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In deregulated power markets, electricity suppliers have the option to trade in the spot market, derivatives market, and bilateral contract market. The spot market is always available and open to competition, but the variability and risk incurred need to be carefully handled. The suppliers might allocate their capacity in the derivatives and bilateral contract market if these alternatives are more viable. The strike price, bilateral contract price, and spot market prices need to be used to decide the capacity allocation problem considering the generation cost of the supplier. This paper first examines the market design and electricity trading in the Turkish electricity market. Then three problems were proposed for a coal-fired coal unit that aims to allocate its capacity to spot, derivative, and bilateral contract markets to maximize its expected profit. A Monte Carlo method is used for allocated electricity capacities, spot market, strike, and bilateral contract price scenarios. A simulation methodology is then proposed that includes capacities allocated to each market and price scenarios. The best capacity allocation strategy is determined that return the highest expected profits for all market price samples. The model is illustrated for a coal unit in the Turkish electricity market. The results are presented for the case, including 100 spot price samples, 100 capacity scenarios, 3 scenarios for the strike, and bilateral contract prices. The sensitivity analysis for spot price volatility on the profit is also presented with 20% volatility increase. It is shown that allocating the capacity to more than one market can increase the total expected profit for a power supplier and the rate of increase varies depending on the scenario set. • Electricity trading of a thermal generator in different markets is discussed. • Capacity allocation to spot, derivative and bilateral contract market is modeled. • Price and capacity scenarios for the Monte carlo simulation is developed. • It is shown that capacity allocation to different markets can increase total profit. • A supplier can determine its strategy based on the price expectations. [ABSTRACT FROM AUTHOR]

This paper presents two different scenarios for the energy system of the Netherlands that achieve the Dutch government's national target of near net-zero greenhouse gas emissions in 2050. Using the system optimisation model OPERA, the authors have analysed the technology, sector and cost implications of the assumptions underlying these scenarios. While the roles of a number of key energy technology and emission mitigation options are strongly dependent on the scenario and cost assumptions, the analysis yields several common elements that appear in both scenarios and that consistently appear under differing cost assumptions. For example, one of the main options for the decarbonisation of the Dutch energy system is electrification of energy use in end-use sectors and for the production of renewable hydrogen with electrolysers. As a result the level of electricity generation in 2050 will be three to four times higher than present generation levels. Ultimately, renewable energy – particularly from wind turbines and solar panels – is projected to account for the vast majority of electricity generation, around 99% in 2050. Imbalances between supply and demand resulting from this variable renewable electricity production can be managed via flexibility options, including demand response and energy storage. Hydrogen also becomes an important energy carrier, notably for transportation and in industry. If import prices are lower than costs of domestic production from natural gas with CCS or through electrolysis from renewable electricity (2.4–2.7 €/kgH 2), the use of hydrogen increases, especially in the built environment. • We explore two scenarios for a near climate-neutral energy system in the Netherlands. • With the OPERA model we determine their technology, sector and cost implications. • The electricity share in primary energy increases from 19% today to 41–71% in 2050. • Hydrogen becomes another important energy carrier, notably in transport and industry. • Biomass use increases, mostly as fuel in transport and industry. [ABSTRACT FROM AUTHOR]

With the exponential penetration of Photovoltaic (PV) plants into the power grid, protection has gained exceptional importance in recent years for ensuring stability, reliability, security, and power quality of the power systems. Thus, to address these issues many countries have established new requirements in the form of grid codes for grid connection of PV plants. One of the main requirements of grid codes is Fault Ride Through (FRT) capability. FRT describes the power generator performance during and in post-fault circumstances. In this paper, an in-depth review is carried out on various scientific aspects of faults and FRT strategies available in the literature. First, various faults occurring in the grid-connected PV system are classified and compared along with a critical and analytical assessment of grid codes especially FRT requirements i.e., Low Voltage Ride Through (LVRT) and High Voltage Ride Through (HVRT) for various countries. Then, FRT approaches and strategies are classified and compared based on improved controller-based methods and external devices methods in detail. The existing FRT strategies are compared based on various aspects i.e., complexity, economically, and technically. After that, a case study that explains the complete design and implementation of conventional Crowbar, Bridge Type Fault Current Limiter (BFCL), and Switch Type Fault Current Limiter (STFCL) as an FRT strategies for 100 kW three-phase grid-connected PV system in MATLAB/Simulink is presented. A comparative assessment is also carried out among these strategies that validate the robust performance of BFCL and STFCL. Lastly, the conclusion is presented along with a brief proposal for future work. • Faults classification and investigation for PV systems. • Analysis of requirements for modern grid codes. • Categorization and comparison of various FRT strategies for grid connected PV system. • Design and evaluation of three FRT strategies for 100 kW three phase grid connected PV system. [ABSTRACT FROM AUTHOR]

With the exponential penetration of Photovoltaic (PV) plants into the power grid, protection has gained exceptional importance in recent years for ensuring stability, reliability, security, and power quality of the power systems. Thus, to address these issues many countries have established new requirements in the form of grid codes for grid connection of PV plants. One of the main requirements of grid codes is Fault Ride Through (FRT) capability. FRT describes the power generator performance during and in post-fault circumstances. In this paper, an in-depth review is carried out on various scientific aspects of faults and FRT strategies available in the literature. First, various faults occurring in the grid-connected PV system are classified and compared along with a critical and analytical assessment of grid codes especially FRT requirements i.e., Low Voltage Ride Through (LVRT) and High Voltage Ride Through (HVRT) for various countries. Then, FRT approaches and strategies are classified and compared based on improved controller-based methods and external devices methods in detail. The existing FRT strategies are compared based on various aspects i.e., complexity, economically, and technically. After that, a case study that explains the complete design and implementation of conventional Crowbar, Bridge Type Fault Current Limiter (BFCL), and Switch Type Fault Current Limiter (STFCL) as an FRT strategies for 100 kW three-phase grid-connected PV system in MATLAB/Simulink is presented. A comparative assessment is also carried out among these strategies that validate the robust performance of BFCL and STFCL. Lastly, the conclusion is presented along with a brief proposal for future work. • Faults classification and investigation for PV systems. • Analysis of requirements for modern grid codes. • Categorization and comparison of various FRT strategies for grid connected PV system. • Design and evaluation of three FRT strategies for 100 kW three phase grid connected PV system. [ABSTRACT FROM AUTHOR]

This paper presents two different scenarios for the energy system of the Netherlands that achieve the Dutch government's national target of near net-zero greenhouse gas emissions in 2050. Using the system optimisation model OPERA, the authors have analysed the technology, sector and cost implications of the assumptions underlying these scenarios. While the roles of a number of key energy technology and emission mitigation options are strongly dependent on the scenario and cost assumptions, the analysis yields several common elements that appear in both scenarios and that consistently appear under differing cost assumptions. For example, one of the main options for the decarbonisation of the Dutch energy system is electrification of energy use in end-use sectors and for the production of renewable hydrogen with electrolysers. As a result the level of electricity generation in 2050 will be three to four times higher than present generation levels. Ultimately, renewable energy – particularly from wind turbines and solar panels – is projected to account for the vast majority of electricity generation, around 99% in 2050. Imbalances between supply and demand resulting from this variable renewable electricity production can be managed via flexibility options, including demand response and energy storage. Hydrogen also becomes an important energy carrier, notably for transportation and in industry. If import prices are lower than costs of domestic production from natural gas with CCS or through electrolysis from renewable electricity (2.4–2.7 €/kgH 2), the use of hydrogen increases, especially in the built environment. • We explore two scenarios for a near climate-neutral energy system in the Netherlands. • With the OPERA model we determine their technology, sector and cost implications. • The electricity share in primary energy increases from 19% today to 41–71% in 2050. • Hydrogen becomes another important energy carrier, notably in transport and industry. • Biomass use increases, mostly as fuel in transport and industry. [ABSTRACT FROM AUTHOR]

Abstract: Global warming is one of the most important issues to handle in the energy sector, due to the high CO2 emissions from fossil fuel based power plants. The district heating sector can play a significant role in reducing the emissions. This, however, depends on how efficiently current and future heat demands are used as a heat sink. This paper presents the results of a model study of a district heating system (DHS). As a case study, a local DHS in a town in Sweden has been modelled using a linear programming method. The electricity generation system in northern Europe is also modelled in simplified way to serve as an input. The purpose of this study and modelling in this way is to answer the questions concerning the choice of technology solutions and fuels from an economic and an environmental point of view where the focus is on the local DHS. The main objective is to study the impact of different levels of biomass prices and emission allowances on the choice of fuels and production technologies (no other taxes, fees or any kind of subsidy are considered). The results show that low biomass prices along with high emission costs promote investment in biomass-based cogeneration. However, this would mean that the market price of existing renewable incentives and CO2 cost must be higher than the current level. Furthermore, biomass as it is used now in traditional CHP system is not system optimal. In an integrated system, plants with high electrical efficiency provide better economy and lower emissions of global CO2 than solutions based on traditional biomass CHP. The need for a system solution where the heat demand is used efficiently is seen in facilities with high electrical efficiency. [Copyright &y& Elsevier]

Abstract: This paper gives a review of small hydropower technology. A Small hydropower (SHP) plant uses impulse or reaction turbines and is mainly ‘run-off-river'. SHP technologies currently used in generating electricity for rural electrification in both developed and underdeveloped countries are helping to slow down climatic change, creating employment opportunities, and are having low maintenance costs (but high capital costs). [Copyright &y& Elsevier]

Abstract: This paper studies pumped storage plants (PSPs) operating all over the EU, in which the key statistical indicators can be found in the European Hydropower database (HYDI), administered and managed by the European Small Hydropower Association (ESHA). The main emphasis is on mixed-type PSPs, which generate electricity from natural inflow; however, pure PSP plants are included in this study. Different analysed, independent PSP data sources (e.g., Eurostat, Eurelectric) show a great variation in the main statistical values (installed capacity and power generation) of the EU pumped storage plant fleet. Presented and analysed PSP layouts and a clear methodology for determining renewable electricity generation from mixed pumped storage plants will avoid ambiguities that actually pertain to power databases to clearly separate renewable and non-renewable electricity generation. Most of the National Renewable Energy Action Plans (NREAP) submitted to the European Commission do not correctly account for renewable electricity generation due to natural inflow into upper basins of PSPs. Moreover, renewable and non-renewable electricity generation types are mixed up. The operating mixed PSP installed capacity and electricity generation were determined in the EU countries, which is a type of renewable source, and their projected estimates in 2020 are provided. [Copyright &y& Elsevier]

Abstract: This paper presents a review of the energy status, conventional and renewable, in Lebanon and illustrates their problems with the suggested recommendations. In addition, a detailed review of the principal directorates of the electricity of Lebanon Company (EDL) is also presented all along with the existing problems and recommended solutions. An economic, environmental optimization of different power sources is studied, where three scenarios are introduced based on the fuel source of different CCGT power plants. The results emphasized on the maximum possible use of wind energy and natural gas in electricity generation. Based on the optimization study, a five-year master plan for electricity generation is modeled. The suggested plan has an investment capital cost of 5553 M$ with the savings and additional incomes being 5900 M$ compared to EDL financial status in the adopted base year, 2009. In addition, this plan exceeds the trend to introduce a 12% share of renewable energy in the power sector by 2020, where the share is supposed to be about 15% out of the total installed capacity before this date. The concluding remarks highlight the role of politics in the development of the energy sector. [Copyright &y& Elsevier]

Abstract: The capacity expansion planning problem of the renewable energy industry involves decisions regarding the optimal mix of different plant types, locations where each plant should be built, and capacity expansion decisions over the planning horizon for each plant. The aim of this paper is to develop a goal programming model, based on a multi-source multi-sink network, in order to locate five renewable energy plants for electric generation in five places located in the autonomous region of Cantabria, in the north of Spain. As different types of plants can be placed in each location, the goal is to locate one plant in each place, maximizing the number of plants that are matched with comparable locations, in a way that the total deviations from goals are minimized. [Copyright &y& Elsevier]

Abstract: This paper presents the current state of geothermal energy production in Poland and its future development prospects. At present, there are four geothermal heating plants in Poland. In addition, warm water is used in seven spa towns in balneology as well as in seven thermal swimming pools for recreational purposes. There has recently been an increase in the number of installed heat pumps in Poland – reaching 10,000 in 2010. In the near future the development of geothermics in Poland is forecast to continue. The first power and heat geothermal plant is being built in Uniejów whilst in more than ten other towns special swimming pool complexes using geothermal warm water are being built or designed. In the coming years heat pumps will be installed in living and office buildings as well as in public use buildings (mostly in newly built ones). Moreover, in Poland it is planned to use heat pumps in order to recover waste heat from factories and power plants. [Copyright &y& Elsevier]

Abstract: There is a great resurgence of interest all over the world in the development of ‘small’ hydropower systems (SHS). The surge is essentially propelled by the belief that SHS, which include mini, micro, and picahydel systems, are a source of clean energy with little or no adverse impacts on the environment. This paper presents an overview of SHS and then examines in detail whether the prevalent belief in the great environment-friendliness of SHS is really justified. It is brought out that widespread use of SHS is likely to cause, per kilowatt of power generated, no less significantly adverse environmental impacts than large hydropower systems and some other conventional sources of energy. While supporting the ongoing global efforts to maximize the use of SHS, the authors advocate much greater circumspection than is being exercised at present vis-a-vis SHS. The authors believe that if the likely pitfalls are foreseen before SHS are put to widespread use, and remedial measures taken accordingly, it may save the world from considerable disillusionment and environmental damage. [Copyright &y& Elsevier]

Abstract: This paper evaluates small hydropower (SHP) development and examines the current situation in Nigeria with respect to the established policies and Energy Power Sector Reform (EPSR) Act 2005. Hydropower sector witnessed about 360% growth between 1971 and 2005 and yet only about 5% of the vast small hydropower (SHP) potential is tapped by the few plants built between 1923 and 1964. Operating and maintenance costs are in favor of SHP development in the country, being the lowest when compared with the situation in European countries. The Nigerian Government has taken steps to diversify energy sources in order to promote renewable energy development by encouraging private investments in the energy sector through reforms, but this may not be adequate as there remain barriers against SHP development in the country. It is concluded that government must incorporate subsidies, feed-in-tariffs, and framework for Price Purchase Agreements (PPA) into the policies in order to further promote renewable energy and attract both indigenous and foreign investments for quick adoption and rapid expansion of SHP technologies. [Copyright &y& Elsevier]

Abstract: Electricity consumption has grown eleven-times within the last 30 years in Iran, which has resulted in about 118Mtons in CO2 emission in 2009. Economic growth in Iran depends on electricity; therefore, the trend of electricity generation should keep going in the future to guarantee this growth. In view of this need, the country has to build many new power plants. If most of them are thermal types, the CO2 and other air pollutant emissions will increase and cause harmful environmental effects. In this paper, Iranian future power plant composition is investigated to predict the fuel consumption and emissions until 2025, which is the end of the country''s 20-year vision plan (2006–2025). Government is planning to change the structure of power industries to a more variety and fewer shares of fossil fuel bases. The results showed that in this new composition, consumption of natural gas will increase by 47% and diesel by 50% by 2025. Coal consumption in power plants will reach to 10,826ktons in the same time span. Whereas if the old composition continues in the future, fuel consumption will increase by 130%, 106% and 69% for natural gas, diesel and fuel oil respectively. It is also found that by 2025, CO2 emission will increase another 2.1 times for the old and 1.6 times for the new power plant composition which government is planning to do. [Copyright &y& Elsevier]

Abstract: In this paper, a new approach has been proposed that allows a robust optimization of sustainable energy planning over a period of years. It is based on the modified energy flow optimization model (EFOM) and minimizes total costs in planning capacities of power plants and CCS to be added, stripped or retrofitted. In the process, it reduces risks due to a high volatility in fuel prices; it also provides robustness against infeasibility with respect to meeting the required emission level by adopting a penalty constant that corresponds to the price level of emission allowances. In this manner, the proposed methodology enables decision makers to determine the optimal capacities of power plants and/or CCS, as well as volumes of emissions trading in the future that will meet the required emission level and satisfy energy demand from various user-sections with minimum costs and maximum robustness. They can also gain valuable insights on the effects that the price of emission allowances has on the competitiveness of RES and CCS technologies; it may be used in, for example, setting appropriate subsidies and tax policies for promoting greater use of these technologies. The proposed methodology is applied to a case based on directions and volumes of energy flows in South Korea during the year 2008. [Copyright &y& Elsevier]

Abstract: As a country lacking energy reserves, Taiwan imports 99.2% of its energy, with only a small portion of indigenous energy, such as hydro, wind, and solar. In 2008, each Taiwanese spent 85,000NTD dollars (1USD∼32NTD) to purchase oil, coal, gas, and nuclear fuel from foreign countries, accounting for a total payment of 1.8trillionNTD, more than the annual budget of the Taiwan government of 1.7trillionNTD. In the same year, Taiwan emitted about 1% of the world''s greenhouse gas (GHG), or 12tons per person-year, ranking 18th globally. These situations in terms of energy security and carbon emission are very severe. To resolve these severe situations, harnessing the power of the Kuroshio in eastern Taiwan offers a great opportunity. The Kuroshio is a branch of the North Pacific Ocean current. Due to the westward-enhanced effect, this ocean current is strong and stable as it passes through eastern Taiwan. The flow rate is about 30sverdrup (Sv) or 1000 times that of the Yangtze River, the average speed is 1m/s, the flow direction is fixed to the north, and the flow path is close to the east coast of Taiwan. By precisely locating high-quality sites and implementing sequential works with careful planning, one can possibly generate exploitable power more than 30GW. With 30GW of clean energy, Taiwan could effectively enhance energy security, reduce GHG emission, and lower energy-purchasing cost. This paper proposes a feasibility study to explore the power of the Kuroshio. The content consists of four parts: (1) assessment of Kuroshio power reserves, (2) development of turbine generators, (3) development of turbine-anchor system, and (4) deep-sea marine engineering of turbine clusters. By integrating these technologies above, we propose a project to construct a 30MW pilot plant. In this project, we also discuss the financial analysis and propose new regulations, environmental impact analysis, risk assessment, and other relevant issues. [Copyright &y& Elsevier]

Abstract: Energy plants play an important role in the development of bioenergy. In the world, there are many kinds of energy plants, but they are not utilized sufficiently. In the current paper, we discussed the situation of the research and development of traditional energy plants and some new energy plants in the world. At the same time, we focused on the distribution of some special energy plants and discussed their advantages in China. At last, we provided some suggestions for developing global energy plant field. [Copyright &y& Elsevier]

Abstract: The recent development of efficient thermal prime movers for distributed generation is changing the focus of the production of electricity from large centralized power plants to local generation units scattered over the territory. The scientific community is addressing the analysis and planning of distributed energy resources with widespread approaches, taking into account technical, environmental, economic and social issues. The coupling of cogeneration systems to absorption/electric chillers or heat pumps, as well as the interactions with renewable sources, allow for setting up multi-generation systems for combined local production of different energy vectors such as electricity, heat (at different enthalpy levels), cooling power, hydrogen, various chemical substances, and so forth. Adoption of composite multi-generation systems may lead to significant benefits in terms of higher energy efficiency, reduced CO2 emissions, and enhanced economy. In this light, a key direction for improving the characteristics of the local energy production concerns the integration of the concepts of distributed energy resources and combined production of different energy vectors into a comprehensive distributed multi-generation (DMG) framework that entails various approaches to energy planning currently available in the literature. This paper outlines the main aspects of the DMG framework, illustrating its characteristics and summarizing the relevant DMG structures. The presentation is backed by an extended review of the most recent journal publications and reports. [Copyright &y& Elsevier]

Abstract: The global market for wind power is expanding faster than any other source of renewable energy. From just 4,800 MW in 1995 raise to fifteen-fold to reach 73,904 MW at the end of 2006. Top five wind electric power generating countries at the end of 2006 were Germany, Spain, United States of America (USA), India and Denmark. Since 1980s, when the first commercial wind turbine was deployed, their capacity, efficiency and visual design have all improved a lot. A modern wind turbine annually produces 180 times more electricity at less than half the cost per unit (kWh) than its equivalent twenty years ago. The largest turbines being manufactured now are of rated power of 5 MW capacity and a rotor diameter of 126m. Modern turbines are modular and quick to install, whilst wind farms vary in size from a few MW to several hundred MW. Keeping these factors in view, an attempt has been made in this paper to present current advances in wind turbine generator technology. Wind energy scenario in the world in general and in India in particular have been presented. Further the cost components of wind turbine electric generation system have been included. [Copyright &y& Elsevier]

Hybrid polygeneration systems offer a great opportunity to meet growing energy demands with cost efficiency and environmental benefits. The identification of the optimal solution (configuration and operational strategy) is strongly affected by the relationship between the system and its surroundings. Previous studies have analyzed the influence of boundary conditions on the synthesis of polygeneration systems for buildings. However, local regulations are often disregarded or oversimplified in those studies. Therefore, this paper aims to evaluate the influence of legal conditions on the integration of renewable energy technologies in polygeneration systems for buildings. A comprehensive synthesis model is developed, including different types of legal conditions, such as power exchange modalities, subsidies/surcharges on energy prices and investment costs, and total ban on fossil fuels. Then, the model is applied to the case study of a Brazilian hospital. The current Brazilian net metering scheme is implemented. Results show that natural gas cogeneration is an attractive solution to cover the hospital's energy demands with or without the possibility of selling/exporting electricity. Also, the Brazilian net metering scheme, by itself, is not enough to ensure renewable energy deployment. An in-depth discussion about the conditions that would promote renewable energy integration is reported and recommendations are made on how current policies can be improved, including the need to explicitly address renewable technologies, the application of minimum renewable fractions, and the role of renewable heat/cooling. While the case study considers the specific circumstances in Brazil, it provides insights that can be extended to other countries or applications. • Synthesis model of hybrid renewable polygeneration systems for buildings. • Influence of legal constraints on the integration of renewable energy technologies. • Power exchange modalities, subsidies/surcharges, and fossil fuel ban are considered. • Technical, economic, and environmental analysis of a Brazilian hospital case study. • The Brazilian net metering scheme did not promote renewable energy technologies. [ABSTRACT FROM AUTHOR]

Abstract: Wind power is not widely used in Lithuania yet. Currently only few small-scale wind turbines with total capacity of 0.995MW are operating. However, Lithuania is planning to install wind power plants with total capacity of 200MW by the year 2010. In this paper, wind energy resource assessment experience as well as current situation and future prospective of wind energy usage in Lithuania are reviewed. Main features of Lithuanian electrical system are presented and issues related to wind energy integration in electrical networks are discussed. The aim of this work is to point up the importance of wind power prediction in Lithuania. Thus a short review of wind power prediction methods is presented which has shown that selection of most suitable prediction models for Lithuanian conditions requires detailed research. [Copyright &y& Elsevier]

Abstract: The increase in the use of natural gas in Brazil has stimulated public and private sectors to analyse the possibility of using combined cycle systems for generation of electrical energy. Gas turbine combined cycle power plants are becoming increasingly common due to their high efficiency, short lead times, and ability to meet environmental standards. Power is produced in a generator linked directly to the gas turbine. The gas turbine exhaust gases are sent to a heat recovery steam generator to produce superheated steam that can be used in a steam turbine to produce additional power. In this paper a comparative study between a 1000 MW combined cycle power plant and 1000kW diesel power plant is presented. In first step, the energetic situation in Brazil, the needs of the electric sector modification and the needs of demand management and integrated means planning are clarified. In another step the characteristics of large and small thermoelectric power plants that use natural gas and diesel fuel, respectively, are presented. The ecological efficiency levels of each type of power plant is considered in the discussion, presenting the emissions of particulate material, sulphur dioxide (SO2), carbon dioxide (CO2) and nitrogen oxides (NO x ). [Copyright &y& Elsevier]

This paper describes the material flows and emissions in all the life stages of CdTe PV modules, from extracting refining and purifying raw materials through the production, use, and disposal or recycling of the modules. The prime focus is on cadmium flows and cadmium emissions into the environment. This assessment also compares the cadmium environmental inventories in CdTe PV modules with those of Ni–Cd batteries and of coal fuel in power plants. Previous studies are reviewed and their findings assessed in light of new data. [Copyright &y& Elsevier]

The unit commitment problem is one of the most significant and basic issues in the monitor, control, and operation of modern power systems, which has always been a subject of great concern to researchers and operators as the most extensive human-made system. Before restructuring, one of the main objectives of unit commitment problem was the minimization of the total operation cost of power plants subject to various constraints, including unit and network ones. As the privatization and restructuring process became more serious, the primary purpose of the unit commitment problem has been changed to maximizing the total profit, which led to the emergence of a new concept known as profit-based unit commitment problem. Accordingly, the maximization of the profit for generation companies, all over the studied period, is a top-priority direction. This paper presents a comprehensive overview of the profit-based unit commitment problem in restructured power systems by investigating the most important studies on this topic and providing a complete classification. It also outlines the challenges facing researchers in this field, offers new insights, and suggests future directions. • Describing a comprehensive formulation for profit-based unit commitment problem. • Presenting a complete and comprehensive overview of profit-based unit commitment problem. • Reporting the used case study systems, simulation tools, hardware, and run-time. • Briefly reviewing the fitness functions, parameter setting, convergence criterion, and the obtained profit values. • Addressing the main challenging issues regarding the mentioned problem. [ABSTRACT FROM AUTHOR]

Increasingly tight integration of renewable power sources with thermal power sources leads to frequent operation at off-design modes of thermal power plants. It brings challenges including reduced efficiency, increased costs and safety issues in power plants. At a component level, load changes of thermal power plants are mainly carried out through actions of control stage systems of steam turbines. Accurate performance monitoring of control stage systems is key to enable faster and more flexible operation of thermal power plants thus provides opportunities to accommodate more renewable power with limited penalty to efficiency and safety. In this paper, a hybrid modelling method based on operation data and first-principle mechanism is proposed for performance monitoring of control stage systems. The hybrid modelling method features a) flow rate calculation of high-pressure control valves with limited measurement data, and b) flow and efficiency characteristics calculation over full working ranges of control stages. The proposed hybrid modelling method is validated via two case studies of a 330 MW subcritical steam turbine and a 1000 MW ultra-supercritical steam turbine, where digital twins of control stages are developed. Results show that average relative errors between simulated and measured values of exit pressure and exit temperature of control stages are within a range of one percent, providing great potential for plant-wide digital twin development and online performance monitoring. • The hybrid method combines physical mechanism and operation data. • Actual characteristics of control stages are obtained using operation data. • High-precision monitoring of control stages is realized over full working ranges. • The model framework can be applied to subcritical and ultra-supercritical units. [ABSTRACT FROM AUTHOR]

The basic trend of low-carbon power sector transition is the expansion of non-fossil power, especially the power generation from renewable energy sources. With the higher penetration of renewable energy into the power system, the flexibility requirements and integration costs are important issues. The flexible generation of thermal power plants could serve as an effective solution to accommodating high share of variable renewable energy electricity. However, it brings about additional integration costs, which should be quantitatively assessed. In this paper, a long-term power generation expansion planning model incorporating integration costs for renewable energy penetration is proposed. This model is used to obtain the most cost-effective low carbon transition pathway of power sector with high penetration of renewable energy and analyze the impact of incorporating short-term integration costs on the long-term power generation planning. China is selected for a case study as it has the largest scale of thermal power plants in the world and urgent need for low carbon transition. The results indicate that thermal power plants gradually change from baseload providers to flexibility providers in the power system for higher penetration of renewable energy. The variable fuel consumption rate of thermal power plants should be taken into account otherwise the total carbon emissions and emission reduction cost would be underestimated. • High penetration of renewable energy raises the requirements for system flexibility. • Thermal power plants are potential providers of effective flexibility solutions. • A power generation expansion planning model incorporating renewable integration costs is proposed. • Thermal power plants gradually turn from base load to balancing load for renewable energy integration. • Ignoring the flexible operation characteristics would underestimate total emission reduction cost. [ABSTRACT FROM AUTHOR]

The objective of this paper is to evaluate appropriate sites for Small Power Producers (SPP) hybrid, firm renewable energy-based power plants and their scenario suitability, focusing in the southernmost provinces of Thailand. The siting suitability of renewable SPP hybrid, firm power plants was assessed by employing the Analytical Hierarchy Process (AHP) in a Geographic Information System (GIS) environment. Para rubberwood distribution map, 1-km resolution Global Horizontal Irradiance (GHI) map, and high resolution (50 m) wind potential map are overlaid in possible regions for site selection. The inclusion of energy storage is also assessed in order to achieve the firm output of the optimized power plant, as per the requirement of the SPP policy. In total, 14 possible combinations of renewable SPP scenarios, ranging from 10 to 50 MW, were analyzed in order to identify an optimum scenario in terms of technical power potential, environmental suitability and socio-economic viability. The cost of each renewable SPP hybrid scenario was analyzed, as well as the annual energy production (AEP) for each scenario. The cost-benefit and the levelized cost of energy (LCOE) were analyzed using the Response Surface Methodology (RSM) in the ranking of all scenarios. Results show that the optimum scenario is a 40 MW solar PV power plant, complemented with a 10 MW biomass power plant and with a substantial energy storage system (ESS). This configuration has the highest generation capacity, at over 1,200 PWh/yr, the lowest LCOE, at 11.2 US cents/kWh, and avoiding CO 2eq emissions of nearly 38 ktonnes per year. The methodology developed, based on a cost-benefit analysis, levelized cost of energy and greenhouse gas emission reductions, can also be applied in other jurisdictions characterized by the availability of biomass, solar and wind resources for electricity generation. • Sites for Small Power Producers hybrid, firm power plants are assessed. • The power plants are based on renewable energy resources, in southern Thailand. • Wind, solar and biomass resources, including energy storage systems, are assessed. • The levelized cost of energy is analyzed in the ranking of 14 power plant scenarios. • The optimum scenario is a hybrid 40 MW solar PV and 10 MW biomass power plant. [ABSTRACT FROM AUTHOR]

Current power networks and consumers are undergoing a fundamental shift in the way traditional energy systems were designed and managed. The bidirectional peer-to-peer (P–P) energy transactions pushed passive consumers to be prosumers. The future smart grid or the internet of energy (IoE) will facilitate the coordination of all types of prosumers to form virtual power plants (VPP). The paper aims to contribute to this growing area of research by accumulating and summarizing the significant ideas of the integration of distributed prosumers and small-scale VPP to the internet of energy (IoE). The study also reports the characteristics of IoE in comparison to the traditional grid and offers some valuable insights into the control, management and optimization strategies of prosumers, distributed energy resources (DERs) and VPP. As bidirectional P–P energy transaction by the prosumers is a crucial element of IoE, their management strategies including various demand-response approach at the customers'-levels are systematically summarized. The integration of DERs and prosumers to the VPP considering their functions, infrastructure, type, control objectives are also reviewed and summarized. Various optimization techniques and algorithm, and their objectives functions and the types of mathematical formulation that are used to manage the DERs and VPP are discussed and categorized systematically. Finally, the factors which affect the integration of DERs and prosumers to the VPP are identified. • It provides insights into the control, management and optimization strategies of prosumers, DER and VPP. • The integration of DER and prosumers to the VPP considering their functions, type and control objectives are summarized. • Various optimization techniques and algorithm, and their objectives functions to manage the DER and VPP are reported. [ABSTRACT FROM AUTHOR]

Concentrating Solar Power (CSP) plants can make a significant contribution to renewable energy supply in many regions of the world. Several bottom-up engineering performance models for CSP plants have been developed. However, they require the capacity of the plant to be known. In whole-of-grid optimization models, the capacity of the plants is an optimization variable and therefore not known in advance. In this case, researchers have taken a simplified modelling approach that overestimated CSP performance, especially for low-DNI conditions. In this paper, we offer a novel density-based engineering modelling approach in which CSP performance is determined independently of the capacity of the power plant, and which can be used in whole-of-grid optimization models. We investigate a case study of the site of the new Aurora CSP project in Port Augusta, South Australia, to be one of the world's largest solar thermal power plants by 2020. Using a Geographical Information System (GIS)-grid representation of Australia, we compare CSP performance resulting from a simplified model with our new approach. • A novel density-based engineering modelling approach for Concentrating Solar Power (CSP) plants. • CSP performance is determined independently of the capacity of the power plant. • The approach can be used in whole-of-grid optimisation models. • We investigate the site of the new Aurora CSP project in Port Augusta, South Australia to be constructed by 2020. • The new approach is compared to the simplified description of CSP performance, using a GIS-grid representation of Australia. [ABSTRACT FROM AUTHOR]