Conventional Thermal Power Plants Research Articles

Analysis of solar photovoltaic and wind power potential in Afghanistan

Afghanistan has a need for increased access to energy to enable development. In this paper we analyze the potential for large-scale grid-connected solar photovoltaic (PV) and wind power plants in two of Afghanistan's most populous provinces (Balkh and Herat) to meet a large fraction of growing electricity demand. The results presented here represent the first quantitative analysis of potential capacity factors and energy yields of power plants in the country using measured wind speed and typical solar radiation data. Variability of resources is also investigated by comparing temporal profiles with those of electricity demand, using residual load duration curves to determine penetration and curtailment levels for various demand scenarios. We show that solar PV and wind power plants in two provinces could achieve penetration levels of 65%–70% without significant curtailment, which in turn would mean less reliance on unpredictable and unstable power purchase agreements with neighboring countries, longer life of limited domestic fossil fuel resources, and lower imports of diesel fuel, thus avoiding rising costs and detrimental environmental impacts. Our results point to an alternative development pathway from that of previous recommendations for conventional thermal power plants, controversial hydroelectric projects, and a significant dependence on imported power.

Transient Simulation of High Temperature High Pressure Solar Tower Receiver

A solar receiver undergoes frequent transients events and the nature of these transient events is very different from conventional thermal power plants. The SRSG (Solar Receiver Steam Generator) operates during the day when heat from the sun is available and is shut-down during the night. Along with the daily start-up and shut-down, italso undergoes various other transient events including short or long cloud events followed by hot-start, partial load transient during light cloud events, cold start-up transients(after extended shut-down events) and failure modes. The operation and control strategy for the SRSG should incorporate safe operation during all the transient events while optimizing on power generation. It is therefore important to model the SRSG and study the dynamic response of the SRSG under various transient conditions. This paper discusses modeling of Alstom SRSG using the APROS dynamic simulation platform. The paper describes in detail various components of high pressure, high temperature SRSG along with the need for transient modeling during the design phase. It provides details of various transient events that were simulated along with a discussion on the simulation results. The paper highlights the optimized modes of operation procedure developed using transient modeling along with control strategies.

Application of smart grid specifications to overcome excessive load shedding in Alexandria, Egypt

Recently, limited generation capability of conventional thermal power plants due to shortage in fuel supply in addition to the rapid increase in load demand resulted in repeated and prolonged load shedding all over the country. To overcome this problem, the use of renewable energy sources (RES) and modifying the network into a smart grid are necessary. As the utility, in addition to the private sector of investors, are responsible for the construction of renewable energy plants, customers are responsible for the reduction of peak demand. Demand side management (DSM) programs are important tools in a smart grid that helps to reduce the peak demand and adjust the load profile with the contribution of customers. Energy resources planning integrating DSM lead to reduction in the overall operational cost, an increase in the reserve of generating units and improvement of the sustainability of the supply (reduction of load shedding). In this paper, a modified firefly based optimization algorithm is proposed for optimal DSM of different load types and optimal energy resources schedule. The objective of the proposed modified firefly algorithm (MFA) is to minimize the overall operational cost including consumed energy cost, generated energy cost, energy loss cost, grid energy cost, unserved energy cost and startup cost of thermal generating units. A day-ahead unit commitment planning of diesel generators is carried out to provide the required energy while keeping the spinning reserve of the units within its allowable limits. An economic dispatch of committed units is considered for minimum generation cost. The proposed MFA is applied to the 66kV, 45 bus distribution network of Alexandria, Egypt which is supported by multiple, different types of distributed generating units (DGs).

Utilization of Waste Materials from Industrial Processes of a Brazilian Sugarcane Mill for Energy Production

This work presents the thermodynamic, thermoeconomic, and economic analyses of utilization of waste materials from industrial processes of a modern Brazilian sugarcane mill (bagasse, straw and vinasse) for energy production. The first case considers a conventional steam thermal power plant constituted, among other equipment, by a steam boiler of high-pressure and high-temperature and by an extraction-condensation steam turbine, being all mechanical driving electrified, and using just bagasse as fuel. The second case considers a modified steam thermal power plant in which is incorporated systems to be possible the utilization of straw and vinasse as complementary fuel to bagasse by means of a combined cycle, with the addition of a gas turbine and a heat recovery steam generator, among other equipment.

Syngas-fueled, chemical-looping combustion-based power plant lay-out for clean energy generation

Of the various clean combustion technologies with carbon capture and sequestration (CCS) possibilities, chemical-looping combustion (CLC) promises to be an efficient and attractive method for oxidizing fuels without the energy penalty required for oxygen separation from air. The present work reports on a detailed thermodynamic analysis of 1,500 MWth, syngas-fueled, CLC-based power generation system which includes a provision for CCS. Taking account of the exothermic nature of the reaction of syngas with the selected oxygen carrier, NiO, in the fuel reactor, operating temperatures of air and fuel reactors are fixed at 900 and 908 °C, respectively. The CLC reactor system operates at atmospheric pressure on fuel/air side, and generates supercritical steam. An overall plant lay-out has been prepared such that the steam side, which is rated at 240 bar/538/552/566 °C, is very similar to that of a conventional thermal power plant making retrofitting a distinct possibility. A detailed analysis of the ideal cycle shows that a highly promising gross cycle efficiency of 41.22 % and net cycle efficiency of 36.77 % can be achieved after accounting for the energy cost of CO2 compression to 110 bar to facilitate CCS.

Competitiveness of Wind Power with the Conventional Thermal Power Plants Using Oil and Natural Gas as Fuel in Pakistan

The fossil fuels mainly imported oil and natural gas are major sources of electricity generation in Pakistan. The combustion of fossil fuels in thermal power plants has greater environmental impacts like air pollution and global warming. Additionally, the import of oil is a heavy burden on the poor economy of the country. Pakistan is a country with huge renewable sources; wind energy being the major one. This paper elucidate the cost-competitiveness of wind power with the conventional thermal power plants. In this regard, Levelized estimated cost of a 15MW wind power plant is compared with three types of conventional thermal power plants, namely (i) Oil-fired thermal power plant (ii) Natural gas-fire combine cycle power plant (iii) Diesel oil- fired gas turbine cycle 100MW each. The results show that the cost of wind energy is lowest with Rs. 3/kWh. It is concluded that the wind power is cost-competitive to the conventional thermal power plants in Pakistan. The cost estimation for wind energy is lowest of all others with Rs. 3/kWh.

PV–Enhanced Solar Thermal Power

Solar electricity generation using concentrating solar thermal collectors faces the challenge of strongly decreased levelized electricity costs by photovoltaic power plants. One of the selling points favouring solar thermal power is the possibility to generate dispatchable power. Concepts discussed here are solar hybridization of conventional or biomass thermal power plants. Another option is the use of thermal energy storage (TES) charged with solar heat which allow to drive the generation of electricity by steam turbines also during hours with no or low solar irradiation. Usually the solar fields of solar thermal power plants utilizing storage with several hours capacity will be much larger than those of plants without storage. This contributes to much higher cost per installed capacity in the case of storage utilization. In this paper the question shall be tackled in a rather fundamental way whether the combination of solar thermal power with cheaper photovoltaic systems plus minimum solar thermal power with storage may give lower levelized electricity cost plus dispatchability than either photovoltaics alone or solar thermal power alone.For the investigation of a combined PV-enhanced solar thermal power plant no specifically developed software was available. Therefore the simulation of the photovoltaic plant and the solar thermal power plant including TES was done individually. For the solar thermal power plant TES storage capacity and solar field area were varied. Solar field area ranged between solar multiple of two and below one. The latter choice would have been senseless without PV-enhancement. Hourly power generations profiles over a complete year were combined and matched in order to generate electricity according to a prescribed demand curve. Using dispatch prescriptions the scheduling of solar thermal power was controlled. With typical generic cost data and variations of those in a sensitivity study the combined levelized electricity cost were determined and analysed.Photovoltaic generation and solar thermal power generation via thermal energy storage may produce high annual capacity factors above 50% due to dispatchable solar power from the thermal storage. Depending on the climatic conditions and on seasonal and daily load profiles the combinations of photovoltaic and solar thermal power may change. Many open questions have to be solved in order to proceed with the basic idea of PV-enhanced solar thermal power generation. Real cost data and optimization requires a specific project case. Then also the selection of the most promising photovoltaic technology and the different solar thermal technologies may be discussed in more detail.

Advanced Hybrid Solar Tower Combined-cycle Power Plants

Hybrid solar gas-turbine technology is a promising alternative to conventional solar thermal power plants. In order to increase the economic viability of the technology, advanced power plant concepts can be envisioned, with the integration of thermal energy storage and combined-cycle power blocks. In order to pinpoint the most promising configurations, multi-objective optimization has been used to identify Pareto-optimal designs and highlight the trade-offs between minimizing investment costs and minimizing specific CO2 emissions. Advanced solar hybrid combined-cycle power plants provide a 60% reduction in electricity costs compared to parabolic trough power plants. Furthermore, a 22% reduction in costs and a 32% reduction in CO2 emissions are achieved relative to a combination of parabolic trough and combined-cycle power plants.

Development of a Simulation Program to Optimise Process Parameters of Steam Power Cycles

Conventional coal-based thermal power plants have an average overall efficiency in the range of 35-38 %. Any increase in the percent efficiency of these power plants, is subjected to constraints posed by maximum and minimum temperatures, which are restricted by the creep property of materials and ambient temperature, respectively. Hence, an increase of efficiency beyond certain limits is not possible without optimising the process parameters associated with reheat and regenerative cycles. In this work, an attempt is made to optimise reheat and regenerative cycle process parameters such as, reheat pressure, tapping pressure of bled steam, and mass fraction of bled steam, in order to achieve maximum cycle efficiency. The optimisation of the process parameters was achieved by developing a simulation program using Microsoft Visual Studio. This program takes into account isentropic efficiencies of turbines and pumps and pressure drop in the boiler, and it can be used to simulate the optimum operating conditions of multi-stage reheat & regenerative cycle based thermal power plants. A comparison between the efficiencies of eight kinds of steam power cycles, at optimised conditions, has been made for different boiler pressures and steam temperatures at the turbine inlet. This comparison can aid power plant designers in choosing appropriate steam power cycles for a given set of operating conditions. It is observed that the results obtained from the program, such as, the optimum reheat pressures for two stage reheat cycles and optimum bled steam tapping pressures for two stage regenerative cycles are in good agreement with the published literature.

Output increase of conventional thermal power plants by the method of feed water bypassing feed water heaters

Output increase of conventional thermal power plants by the method of feed water bypassing feed water heaters

Unique Challenges in the Design and Operation Philosophy of Solar Thermal Power Plants

Solar thermal power plant design and operation philosophy involves unique challenges as compared to design of conventional thermal power plants. The solar receiver operation should be able to absorb maximum solar load during transient events like daily start-up and shut-down. This requires aggressive ramp rates for transient operation of the power plant. However, the component and system level limitations must be considered in formulating these modes of operation and ramp rates.A solar receiver which usually receives heat from heliostats is designed to receive high heat flux to operate at high temperature and pressure during daytime. However, during night-time the receiver receives no heat flux and is losing heat to the environment. Day-night cyclic operation of a solar thermal power plant induces thermal cycles in the solar receiver pressure parts. Since solar receiver tubes are not insulated, the amplitude of thermal cycling is significant and needs to be addressed with proper tools and design approach. Besides, higher plant cycle efficiency requires higher operating temperature and pressure of a solar receiver, further increasing the amplitude of thermal cycling. The system level and component level response to these day-night cycles has a significant impact on modes of operation as well as on the life usage of various components. It also affects the design, specifications and operation of various plant level components.The solar thermal power plant design and operation process is optimized by having a system level thermal-hydraulics model for the solar receiver to simulate the transient start-up and shut-down events. Since all of the major components of the system are included in the model, it reflects the transient response of each of the components on each other and on the overall system. This simulation can be used to generate input conditions for component level life usage analysis. The component level life usage analysis is done using the finite-element method. The component level life usage analysis determines the permissible ramp rates. The thermal-hydraulics dynamic simulation outlines the operational philosophy of the system.

Estimation of chemical exergy of solid, liquid and gaseous fuels used in thermal power plants

This paper presents the methods for the calculation of chemical exergies of coal, heavy fuel oil and natural gas that are used as fuel in conventional thermal power plants. Calculations have shown that the chemical composition of the fuel greatly influences the value of its chemical exergy. In case of coal in which carbon and hydrogen are not combined together, an increase in both carbon and hydrogen contents increases its chemical exergy value. In case of heavy fuel oils, hydrogen–carbon ratio is the most influencing parameter in the chemical exergy value. An increase in hydrogen–carbon ratio in the fuel tends to increase its chemical exergy. In case of natural gases, a decrease in lighter hydrocarbon gas contents and an increase in heavier hydrocarbon gas contents tend to increase the chemical exergy value of the fuel. High moisture and/or ash contents also tend to lower the value of the chemical exergy.

Powder Technology Contributing to High Efficiency and Clean Utilization of Solid Carbon Fuel Resources

Solid carbon fuel resources like coal and solid biomass are very important energy resources now and for the future. Coal reserves are more abundant than other fossil fuels, so coal will be important energy resource in the future. Biomass is regarded as renewable energy. For a stable supply of energy and protection against the global warming problem, advanced technologies for the utilization of coal and biomass are needed. Powder technology is important for effective utilization of solid carbon fuels. Powder handling technologies, from the mining of coal and the collection of biomass to the utilization of these fuels, is being utilized. In this paper, the role of powder technology in conventional thermal power plants and future high performance power plants is discussed along with the possibility of more effective contribution of powder technology including fuel upgrading technologies.

Pairing Integrated Gasification and Enhanced Geothermal Systems (EGS) in Semiarid Environments

We explore the feasibility of combining the circulation of supercritical CO2 in EGS reservoirs with integrated gasification combined cycle (IGCC) power generation. The symbiotic benefits of this pairing increase net power output over the use of either system in isolation, reduces water use per MWe, and substantially reduces fugitive emissions over conventional thermal power plants. A prototypical plant set in the arid southwestern U.S. (environs of Albuquerque, NM) could sustain anticipated circulation rates of 800–1600 kg/s of CO2 in a 200 °C reservoir, resulting in a thermal output of ∼150–300 MW-thermal to augment the 550 MW from IGCC. This design would reduce annual emissions by 8,200 tons of NOx, 20,000 tons of SO2, and 4.35 million tons of CO2 over conventional thermal plants in an optimal pairing.

Optimal operation of conventional power plants in power system with integrated renewable energy sources

This paper presents an approach for solving the generation scheduling problem of a complex system consisted of conventional and renewable energy sources (RES). Wind power plants are integrated into the system in order to minimize the total thermal unit fuel costs. The gained results for wind farm power production are used as input in the system to determine the optimal amounts of generated power for the thermal generating units and hydro generating units over the study period. The optimization problem consists of minimizing the total production costs, respecting power balance equations for each time interval and all operational system constraints. The proposed approach is applied on a specific system consisted of thermal power plants (TPPs), storage hydro power plants (HPPs), pumped-storage hydro power plant (PSHPP) and wind power plant (WPP). The benefits of energy production from WPP, in terms of reducing the production costs of conventional thermal power plants are also investigated. In the proposed paper two cases are analyzed. In the two analyzed cases power unit’s generation, thermal unit’s fuel costs and stream flows of hydro units are calculated over the study period.

Efficiency enhancement of combined cycles by suitable working fluids and operating conditions

Abstract Solar energy based combined cycle power plants are becoming important as an efficient option among conventional thermal power plants. However conventional thermal efficiency can be significantly improved. This research study is centred on combined cycle efficiency enhancement by researching the capacity of several working fluids such as N2, air, or He for the topping cycle which is a closed Brayton cycle (CBC) and a bottoming cycle which is a Rankine cycle (RC) operating with xenon, ethane or ammonia as working fluids. The applied strategy, which aims to increase the ideal thermal efficiency, is based on the concepts of quasi-critical condensation pressure, residual heat recovery and properly selected working fluids. The decision to propose N2, air, or He, as working fluid for the Brayton part of the CC stems from the fact that they yield high efficiency at high temperatures with acceptable power ratio. A performance study of several organic and nonorganic working fluids such as ethane, xenon and ammonia for the bottoming Rankine cycle and N2, air, or He, for topping CBC is performed. The consequences are a significant positive increment in thermal efficiency in comparison with conventional CC power plants.

A Unified Control Scheme for Coal-Fired Power Plants with Integrated Post Combustion CO2 Capture

Within the DYNCAP project, a unified control scheme for coal-fired power plants with integrated CO 2 capture cycle is developed. For seamless integration into existing power plant technologies, the German technical guideline VDI3508 for conventional thermal power plants is taken as starting point. Interactions between steam cycle and post-combustion carbon dioxide capture cycle are identified and communication interfaces between its control units are defined. An according extension of VDI3508 is implemented on the computer using the library ClaRaCCS written in Modelica. By direct computer simulation the validity of the novel control scheme is demonstrated under transient operation of the power plant coupled to the carbon capture cycle. The simulation results are discussed and recommendations for further improvement of the scheme are given.

Controller parameters design of doubly feed induction generator using Particle Swarm Optimization

The integration of wind farms into the electricity grid has become an important challenge for the utilization and control of electric power systems, because of the fluctuating and intermittent behavior of wind power generation. Doubly fed induction generators (DFIG) are commonly used wind turbine generators (WTG) in electricity networks. In DFIG there are three control loops which should be implemented in order to appropriate performance of WTG. These control loops are pitch angle control, rotor speed control and voltage control. In this paper a unified scheme is used to adjust these controllers in the same time. Particle Swarm Optimization (PSO) is used to adjustment the proposed controllers. The results of wind power on the system performance are compared with a conventional thermal power plant.

Development of Wet-Bulb-Temperatures in Germany with special regard to conventional thermal Power Plants using Wet Cooling Towers

Development of Wet-Bulb-Temperatures in Germany with special regard to conventional thermal Power Plants using Wet Cooling Towers

Locating new coal-fired power plants with Carbon Capture Ready design–A GIS case study of Guangdong province in China

Abstract Making new coal-fired power plants carbon capture ready (Carbon Capture Ready) in China has been recognised as a crucial by a number of stakeholders academics, energy companies and regional government, based on a study in EU-UK-China NZEC project. A number of publications have investigated the definition, engineering requirements, economic and finance of CCR for China. However there remain a number of questions regarding the extent to which a plant’s physical location might constrain the feasibility of CCS retrofit. To address this issue, a Geographical Information System (GIS) has been used as a tool for mapping current and planned large carbon dioxide sources in Guangdong, also illustrating potential storage sites and calculating possible carbon dioxide transportation route. This paper investigates the location factors that should be considered when locating new build CCR power plants and demonstrates the methodology of using GIS software with spatial analysis in planning new build power plant in Guangdong. A preliminary study has identified over 30 large power plants within the region, with plant locations and historical emission data collected and presented in ArcGIS. Factors such as distance to potential storage site, route of CO 2 pipeline, extra space on site and potential development plan etc. were investigated in the modelling and calculated the potential source and sink solution. The study then moves on to suggest possible new build plant locations which can be easily fitted in to the current network, based on economic optimisation. The scope for future coal plant development combined with a possible nuclear plant siting plan is discussed towards the end of the paper. Guangdong province, which owns the third largest coal-fired power installed capacity out of 31 provinces, generated over 8% of China’s total electricity every year for the past 15 years. CO 2 storage opportunities could be found in the surrounding South China Sea, where Guangdong has a total of 4,300 km of coastline and some small scale oil fields on shore within the region. It is also among the first places to start the national open and reform policy in China. The province is one of the richest in China, with the highest GDP among all other provinces since 1989, and the foreign trade accounts for more than a quarter of China’s total amount. It also contributes around 12 of the total national economic output. Currently, the provincial government is proposing a low carbon roadmap, which is the first of its kind in China. The work has created a totally new thinking on capture ready power plant planning. This differs from existing studies (e.g., which aim to investigate the existing carbon dioxide emission sources at specified location and provide source and sink matching analysis. Instead the study focuses on policy implementation for new build capture ready power plants. Three clusters within Guangdong province are identified as potential temporary CO 2 storage hubs before transporting the gas to a long term storage site. When officials are planning new power plant locations from a capture ready perspective, the plants should not necessarily be close to storage sites in straight line, but rather should be within a reasonable distance of a cluster. Transport of the captured CO 2 will not be limited to pipelines, but could be extended to road and rail tankers. Power plant parameters and storage site data were collected for this research. Public transportation, utilities, landscapes, river, land used and population data were referenced from various sources; therefore, some of the data could be out of date. Nevertheless, it should still provide enough information when deciding the location of the transport cluster. Any future work could build on the existing model with updated data. Moreover, it could fit in with the national natural gas transportation network and utility planning network to provide long term integrated energy system analysis. The paper could provide policy makers, investors and urban planning officials with a view on how conventional thermal power plant investment and planning could be optimised, using Carbon Capture Ready designs, to keep the CCS retrofitting option open.