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Solar pond undoubtedly has been a reliable source of low grade heat supply by acting as both collector and storage for the incoming solar radiation. The thermal efficiency of the solar ponds is between 15 and 25% of the incoming horizontal solar radiation. Meanwhile, the thermoelectric technology enables the conversion of heat into electricity using thermoelectric modules. In this paper, the feasibility of the system by combining solar pond and thermoelectric modules is presented. This system can be achieved by using a thermoelectric modules-embedded heat exchanger module that will able to extract the heat available from the lower convective zone of the solar pond. The analysis in this paper was conducted by investigating the solar ponds operating in different climate conditions, which are Group A (Kuala Lumpur), Group B (Riyadh) and Group C (Melbourne and Granada) base on Köppen climate classification. The theoretical feasibility draws the limit on the performance and cost of the solar pond-thermoelectric system under commercially available thermoelectric technology at the present state. Later, the result was contrasted against the performance of the power generation units operate under realisable operating condition with solar pond. The result in this study revealed that, under ideal condition, the system is at least 10 times costly compared to other renewable energy sources like off-grid solar photovoltaic system with storage. Meanwhile, at its best operating climate, this system will be able to achieve annual carbon dioxide reduction of 2.38 kg/m 2 -year in a practical case. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Use of solar chimney can reduce the semi-transparent PV temperature by up to 38 °C. • Use of solar chimney results enhances the PV generated power by around 30%. • There is an optimum packing factor that maximizes the power generation. • There is an optimal chimney height at which the best cooling effect is achieved. Abstract Semi-transparent photovoltaic (STPV) system’s performance strongly depends on its surface temperature. To provide a mechanism that decrease the temperature of STPV can improve the power generation significantly. This cooling mechanism will be more interesting if it needs no additional energy. In this paper a novel solar chimney system is proposed to cool a STPV system. The STPV is employed as a roof for the solar chimney and an air flow generated by the solar chimney cools the STPV. Based on the energy balance for three main components: STPV, air and ground, a theoretical model is developed for the proposed system. Convection heat transfer coefficients are calculated precisely for the heat transfers taking place in the system and the obtained results for the solar chimney are compared with the existing experimental data in literature. Results of proposed model have a good agreement with the previous data. It’s shown that there is an optimum packing factor that maximizes the generated power for each radiation intensity. It is observed that the proposed system effectiveness depends on the radiation intensity as well as on the structural parameters. The proposed system can reduce the average temperature of the STPV up to 15 °C. It is concluded that, by cooling the STPV power plant with the solar chimney for a solar radiation of 500 W/m2, an enhancement of about 29% in power generation is gained. [ABSTRACT FROM AUTHOR]

In the present paper, a novel method is proposed to enhance the power production and resolve the inconsistent electricity generation of solar chimney power plants (SCPPs) during nighttime. For this purpose, an integrated renewable cycle is proposed by incorporating two technologies: solar chimney and waste-to-energy. The combination is performed by exploiting the warm air of the condensers outlet into the SCPP. The waste-to-energy (WTE) plant in Tehran is thermodynamically analyzed and the mass flow rate of the condensers cooling air is found. Results indicate that by decreasing the humidity of the municipal solid waste (MSW) from 40% to 30% or by increasing MSW feeding rate (0.934–1.146 kg/s), the mass flow rate of the condenser cooling air increases from 190.3 kg/s to 233.7 kg/s. In addition, by increasing the feeding rate or by decreasing the humidity of MSW in the mentioned range, net power output of the WTE plant increases from 1350 kW to 1650 kW. The best injection method is proposed for the warm air of the condensers outlet into the SCPP. Subsequently, the average power increase is examined in different months and parametric study is performed to assess the influence of the effective WTE parameters and meteorological variables on the power output of the SCPP. The final power of the SCPP reaches 20–70 kW (even at the hottest night of the year with 5% relative humidity) and increases 20–1200% and 65–94% (monthly average) compared to the case of without injection. Results demonstrate that in the integrated system, by a 22% increase in the MSW feeding rate (from 0.934 kg/s to 1.146 kg/s) or by decreasing the MSW moisture content (from 40% to 30%), power output of the WTE plant and SCPP increases by 22% and 7%, respectively. Additionally, relative humidity of the surrounding air can increase the SCPP power production by 25%. In addition, the results indicate that wind speeds higher than 12.5 m/s will not affect power production of the SCPP, while relative humidity of the surrounding air, ambient temperature, the MSW feeding rate, and humidity of the MSW have considerable effects on the SCPP power production. In average, total energy and useful exergy efficiency of the proposed system is increased by 0.15% and 0.12% compared to the standalone WTE plant during nighttime. The integration of SCPP with the WTE plant is an applicable method to enhance the power generation and overcome the inconsistent power production of SCPP during nighttime. [ABSTRACT FROM AUTHOR]

A significant amount of global electric power generation is produced from the combustion of fossil fuels. Steam boilers are one of the most important components for steam and electricity production. The objective of this paper is to establish a theoretical framework for the sustainability analysis of a utility boiler. These analyses can be used by decision-makers to diagnose and optimize the sustainability of a utility boiler. Seven utility boiler systems are analyzed using energy and embodied solar energy (emergy) principles in order to evaluate their environmental efficiencies. They include a subcritical coal fired boiler, a supercritical coal fired boiler, an oil fired boiler, a natural gas fired boiler, a concentrating solar power boiler utilizing a tower configuration, a biomass boiler, and a refuse derived fuel boiler. Their relative environmental impacts were compared. The results show that the natural gas boiler has significantly lower CO 2 emission than an equivalent coal or oil fired boiler. The refuse derived fuel boiler has about the same CO 2 emissions as the natural gas boiler. The emergy sustainability index of a utility boiler system is determined as the measure of its sustainability from an environmental perspective. Our analyses results indicate that the natural gas boiler has a relatively high emergy sustainability index compared to other fossil fuel boilers. Converting existing coal boilers to natural gas boilers is a feasible option to achieve better sustainability. The results also show that the biomass boiler has the best emergy sustainability index and it will remain a means to utilize the renewable energy within the Rankine steam cycle. Before solar boiler technology can be widely used in the United States’ utility power industry, its capital cost and the O&M cost should be reduced. Using the results of this research, decision-makers can make better-informed, environmentally-efficient selections of future utility scale boilers. [ABSTRACT FROM AUTHOR]

This paper proposes an adaptive control algorithm for grid-interfacing inverters in renewable energy-based distributed generation systems. The proposed control algorithm functions in two different modes: basic power generation mode, harmonics compensation mode. In basic power generation mode, the inverter pumps desired amounts of active and reactive powers into the grid at the point of common coupling. In harmonics compensation mode, the control algorithm ensures sinusoidal grid current through load current harmonics mitigation in addition to desired power generation. Moreover, the proposed control algorithm does not use any detection methods for compensation of harmonic currents. Hence, it results in low computational burden. Based on the requirements, the proposed control algorithm can be operated in either of the modes. A proportional–integral controller-based closed loop control is employed for accurate control of the power injected into the grid. A frequency adaptive notch filter is used to synchronize the grid-interfacing inverter with the fundamental component of grid voltage without using any phase locked loop. The effectiveness of the proposed control algorithm in reference active and reactive powers generation, current harmonics compensation is demonstrated successfully by simulation and experimental results. [ABSTRACT FROM AUTHOR]

The key objective of this paper is to analyze the techno-economic feasibility of this alternative for the Brazilian municipalities, classified according to population subgroups, using this parameter as a basis for the calculation of the municipal solid waste generated, the project costs and revenues. Different expenses were taken into consideration, like equipments and installation costs, operation and maintenance costs and the interest rate of the investment. In relation to revenues, they come from of the sale of electricity, the incomes of the recyclable materials, the fees paid by the Brazilian municipalities for the disposal of municipal solid waste in sanitary landfills and incomes by the carbon credits. An analysis of each population subgroup, combining three different economical scenarios was done, with an annual rate of interests of 10.58% for Scenario 1, 7.5% for Scenario 2 and 15% for Scenario 3. The economic feasibility was evaluated using as economic indicators the net present value and the internal rate of return. The net present value was positive for the municipalities with more than 60,714 inhabitants for the Scenario 1, 34,203 for Scenario 2 and 259,845 for Scenario 3. A hypothetic gasification plant is capable to generate 905 kW/ton municipal solid waste for a population of 60,714 inhabitants (Scenario 1), 794 kW/ton municipal solid waste for a population of 34,203 inhabitants (Scenario 2) and 1065 kW/ton municipal solid waste for a population of 259,845 inhabitants (Scenario 3). It is concluded that the economic feasibility increases with the installation of bigger units, showing a positive scale up gains, therefore as higher the capacity of the installation lower the specific costs and higher are the benefits. [ABSTRACT FROM AUTHOR]

Reliable and inexpensive electricity provision is one of the significant research objectives since decades. Various Economic Dispatch (ED) methods have been developed in order to address the challenge of continuous and sustainable electricity provision at optimized cost. Rapid escalation of fuel prices, depletion of fossil fuel reserves and environmental concerns have compelled us to incorporate the Renewable Energy (RE) resources in the energy mix. This paper presents Combined Emission Economic Dispatch (CEED) models developed for a system consisting of multiple Photo Voltaic (PV) plants and thermal units. Based on the nature of decision variables, our proposed model is essentially a Mixed Integer Optimization Problem (MIOP). Particle Swarm Optimization (PSO) is used to solve the optimization problem for a scenario involving six conventional and thirteen PV plants. Two test cases, Combined Static Emission Economic Dispatch (SCEED) and Combined Dynamic Emission Economic Dispatch (DCEED), have been considered. SCEED is performed for full solar radiation level as well as for reduced radiation level due to clouds effect. Simulation results have proved the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

• Comprehensive thermo-economic assessments of small-scale solar ORC systems are presented. • Various solar collectors, ORC configurations, expanders and fluids are considered. • Evacuated collectors, subcritical recuperated cycle, piston expander, isobutane are preferred. • Highest electricity generation and thermal efficiency are 73 kWh/year/m2 and 5.5%. • Levelised cost and payback as low as 0.35 $/kWh and 16 years in high solar-resource areas. In this paper, results from comprehensive thermoeconomic assessments of small-scale solar organic Rankine cycle (ORC) systems are presented based on weather data in London, UK, which is taken as representative of a temperate climate with modest temperature changes, mild winters and moderate summers. The assessments consider a range of: (i) solar collector types (flat-plate, evacuated-tube, and evacuated flat-plate collectors); (ii) power cycle configurations (basic/recuperative, partial/full evaporating, and subcritical/transcritical cycles); (iii) expander types (scroll, screw, and piston) and designs; and (iv) a set of suitable working fluids. All possible solar-ORC system designs are optimised by considering simultaneously key parameters in the solar field and in the power cycle in order to obtain the highest electricity generation, from which the best-performing systems are identified. Selected designs are then subjected to detailed, annual simulations considering the systems' operation, explicitly considering off-design performance under actual varying weather conditions. The results indicate that, among all investigated designs, solar-ORC systems based on the subcritical recuperative ORC (SRORC), evacuated flat-plate collectors (EFPCs), a piston expander, and isobutane as the working fluid outperforms all the other system designs on thermodynamic performance, whilst having the highest annual electricity generation of 1,100 kW·h/year (73 kW·h/year/m2) and an overall thermal efficiency of 5.5%. This system also leads to the best economic performance with a levelised cost of energy (LCOE) of ~1 $/kW·h. Apart from the specific weather data used for these detailed system simulations, this study also proceeds to consider a wider range of climates associated with other global regions by varying the solar resource available to the system. Interestingly, it is found that the optimal solar-ORC system design remains unchanged for different conditions, however, the LCOE can drop below 0.35 $/kW·h and payback times can be shorter than 16 years in high solar-resource regions, even in the absence of incentives that would otherwise lead to even better economic performance. This work complements previous efforts in the literature by considering the full design and operational features of solar-ORC systems, thereby providing valuable guidance for selecting appropriate cycle configurations, components, working fluids and other characteristics and, for the first time, presents a comprehensive comparison of such systems in small-scale applications. [ABSTRACT FROM AUTHOR]

Abstract: The electricity production sector has currently and for the past years been dominated by fossil fuel technologies, mostly coal, oil and natural gas. This has had various environmental consequences, such as increased gaseous emissions, soil and water pollution, global warming, as well as fossil resource depletion. As a result, the need to pursue Sustainable Development (SD), in order to reduce dependency on fossil fuel, to achieve Greenhouse Gas (GHG) mitigation and to reverse the effects of climate change has currently become imperative. SD is considered to be one of the most important factors for countries’ energy policy today and efforts, such as the ones materialized through the Kyoto Protocol mechanisms, are being made to promote sustainable electricity production technologies globally. Nuclear and renewable energy technologies both have the potential of contributing to the increasing global energy demands, while simultaneously lowering GHG emissions and also having a positive economic and social impact. In view of their differences and the ongoing nuclear debate, this paper aims to compare specific promising and emerging nuclear and renewable energy technologies in terms of their contribution to SD and prospects for deployment. The comparison showed that each technology contributes in its own way to SD and that political decisions, individual country energy policies and public opinion will probably determine the future deployment of each energy technology. [Copyright &y& Elsevier]

• The European Union trends create an opportunity for geothermal power plants. • The combine analysis of heat source, Organic Rankine Cycle and turbine were done. • The binary geothermal power plant can obtain approximately 2 MW of power output. • The parameters of a low-temperature heat source for Polish conditions are determined. • Designed the two-stage axial turbine reached the internal efficiency of 79%. In recent years, pressure has been growing to increase the share of renewable energy sources in electricity generation, which may offer opportunities for the development of geothermal energy in regions that have been so far considered unprofitable in this respect. One such country currently undergoing an energy transition is Poland in which low-temperature geothermal resources are currently used for district heating and recreation purposes. Nevertheless, research on the possibilities of using geothermal energy for electricity production is ongoing. The objective of this paper was to perform a comprehensive analysis of a binary power plant construction in relation to low-temperature petro-geothermal resources. The potential binary power plant is located in the area characterized by temperature of 120 °C at depths of 5000 m. About half of Poland's area, especially the regions of western and central Poland, has these characteristics. It was assumed that brine at volume flow rate of 400 m3/h is a heat source for the Organic Rankine Cycle with isobutane as a working medium. The thermal efficiency based on the First Law of Thermodynamics and the power output were estimated at 10.5% and 1.79 MW e , respectively. In addition, the thermal efficiency based on the Second Law of Thermodynamics was calculated at 29.0%. For the calculated cycle parameters, a preliminary design of a two-stage axial turbine was constructed. All results were compared to the other binary power plants and they confirm that establishing the binary power plant in Poland would be thermodynamically justified. The main novelty of the present work is the combination of three issues, namely the selection of the low- temperature heat source, the design and analysis of the cycle together with a turbine adapted to these conditions. [ABSTRACT FROM AUTHOR]