Small-scale Concentrated Solar Power Research Articles

Simulation and survey-based feasibility study of concentrated solar plant in northern and central Bangladesh

A comprehensive simulation and survey-based feasibility study have been carried out for the possible implementation of a CSP (concentrated solar power) plant in the middle and northern parts of Bangladesh. Area-specific optimization of plant-related parameters like tower height, heliostat number, heliostat cost, and heliostat area has been conducted using weather data. The design and analysis of small-scale CSP plants (1, 50, and 100 MW) were performed using the System Advisor Model (SAM) platform. Also, a sensor-based study was conducted to measure the sun's direct normal irradiance, temperature, and humidity at various time intervals throughout the year. The results of the plant cost, followed by the identification of the most suitable CSP technology, and the electricity output over a certain period of time were evaluated, and a good result was observed for a 1 MW CSP installation in Bangladesh. The simulated findings suggest that the high-elevation area in northern Bangladesh, such as Rajshahi, is more suitable for generating 100 MW of power, whereas the central region of Bangladesh, such as Katiyadi and Tarakandi, demonstrated better results for generating 50 MW of power.

Experimental Investigation of a Small-Scale Parabolic Trough Concentrated Solar Power ‎Systems

Large-scale systems have a lower levelized cost of electricity than small-scale concentrated solar power systems. Thus, the purpose of the present study is to evaluate the potential of using standalone small-‎scale ‎concentrated ‎solar power collectors in order to generate process ‎heat ‎at ‎a ‎moderate ‎temperature, which directly utilizes thermal energy without the need to generate electricity. ‎A ‎parabolic trough ‎collector (3.6m2) ‎was ‎designed ‎and ‎manufactured, including a dual-axis solar tracking system with and without an insulating function. An ‎insulating ‎cavity ‎was incorporated to ‎minimize the heat ‎losses collected by the absorbed ‎tube. ‎The experiments ‎were ‎carried out during a time of high winds and unfavorable weather ‎in ‎Sabratha City. The findings of the experiments demonstrated that the produced temperature and the collected heat energy progressively increase until they reach their maximum value, and then gradually decrease. The maximum water ‎temperature ‎was 96ºC at ‎a ‎flow rate ‎of ‎‎0.5L/min, and ‎the highest amount of ‎heat energy was 550W/m². ‎Wind speed showed an important impact on the produced temperature; therefore, various comparative experiments were carried out in the same climate condition; ‎the experiment with the insulating function ‎presented the least heat loss, and it takes a higher edge of 11% in terms of efficiency. ‎In addition, the water temperature rose to 120°C where steam was generated at a zero flow rate, while the oil ‎reached 194ºC. In addition, a mathematical model was also implemented to theoretically study energy balance; with little expected discrepancy, its predictions and the experimental results agreed. In conclusion, the results presented reasonable markers of interest despite the poor environmental conditions during the experiments.‎

Experimental evaluation for enhancement of small-scale concentrated solar power ‎systems – a case study ‎for solar cooking

ABSTRACT Small-scale concentrated solar power systems have a higher levelized cost of electricity than large-scale systems. Therefore, this ‎study aims to evaluate small-scale concentrated solar ‎power ‎systems, ‎which use thermal energy ‎directly without having to produce ‎electricity, with particular emphasis on the use of solar ‎cooking. ‎ The sun’s rays are reflected using a huge number of mirrors and focused on a ‎focal ‎point (the target), in this study, the bottom of the ‎cooking pot.‎ ‎The study encompasses three ‎main ‎parts: 1) the design and manufacture of a small-scale central receivers model for solar cooking; 2) the installation of an automated solar tracking system; and 3) the ‎experimental studies. The area of the proposed model is 1 ‎m2, while the ‎heliostat ‎area is 0.56 ‎m2. For the tracking procedure, the astronomical almanac method was utilized to estimate the sun’s position; this technique is not affected by ‎ambient ‎conditions like ‎clouds.‎ Despite employing normal flat mirrors and conducting the tests in inclement weather (winter), the results were excellent and suggested a possible interest. A half-liter of water took 20 minutes to heat up to the point of starting boil, and 193°C was the oil’s highest measured temperature‎. This result can be improved by using high-absorptivity cooking pots and specialized mirrors such as Fresnel lenses. Efficiency for the water studies varied from 50% to 76%, where a half litter took only 18 minutes to get to the highest temperature, while for a half litter of oil, efficiency was 79%.

Small-scale concentrated solar power system with thermal energy storage: System-level modelling and techno-economic optimisation

A dynamic, techno-economic model of a small-scale, 31.5 kWe concentrated solar power (CSP) plant with a dish collector, two-tank molten salt storage, and a sCO2 power block is analysed in this study. Plant solar multiple and storage hours are optimised using a multi-objective genetic algorithm to minimise the levelised cost of electricity (LCOE) and maximise the capacity factor (CF). The optimal LCOE is found to be ranging from 122.7 USD/MWhe to 217.8 USD/MWhe when using optimistic and pessimistic power block cost assumptions. In contrast, the literature reports an LCOE of 193.9 USD/MWhe for a similar 31.5 kWe CSP system without storage. The addition of thermal energy storage in the system configuration dramatically improves the CF from 30.4%—reported in the literature—to 87.2% obtained from the present model. The sensitivity analysis suggests that upscaling the system to 400 kWe reduces the LCOE to 121.9–172.2 USD/MWhe as a result of lower unit power block costs at larger scales. The comparison of CSP and PV-battery systems in three distinct locations—characterised by varying direct and global solar resources—indicates that the CSP system is promising in locations with abundant direct normal irradiance (DNI). For locations with medium DNI resource, the LCOE of PV-battery system is within the margin of uncertainty of CSP system. In low-DNI locations, PV-battery systems proved to be preferable.

Detailed transient assessment of a small-scale concentrated solar power plant based on the organic Rankine cycle

• New procedures for modeling the components of solar-ORC power plant are proposed. • A routine for optimizing the turbine geometry and evaluating its performance is used. • The power plant results are obtained by coupling the accurate components models. • A power plant continuously supplying electricity to remote communities is designed. • The low ODP and GWP refrigerant R1233zd(E) provided the best performance. Motivated by environmental issues and the needs of communities that live far from the electricity grid, this work presents an innovative methodology for modeling a small-scale concentrated solar power plant based on the organic Rankine cycle. An integrated simulation tool, which consists of accurate computational routines of the energy storage tank, parabolic trough collector, plate heat exchanger, finned air-cooled condenser, and inward-flow radial turbine, is developed. The components are modeled according to distributed models and the mean line method for the turbine in homemade codes to account for local property changes. The transient power plant performance is assessed by employing solar irradiation data of three locations that present mean direct normal irradiation rates of 6306, 4712, and 3220 Wh/m 2 .day. The following working fluids were considered: a low GWP and ODP refrigerant (R1233zd(E)), a natural one (R600a), and a high GWP fluid that is currently employed for such applications (R245fa). The smallest configuration that led to annual uninterrupted power production is a 565-m 2 collector and a 90-m 3 storage tank. The R1233zd(E) refrigerant presented the best overall performance by providing about 2% and 30% higher turbine power output, 3% and 29% higher turbine efficiency, and 4% and 36% higher ORC first-law efficiency than R245fa and R600a, respectively. The designed solar power plant generated 48.396 MWh/year of electricity and 80.621 MWh/year of cogeneration energy with R1233zd(E), which is enough to provide electricity and sanitary hot water to about 33 and 64 houses, respectively.

Development of a smart control unit for small-scale concentrated solar combined heat and power systems for residential applications

Solar energy has a significant potential for future power generation but its intermittent and variable nature results in fluctuations of the operational performance of solar power plants. Despite thermal energy storage (TES) systems improving the flexibility and the sustainability of the performance of Concentrated Solar Power (CSP) plants, smart management is required to deal with the complex dynamic variations in the behaviour and interaction of the different plant's subsystems. In this paper, the design, manufacture, and validation of a smart control unit with extended capabilities for a small-scale CSP combined heat and power (CHP) system are described. More precisely, the control unit has been designed to control and optimise the operation of a micro-scale Organic Rankine Cycle (ORC) unit coupled with Linear Fresnel Reflectors solar field and an advanced latent heat thermal energy storage tank which were developed by a consortium of universities and companies in the framework of the EU-funded project “Innova Microsolar”.In parallel to the designing and building the smart control unit, an advanced simulator has been developed in Matlab/Simulink® to investigate the performance of the plant for a wide range of varying ambient and operating conditions. The simulation framework has been connected to the real control unit according to a hardware-in-the-loop (HiL) approach to optimise the control logic of the integrated plant to overcome potential technical and reliability issues during the commissioning of the plant. The developed hardware and the proposed scientific approach can be extended to a wide range of complex solar energy systems equipped with TES and to be integrated into the built environment.

Environmental Impacts of a Solar Dish Coupled With a Micro-Gas Turbine for Power Generation

Concentrated solar power (CSP) systems are regarded as a renewable energy source technology that can contribute to decoupling the energy mix from fossil fuel combustion and related environmental impacts. However, current small-scale CSP technologies (e.g., Dish-Stirling) have not entered the market yet due to high costs, complexity, and poor reliability. The EU-funded OMSoP (Optimised Microturbine Solar Power) project aimed at solving the small-scale CSP shortcomings by coupling a solar dish with the consolidated and relatively cheap technology of the micro gas turbine (MGT). In this study, an environmental life cycle assessment analysis of the production and operation of a CSP-MGT system is performed following an eco-design approach, thus identifying the environmental hotspots and how the system can be improved in terms of environmental impacts. The results of the analysis, per unit of electricity produced, were compared to other renewable technologies with the same level of dispatchability to better evaluate strengths and weaknesses of the system under exam. With regard to climate change, the greenhouse gas (GHG) emissions of the CSP-MGT system resulted in the same range as those generated by photovoltaic systems. However, the system can substantially be optimized and the GHG emissions per kWh can be reduced up to 73% with respect to the built prototype. The GHG emissions are much lower than the current Italian energy mix (by up to 94%). To reduce the environmental burden of CSP-MGT plants, the system design here considered should be revised by improving the component’s performance and significantly reducing the reflective surface and therefore the structural materials for the dish foundation and frame. The replacement of steel in the dish frame with aluminum increases all the environmental impact parameters and primary energy demand (17%–27% depending on the environmental category considered) but slightly reduces abiotic element depletion (by 9%).

Coupling a small-scale concentrated solar power plant with a single effect thermal desalination system: Analysis of the performance

In this paper, the potential of coupling a small-scale non-imaging focusing heliostat CSP plant with a compact single effect thermal desalination plant is presented and an analytical model for assessing the overall performance is described.The main novelty of this work relies on the study of two small-scale prototype units designed and tested by the authors. More precisely, the system consists of 25 hexagonal non-imaging heliostats for a total reflective area of 9.5 m2 with a peak power output of 6 kWt and of a single stage thermal desalination plant for fresh water production of few hundred liters per day.In order to better evaluate the potential of such a coupling, three different locations in the Mediterranean area have been considered: Palma de Mallorca, Pantelleria and Crendi.The simulation analysis proved interesting results. Compared to electrically driven desalination plant, the performance of the proposed plant is only slightly affected by the salt content of the treated water. In terms of fresh water production, the yearly fresh water production in Crendi is about 60% higher than in Pantelleria because of the higher DNI throughout the year. On the contrary, the maximum daily fresh water production differs to a smaller extent: it reaches a peak of about 70.5 L/day in Pantelleria and 75.0 L/day in Crendi whilst it is always <60 L in Palma.Despite further improvements are needed to reduce the cost of the fresh water produced by similar small-scale CSP desalination plant to overcome the market uptake, the results of the analysis have shown that such a coupling could have a very interesting potential especially for small-scale applications in rural and remote areas where the fresh water demand ranges between 30 L and 60 L per day.

The Ottana solar facility: dispatchable power from small-scale CSP plants based on ORC systems

The Ottana solar facility aims to demonstrate the capabilities of concentrating solar technologies to provide dispatchable power and ancillary services at distribution level. The facility includes a 630 kW Concentrating Solar Power (CSP) plant with thermal storage coupled with a 400 kW Concentrating Photovoltaic (CPV) plant with electrochemical storage. The CSP + CPV plant aims to study the ability of the integrated concentrating solar systems to deliver scheduled power profiles for the following day on the basis of weather forecasting data. The CSP section is based on linear Fresnel collectors using thermal oil as heat transfer fluid and a two-tank direct Thermal Energy Storage (TES) system with a storage capacity of about 15 MWht. The power generation is carried out by a 630 kW Turboden 6HR Special ORC unit. This paper focuses on a description of the CSP plant section and on the analysis of its expected performance. In particular, the control strategy developed for determining the daily power profiles starting from the weather forecasting data is presented. Moreover, the first operating results and the expected performance of the CSP plant are reported and discussed.

Maintenance of a Small-Scale Parabolic Trough Concentrating Solar Power Plant in Louisiana

An accurate estimate of fixed operating costs is essential to determine the financial viability of any proposed project. Although other researchers have reported maintenance costs for large-scale concentrating solar power (CSP) plants in the United States [1 - 2], there is currently little information available specifically for small-scale CSP or solar Industrial Process Heat (IPH) plants. This paper discusses the maintenance of an operating small-scale CSP plant in Louisiana over a four year period. The results are also applicable to a small-scale IPH plant. Maintenance activities and costs are discussed for the collector field, the power block, and the cooling tower. For the collector field, a study of the degradation of mirror reflectance between washings was performed for three different types of reflective polymer thin films (3M 1100, 3M 2020, and Konica Minolta). Overall, the 3M 2020 film provided better reflectivity between washings than the other films. An optimized mirror washing schedule was determined. Optimal mirror washing schedules are very site-dependent, but for this humid subtropical location, the most economical washing schedule was found to be every 114 days, or approximately three times per year. A recommended maintenance plan for small-scale CSP and IPH plants is presented and actual maintenance costs over a four year period are provided. It was found that maintenance costs for small-scale plants are substantially larger than for large-scale plants, and that maintenance costs for small-scale IPH plants are much lower than for small-scale CSP plants, making IPH applications significantly more attractive. The average annual maintenance cost for a small-scale CSP plant was found to be approximately $457/kWe, or $0.27/kWhe. For a small-scale IPH plant the costs were $3.72/m2, $7.81/kWt, and $0.005/kWht.

Numerical Model and Performance Validation of a Small-Scale Concentrating Solar Thermal Power Plant in Louisiana

A simplified numerical model of a small-scale (25 - 100 kWe) parabolic concentrating solar power (CSP) plant is presented that can be utilized during the planning stages for a CSP plant, utilizing only simplified information that would be available at the preliminary stages of a project. This is important because existing models currently used for planning purposes, such as the System Advisor Model (SAM) from the National Renewable Energy Laboratory (NREL), do not cover small-scale CSP plants. The model can be used to predict real-time performance, or it can be used with TMY data to estimate annual performance. The model was validated using performance data from an operating small-scale CSP power plant, which is a unique contribution of this work. The results showed that the model correlated well with actual operating measurements for all seasons of the year, and provided a useful tool for planning of future small-scale CSP plants.

Jatropha curcas crude oil as heat transfer fluid or thermal energy storage material for concentrating solar power plants

Valorisation of local and low cost eco-materials has become an imperative for the sustainable development of Concentrating Solar Power (CSP) in West Africa. In this study, Jatropha curcas crude oil is studied as alternative heat transfer fluid or thermal energy storage material, particularly as a thermal oil substitute. The thermal stability of Jatropha curcas crude oil was experimentally investigated. The crude oil was aged by through thermal treatments, using galvanised steel and 316L stainless steel reactor under steady-state and dynamic conditions up to 210°C. The change in physico-chemical parameters of Jatropha curcas crude oil, such as viscosity, flash point, acidity number, water content, iodine value, peroxide value and chemical composition was monitored. The results indicate a relative stability of the total acid number during the dynamic and pseudo-static tests both in galvanised steel and in 316L stainless steel reactors. The results also show that the measured viscosity at 40°C remains practically constant after tests in steady-state conditions. This is also the case of the total acidity number. The evolution of iron and zinc contents of the oil shows that the use of 316L stainless steel material highly limits the degradation process of Jatropha curcas crude oil. Therefore, the main benefits of Jatropha curcas crude oil are its sustainable character, wide availability, good energy storage density, low cost and absence of use conflict. The oil can, therefore, be considered a suitable candidate for thermal applications up to 210°C, such as small scale CSP plants.

State of the Art on Small-Scale Concentrated Solar Power Plants

Many efforts have been spent in the design and development of Concentrated Solar Power (CSP) Plants worldwide. Most of them are for on-grid electricity generation and they are medium or large plants (in the order of MWs) which can benefit from the economies of scale.Nevertheless, several potential applications for Small-Scale CSP plants (< 1 MW) can be relevant in the industrial sector as well as for off-grid purposes (i.e. in rural contexts).This paper presents the technologies suitable for off-grid applications, for electricity or cogenerated production. Major characteristics are illustrated and advantages and drawbacks for each configuration identified and discussed.

Heat Transfer Analysis for a Small-Size Direct-Flow Coaxial Concentrating Collector

A coaxial evacuated solar tube has been analyzed. The tube is included in a small-scale concentrated solar power (CSP) system, which runs a cogeneration Stirling engine unit. The engine provides electricity and at the same time generates hot water for heating and sanitary purposes, by cooling down the compression cylinder. The present work is focused on the thermodynamic characterization for a forced-flow in the coaxial evacuated tube, which can heat thermal oil up to 300 °C, when coupled with a parabolic trough collector. The single coaxial tube is 2 m long, it has one glass penetration, it is provided with a glass–metal seal and it has an absorber tube in the focal point with a diameter of 12 mm. A model based on heat transfer analysis coupled with fluid dynamic is presented and discussed. The model is then used to investigate spatial temperature profiles and thermal behaviors for the whole solar collector. It improves previous works in the field of concentrating solar collectors and covers the research in small-size concentrating system using thermal oil as heat transfer fluid.

Approach to designing a solar concentrator for small-scale remote power application

A small-scale concentrated solar power (CSP) unit was designed to provide electricity and hot water using an organic Rankine cycle (ORC) for Egypt as part of an undergraduate capstone project. The system was designed for a target power output of 3 kW. It uses parabolic troughs to heat ethylene glycol used as the heat transfer fluid, which absorbs heat in the trough collector and transfers it to the working fluid through a heat exchanger. The system consists of 9 parabolic troughs and a total aperture area of 67 m2, providing the required 3 kW of energy to the ORC. One parabolic trough was manufactured to test its thermal efficiency according to ASHRAE standard 93-2003 [Methods of Testing to Determine the Thermal Performance of Solar Collectors (ASHRAE, Inc., 1791 Tullie Circle, NE, Atlanta, GA 30329, 2003)] and compared it to its calculated value. A simple microcontroller-based system was used to track the sun.