Integrated Solar-Thermal Power Plants: TPP Bitola Case Study

Thermal Engineering, 2023

The major part of electric energy is presently generated by fossil fuel-fired thermal power plants operating according to the Rankine cycle. In the last decades, power technologies on the basis of solar concentrators (SCs) are becoming increasingly more attractive. The article shows the possibility of using heat obtained from solar energy (referred to henceforth as solar energy heat) at existing steam turbine thermal power plants (TPPs). A scheme for connecting an SC to the PVK-150 steam turbine power unit at the Tashkent TPP has been developed, due to which solar energy heat can be used instead of the heat obtained in the low- and high-pressure regenerative heaters (LPH and HPH) and also for partially replacing the heat from the economizer and evaporative heating surfaces of the existing steam generator. Calculations were carried out for different values of the solar energy heat share: in the range from 20 to 80%. Parabolocylindrical concentrators (PCCs) are used as SCs. A formula is proposed for calculating the solar energy into electricity conversion efficiency at hybrid solar and fossil fuel-fired TPPs constructed on the basis of existing steam turbine TPPs. The results obtained from modernizing the PVK-150 power unit by connecting an SC to it are presented. It has been determined in the course of investigations that, in using solar energy heat in the PVK-150 power unit for replacing the heat obtained in the regenerative feed water heaters, the solar energy into electricity conversion efficiency reaches 27.06 and 34.4% in the case of partial replacement of the economizer and evaporative surfaces of the existing steam generator with a solar steam generator.

Pollution and increasing fuel prices are the main focus for governments today. The main cause of pollution is existing electricity power plants that use huge quantities of fossil fuel. A new strategy should be applied in the coming decades based on the integration of existing power plants with renewable energy sources, such as solar and wind energy. Hybridization of existing power plants with solar energy is one proven option to overcome the problems of pollution and increasing fuel prices. In this paper, a review of the previous studies and papers for integrating solar thermal energy with conventional and non-conventional power plants was carried out. The focus on hybrid solar conventional power plants includes: the review of studies of hybrid solar-steam cycle power plants, integrated solar combined-cycle systems (ISCCS) and hybrid solar-gas turbine power plants, while for hybrid solar non-conventional power plants the focus of study is hybrid solar-geothermal power plants. The most successful option is ISCCS due to their advantages and the plans for implementation at various power plants in the world like in Tunisia, Egypt, Spain, and Iran.

Solar thermal energy is a groundbreaking technology for harnessing solar energy to produce heat energy. Solar thermal collectors can be classified as low or high-temperature collectors. Low-temperature collectors are flat plates typically used to warm swimming pools, heating water or heating air for residential. However, the cost of electricity from contemporary solar thermal power plants remains high, despite several decades of development, and a step-change in technology is needed to drive down costs. Solar gas-turbine power plants are a promising new alternative, allowing increased conversion efficiencies and a significant reduction in water consumption. Hybrid operation is a further attractive feature of solar gas-turbine technology, facilitating control and ensuring the power plant is available to meet demand whenever it occurs. The objective of this research is to develop a new type of hybrid concentrated Photovoltaic/Thermal (CPV/T) solar collector system that could partially fulfill a typical four people family's heat and electricity demands in many parts of the world and industrial use.

2016

The present study aims to investigate technical, economic and environmental aspects of integrating a Parabolic Trough Collector with existing feed-water heating system in an old “33 MW unit” in Al-Hussein Thermal Power Plant in Jordan. Such integration should improve the performance of the existing power plant and reduce the rate of fuel consumption, consequently the resultant pollutants’, including Greenhouse Gases (GHG), emissions will be reduced. System Advisor Model software was used as a simulation tool in this study to optimize the required solar field aperture area and to predict the performance of employed solar system. Thermodynamic basic relations, energy and mass balances, are used to simulate various main components of the existing standard steam, Rankine, cycle. Different scenarios of feed-water heating arrangement with solar-replacement are presented and discussed. It was found that efficiency of the existing power unit could be increased by 3% due to higher turbine’s ...

Sustainable Energy Technologies and Assessments, 2020

This paper introduces a new combination of solar fields to reduce LCOE and increase solar share. One Solar Field (PTC or LFR) with molten salt as heat transfer fluid is used to store energy during the day, and two independent LFRs are used for direct steam generation for high-pressure turbines and low-pressure turbines. Due to the low price of natural gas, using solar field is not economical, and using thermal energy storage is affordable only for a higher price of natural gas. The PTC with a lower energy storage than LFR has a higher solar share, but using LFR is more economical. In this paper, the effects of several parameters on the LCOE are investigated, and the key factors are introduced. According to the results, three independent LFRs create the best combination to meet the required energy. The LCOE of a photovoltaic power-plant is less than the LCOE of a solar thermal one, but the photovoltaic power plant cannot supply the energy needed at night. Therefore, in the end, to further increase system performance and reduce the LCOE, the solar thermal power-plant is combined with a photovoltaic system and the effects of using different sizes of photovoltaic power-plant on the hybrid system are investigated.

Zenodo (CERN European Organization for Nuclear Research), 2023

Sun's energy is available in abundant quantity and also it is quite sustainable in its natural form hence forming a good alternative to match the ever-increasing demand for energy. The current solar power system efficiencies are relatively low as compared to the existing power systems running on fossil fuels which is a major hindrance to its global adoption .A thorough study is done on the current scenario in the power plants using the sun's energy is performed along with recent technological developments. New advancements in the materials capable of storing large amount of heat by changing phase at constant temperature (PCM) are also highlighted. Various hybrid modes of solar thermal power plants were compared based on parameters like Levelized cost of energy (LCOE) and found to be competitive with their conventional counterparts. The paper also highlights various algorithms and methodologies applicable for enhancing the efficiency of the plants using the sun's energy.

Applied Energy, 2010

Fossil fuel based power generation is and will still be the back bone of our world economy, albeit such form of power generation significantly contributes to global CO 2 emissions. Solar energy is a clean, environmental friendly energy source for power generation, however solar photovoltaic electricity generation is not practical for large commercial scales due to its cost and high-tech nature. Solar thermal is another way to use solar energy to generate power. Many attempts to establish solar (solo) thermal power stations have been practiced all over the world. Although there are some advantages in solo solar thermal power systems, the efficiencies and costs of these systems are not so attractive. Alternately by modifying, if possible, the existing coal-fired power stations to generate green sustainable power, a much more efficient means of power generation can be reached. This paper presents the concept of solar aided power generation in conventional coal-fired power stations, i.e., integrating solar (thermal) energy into conventional fossil fuelled power generation cycles (termed as solar aided thermal power). The solar aided power generation (SAPG) concept has technically been derived to use the strong points of the two technologies (traditional regenerative Rankine cycle with relatively higher efficiency and solar heating at relatively low temperature range). The SAPG does not only contribute to increase the efficiencies of the conventional power station and reduce its emission of the greenhouse gases, but also provides a better way to use solar heat to generate the power. This paper presents the advantages of the SAPG at conceptual level.

Volume 1: Fuels, Combustion, and Material Handling; Combustion Turbines Combined Cycles; Boilers and Heat Recovery Steam Generators; Virtual Plant and Cyber-Physical Systems; Plant Development and Construction; Renewable Energy Systems, 2018

The small solar thermal power plant is being developed with funding from EU Horizon 2020 Program. The plant is configured around a 2-kWel Organic Rankine Cycle turbine and solar field, made of Fresnel mirrors. The solar field is used to heat thermal oil to the temperature of about 240 o C. This thermal energy is used to run the Organic Rankine Cycle turbine and the heat rejected in its condenser (about 18-kWth) is utilized for hot water production and living space heating. The plant is equipped with a latent heat thermal storage to extend its operation by about 4 hours during the evening building occupancy period. The phase change material used is Solar salt with the melting/solidification point at about 220 o C. The total mass of the PCM is about 3,800 kg and the thermal storage capacity is about 100 kWh. The operation of the plant is monitored by a central controller unit. The main components of the plant are being manufactured and laboratory tested with the aim to assemble the plant at the demonstration site, located in Catalonia, Spain. At the first stage of investigations the ORC turbine will be directly integrated with the solar filed to evaluate their joint performance. During the second stage of tests, the Latent Heat Thermal Storage will be incorporated into the plant and its performance during the charging and discharging processes will be investigated. It is planned that the continuous filed tests of the whole plant will be performed during the 2018-2019 period.

Clean Technol. 2022, 4(1), 97-131,@MDPIOpenAccess, 2022

Industrial manufacturing approaches are associated with processing materials that consume a significant amount of thermal energy, termed as industrial process heat. Industrial sectors consume a substantial amount of energy for process heating over a wide range of temperatures (up to 400 °C) from agriculture, HVAC to power plants. However, the intensive industrial application of fossil fuels causes unfavorable environmental effects that cannot be ignored. To address this issue, green energy sources have manifested their potential as economical and pollution-free energy sources. Nevertheless, the adoption of solar industrial process heating systems is still limited due to a lack of knowledge in the design/installation aspects, reluctance to experience the technical/infrastructural changes, low price of fossil fuels, and lack of relative incentives. For successful solar process heat integration in industries, a proper understanding of the associated design factors is essential. This paper comprehensively reviews the integration strategies of solar industrial process heating systems, appraisal of the integration points, different aspects of solar collectors, installed thermal power, and thermal storage volume covering case studies, reports and reviews. The integration aspects of solar process heat, findings, and obstacles of several projects from the literature are also highlighted. Finally, the integration locations of SHIP systems are compared for different industrial sectors to find out the most used integration point for a certain sector and operation. It was found that for the food, beverage, and agriculture sector, 51% of solar process heat integration occurs at the supply level and 27.3% at the process-level.

Renewable Energy, 2016

The demands for space air conditioning and clean drinking water are relatively high in Middle East North African (MENA) countries. A sustainable and innovative approach to meet these demands along with the production of domestic hot water is experimentally investigated in this paper. A novel solar thermal poly-generation (STP) pilot plant is designed and developed for production of chilled water for air conditioning using absorption chiller, clean drinking water with membrane distillation units and domestic hot water by heat recovery. The STP system is developed with a flexibility to operate in four different modes: (i) solar cooling mode (ii) cogeneration of drinking water and domestic hot water (iii) cogeneration of cooling and desalination (iv) trigeneration. Operational flexibility allows consumers to utilize the available energy based on seasonal requirements. Performance of STP system is analyzed during summer months in RAKRIC research facility. Energy flows in STP pilot plant during peak load operations are analyzed for all four modes. STP system with trigeneration mode utilizes 23% more useful energy compared to solar cooling mode, which improves overall efficiency of the plant. Economic benefits of STP with trigeneration mode are evaluated with fuel cost inflation rate of 10%. STP plant has potential payback period of 9.08 years and net cumulative savings of $454,000 based on economic evaluation.