Large Solar Plants Research Articles

Yearly changes in surface solar radiation in New Caledonia

Abstract. New Caledonia experiences a decrease in surface solar irradiation since 2004. It is of order of 4% of the mean yearly irradiation over the 10 years period: 2004–2013, and amounts to −9 W m−2. The preeminent roles of the changes in cloud cover and to a lesser extent, those in aerosol optical depth on the decrease in yearly irradiation are evidenced. The study highlights the role of data sets offering a worldwide coverage in understanding changes in solar radiation and planning large solar energy plants such as the ICOADS (International Comprehensive Ocean-Atmosphere Data Set) of the NOAA and MACC (Monitoring Atmosphere Composition and Climate) data sets combined with the McClear model.

Power Smoothing of Large Solar PV Plant Using Hybrid Energy Storage

This paper proposes a power smoothing strategy for a 1-MW grid-connected solar photovoltaic (PV) power plant. A hybrid energy storage system (HESS) composed of a vanadium redox battery and a supercapacitor bank is used to smooth the fluctuating output power of the PV plant. The power management of the HESS is purposely designed to reduce the required power rating of the SCB to only one-fifth of the VRB rating and to avoid the operation of the VRB at low power levels, thus increasing its overall efficiency. The PV plant including the HESS has been modeled using MATLAB/Simulink and PLECS software environment. The effectiveness of the proposed power control strategy is confirmed through extensive simulation results.

India to build world's largest solar plant

India to build world's largest solar plant

A GIS Tool for the Land Carrying Capacity of Large Solar Plants

A tool for the estimation of the land carrying capacity of large solar plants, such as ground-mounted PV plants or solar thermal plants, is developed in GIS environment. The scope is to verify to what extent the constraints that governments and authorities have imposed on the construction of new large ground-mounted soalr plants affect the future developments of PV. The tool is applied to a large study area of North-Italy and specifically to solar photovoltaic plants but the results can be easily generalized to include large solar thermal plants. The peculiarity of the tool development is that both qualitative and quantitative criteria are merged together in order to obtain the final indicator, and that the weight of the objective function are estimated by means of an ANN. The available area are very limited and strongly influenced by the normative qualitative criteria (restricted areas).

Design, Control and First Monitoring Data of a Large Scale Solar Plant at the Meat Factory Berger, Austria

Within the European FP7 Project InSun, which started in April 2012, three large scale solar plants for industrial processes in three different countries are installed and will be monitored in detail over a period of almost two years. The main idea of InSun is to demonstrate the reliability and quality of large scale solar thermal systems using different types of collectors for the generation of heat employed in different industrial processes.One of these demonstration plants is located in Austria and it is providing heat up to 90°C for the manufacture of meat products in the factory Berger. Zafh.net, the coordinator of the project, developed a dynamic simulation model of this plant, which should be used to improve the control strategy of the real process. After two months of operation, the first monitoring data are available and will be compared with the simulation results. Based on this comparison, key performance figures (e.g. solar yield) could be predicted for the whole lifetime of the plant. Furthermore economical outputs could be calculated more precisely, which provides essential information for the key stakeholders in the industry.

National Incentive Programs for CSP – Lessons Learned

Acknowledging that Concentrated Solar Power (CSP) stands out among other renewable technologies for technical features such as dispatchability - through storage and hybridization - and its potential for higher macroeconomic impact on the local economy, national and regional governments have set up incentive programs to promote the development of large scale solar thermal plants in recent years. These support mechanisms have largely contributed to the rapid growth of the global market since 2007. While Spain and USA remain leaders, representing most of the current ∼2.5 GW in operation, other countries have emerged within a short time as very ambitious players.In our research, we reviewed some of the most relevant national incentive programs introduced worldwide: Spain, India, South Africa, Morocco and Australia. The paper will give an overview of the mechanics of the different markets, covering key aspects such as: capacity allocation, phases and timelines, qualification criteria, technical and financial requirements, local content requirements, etc, and how these elements affected competition, tariffs and the global outcome of the programs.The lessons learned from the analysis constitute a useful set of guidelines for policy makers and developers, and could contribute to the design of future effective support mechanisms that will pave the way for the further uptake of CSP technologies.The research presented in the paper has been undertaken in the framework of a technical assistance to the Ministry of New and Renewable Energy of India on the preparation of the Utility Scale Concentrated Solar Power Program.

Solar Thermal Potential for Collective Systems in Palma Beach (Balearic Island's)

Palma Beach is the most developed tourist area in the Balearic Islands, there is a Master Plan who wants to build a District Heating and Cooling system. The aim of this study is to identify the viability of integrating Large Solar Plants, in buildings of tourist and residential areas. The energy costs, by a sample of collectors with different temperatures will be used in this study. The results show that collective system can reduce about a 60% the CO2 emissions using only Solar Thermal energy and find out future net zero energy building scenarios with other renewable energy sources.

The cost Benefit Analysis of Large Scale Solar Photovoltaic Power Plant under New Market Environment in China

A newly constructed 10MW solar photovoltaic power plant in Qinghai province China is examined for the latest cost benefits evaluation in this research, the RETScreen analysis software tool is used for the energy production estimation, financial feasibility analysis and environmental benefit analysis. Initial results show high solar PV potential in Qinghai province China, 20GWh power electricity generation can reduce more than 18,000 tons of CO2 emissions annually. Although current LCOE of PV power is still double than fossil fuel electricity, but the investment of solar PV is motivated by governmental subsidy policy, the payback of the solar PV project became attractive under the new market environment, the IRR could reach more than 20%, with further material cost decrease, efficiency improvement and continues subsidy policy, the solar PV power will be a trend of renewable energy in China. The GHG emissions reduction is another driving reason to encourage solar PV power development in China.

Integration of temperature and dust effects in siting large PV power plant in hot arid area

Recently, solar PV technologies witnessed a commercial vigor due to their tremendously decreasing prices. However, these technologies are vulnerable to dust and temperature which can significantly degrade their efficiency. Taking into account, the effect of dust and temperature during the site assessment for large PV power plant will reduce their vulnerability and optimize their operation efficiency. Most of the site assessment for large PV power plants does not take into consideration spatio-temporal variability of dust and temperature effects due to their measurement complexity. This paper presents an original approach of integration of the effects of temperature and dust in siting large PV power plant using Fuzzy logic and GIS-based spatial multi-criteria evaluation. Dynamical downscaling approach of the high resolution COSMO Numerical Weather Prediction model is used to simulate the annual pattern of temperature and the Aerosol Optical Depth (AOD) derived from Multi-angle Imaging Spectro-Radiometer (MISR) is used to retrieve the contamination degree of the air with mineral aerosol. Land suitability analysis for large PV farms implementation is carried out for the case study of Oman. Compared to previous results obtained without temperature and AOD, the new results show that several areas are declassified because of their exposure to high temperature and dust risks. It is noticed that the highly suitable land areas decreased significantly by 81% after considering the temperature and dust constraint layers. Different PV technologies are considered and it is found that the Concentrated Photovoltaics (CPV) technology provides higher potential for implementing large solar plants. In fact, if all highly suitable land is exploited for CPV farms, it can supply more than 750 times the current total power supply in Oman estimated at 16.1 TWh in 2010.

Multicriteria optimization of a distributed energy supply system for an industrial area

In the paper a multi-objective optimization model for distributed energy supply systems optimization is presented. The superstructure of the system comprehends a district heating network that connects the users to each other, small-scale CHP systems, large centralized solar plant and a thermal storage. The optimization has to determine the optimal structure of the system, the size of each component inside the optimal solution and the optimal operation strategy. The multi-objective optimization is based on a MILP (Mixed Integer Linear Programming) model and takes into account as objective function a linear combination of the annual cost for owning, maintaining and operating the whole system and the CO2 emissions associated to the system operation. The model allows to obtain different optimal solutions by varying the relative weight of the economic and the environmental objectives. In this way the Pareto Front is identified and the possible improvements in both economic and environmental terms can be highlighted. The model has been applied to a specific case study and it has been optimized for different superstructure configurations and for two different values of the electricity carbon intensity. The obtained results show that the solar plant, coupled with the optimal thermal storage, allows reaching both environmental and economic goals.

Africa's largest solar plant to be built in Ghana

Africa's largest solar plant to be built in Ghana

Financing of Large Solar Thermal Systems for Cooling and Process Heat

To put solar thermal energy back into the briefings of investors, executives and financial officers, SOLID has proven that financing of large scale solar thermal plants has controllable risks and strong return.

Evaluation of the Potential of Large Solar Heating Plants in Spain

An evaluation of Central Solar Heating Plants with Seasonal Storage in Spain has been performed with dynamic simulations built on TRNSYS. The model has been designed for several Spanish cities that are representative of the different climatic areas with a significant demand of thermal energy for heating. The system should cover the heating demand of 1000 apartments of 100 m2 in multifamily buildings with similar features, providing a solar fraction of about 50% without wasting solar heat in summer and without oversizing the seasonal storage tank. Climatic and specific demand data for each city have been used. The model simulates the solar collector field, pipe lines, heat exchangers, a seasonal storage tank, pumps, auxiliary boiler and auxiliary pieces of equipment needed in the model. The obtained results show that CSHPSS with a solar fraction of about 50% require in the case of Spain a relatively small Ratio Area of solar collectors versus heating Demand and a high Ratio of seasonal storage tank Volume versus solar collector Area. The estimated cost of the heat produced in CSHPSS with a solar fraction of 50% can be competitive with the heat cost of domestic heat boilers, which is a very common solution for heating in residential buildings in Spain. The obtained results show that CSHPSS represent an interesting and promising alternative for covering the heating demand in residential buildings in Spain.

Interannual variability of solar energy generation in Australia

Australia has an abundant solar energy resource that is likely to be used for energy generation on a large scale. Variable sources of electricity generation require knowledge of the nature of their variability at all time scales. This study examines the effect that El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) have on solar radiation in Australia, in order to establish the role for seasonal forecasting of solar power. Calendar years are classified into their ENSO state using a sea surface temperature index. The ERA-Interim and NCEP reanalysis products are then used to estimate the effect of ENSO on global horizontal solar irradiance over the continent. A bootstrap technique is used to obtain confidence regions for the effect in both winter and summer. The main impact of ENSO occurs during winter over a large part of eastern Australia. Little impact was observed over the continent during summer. A similar analysis is conducted for the Indian Ocean Dipole (IOD) to ensure that the observed ENSO effect is not a manifestation of the IOD. This study indicates that the ENSO phenomenon may account for solar energy changes of more than 10% in some locations on a seasonal basis. We show that the solar radiation analysis is directly applicable to solar energy yield. Knowledge of this variability may influence the location of large solar generation plants. Also, there is a potential to predict solar energy a few months ahead by means of seasonal forecasting systems, which would help to assist with planning for electricity grid.

PV site suitability analysis using GIS-based spatial fuzzy multi-criteria evaluation

This paper presents some preliminary results from a research study conducted on solar energy resource assessment in Oman. GIS-based spatial multi-criteria evaluation approach, in terms of the FLOWA module was used to assess the land suitability for large PV farms implementation in Oman. The tool used applies fuzzy quantifiers within ArcGIS environment allowing the integration of a multi-criteria decision analysis. Land suitability analysis for large PV farms implementation was carried out for the case study of Oman. The overlay results obtained from the analysis of the resultant maps showed that 0.5% of the total land area demonstrate a high suitability level. Different PV technologies were considered for implementation. It was found that the CPV technology provides very high technical potential for implementing large solar plants. In fact, if all highly suitable land is completely exploited for CPV implementation, it can produce almost 45.5 times the present total power demand in Oman.

Beam-Down Mirror: Thermal and Stress Analyses

The “beam-down” optics or solar tower reflector, developed and demonstrated at the Weizmann Institute of Science during the past 9 years, could be a useful modification of the classic solar tower technology, especially for solar applications where reacting solids are involved or heavy equipment has to be placed on top of a conventional tower. The theory of this optics has been thoroughly studied and reported elsewhere. This paper details the development and experience gained with the mirror facets of the tower reflector. Thermal and stress analyses are presented here, validated by temperature measurements and calculated incident flux map. The projection for a large scale solar plant of about 100 MW at the aperture of the receiver is illustrated. The current basic design of the facet made of a sandwich of mirrors glued back-to-back seems to be a feasible solution for future applications. Aluminum-glass facets failed, and cracks in the glass were observed in the course of time. Years of experience proved that using only natural cooling to the surrounding, for the glass/glass facets, which can reach 130–140°C during operation under average incident solar flux of about 30 kW/m2, is a viable design. Maximum working temperatures of 160°C were experienced without any degradation of the reflectivity and the performance of these facets after several hundreds of operation hours.

Long-term scenarios for energy and environment: Energy from the desert with very large solar plants using liquid hydrogen and superconducting technologies

Among the long-term energy scenarios identified by major international organizations in order to drastically reduce fossil fuels consumption and to develop a sustainable energy system within the 21st century, the exploitation of desert areas for large-scale renewable energy production, must be seriously considered. Desert areas are characterized by large land availability, with high levels of solar radiation and wind. However, apart from generating costs (which should fall down in future), two main problems have to be faced. First, fluctuations of renewable power availability may lead to electric grid instability, reducing the quality of energy supply. Second, since deserts are typically far from energy-demanding areas, large power transport lines are needed. The system proposed in this paper resorts to the use of liquid hydrogen (LH 2) for energy storage, and to the combined transport of electric energy and LH 2 with a MgB 2 superconducting line. The system allows flexible delivering of energy in electric and chemical form, depending on end-users demands.

Screening of high melting point phase change materials (PCM) in solar thermal concentrating technology based on CLFR

We have investigated the suitability of high melting point phase change materials for use in new, large scale solar thermal electricity plants. Candidate materials for latent heat thermal energy storage are identified and their operating parameters modeled and analysed. The mathematical characteristics of charging and discharging these storage materials are discussed. Several high melting point, high conductivity materials are shown to be suitable and advantageous for use with solar thermal electricity plants, such as Sydney University’s novel, low cost CLFR and MTSA collector systems, as well as existing parabolic trough and tower technologies.

Solar ground reformer

The possibility to couple a large-scale solar tubular reformer (a chemical reactor where a low hydrocarbon, e.g., methane, is reacting with steam and/or CO 2 to produce synthesis gas, a mixture of carbon monoxide and hydrogen), with a solar tower beam-down optics, is explored and analyzed. The reformer is installed on the ground and the concentrated solar energy enters through an aperture in the ceiling of the reformer enclosure and heats the reactor tubes, arranged within the enclosure along its walls. This arrangement enables, potentially, to adapt a large solar plant to a modified conventionally designed reformer. Through an example where about 50 MW of solar energy is introduced into an array of ground reformers, the optical path and the radiative heat exchange within the reformer cavity, coupled with the reactor tube side, are calculated and illustrated. Detailed calculation results describing the radiation flux profile inside the cavity, the surface temperatures of the reactor tubes and the composition of the process gas along the tubes, as well as the annual performance of the reformer, are shown. The results demonstrate that the solar reformer illustrated in this study can be connected to a combined cycle-power generation unit having a nominal capacity of 100-MW electricity. A power generation unit of this kind, if operating annually during roughly 2000 sunny hours, will produce about 25% of its power, supplied by the solar energy source.

Solar chimney turbine characteristics

A typical layout of a solar chimney power plant has a single axial turbine with radial inflow through inlet guide vanes at the base of the chimney. Turbine efficiency depends on the turbine blade row and turbine diffuser loss coefficients. The paper presents analytical equations in terms of turbine flow and load coefficient and degree of reaction, to express the influence of each coefficient on turbine efficiency. It finds analytical solutions for optimum degree of reaction, maximum turbine efficiency for required power and maximum efficiency for constrained turbine size. Characteristics measured on a 720 mm diameter turbine model confirm the validity of the analytical model. Application to a proposed large solar chimney plant indicates that a peak turbine total-to-total efficiency of around 90% is attainable, but not necessarily over the full range of plant operating points.