex administrative and bureaucratic issues in India are the major inhibitor of large-scale CSP implementation • Solar PV is the competitor of CSP due to dramatic reduction in cost • Lack of government support and policy initiative slowing down CSP progress • With the existing coal-based power plant CSP plant can be hybridized [105] 2016 Control methods of direct steam generation in linefocus CSP Solar field RSER • An innovative Fresnel collector using a recirculation architecture was system developed by CNIM company to control several components in the power block but further research required [106] 2016 High-temperature receivers for CSP Solar field Applied Thermal Engineering • Performance of particle receivers is higher than with conventional molten nitrate salts • There are two types of particle receivers: direct which has high efficiencies due to direct irradiance of the heat transfer medium whereas “gravity-driven particle flow through enclosures” and “fluidized particle flow through tubes” are two types of indirect particle receiver • If particle receivers are used instead of utility-scale energy storage technologies such as batteries, pumped hydro, and compressed air energy storage then levelized cost of thermal storage and electricity conversion was calculated to be ∼ US$10/MW h [107] 2016 Occupational health and safety in central receiver CSP plant – RSER • Simulation study of the outdoor extreme weather conditions • Assessing work conditions and standard of safety measures at the receiver and surface installations [108] 2017 Progress in PTC collector Solar field RSER • Needs research on following issues 1. potential ways to improve operating temperatures 1006 2. next generation HTFis needed to be developed for large scale application 3. material of the metal tube of tube receiver operating at high temperature 4. in case of using molten salt corrosion characteristics 5. in water/steam system, high temperature and high pressure operating condition from the control point of view 6. uniform temperature distribution in case of tube receiver 7. application of inexpensive metal materials with high thermo-mechanical properties to solve specific problems such as tube receiver deflection and glass cover rupture [109] 2017 Life-cycle GHG emission of CSP – Energies • Life-cycle GHG emissions for the PTC, central receiver, SPD were computed as

79.8 gCO2e/kW h, 85.67 gCO2e/kW h, 41 gCO2e/kW h Renewa • PTC and central receiver CSP emitted approximately 50% more GHGs than the SPD • LCA study on SPD CSP for assessing environmental contributions is an open ble andSustainableEnergyReviews91(2018)987–1018 future research topic [110] 2017 Thermal energy storage of CSP Thermal storage unit RSER • Prospect of latent storage and thermochemical storage is tremendous and needs research in the area 1. properties enhancement of PCMs and thermochemical materials 2. process of removing solid debris in between the exchange surface of PCM and HTF 3. development of modular TES assembly and its management 4. enhancement in heat and mass transfer of thermochemical reactions 5. easy-to-use TES integration at CSP plants 6. optimize the charge and discharge transition time of latent-heat storage (continued on next page) ..Ilme al. et Islam M.T.

Table 9 (continued)

Ref Year of Topic Components in the CSP Name of the journal Major findings and/or future research direction publication system

[111] 2017 CSP's economic assessment – RSER • To make better techno-economic assessment, following are three areas that need further consideration 1. model and method standardization 2. designing new approaches for electricity market and optimization with operational policy 3. quantification of economic assessments considering uncertainty and assumptions [112] 2017 CSP hybridization strategies – RSER • Reliability and optimality in hybrid configurations using solar energy need further attention in intelligent plant maintenance [113] 2017 Design parameters of line-focus based CSP plants (LFR and Clean Technologies and • Future research should be conducted on PTC) Environmental Policy 1. optical efficiency improvement and cost optimization for LFR 2. efficient LFR receiver design with minimal heat loss and cost-efficient superheating alternatives 3. development of heat-transfer fluid that would have lower freezing point, higher thermal and chemical stability 4. development of cost-effective TES system 5. coal-based thermal power plants and natural-gas based combined-cycle power plants in conjunction with CSP need further thermal thermo-economic assessment 6. control strategies for integrated CSP plants with storage 7. development of techno-economically viable supply-chain management of solar 1007 field [114] 2017 Technical and economical assessment of commercial TES – RSER • Steam-accumulator TES system possesses the best alternatives as a buffer storage rather than large capacity storage • location of the plant, demand profile and market conditions, O&M costs, materials costs, storage hours, power and efficiency of the cycle, integration and operation strategies of the TES system into the power plant are some of the crucial parameters for holistic assessment of the total LOCE [115] 2017 Simulation-based alternatives for Saudi Arabia's CSP – RSER • Long-term weather data is required for accurate simulation study deployment • Due to maturity, PTCs have comparatively large potential • LFR showed lowest levelized cost of energy CFs per initial cost is significant for solar SPT • Renewa [116] 2017 Progress of CSP in India – RSER • Rajasthan, Gujrat and part of the Andhra Pradesh are popular sites for CSP plants in India [117] 2017 Technical and economic potential of CSP in India – RSER • Market-based-energy-storage capacity development is crucial ble andSustainableEnergyReviews91(2018)987–1018 • bankable DNI database development for potential locations • with low DNI hours generally during morning and late evening, diesel or gas fuel back-up system should be integrated for smooth operation [118] 2017 Use of PCM in thermal storage and heat transfer materials for Thermal storage unit Energies • encapsulated phase-change materials (EPCMs) have significant thermal-storage CSP capabilities (energy density: 1.25 GJ/m3) [119] 2017 CSP application in India – RSER • medium temperature (80–250 °C) can be conveniently applied to heating, space heating and cooling, refrigeration and industrial process heat • Cost of the technology and its payback period are negligible when fossil-fuel saving and avoidance of CO2 are considered (continued on next page) M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018 ndings and/or future research direction erent types of CSP technologies, interaction and interrelationships between fi ff CSP deployment in Brazilenergy is less market advantageous asDue a to latecomer lack in of thecompared government's solar- to policy solar priority PV CSPmarket installation, investment feasibility in and FiT China lags needsAppropriate further revision selection of according thermal to HTFparameters was for found PTC to CSP alongsite be one with characteristics, of other infrastructure the variables connections, crucial market such the and as cost water political of availability, environment installationFurther for and investigations establishing are global required CSPdi in project the area of drivers/barriers of four the driver/barriers and policy mix for CSP at EU level • • • • RSER Name of the journal Major RSER RSER

Fig. 14. Number of CSP-related publications over the years (1981 – January 2018). – system – – distribution of all the publications over the years, from 1981 to January 2018. It is clear that the total number of publications has continuously grown. This growth has been significant in the last decade (2007–2017), as the research published after 2007 consists of 91.5% of all the papers published in CSP-related studies. In 2017, the highest number of papers (157 papers) were published. In total, we identified 114 major publication sources (including both journals and conferences). It is found that CSP-related research are mainly progressed through journals (except AIP conference proceed- ings) and that the top 15 sources are responsible for around 55% of all the papers, while the remaining 99 sources are responsible for 36% of the publications. The rest 9% is from other 104 sources. Fig. 15 shows the historical progression of the top 15 publication sources. SOLAR ENERGY and ENERGY PROCEDIA are the two journals where the ma- jority of the articles have been published in recent times, while REN- EWABLE SUSTAINABLE ENERGY REVIEWS is the journal that has contributed progressively and promisingly from the year 2009. Topic Components in the CSP feasibility assessment of CSP in Morocco 6.2. Global distribution of publications on CSP

Among the various countries that published CSP-related papers, the ) USA and Spain published more than 38% of all the publications in the North American and European regions, respectively. In Asia, China 2017 China and Brazil's deployment of CSP technology publication continued 20182018 Energy analysis with a proposed model and technical Drivers and barriers of CSP in European Union published 81 papers and India 44 papers. Fig. 16 shows the distribution ( of the publications in different regions in the world. Although global solar energy and CSP potential is high comparatively in the MENA [120] Ref Year of [121] [122]

Table 9 countries, as well as Organisation for Economic Co-operation and

1008 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 15. Historical development of CSP-related studies at different journals.

Fig. 16. Distribution of CSP-related publications in the world.

Development (OECD) countries such as Australia, research progress is the publications of 1981 to January 2018. These were further reduced less than those of their counterparts. There is a clear opportunity for the using the requirement of minimum occurrence of 10 and a thesaurus researchers from the regions to investigate the development potential of file, to 262 keywords. Fig. 17 shows the resulting scientific landscape of CSP technologies in collaboration with the countries that are fron- the co-occurrence map of the terms found in the title and abstract of the trunners in CSP technology development. CSP publications. Each circle represents a term or keyword. The size of each keyword indicates the utilization of the keyword measured in terms of publications. The distances between the keywords in this map 6.3. Scientific landscape of CSP research and latest developments are also important. In general, the smaller the distance between two keywords, the higher the number of co-occurrences. In the figure, there Using the title and abstract, a total of 18,288 terms were found from

1009 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 17. Scientific landscape of CSP publications from 1981 to 2018.

Table 10. Result of keyword clustering by the publication.

Cluster color Research topic Observed keywords Number of keywords

Red Overall CSP plant development and electricity Development, electricity, region, country, assessment, methodology, framework, 115 generation potential, levelized cost of electricity, country Blue Solar collector Solar collector, receiver, radiation, surface, tube, modeling, conversion 68 Green Thermal-energy storage Temperature, fluid, degree Celsius, heat exchanger, heat transfer, salt, phase-change 79 material

are three clusters, i.e. green, blue and red for the thermal-energy sto- development related researchers does not use the thermal-energy sto- rage, solar-collector and electricity-generation related keywords, re- rage keywords. Conversely, thermal-energy storage researchers con- spectively. Table 10 summarizes the clustering result. centrated on the principle of energy storage rather than on research We can observe that the distance between the green and blue results from solar collectors. clusters is the shortest whereas the red clusters are situated at the right- There is a clear opportunity for the researcher here in bridging the hand side of the landscape representing the largest inter-cluster dis- common aspects of CSP technology development by taking into account tance from the former clusters. The red cluster contains terms that are various factors such as the LCOE, methodology for assessing potential essentially common for overall CSP plant development and electricity renewable-energy source integration with contextual understanding of generation considering economic analysis and regional focus. On the the economics of electricity generation from technological knowledge other hand, in blue and green clusters more of the technical terms ap- gathered from solar-collector and thermal-energy storage researchers. pear in scientific research on CSP. This indicates that the keywords for Currently, as well as historically, this bridging has been achieved thermal-energy storage and solar-collector research are the least oc- through one most widely applied CSP technology the parabolic-trough curring keywords in the field of solar thermal electricity generation as a (ptc) (located at the middle of the figure). Fresnel lenses are located in whole, in general. In addition, this figure also indicates that three major the solar-collector cluster whereas SPDes are a less researched issue types of researcher are working in the field of CSP research, namely as from the same cluster, located far within the cluster. heat-transfer fluid development for efficient thermal-energy storage, If we take a closer look at Fig. 17 we can see that “direct steam optical performance enhancement of solar collectors and techno-eco- generation” is the new term that appears at the top center of the nomic assessment of CSP plant development in the world. landscape, situated far from the blue cluster even though it is a part of In addition, from the clustering result, it is seen that co-occurrence it. An overlay visualization is also generated which also reflects that of thermal-energy storage research related keywords are occur less in direct steam generation (DSG) is a comparatively new keyword that the area of solar-collector research. In other words, thermal-energy appeared in the literature after 2014. Other keywords appearing most storage research papers do not contain solar-collector related keywords. recently are solar multiple (12), flexibility (21), levelized cost of elec- We can infer from this that the focus of solar-collector design and tricity (44), system advisory model (17), organic rankine cycle (19),

1010 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 18. Scientific landscape of CSP publications from 2011 to 2015.

supercritical CO2 (23), calcium (10), thermos chemical-energy storage Uzbekistan. Nine articles were published in RSER and eight in Solar (17). Fig. 18 shows the appearance of the keywords in the scientific Energy – two highly influential scientific journals. The least number of landscape of CSP research from the year 2011 to 2015 and onwards. In citations (69) was received by the article “Life Cycle Assessment of a the next section we conduct a citation analysis by which we can identify PTC Concentrating Solar Power Plant and the Impacts of Key Design influential research papers and their contribution to the expanding CSP Alternatives” by Burkhardt [129] published in Environmental Science & research. Technology with yearly average citations of 8.63.

6.4. Top cited papers in the CSP research 6.5. Direct steam generation (DSG) – research trends and perspectives

With the methodology described for citation analysis, 29 publica- As observed in figures (Figs. 17 and 18), DSG is one of the tech- tions were found that are considered as the most influential, based on nologies/processes that is receiving attention from the research com- their total citation and yearly average citation. Table 10 shows the most munity, and we conduct further investigation on this term. We have highly cited articles by their title, name of the journal where the paper seen in the global progress in CSP technology, PTC is the most widely was published, author's name, country of the corresponding author, commercialized CSP plant type that is subject to continuous advance- year of publication, total citation and average annual citation. The ment. Within this incremental improvement effort, DSG is a developing impact of publications can be identified by the annual variations in the technology that is already identified as a cheaper system for electricity- number of citations. The most highly cited article was entitled “Solar generation and heat-process requirements [154,155]. According to Al- thermal collectors and applications” authored by Kalogirou [46] and hayek et al. [156], DSG is a process by which steam is directly produced published in Progress in Energy and Combustion Science with 895 ci- in the PTC fields and supplied to a power block for electricity produc- tations and 59.67 annual citations. “State of the art on high temperature tion. This process simplifies operation and improves the cost-effec- thermal energy storage for power generation. Part 1-Concepts, mate- tiveness of the PTC plant by increasing the permissible temperature of rials and modellization” authored by Gil [128] and published in RSER, the working fluid. Instead of the current synthetic-oil based HTF tech- took the second position in terms of annual average citations (59.22). nology, DSG diminishes the necessity for any intermediary for heat Of the 29 articles listed in Table 11, 13 articles came from Europe transfer and overcomes the intermittent nature of solar (for TES). Be- (including the two most cited articles), underscoring that Europe has a sides, application in the PTC, DSG is the next-generation CSP plants that tremendous influence on CSP research. In contrast, 9 articles came from can be widely used in other thermal applications such as sterilization the USA and the remaining few were from Australia, China and processes and desalination evaporator supplies [157]. Fig. 19 shows the

1011 ..Ilme al. et Islam M.T.

Table 11. Citation analysis of the publications in CSP research (2000–2016).

Title Journal Corresponding author Country of corresponding Publication year Total number of Average citations author citations per year

Solar thermal collectors and applications [46] Progress in Energy and Combustion Kalogirou SA Cyprus 2004 895 59.67 Science Solar thermochemical production of hydrogen – a review [130] Solar Energy Steinfeld A Switzerland 2005 652 46.57 State of the art on high-temperature thermal energy storage for power RSER Medrano M Spain 2010 533 28.67 generation. Part 2 – Case studies [131] State of the art on high temperature thermal energy storage for power RSER Gil A Spain 2010 533 59.22 generation. Part 1-Concepts, materials and modellization [128] Advances in solar thermal electricity technology [132] Solar Energy Mills D Australia 2004 376 25.07 Advances in PTC solar power technology [133] Journal of Solar Energy Price H USA 2002 373 21.94 Engineering-Transactions of the ASME Parabolic-trough solar collectors and their applications [53] RSER Fernandez-garcia A Spain 2010 336 37.33 A review of solar collectors and thermal energy storage in solar thermal Applied Energy Tian Y China 2013 329 54.83 applications [134] Thermal energy storage technologies and systems for concentrating solar power Progress in Energy and Combustion Kuravi S USA 2013 295 49.17 plants [34] Science High-temperature phase change materials for thermal energy storage [135] RSER Kenisarin MM Uzbekistan 2010 277 30.78 Two-tank molten salt storage for PTC solar power plants [136] Energy Herrmann U Germany 2004 226 15.07 Development of a molten-salt thermocline thermal storage system for PTC plants Journal of Solar Energy Pacheco JE USA 2002 217 12.76 [137] Engineering-Transactions of the ASME

1012 Performance of a concentrating photovoltaic/thermal solar collector [138] Solar Energy Coventry JS Australia 2005 199 14.21 Concentrated solar power plants: Review and design methodology [139] RSER Zhang HL Belgium 2013 191 31.83 Assessment of a molten salt HTFin a PTC solar field [140] Journal of Solar Energy Kearney D USA 2003 187 11.69 Engineering-Transactions of the ASME Volumetric receivers in Solar Thermal Power Plants with Central Receiver Solar Energy Avila-marin AL Spain 2011 180 22.50 System technology: A review [141] A review of studies on central receiver solar thermal power plants [142] RSER Behar O Algeria 2013 175 29.17 Survey of thermal energy storage for PTC power plants [143] Journal of Solar Energy Herrmann U Germany 2002 175 10.29 Engineering-Transactions of the ASME Renewa Innovation in concentrated solar power [144] Solar Energy Materials and Solar Barlev D USA 2011 170 21.25 Cells

Review of high-temperature central receiver designs for concentrating solar RSER Ho CK USA 2014 149 29.80 ble andSustainableEnergyReviews91(2018)987–1018 power [145] Compact LFR solar thermal powerplants [146] Solar Energy Mills DR Australia 2000 134 7.05 Comparison of Linear Fresnel and PTC Collector power plants [147] Solar Energy Morin G Germany 2012 130 18.57 A review on high temperature thermochemical heat energy storage [148] RSER Parbo P France 2014 123 24.60 Thermal analysis of storage in a molten-salt thermocline Solar Energy Yang Z USA 2010 120 13.33 [149] Review on concentrating solar power plants and new developments in high RSER Liu M Australia 2016 95 31.67 temperature thermal energy storage technologies [150] Heat transfer fluids for concentrating solar power systems – A review [151] Applied Energy Vignarooban K USA 2015 93 23.25 Performance model for PTC solar thermal power plants with thermal storage: Solar Energy Garcia LI Spain 2011 90 11.25 Comparison to operating plant data [152] The potential role of concentrated solar power (CSP) in Africa and Europe-A Energy policy Viebahn P Germany 2011 81 10.13 dynamic assessment of technology development, cost development and life cycle inventories until 2050 [153] Life Cycle Assessment of a PTC Concentrating Solar Power Plant and the Impacts Environmental Science & Burkhardt JJ USA 2011 69 8.63 of Key Design Alternatives [129] Technology M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

Fig. 19. Comparison between (a) direct steam generation (DSG) and (b) heat transfer fluid (HTF) CSP power plants [158].

PTC type CSP plant with DSG and with typical HTF. DSG integration in these types of plants, which can be overcome by According to Fernández-García et al. [53], DSG has the following continuous management of solar collectors during sunrise and sunset advantages over a conventional synthetic-oil based PTC system: 1) no [20]. Fossil and biomass hybridization with PTC plant using DSG environmental risk of fire and leakage, 2) a maximum temperature for technology is found to be an economically competitive viable option the thermodynamic cycle can be achieved of over 400 °C, which is [156,159]. difficult to achieve in the presence of synthetic oil, 3) as there is no oil/ ffi steam heat exchanger, overall plant e ciency can be higher, 4) sim- 7. Conclusion and future work plified plant configuration with lower capital investment, and finally 5) operation and maintenance costs are lower than for a synthetic oil Electricity production from conventional energy sources creates based PTC system, primarily as there is no auxiliary heating system. several bottlenecks such as the risk of a sudden drop in supply quantity, As there is a large body of literature in the CSP research field, it is emission of major GHGs like CO2, and a threat to overall environmental worthwhile to investigate such a promising technology, in particular. sustainability. On the other hand, renewable-energy sources provide Table 12 summarizes the most recent and relevant articles published in abundant, clean and sustainable energy that will clearly be at the DSG technology. We sub-grouped the publications according to their forefront in terms of delivering an inexhaustible supply of energy. CSP type of research and CSP component level in relation to the DSG. There is capable of bulk electricity generation and many of the industrialized ff fi are a total of forty four di erent studies identi ed on DSG, where nations are investing heavily in CSP technology. Among the four dif- studies were based on analytical methodology (2), dynamic modeling ferent types of CSP technologies, the parabolic trough collector (PTC) and simulation (1), energetic analysis (1), energy and exergy analysis and the solar power tower (SPT) are the two popular technologies that (1), energy-economic analysis (1), exergy and exergy-economic analysis are currently installed in many countries, such as Spain, USA, China, (1), experimental (7), experimental and simulation (1), Mathematical and India. Research and publications on CSP is expanding at a tre- modeling (2), modeling and dynamic analysis (2), modeling and ex- mendous pace. With VOSviewer text-mining software, a bibliometric perimental (2), modeling and optimization (1), modeling and simula- analysis on CSP research was performed and the scientific landscape of tion (10), multi-level analytical methodology (1), performance assess- the most widely researched, newly emerging topics and the most in- ment (1), simulation (7), thermo-economic analysis (2). fluential articles were identified and reviewed. The direct steam gen- Among the experimental work, most were related to designing and eration (DSG) technology of the PTC collector is a comparatively optimization of thermal-energy storage. Modeling and simulation stu- evolving research topic which possesses opportunity in hybridizing dies focused on designing and validating a control system for optimum with other CSP technologies for electricity and thermal heat produc- fl steam generation, its ow pattern and thermodynamic performance in a tion. Other potential research topics on CSP are optimization of solar DSG system at PTC-type plant. Although DSG was originally developed fields (solar multiple), estimation of levelized cost of electricity with for a PTC-type plant, recent studies showed that hybridization of the sensitivity analysis, application of system advisory model (SAM) in CSP PTC plant with other types of CSP plant such as a SPT and LFR even a plant development, implementation of organic rankine cycle engine for SPD using DSG, were also being considered for cost reduction in steam heat and power production, investigation on supercritical CO power fi 2 and electricity generation. However, synchronizing solar elds with cycle in CSP plants, performance analysis of calcium-looping and receivers and supercritical steam turbines are the major challenges of thermo-chemical energy storage in the CSP systems. Desalination, life-

1013 ..Ilme al. et Islam M.T. Table 12 Related studies in direct steam generation (DSG) of CSP plant.

Ref. Author(s) Year of Topic Type of CSP Type Relation to DSG publication plant

[160] Guo et al. 2018 Design and optimization of storage system PTC Experimental Influence of thermal storage system on DSG [161] Li et al. 2017 Thermal load and bending analysis of heat collection element PTC Modeling and simulation Evaporation and superheating stages of DSG [156] Alhayek et al. 2017 Steam generation in hybridized system (biomass boiler PTC Energy and exergy analyses Innovative hybridization integration) [162] Biencinto et al. 2017 Behavior and yearly performance in electricity production PTC Modeling and Simulation Steam pressure regulation by sliding-pressure strategies at turbine inlet [163] Guo et al. 2017 Modeling and controlling for recirculation mode PTC Dynamic modeling and simulation Designing, testing and validation of automatic control system [164] Serrano-Aguilera et al. 2017 Thermal hydraulic RELAP5 model PTC Modeling and experimental Reliable and efficient two-phase flow modeling tools [165] Guo et al. 2017 Dynamic behavior of solar collector under moving shadow PTC Modeling and simulation Fluid parameters conditions [166] Abdel Dayem et al. 2017 Performance assessment PTC Simulation Performance comparison with saturated steam and superheated production [167] Li et al. 2017 Thermodynamic and economic investigation PTC Mathematical modeling Operational performance and economics of steam accumulator and screw expander [168] Ruiz-Cabañas et al. 2017 Cost and thermal efficiency optimization by integrated steam- PTC Experimental High-temperature hydroxides corrosion PCM heat exchanger [169] Bortolato et al. 2017 Designing and performance analysis of flat plate absorber PTC Experimental Thermal performance solar collector during steam generation [170] Suojanen et al. 2017 Modeling, analysis and comparison of three hybrid configurations LFR Simulation Application of DSG in a CSP plant coupled with in a combined CSP and conventional steam power plant steam boiler [171] Li et al. 2017 Optical-hydraulic-thermal-elastic synergistic issue of a CSP plant PTC Analytical methodology Performance prediction and component-orientated 1014 monitoring with the presence of DSG [172] Li et al. 2017 Performance evaluation of a DSG-PTC-CSP plant PTC Multi-level analytical methodology Performance prediction with the presence of DSG system [173] Liu et al. 2016 Flow field optimization of solar receiver PTC Simulation Reliability of solar receivers based on circumferential temperature difference [174] Guo et al. 2016 Non-linear distributed parameter model (NDPM) development for PTC Modeling and dynamic analysis Operation and control of DSG solar collectors [175] Hoffmann et al. 2016 Dynamics of severe slugging PTC Simulation Performance evaluation of water steam flows [176] Núnez Bootello et al. 2016 Designing flat parametric trough collector by simultaneous PTC Modeling Optical analysis of multi-tube receiver multiple-surface (SMS) method [177] Olson and Talghader 2016 Optimization of solar selective coating PTC Modeling and optimization Thermal performance Renewa [178] Biencinto et al. 2016 TRNSYS software based modeling for pipes and collector PTC Simulation Dynamic behavior of DSG at transient conditions components [66] Manente et al. 2016 Integrated solar combined cycles PTC, LFR Modeling by Thermoflex® environment Hybrid application ble andSustainableEnergyReviews91(2018)987–1018 and SPT [179] Ortega-Delgado et al. 2016 Cost of steam consumption in distillation process PTC Thermo-economic analysis - joint Application of DSG production of electricity and water [180] Coco-Enríquez et al. 2015 Innovative DSG + supercritical CO2 solar power plants for PTC Modeling and simulation Thermodynamic performance supercritical Brayton power cycles [181] Elsafi 2015 Thermo-hydraulic performance analysis PTC Modeling and simulation Prediction of flow patterns at evaporation section [182] Elsafi 2015 Designing and optimization of DSG power plant PTC Exergy and exergoeconomic analysis Non-reheating and reheating by steam–steam heat exchanger configuration [183] Nolte et al. 2015 Solar receiver tube and plant design PTC Mathematical modeling Mass flow rates, tube diameters and operating pressures [13] Sun et al. 2015 Characteristics, performance and operational strategy PTC Modeling and simulation Exergy efficiency DSG loop in recirculation mode [184] Bouvier et al. 2015 Performance analysis of micro-cogeneration system PTC Micro-CHP Two-phase flow saturated steam production [185] Zapata 2015 Designing of once-through steam-cavity receiver PTC Modeling and simulation State-space based control strategies [186] Zapata 2015 Designing and testing of full state linear-feedback controller SPD Experimental Mass flow control strategy [187] Xu and Wiesner 2015 Development and performance analysis of closed form DSG PTC Simulation Temperature profiles of the glass envelope and absorber wall (continued on next page) M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

cycle assessment, hydrogen production and phase-change material (PCM) should be reviewed in the further studies.

Acknowledgements

The authors would like to thank two anonymous reviewers for their constructive comments on the manuscript. Thanks to Dr. Keith Imrie for proofreading the manuscript. The first author acknowledges funding support from Macquarie University under an International Research

eld, sizing of power block and Training Program (iMQRTP) scholarship. fi elds for cheaper alternative to PTC fi References

ows in the integrated plant [1] Islam MT, Shahir S, Uddin TI, Saifullah A. Current energy scenario and future Behavioral analysis of solarOptimum absorber design tube radiation (DNI) of a CSP plant, Steam electrolysis process optimization Regenerators and latent heat storage Application of storage material for DSG Sizing of solar Cost of steam production and turbine steam mass Energy and economic performance Relation to DSG deciding power cycle parameters Cycle temperature and pressure optimization Rankine cycle steam management Thermocline TES in steam generation DSG of LFR fl prospect of renewable energy in Bangladesh. Renew Sustain Energy Rev 2014;39:1074–88. [2] Mekhilef S, Saidur R, Safari A. A review on solar energy use in industries. Renew Sustain Energy Rev 2011;15:1777–90. [3] Pavlović TM, Radonjić IS, Milosavljević DD, Pantić LS. A review of concentrating solar power plants in the world and their potential use in Serbia. Renew Sustain Energy Rev 2012;16:3891–902. [4] Hasan M, Mahlia T, Nur H. A review on energy scenario and sustainable energy in Indonesia. Renew Sustain Energy Rev 2012;16:2316–28. [5] WPB. World population balance population and energy consumption. Available from 〈http://www.worldpopulationbalance.org/population_energy〉; 2015 [Last accessed on 10 October 2016]. [6] Zhang Z, Yuan Y, Zhang N, Sun Q, Cao X, Sun L. Thermal properties enforcement of carbonate ternary via lithium fluoride: a heat transfer fluid for concentrating solar power systems. Renew Energy 2017;111:523–31. [7] Ummadisingu A, Soni M. Concentrating solar power–technology, potential and Modeling and simulation Energetic analysis Experimental and simulation Experimental Numerical modeling and experimental Radial domain discretization of DSG absorbers Energy-economic analysis Type of Selection diagram Simulation Performance assessment Experimental Modeling and simulation Experimental policy in India. Renew Sustain Energy Rev 2011;15:5169–75. [8] Ahmed S, Islam MT, Karim MA, Karim NM. Exploitation of renewable energy for sustainable development and overcoming power crisis in Bangladesh. Renew Energy 2014;72:223–35. [9] Sims RE, Rogner H-H, Gregory K. Carbon emission and mitigation cost compar- isons between fossil fuel, nuclear and renewable energy resources for electricity PTC SPT PTC and LFR Analytical methodology PTC and LFR Thermo-economic analysis and application PTC PTC Type of CSP PTC plant PTC PTC SPT PTC SPT generation. Energy Policy 2003;31:1315–26. [10] EIA. U.S. Energy Information Administration international energy outlook. eld 〈 〉 fi Available from https://www.eia.gov/outlooks/ieo/pdf/0484(2017).pdf ; 2017 [Last accessed on 22 January 2018]. [11] IEA. Energy Technology Perspectives 2015: Mobilising Innovation to Accelerate Climate Action. Paris: IEA. Available from 〈https://www.iea.org/ newsroomandevents/speeches/150504_ETP_slides.pdf〉; 2015 [Last accessed on 17 November 2015]. [12] Sharma A. A comprehensive study of and World. Renew Sustain Energy Rev 2011;15:1767–76. [13] Sun J, Liu Q, Hong H. Numerical study of parabolic-trough direct steam generation loop in recirculation mode: characteristics, performance and general operation strategy. Energy Convers Manag 2015;96:287–302. [14] SolarPACES. Solar thermal electricity global outlook 2016. Available from 〈http:// ow and one-dimensional heat transfer PTC

fl www.solarpaces.org/images/GP-ESTELA-SolarPACES_Solar-Thermal-Electricity- Global-Outlook-2016_Executive-Summary.pdf〉; 2016 [Last accessed on 07 May 2016]. [15] Izquierdo S, Montanes C, Dopazo C, Fueyo N. Analysis of CSP plants for the de- finition of energy policies: the influence on electricity cost of solar multiples, ca- pacity factors and energy storage. Energy Policy 2010;38:6215–21. [16] Teske S, Leung J, Crespo L, Bial M, Dufour E, Richter C, et al. Solar thermal electricity: Global outlook 2016. Eur Sol Therm Electr Assoc 2016. [17] Yasinskiy A, Navas J, Aguilar T, Alcántara R, Gallardo JJ, Sánchez-Coronilla A, et al. Dramatically enhanced thermal properties for TiO2-based nanofluids for Designing of single-phase PCM for TES Thermodynamic performance of Kalina cycle with two-tank Optical performance analysis and optimization of heliostat Carbon-free hydrogen production process Optimization, energy and economicenergy analysis storage of PTC without Design optimization and integration Topic Dynamic simulation, design improvements and control issues in Model development for TES Performance analysis by multiphase CFD modeling Conceptual CSP plant design without energy storage Integration of Ultra Super Critical (USC) power plants with Sobol's-method based analysis on global sensitivity and thermal energy storage Carbon Capture and Storagesystems (CCS) and concentrating solar and receiver absorbers arrangement uncertainty molten-salt storage being used as heat transfer fluids in concentrating solar power plants. Renew Energy 2017;119:809–19. [18] Franz Trieb, Christoph Schillings, Marlene O‘Sullivan, Thomas Pregger, Hoyer- Klick C. Global potential of concentrating solar power. In: Proceedings of the SolarPACES. Berlin, Germany; 2009. [19] Brenna M, Foiadelli F, Roscia M, Zaninelli D. Evaluation of solar collector plant to contribute climate change mitigation. In: Proceedings of the IEEE international conference on sustainable energy technologies, ICSET. Singapore; 2008. p. Year of 2015 2015 publication 2014 2014 2014 2014 2014 2014 198–202. [20] Philibert C. Technology roadmap: concentrating solar power: OECD/IEA; 2010. [21] FirstGreen. Comparison of CSP technologies. Available from 〈https:// firstgreenconsulting.wordpress.com/2012/06/04/comparison-of-csp- technologies/comparison-of-csp-technologies/〉; 2012 [Last accessed on 18 October 2016]. ) [22] CEC. California Energy Commission solar power plant licensing projects. Available from 〈http://www.energy.ca.gov/maps/renewable/Solar_Power_Plant_Licensing_ Projects.pdf〉; 2014 [Last accessed on 04 May 2017].

continued [23] Richter C, Teske S, Nebrera J. Concentrating solar power global outlook 09. ( Desai and Bandyopadhyay Desai and Bandyopadhyay Serrano-Aguilera et al. 2014 Desai et al. Manenti et al. Cau et al. Blanco-Rodríguez et al.Stückle et al. Silva 2014 et al. Modi and HaglindSanz-Bermejo et al. 2014 Lobón et al. 2014 Sanz-Bermejo et al. 2014 Greenpeace International/European Solar Thermal Electricity Association (ESTELA)/IEA SolarPACES, Report; 2009. [24] EU. European Commission, Energy Research Knowledge Centre (ERKC). Thematic [188] [189] Ref. Author(s) [190] [198] [199] [200] [192] [193] [194] [195] [196] [197] [191] research summary – concentrating solar power. Available from 〈https://setis.ec. Table 12

1015 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

europa.eu/energy-research/sites/default/files/library/ERKC_TRS_Concentrating_ [55] Manzolini G, Giostri A, Saccilotto C, Silva P, Macchi E. Development of an in- solar_power.pdf〉; 2013 [Last accessed on 04 May 2017]. novative code for the design of thermodynamic solar power plants part A: code [25] SolarPACES. CSP projects around the world. Available from 〈http://www. description and test case. Renew Energy 2011;36:1993–2003. solarpaces.org/csp-technology/csp-projects-around-the-world〉; 2016 [Last ac- [56] Duddu P. The world's biggest solar power plants. Available from 〈http://www. cessed on 07 May 2016]. power-technology.com/features/feature-largest-solar-power-plants-in-the-world/ [26] EC. European Commission TECHNICAL BACKGROUND: concentrated solar power. 〉; 2013 [Last accessed on 23 January 2018]. Available from 〈http://ec.europa.eu/research/energy/eu/index_en.cfm?pg= [57] DLR. Deutsches Zentrum für Luft- und Raumfahrt first solar thermal power plant in research-csp-background〉; 2015 [Last accessed on 07 May 2016]. Southeast Asia is fully operational. Available from 〈http://www.dlr.de/dlr/ [27] REN21. REN21 Secretariat. Renewables 2017 global status report. Available from presse/en/desktopdefault.aspx/tabid-10309/472_read-2343/year-2012/#/ 〈http://www.ren21.net/wp-content/uploads/2017/06/17-8399_GSR_2017_Full_ gallery/4363〉; 2012 [Last accessed on 23 January 2018]. Report_0621_Opt.pdf〉; 2017 [Last accessed on 23 January 2018]. [58] Behar O, Khellaf A, Mohammedi K. A review of studies on central receiver solar [28] Pitz-Paal R. Encyclopedia of life support system (EOLSS) high temperature solar thermal power plants. Renew Sustain Energy Rev 2013;23:12–39. concentrators. Available from 〈http://www.eolss.net/ebooks/Sample [59] Müller-Steinhagen H, Trieb F, Trieb F. Concentrating solar power: a review of the %20Chapters/C08/E6-106-06-00.pdf〉; 2007 [Last accessed on 04 May 2017]. technology. Available from 〈http://www.dlr.de/tt/Portaldata/41/Resources/ [29] Crane K, Curtright AE, Ortiz DS, Samaras C, Burger N. The economic costs of re- dokumente/institut/system/publications/Concentrating_Solar_Power_Part_1.pdf〉; ducing greenhouse gas emissions under a US national renewable electricity man- 2004 [Last accessed on 16 October 2016]. date. Energy Policy 2011;39:2730–9. [60] Brakmann G, Aringhoff R, Geyer M. ESTIA, : Greenpeace International, [30] Xu X, Vignarooban K, Xu B, Hsu K, Kannan AM. Prospects and problems of con- Amsterdam, IEA SolarPACES Implementing Agreement. Concentrated solar centrating solar power technologies for power generation in the desert regions. thermal power – now! Available from 〈http://www.preppers.info/uploads/ Renew Sustain Energy Rev 2016;53:1106–31. Concentrated-Solar-Thermal-Power.pdf〉; 2005 [Last accessed on 04 May 2017]. [31] Peters M, Schmidt TS, Wiederkehr D, Schneider M. Shedding light on solar tech- [61] USDOE. Office of Energy Efficiency & Renewable Energy concentrating solar nologies—a techno-economic assessment and its policy implications. Energy power. Available from 〈http://energy.gov/eere/sunshot/concentrating-solar- Policy 2011;39:6422–39. power〉; 2016 [Last accessed on 16 October 2016]. [32] Santos-Alamillos FJ, Pozo-Vázquez D, Ruiz-Arias JA, Von Bremen L, Tovar- [62] Sharma C, Sharma AK, Mullick SC, Kandpal TC. Assessment of solar thermal power Pescador J. Combining wind farms with concentrating solar plants to provide generation potential in India. Renew Sustain Energy Rev 2015;42:902–12. stable renewable power. Renew Energy 2015;76:539–50. [63] Shouman ER, Khattab N. Future economic of concentrating solar power (CSP) for [33] Kaygusuz K. Prospect of concentrating : the sustainable fu- electricity generation in Egypt. Renew Sustain Energy Rev 2015;41:1119–27. ture. Renew Sustain Energy Rev 2011;15:808–14. [64] Alexopoulos S, Hoffschmidt B. Solar tower power plant in Germany and future [34] Kuravi S, Trahan J, Goswami DY, Rahman MM, Stefanakos EK. Thermal energy perspectives of the development of the technology in Greece and Cyprus. Renew storage technologies and systems for concentrating solar power plants. Prog Energy 2010;35:1352–6. Energy Combust Sci 2013;39:285–319. [65] SolarPACES. Technology characterization solar power towers. Available from [35] Nixon J, Dey P, Davies P. Which is the best solar thermal collection technology for 〈http://www.solarpaces.org/images/pdfs/solar_tower.pdf〉;2016 [Last accessed electricity generation in north-west India? Evaluation of options using the analy- on 16 October 2016]. tical hierarchy process. Energy 2010;35:5230–40. [66] Manente G, Rech S, Lazzaretto A. Optimum choice and placement of concentrating [36] Liu M, Steven Tay NH, Bell S, Belusko M, Jacob R, Will G, et al. Review on con- solar power technologies in integrated solar combined cycle systems. Renew centrating solar power plants and new developments in high temperature thermal Energy 2016;96:172–89. energy storage technologies. Renew Sustain Energy Rev 2016;53:1411–32. [67] Kolb GJ. Economic evaluation of solar-only and hybrid power towers using [37] Zhang W. Institut für Energiewirtschaft und Rationelle Energieanwendung. molten-salt technology. Sol Energy 1998;62:51–61. Concentrating solar power – state of the art, cost analysis and pre-feasibility study [68] Philibert C. Technology roadmap: solar thermal electricity—2014 edition. Paris, for the implementation in China. Available from 〈http://www.efchina.org/ France: IEA; 2014. Attachments/Report/reports-efchina-20101222-2-en/Concentrating%20Solar [69] El Gharbi N, Derbal H, Bouaichaoui S, Said N. A comparative study between %20Power%20-%20State%20of%20the%20Art,%20Cost%20Analysis%20and parabolic trough collector and linear Fresnel reflector technologies. Energy %20Pre-Feasibility%20Study%20for%20the%20Implementation%20in%20China. Procedia 2011;6:565–72. pdf〉; 2009 [Last accessed on 18 October 2016]. [70] Chemisana D. Building integrated concentrating : a review. Renew [38] Steinmann W-D, Laing D, Tamme R. Latent heat storage systems for solar thermal Sustain Energy Rev 2011;15:603–11. power plants and process heat applications. J Sol Energy Eng 2010;132:021003. [71] Zhang H, Baeyens J, Degrève J, Cacères G. Concentrated solar power plants: re- [39] SolarPACES. SolarPACES technology characterization solar dish systems. Available view and design methodology. Renew Sustain Energy Rev 2013;22:466–81. from 〈http://www.solarpaces.org/images/pdfs/solar_dish.pdf〉; 2016 [Last ac- [72] STELA. Fresnel collector – PSA. Available from 〈http://www.stelaworld.org/ cessed on 10 October 2016]. linear-fresnel-reflectors/〉; 2018 [Last accessed on 24 January 2018]. [40] Ab Kadir MZA, Rafeeu Y, Adam NM. Prospective scenarios for the full solar energy [73] Charabi Y, Gastli A. GIS assessment of large CSP plant in Duqum, Oman. Renew development in Malaysia. Renew Sustain Energy Rev 2010;14:3023–31. Sustain Energy Rev 2010;14:835–41. [41] Tyagi V, Kaushik S, Tyagi S. Advancement in solar photovoltaic/thermal (PV/T) [74] Pitz-Paal R, Dersch J, Milow B. German Aerospace Center European concentrated hybrid collector technology. Renew Sustain Energy Rev 2012;16:1383–98. solar thermal road-mapping. Available from 〈http://www.promes.cnrs.fr/ [42] Braun FG, Hooper E, Wand R, Zloczysti P. Holding a candle to innovation in uploads/pdfs/ecostar/ECOSTAR.Roadmap.pdf〉; 2004 [Last accessed on 04 May concentrating solar power technologies: a study drawing on patent data. Energy 2017]. Policy 2011;39:2441–56. [75] Poullikkas A. Economic analysis of power generation from parabolic trough solar [43] Cavallaro F. Multi-criteria decision aid to assess concentrated solar thermal tech- thermal plants for the Mediterranean region—a case study for the island of Cyprus. nologies. Renew Energy 2009;34:1678–85. Renew Sustain Energy Rev 2009;13:2474–84. [44] Poullikkas A, Kourtis G, Hadjipaschalis I. Parametric analysis for the installation of [76] Hang Q, Jun Z, Xiao Y, Junkui C. Prospect of concentrating solar power in solar dish technologies in Mediterranean regions. Renew Sustain Energy Rev China—the sustainable future. Renew Sustain Energy Rev 2008;12:2505–14. 2010;14:2772–83. [77] Li J. Scaling up concentrating solar thermal technology in China. Renew Sustain [45] El-Tous Y. Assessment of one-axis concentrating solar power technologies in Energy Rev 2009;13:2051–60. Jordan using fuzzy logic. Int J Energy Convers (IRECON) 2013;1:238–42. [78] Kandilli C, Ulgen K. Review and modelling the systems of transmission con- [46] Kalogirou SA. Solar thermal collectors and applications. Progress Energy Combust centrated solar energy via optical fibres. Renew Sustain Energy Rev Sci 2004;30:231–95. 2009;13:67–84. [47] Lovegrove K, Taumoefolau T, Paitoonsurikarn S, Siangsukone P, Burgess G, Luzzi [79] Xie WT, Dai YJ, Wang RZ, Sumathy K. Concentrated solar energy applications A, et al. Paraboloidal dish solar concentrators for multi-megawatt power genera- using Fresnel lenses: a review. Renew Sustain Energy Rev 2011;15:2588–606. tion. In: Proceedings of the ISES; 2003. p. 14–9. [80] Romero M, Steinfeld A. Concentrating solar thermal power and thermochemical [48] Affandi R, Gan CK, Ghani A, Ruddin M. Performance comparison for parabolic dish fuels. Energy Environ Sci 2012;5:9234–45. concentrating solar power in high level DNI locations with George Town, [81] Burkhardt JJ, Heath G, Cohen E. Life cycle greenhouse gas emissions of trough and Malaysia, Appl Mech Mater; 2015. p. 570–6. tower concentrating solar power electricity generation. J Ind Ecol [49] Ridden P. First Suncatcher solar dishes to be used in Arizona. Available from 2012;16:S93–109. 〈http://newatlas.com/suncatcher-solar-power-generation/12684/〉; 2009 [Last [82] Pitz-Paal R, Amin A, Bettzuge MO, Eames P, Flamant G, Fabrizi F, et al. accessed on 10 October 2016]. Concentrating solar power in Europe, the Middle East and North Africa: a review [50] Solar M. Tessera Solar North America. Available from 〈http://www.mortenson. of development issues and potential to 2050. J Sol Energy Eng 2012;134:024501. com/solar/projects/maricopa-solar〉; 2018 [Last accessed on 23 January 2018]. [83] Liu Z-q, Xu A-x, Lv Y-y, Wang X-x. Promoting the development of distributed [51] AGA. American Galvanizers Association Stirling Solar Array – Tooele Army Depot. concentrated solar thermal technology in China. Renew Sustain Energy Rev Available from 〈https://www.galvanizeit.org/project-gallery/gallery/stirling- 2012;16:1174–9. solar-array-tooele-army-depot〉; 2018 [Last accessed on 23 January 2018]. [84] Peterseim JH, White S, Tadros A, Hellwig U. Concentrated solar power hybrid [52] Mohamad A, Orfi J, Alansary H. Heat losses from parabolic trough solar collectors. plants, which technologies are best suited for hybridisation? Renew Energy Int J Energy Res 2014;38:20–8. 2013;57:520–32. [53] Fernández-García A, Zarza E, Valenzuela L, Pérez M. Parabolic-trough solar col- [85] Py X, Azoumah Y, Olives R. Concentrated solar power: current technologies, major lectors and their applications. Renew Sustain Energy Rev 2010;14:1695–721. innovative issues and applicability to West African countries. Renew Sustain [54] IEA. International Energy Agency Technology Roadmap – concentrating solar Energy Rev 2013;18:306–15. power. Available from 〈https://www.iea.org/publications/freepublications/ [86] Ho CK, Iverson BD. Review of high-temperature central receiver designs for con- publication/csp_roadmap.pdf〉; 2010 [Last accessed on 12 October 2016]. centrating solar power. Renew Sustain Energy Rev 2014;29:835–46.

1016 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

[87] Dunham MT, Iverson BD. High-efficiency thermodynamic power cycles for con- [119] Naik H, Baredar P, Kumar A. Medium temperature application of concentrated centrated solar power systems. Renew Sustain Energy Rev 2014;30:758–70. solar thermal technology: indian perspective. Renew Sustain Energy Rev [88] Corgnale C, Hardy B, Motyka T, Zidan R, Teprovich J, Peters B. Screening analysis 2017;76:369–78. of metal hydride based thermal energy storage systems for concentrating solar [120] Vieira de Souza LE, Gilmanova Cavalcante AM. Concentrated solar power de- power plants. Renew Sustain Energy Rev 2014;38:821–33. ployment in emerging economies: the cases of China and Brazil. Renew Sustain [89] Li C-J, Li P, Wang K, Molina EE. Survey of properties of key single and mixture Energy Rev 2017;72:1094–103. halide salts for potential application as high temperature heat transfer fluids for [121] Bouhal T, Agrouaz Y, Kousksou T, Allouhi A, El Rhafiki T, Jamil A, et al. Technical concentrated solar thermal power systems. AIMS Energy 2014;2:133–57. feasibility of a sustainable concentrated through an energy [90] Wetzel T, Pacio J, Marocco L, Weisenburger A, Heinzel A, Hering W, et al. Liquid analysis. Renew Sustain Energy Rev 2018;81:1087–95. metal technology for concentrated solar power systems: contributions by the [122] del Río P, Peñasco C, Mir-Artigues P. An overview of drivers and barriers to German research program. AIMS Energy 2014;2:89–98. concentrated solar power in the European Union. Renew Sustain Energy Rev [91] Komendantova N, Patt A. Employment under vertical and horizontal transfer of 2018;81:1019–29. concentrated solar power technology to North African countries. Renew Sustain [123] Van Eck NJ, Waltman L. Software survey: VOSviewer, a computer program for Energy Rev 2014;40:1192–201. bibliometric mapping. Scientometrics 2010;84:523–38. [92] Vignarooban K, Xu X, Arvay A, Hsu K, Kannan AM. Heat transfer fluids for con- [124] van Eck NJ, Waltman L. VOSviewer manual. Leiden: Univeristeit Leiden; 2013. centrating solar power systems – a review. Appl Energy 2015;146:383–96. p. 1. [93] Xu B, Li P, Chan C. Application of phase change materials for thermal energy [125] Park JY, Nagy Z. Comprehensive analysis of the relationship between thermal storage in concentrated solar thermal power plants: a review to recent develop- comfort and building control research-A data-driven literature review. Renew ments. Appl Energy 2015;160:286–307. Sustain Energy Rev 2017;82:2664–79. [94] Baharoon DA, Rahman HA, Omar WZW, Fadhl SO. Historical development of [126] VOSviewer. Centre for Science and Technology Studies, Leiden University concentrating solar power technologies to generate clean electricity efficiently – a Publications. Available from 〈http://www.vosviewer.com/publications〉; 2018 review. Renew Sustain Energy Rev 2015;41:996–1027. [Last accessed on 25 January 2018]. [95] Weinstein LA, Loomis J, Bhatia B, Bierman DM, Wang EN, Chen G. Concentrating [127] Rubin RE. Foundations of library and information science. Chicago, USA: solar power. Chem Rev 2015;115:12797–838. American Library Association; 2016. [96] Kumar V, Shrivastava RL, Untawale SP. Fresnel lens: a promising alternative of [128] Gil A, Medrano M, Martorell I, Lázaro A, Dolado P, Zalba B, et al. State of the art reflectors in concentrated solar power. Renew Sustain Energy Rev on high temperature thermal energy storage for power generation. Part 1—con- 2015;44:376–90. cepts, materials and modellization. Renew Sustain Energy Rev 2010;14:31–55. [97] Colmenar-Santos A, Bonilla-Gómez J-L, Borge-Diez D, Castro-Gil M. Hybridization [129] Burkhardt III JJ, Heath GA, Turchi CS. Life cycle assessment of a parabolic trough of concentrated solar power plants with biogas production systems as an alter- concentrating solar power plant and the impacts of key design alternatives. native to premiums: the case of Spain. Renew Sustain Energy Rev 2015;47:186–97. Environ Sci Technol 2011;45:2457–64. [98] Mathews JA, Hu M-C, Wu C-Y. Are the land and other resources required for total [130] Steinfeld A. Solar thermochemical production of hydrogen––a review. Sol Energy substitution of fossil fuel power systems impossibly large? Evidence from con- 2005;78:603–15. centrating solar power and China. Renew Sustain Energy Rev 2015;46:275–81. [131] Medrano M, Gil A, Martorell I, Potau X, Cabeza LF. State of the art on high-tem- [99] Shouman ER, Khattab NM. Future economic of concentrating solar power (CSP) for perature thermal energy storage for power generation. Part 2—case studies. electricity generation in Egypt. Renew Sustain Energy Rev 2015;41:1119–27. Renew Sustain Energy Rev 2010;14:56–72. [100] Prieto C, Cooper P, Fernández AI, Cabeza LF. Review of technology: thermo- [132] Mills D. Advances in solar thermal electricity technology. Sol Energy chemical energy storage for concentrated solar power plants. Renew Sustain 2004;76:19–31. Energy Rev 2016;60:909–29. [133] Price H, Lupfert E, Kearney D, Zarza E, Cohen G, Gee R, et al. Advances in para- [101] Mao Q. Recent developments in geometrical configurations of thermal energy bolic trough solar power technology. J Sol Energy Eng 2002;124:109–25. storage for concentrating solar power plant. Renew Sustain Energy Rev [134] Tian Y, Zhao C-Y. A review of solar collectors and thermal energy storage in solar 2016;59:320–7. thermal applications. Appl Energy 2013;104:538–53. [102] Balghouthi M, Trabelsi SE, Amara MB, Ali ABH, Guizani A. Potential of con- [135] Kenisarin MM. High-temperature phase change materials for thermal energy sto- centrating solar power (CSP) technology in Tunisia and the possibility of inter- rage. Renew Sustain Energy Rev 2010;14:955–70. connection with Europe. Renew Sustain Energy Rev 2016;56:1227–48. [136] Herrmann U, Kelly B, Price H. Two-tank molten salt storage for parabolic trough [103] Ehtiwesh IAS, Coelho MC, Sousa ACM. Exergetic and environmental life cycle solar power plants. Energy 2004;29:883–93. assessment analysis of concentrated solar power plants. Renew Sustain Energy Rev [137] Pacheco JE, Showalter SK, Kolb WJ. Development of a molten-salt thermocline 2016;56:145–55. thermal storage system for parabolic trough plants. Trans-Am Soc Mech Eng J Sol [104] Bijarniya JP, Sudhakar K, Baredar P. Concentrated solar power technology in Energy Eng 2002;124:153–9. India: a review. Renew Sustain Energy Rev 2016;63:593–603. [138] Coventry JS. Performance of a concentrating photovoltaic/thermal solar collector. [105] Aurousseau A, Vuillerme V, Bezian J-J. Control systems for direct steam genera- Sol Energy 2005;78:211–22. tion in linear concentrating solar power plants – a review. Renew Sustain Energy [139] Zhang HL, Baeyens J, Degrève J, Cacères G. Concentrated solar power plants: Rev 2016;56:611–30. review and design methodology. Renew Sustain Energy Rev 2013;22:466–81. [106] Ho CK. A review of high-temperature particle receivers for concentrating solar [140] Kearney D, Herrmann U, Nava P, Kelly B, Mahoney R, Pacheco J, et al. Assessment power. Appl Therm Eng 2016;109:958–69. of a molten salt heat transfer fluid in a parabolic trough solar field. J Sol Energy [107] Rascón DS, Ferreira AD, da Silva MG. Occupational exposures to solar radiation in Eng 2003;125:170–6. concentrated solar power systems: a general framework in central receiver sys- [141] Avila-Marin AL. Volumetric receivers in solar thermal power plants with central tems. Renew Sustain Energy Rev 2016;65:387–401. receiver system technology: a review. Sol Energy 2011;85:891–910. [108] Fuqiang W, Ziming C, Jianyu T, Yuan Y, Yong S, Linhua L. Progress in con- [142] Behar O, Khellaf A, Mohammedi K. A review of studies on central receiver solar centrated solar power technology with parabolic trough collector system: a com- thermal power plants. Renew Sustain Energy Rev 2013;23:12–39. prehensive review. Renew Sustain Energy Rev 2017;79:1314–28. [143] Herrmann U, Kearney DW. Survey of thermal energy storage for parabolic trough [109] Kommalapati R, Kadiyala A, Shahriar MT, Huque Z. Review of the life cycle power plants. J Sol Energy Eng 2002;124:145–52. greenhouse gas emissions from different photovoltaic and concentrating solar [144] Barlev D, Vidu R, Stroeve P. Innovation in concentrated solar power. Sol Energy power electricity generation systems. Energies 2017;10:350. Mater Sol Cells 2011;95:2703–25. [110] Pelay U, Luo L, Fan Y, Stitou D, Rood M. Thermal energy storage systems for [145] Ho CK, Iverson BD. Review of high-temperature central receiver designs for con- concentrated solar power plants. Renew Sustain Energy Rev 2017;79:82–100. centrating solar power. Renew Sustain Energy Rev 2014;29:835–46. [111] Dowling AW, Zheng T, Zavala VM. Economic assessment of concentrated solar [146] Mills DR, Morrison GL. Compact linear Fresnel reflector solar thermal power- power technologies: a review. Renew Sustain Energy Rev 2017;72:1019–32. plants. Sol Energy 2000;68:263–83. [112] Powell KM, Rashid K, Ellingwood K, Tuttle J, Iverson BD. Hybrid concentrated [147] Morin G, Dersch J, Platzer W, Eck M, Häberle A. Comparison of linear Fresnel and solar thermal power systems: a review. Renew Sustain Energy Rev parabolic trough collector power plants. Sol Energy 2012;86:1–12. 2017;80:215–37. [148] Pardo P, Deydier A, Anxionnaz-Minvielle Z, Rougé S, Cabassud M, Cognet P. A [113] Desai NB, Bandyopadhyay S. Line-focusing concentrating solar collector-based review on high temperature thermochemical heat energy storage. Renew Sustain power plants: a review. Clean Technol Environ Policy 2017;19:9–35. Energy Rev 2014;32:591–610. [114] González-Roubaud E, Pérez-Osorio D, Prieto C. Review of commercial thermal [149] Yang Z, Garimella SV. Thermal analysis of solar thermal energy storage in a energy storage in concentrated solar power plants: steam vs. molten salts. Renew molten-salt thermocline. Sol Energy 2010;84:974–85. Sustain Energy Rev 2017;80:133–48. [150] Liu M, Tay NS, Bell S, Belusko M, Jacob R, Will G, et al. Review on concentrating [115] Kassem A, Al-Haddad K, Komljenovic D. Concentrated solar thermal power in solar power plants and new developments in high temperature thermal energy Saudi Arabia: definition and simulation of alternative scenarios. Renew Sustain storage technologies. Renew Sustain Energy Rev 2016;53:1411–32. Energy Rev 2017;80:75–91. [151] Vignarooban K, Xu X, Arvay A, Hsu K, Kannan A. Heat transfer fluids for con- [116] Kumar A, Prakash O, Dube A. A review on progress of concentrated solar power in centrating solar power systems–a review. Appl Energy 2015;146:383–96. India. Renew Sustain Energy Rev 2017;79:304–7. [152] García IL, Álvarez JL, Blanco D. Performance model for parabolic trough solar [117] Purohit I, Purohit P. Technical and economic potential of concentrating solar thermal power plants with thermal storage: comparison to operating plant data. thermal power generation in India. Renew Sustain Energy Rev 2017;78:648–67. Sol Energy 2011;85:2443–60. [118] Cáceres G, Fullenkamp K, Montané M, Naplocha K, Dmitruk A. Encapsulated ni- [153] Viebahn P, Lechon Y, Trieb F. The potential role of concentrated solar power (CSP) trates phase change material selection for use as thermal storage and heat transfer in Africa and Europe—a dynamic assessment of technology development, cost materials at high temperature in concentrated solar power plants. Energies development and life cycle inventories until 2050. Energy Policy 2017;10:1318. 2011;39:4420–30.

1017 M.T. Islam et al. Renewable and Sustainable Energy Reviews 91 (2018) 987–1018

[154] Serrano-Aguilera J, Valenzuela L, Parras L. Thermal 3D model for direct solar [178] Biencinto M, González L, Valenzuela L. A quasi-dynamic simulation model for steam generation under superheated conditions. Appl Energy 2014;132:370–82. direct steam generation in parabolic troughs using TRNSYS. Appl Energy [155] Pramanik S, Ravikrishna R. A review of concentrated solar power hybrid tech- 2016;161:133–42. nologies. Appl Therm Eng 2017;127:602–37. [179] Ortega-Delgado B, García-Rodríguez L, Alarcón-Padilla D-C. Thermoeconomic [156] Alhayek B, Agelin-Chaab M, Reddy B. Analysis of an innovative direct steam comparison of integrating seawater desalination processes in a concentrating solar generation-based parabolic trough collector plant hybridized with a biomass power plant of 5 MWe. Desalination 2016;392:102–17. boiler. Int J Energy Res 2017;41:2236–47. [180] Coco-Enríquez L, Muñoz-Antón J, Martínez-Val JM. Integration between direct [157] Sun J, Liu Q, Hong H. Numerical study of parabolic-trough direct steam generation steam generation in linear solar collectors and supercritical carbon dioxide loop in recirculation mode: characteristics, performance and general operation Brayton power cycles. Int J Hydrog Energy 2015;40:15284–300. strategy. Energy Convers Manag 2015;96:287–302. [181] Elsafi AM. On thermo-hydraulic modeling of direct steam generation. Sol Energy [158] Feldhoff JF. SFERA Summer School 2012 direct steam generation (DSG)-tech- 2015;120:636–50. nology overview. Available from 〈http://elib.dlr.de/79195/〉; 2012 [Last accessed [182] Elsafi AM. Exergy and exergoeconomic analysis of sustainable direct steam gen- on 30 January 2018]. eration solar power plants. Energy Convers Manag 2015;103:338–47. [159] Montes MJ, Abánades A, Martínez-Val JM. Performance of a direct steam gen- [183] Nolte HC, Bello-Ochende T, Meyer JP. Second law analysis and optimization of a eration solar thermal power plant for electricity production as a function of the parabolic trough receiver tube for direct steam generation. Heat Mass Transf solar multiple. Sol Energy 2009;83:679–89. 2015;51:875–87. [160] Guo J, Huai X, Cheng K. The comparative analysis on thermal storage systems for [184] Bouvier J-L, Michaux G, Salagnac P, Nepveu F, Rochier D, Kientz T. Experimental solar power with direct steam generation. Renew Energy 2018;115:217–25. characterisation of a solar parabolic trough collector used in a micro-CHP (micro- [161] Li L, Sun J, Li Y. Thermal load and bending analysis of heat collection element of cogeneration) system with direct steam generation. Energy 2015;83:474–85. direct-steam-generation parabolic-trough solar power plant. Appl Therm Eng [185] Zapata JI. State estimation of a solar direct steam generation mono-tube cavity 2017;127:1530–42. receiver using a modified extended Kalman filtering scheme. Sol Energy [162] Biencinto M, Montes MJ, Valenzuela L, González L. Simulation and comparison 2015;114:152–66. between fixed and sliding-pressure strategies in parabolic-trough solar power [186] Zapata JI. Full state feedback control of steam temperature in a once-through plants with direct steam generation. Appl Therm Eng 2017;125:735–45. direct steam generation receiver powered by a paraboloidal dish. J Sol Energy Eng [163] Guo S, Liu D, Chen X, Chu Y, Xu C, Liu Q, et al. Model and control scheme for 2015;137:021017. [–10]. recirculation mode direct steam generation parabolic trough solar power plants. [187] Xu R, Wiesner TF. Closed-form modeling of direct steam generation in a parabolic Appl Energy 2017;202:700–14. trough solar receiver. Energy 2015;79:163–76. [164] Serrano-Aguilera JJ, Valenzuela L, Parras L. Thermal hydraulic RELAP5 model for [188] Desai NB, Bandyopadhyay S. Optimization of concentrating solar thermal power a solar direct steam generation system based on parabolic trough collectors op- plant based on parabolic trough collector. J Clean Prod 2015;89:262–71. erating in once-through mode. Energy 2017;133:796–807. [189] Desai NB, Bandyopadhyay S. Integration of parabolic trough and linear Fresnel [165] Guo S, Chu Y, Liu D, Chen X, Xu C, Coimbra CFM, et al. The dynamic behavior of collectors for optimum design of concentrating solar thermal power plant. Clean once-through direct steam generation parabolic trough solar collector row under Technol Environ Policy 2015;17:1945–61. moving shadow conditions. J Sol Energy Eng 2017;139(041002):9. [190] Serrano-Aguilera JJ, Valenzuela L, Parras L. Thermal 3D model for direct solar [166] Abdel Dayem AM, Al-Ghamdi AS. Transient performance of direct steam genera- steam generation under superheated conditions. Appl Energy 2014;132:370–82. tion solar power plants. Int J Energy Res 2017;41:1070–8. [191] Sanz-Bermejo J, Muñoz-Antón J, Gonzalez-Aguilar J, Romero M. Optimal in- [167] Li J, Li P, Gao G, Pei G, Su Y, Ji J. Thermodynamic and economic investigation of a tegration of a solid-oxide electrolyser cell into a direct steam generation solar screw expander-based direct steam generation solar cascade Rankine cycle system tower plant for zero-emission hydrogen production. Appl Energy using water as thermal storage fluid. Appl Energy 2017;195:137–51. 2014;131:238–47. [168] Ruiz-Cabañas FJ, Jové A, Prieto C, Madina V, Fernández AI, Cabeza LF. Materials [192] Blanco-Rodríguez P, Rodríguez-Aseguinolaza J, Risueño E, Tello M. selection of steam-phase change material (PCM) heat exchanger for thermal en- Thermophysical characterization of Mg–51%Zn eutectic metal alloy: a phase ergy storage systems in direct steam generation facilities. Sol Energy Mater Sol change material for thermal energy storage in direct steam generation applica- Cells 2017;159:526–35. tions. Energy 2014;72:414–20. [169] Bortolato M, Dugaria S, Del Col D. Experimental study of a parabolic trough solar [193] Stückle A, Laing D, Müller-Steinhagen H. Numerical simulation and experimental collector with flat bar-and-plate absorber during direct steam generation. Energy analysis of a modular storage system for direct steam generation. Heat Transf Eng 2016;116:1039–50. 2014;35:812–21. [170] Suojanen S, Hakkarainen E, Tähtinen M, Sihvonen T. Modeling and analysis of [194] Silva R, Pérez M, Berenguel M, Valenzuela L, Zarza E. Uncertainty and global process configurations for hybrid concentrated solar power and conventional sensitivity analysis in the design of parabolic-trough direct steam generation steam power plants. Energy Convers Manag 2017;134:327–39. plants for process heat applications. Appl Energy 2014;121:233–44. [171] Li L, Sun J, Li Y. Prospective fully-coupled multi-level analytical methodology for [195] Modi A, Haglind F. Performance analysis of a Kalina cycle for a central receiver concentrated solar power plants: general modelling. Appl Therm Eng solar thermal power plant with direct steam generation. Appl Therm Eng 2017;118:171–87. 2014;65:201–8. [172] Li L, Li Y, Sun J. Prospective fully-coupled multi-level analytical methodology for [196] Sanz-Bermejo J, Gallardo-Natividad V, Gonzalez-Aguilar J, Romero M. concentrated solar power plants: applications. Appl Therm Eng 2017;118:159–70. Comparative system performance analysis of direct steam generation central re- [173] Liu Y, Chen Q, Hu K, Hao J-H. Flow field optimization for the solar parabolic ceiver solar thermal power plants in megawatt range. J Sol Energy Eng trough receivers in direct steam generation systems by the variational principle. 2014;136:010908. [–9]. Int J Heat Mass Transf 2016;102:1073–81. [197] Lobón DH, Baglietto E, Valenzuela L, Zarza E. Modeling direct steam generation in [174] Guo S, Liu D, Chu Y, Chen X, Shen B, Xu C, et al. Real-time dynamic analysis for solar collectors with multiphase CFD. Appl Energy 2014;113:1338–48. complete loop of direct steam generation solar trough collector. Energy Convers [198] Desai NB, Kedare SB, Bandyopadhyay S. Optimization of design radiation for Manag 2016;126:573–80. concentrating solar thermal power plants without storage. Sol Energy [175] Hoffmann A, Hirsch T, Pitz-Paal R. Numerical investigation of severe slugging 2014;107:98–112. under conditions of a parabolic trough power plant with direct steam generation. [199] Manenti F, Leon-Garzon AR, Ravaghi-Ardebili Z, Pirola C. Assessing thermal en- Sol Energy 2016;133:567–85. ergy storage technologies of concentrating solar plants for the direct coupling with [176] Núnez Bootello JP, Price H, Pérez MS, Castellano MD. Optical analysis of a two chemical processes. The case of solar-driven biomass gasification. Energy stage XX simultaneous multiple surface concentrator for parametric trough pri- 2014;75:45–52. mary and flat absorber with application in direct steam generation solar thermal [200] Cau G, Cocco D, Tola V. Performance assessment of USC power plants integrated plants. J Sol Energy Eng 2016;138:021002. [–6]. with CCS and concentrating solar collectors. Energy Convers Manag [177] Olson KD, Talghader JJ. Solar selective coating optimization for direct steam 2014;88:973–84. generation parabolic trough designs. Sol Energy 2016;124:82–8.

1018