Showing papers on "Thermal power station published in 2021"

Sources of inefficient power generation by coal-fired thermal power plants in China: A metafrontier DEA decomposition approach

Abstract: China is the world's largest CO2 emitting country, and coal-fired thermal power generation accounted for over 50% of the total electricity generation in China in 2015. This study reports the changes in the power generation efficiency of coal-fired thermal power plants in China from 2009 to 2011 and elucidates how the differences in the production scale of the power plants and regional heterogeneity affect the power generation efficiency. We propose a metafrontier data envelopment analysis (DEA) decomposition framework to investigate the sources of inefficiency in power generation. The results suggest that, on average, the power generation efficiency of large-scale power plants is 13% higher than that of small-scale power plants. Although operational inefficiency is the main source of inefficiency in eastern and central China, the technology gap - the differences in the quality of coal consumed for electricity production and in the equipment of the power plants among regions - is the main source of inefficiency in western China. This study uses the results of the framework to discuss the scrapping policies for coal-fired thermal power plants in China. For large-scale power plants in western China, the components of inefficiency vary and, thus, policymakers should consider scrapping thermal power plants based not only on the level of inefficiency but also on their components.

An Energy Management System Design Using Fuzzy Logic Control: Smoothing the Grid Power Profile of a Residential Electro-Thermal Microgrid

Abstract: This work deals with the design of a Fuzzy Logic Control (FLC) based Energy Management System (EMS) for smoothing the grid power profile of a grid-connected electro-thermal microgrid. The case study aims to design an Energy Management System (EMS) to reduce the impact on the grid power when renewable energy sources are incorporated to pre-existing grid-connected household appliances. The scenario considers a residential microgrid comprising photovoltaic and wind generators, flat-plate collectors, electric and thermal loads and electrical and thermal energy storage systems and assumes that neither renewable generation nor the electrical and thermal load demands are controllable. The EMS is built through two low-complexity FLC blocks of only 25 rules each. The first one is in charge of smoothing the power profile exchanged with the grid, whereas the second FLC block drives the power of the Electrical Water Heater (EWH). The EMS uses the forecast of the electrical and thermal power balance between generation and consumption to predict the microgrid behavior, for each 15-minute interval, over the next 12 hours. Simulations results, using real one-year measured data show that the proposed EMS design achieves 11.4% reduction of the maximum power absorbed from the grid and an outstanding reduction of the grid power profile ramp-rates when compared with other state-of-the-art studies.

Performance analysis of an integrated pumped-hydro and compressed-air energy storage system and solar organic Rankine cycle

Abstract: This research presents the performance study of a new energy storage system, i.e. Pumped-Hydro and Compressed-Air storage system, coupled with organic Rankine cycle (ORC) and Linear Fresnel solar reflector (LFR). The proposed cycle is capable of generating electricity and heat as well as storing storage. The LFR receives solar energy and turns it to the thermal power. The heat obtained from this way is used to supply heat to the evaporator of the ORC, and this system generates power. This power is then fed to the storage system pump. In the result section, the performances of storage system, solar and ORC systems, as well as coupled process are examined. The effect of key parameters such as operating pressures of the storage system, inlet temperature and pressure of organic fluid of the turbine of ORC, solar system inlet temperature and solar irradiance on process operation is examined. Furthermore, it is assumed that the solar collector works in the weather conditions of Esfahan (in Iran). The findings showed that the energy required by the pump and the energy level in the vessel for the isothermal process are 3.24 and 2.43 MJ/m3, respectively. These values were 2.79 and 2.09 MJ/m3, respectively, for the isentropic process. In addition, the system storage efficiency is equal to 60%. Furthermore, the isentropic process compared to isothermal process requires less solar collector area.

Performance of thermal-sprayed coatings to combat hot corrosion of coal-fired boiler tube and effect of process parameters and post-coating heat treatment on coating performance: a review

Abstract: High-temperature corrosion of coal-fired boiler parts such as water walls and superheated tubes poses a serious threat to the efficiency of the thermal power plant. To overcome this, numbers of cor...

Thermodynamics, economic and environmental analyses of a hybrid waste–solar thermal power plant

Abstract: A novel hybrid configuration of solar parabolic trough collectors–waste incineration power plant was recently analyzed energetically in Denmark. Taking into account the true meaning of sustainability which is environmental friendliness and cost-effectiveness, and considering the existing gap of knowledge on the thermodynamic performance aspects of this hybrid system, this work conducts a thorough thermodynamic and sustainability analysis of this power plant. The main aim is to give a clear picture of the main advantages and any possible shortcomings of the hybrid power plant. For this purpose, the performance of the system is simulated for an entire year of operation under realistic solar irradiation fluctuations. The energy performance indices of the system are quantified and discussed. The exergy assessment of the hybrid cycle is accomplished, and the main sources of exergy destruction and economic losses are identified. The results show that the steam generator and the turbine cause the largest rates of irreversibilities of 36% and 20.8%. The environmental benefits and the overall cost of energy production of the system are calculated and compared to some other alternative power plants. In addition to the consistency of electricity production, the LCOE of the hybrid power plant decreases by 67% in comparison with the solar power plant. Comparing the system with a natural gas-fired power plant in terms of CO2 emission, it is shown that the hybrid system leads to less 74.5 thousand tonnes of CO2 emitted over an entire year.

Thermodynamic potential of a high-concentration hybrid photovoltaic/thermal plant for co-production of steam and electricity

Abstract: A thermodynamic model was developed to assess the energetic performance of a dual receiver concentrated photovoltaic/thermal plant for the co-production of steam, electricity and hot water/air. The system utilizes a dual receiver including a steam generator based on a solar receiver and a concentrated PV/thermal receiver. The system is regulated so that a fraction (φ) of the thermal energy absorbed by the solar field is partitioned for the steam generator, while the rest is dedicated to the CPV/T unit. The results showed that the thermal performance of the system strongly depends on the φ value such that the system can simultaneously produce electricity and steam, while warm air and water can also be produced by cooling the CPV/T unit. Also, the thermal performance of the coolant is a key element to the system, which highlights the potential of nano-suspensions as a coolant in the system. Likewise, the assessment of the process plant was performed at field area of 2500–10,000 m2, the solar concentration ratio of 50–200 and the CPV/T coolant’s outlet temperature of 323–353 K. It was found that the highest values of thermal losses can be ~ 2% of the total thermal input of the plant. Also, a trade-off trend was identified between the φ value, steam and electricity production. It was also found that at a solar concentration ratio of 2000, the system is competitive to produce steam to be fed into a multi-flash desalination system. The energetic performance of the system revealed that at φ = 0.75, about 48% of the energy is partitioned for the hot water and hot air production for the agricultural application, while 24% is used for the electricity and 26% is used for the steam production.

Recent Advances in Ammonia Combustion Technology in Thermal Power Generation System for Carbon Emission Reduction

Abstract: With the formation of an international carbon-neutral framework, interest in reducing greenhouse gas emissions is increasing. Ammonia is a carbon-free fuel that can be directly combusted with the role of an effective hydrogen energy carrier, and its application range is expanding. In particular, as research results applied to power generation systems such as gas turbines and coal-fired power plants have been reported, the technology to use them is gradually being advanced. In the present study, starting with a fundamental combustion research case conducted to use ammonia as a fuel, the application research case for gas turbines and coal-fired power plants was analyzed. Finally, we report the results of the ammonia-air burning flame and pulverized coal-ammonia-air co-fired research conducted at the authors’ research institute.

Integration of solar heating systems for low-temperature heat demand in food processing industry – A review

Abstract: The future of climate-resilient energy systems relies on the transition to incorporate renewable energy with energy storage, such as solar energy. Solar thermal provides desirable thermal energy (heat) for industry, commercial, and residential sectors. Significant attempts have been made to improve the design and its integrated systems, thus reducing the costs and making the technology more competitive for industrial applications. This paper evaluates the solar thermal potential and the economic feasibility standard of the technology from low-temperature heat demand up to 100 °C by focusing on the food industry. Throughout this review, theoretical concepts, design types, and recent developments related to this sector's integration systems are explored. This study also highlights the integrated systems gap and emphasises the assessment of integration points and the range of operating temperature. This review aims to assist industries in the food processing sector to keep them abreast with the latest solar technology developments for the food industry. Up to 2020, at least 95 solar thermal plants with a total capacity of 41 MWth had been installed globally for the food industry. The flat plate collectors were the most applied solar collectors in the food industry, represented by 38%. It has been shown that the most common heat applications are pre-heating, cleaning and pasteurisation. The configuration and design of the integration framework for this sector rely primarily on each application's specific features and nature of the process. Based on the installed solar thermal plant, 27% was used for heating of make-up water.

Providing large-scale electricity demand with photovoltaics and molten-salt storage

Abstract: A strategy for feasibly and affordably achieving high electrical grid penetration (24 h/day, 365 days/yr) from electricity produced by large-scale low-cost photovoltaic (PV) systems is proposed and evaluated. It is based on oversizing no-storage PV plants beyond meeting their peak daytime demand, and storing the excess energy as high-temperature heat in molten salts, from which high-efficiency steam turbines can be driven. Grid penetration levels of ~80–95% can be realized with storage capacities of only ~12 h of average electricity demand. The feasibility reflects a striking difference between economic and thermodynamic factors. The recent dramatic decrease in PV costs more than compensates for the sizable efficiency penalty. All components are off-the-shelf, mass-produced technologies. Hence, the proposal is ready for immediate implementation. First, the thermodynamic arguments for the size and performance of such systems are reviewed. Then it is shown that the cost of electricity would be competitive with that of conventional power plants, and far better than using lithium-ion batteries. The geographic decoupling of PV fields from the storage facilities and turbines permits greater decentralization of PV fields and/or more centralization of larger storage facilities and power blocks. Because PVs collect and convert diffuse solar radiation, they are viable for areas with high global, but not direct, solar radiation, where concentrating solar thermal power plants are not feasible. It is also shown that none of the system components constitutes a limited resource. This also applies to future scenarios of much greater electricity use linked to the global transition to all-electric vehicles.