Search Results (71)

Solar energy and biomass offer sustainable alternatives to meet the energy demand and reduce the environmental impact of fossil fuels. In this study, through mass and energy balances, a comparative analysis of energy, exergy, and environmental impact (LCA) was conducted on two renewable thermal sources: solar energy and coconut shell biomass, both coupled to a supercritical CO₂ Brayton cycle (sCO₂) with an organic Rankine cycle (ORC) for waste heat recovery. The sCO₂–ORC–biomass configuration showed higher exergy efficiency (41.1%) and lower exergy destruction (188.88 kW) compared to the sCO₂–ORC–solar system (23.76% and 422.63 kW). Thermal efficiency (50.6%) and net power output (131.73 kW) were similar for both sources. However, the solar system (204,055.57 kg CO₂-equi) had an 85.6% higher environmental impact than the biomass system (109,933.63 kg CO₂-equi). Additionally, the construction phase contributed ~95% of emissions in both systems, followed by decommissioning (~4.5%) and operation (~0.1%). Finally, systems built with aluminum generate a higher carbon footprint than those with copper, with differences of 2% and 3.2% in sCO₂–ORC–solar and sCO₂–ORC–biomass, respectively. This study and an economic analysis make these systems viable thermo-sustainable options for clean energy generation. Full article

The increasing environmental challenges posed by the widespread use of fossil fuels and the fluctuating nature of renewable energy have driven the need for more efficient and sustainable energy solutions. Current research is actively exploring hybrid energy systems as a means to address these issues. One such area of focus is the integration of Organic Rankine Cycles (ORCs) with gas and steam turbines, utilizing both natural gas (NG) and solar parabolic trough collectors (PTCs) as energy sources. This study examines the performance of a hybrid system implemented in Kirkuk, Iraq, a region known for its substantial solar radiation. Previous research has shown that hybrid systems can effectively enhance energy conversion efficiency and reduce environmental impacts, but there is still a need to assess the specific benefits of such systems in different geographical and operational contexts. The analysis reveals a thermal efficiency of 59.32% and an exergy efficiency of 57.28%. The exergoeconomic analysis highlights the optimal energy cost at USD 71.93/MWh when the compressor pressure ratio is set to 8 bar. The environmental assessment demonstrates a significant reduction in ${\mathrm{C}\mathrm{O}}_2$/emissions, with a carbon footprint of 316.3 kg ${\mathrm{C}\mathrm{O}}_2$/MWh at higher compressor pressure ratios. These results suggest that integrating solar energy with natural gas can substantially improve electricity generation while being both cost-effective and environmentally sustainable. Full article

Hybrid solar–biomass organic Rankine cycle (ORC) systems represent a promising avenue for sustainable energy production by combining abundant but intermittent solar energy with the reliable biomass energy. This study conducts a detailed thermodynamic and economic assessment of these hybrid systems, focusing on their potential to enhance energy efficiency and reduce greenhouse gas emissions. The study also evaluates the performance of various working fluids, identifying optimal configurations for different operating conditions. A key finding is that the hybrid system, with an optimized solar–biomass ratio, achieves up to a 21 to 31% improvement in efficiency and a 33% reduction in levelized cost of electricity (LCOE) compared to solar-only systems. Additionally, the study examines case studies of real-world applications, offering insights into the scalability and cost-effectiveness of these systems in regions with high solar irradiation and biomass availability. These results underline the need for continued technological innovation and policy support to promote widespread adoption of hybrid ORC systems, particularly in the context of global decarbonization efforts. Full article

The Organic Rankine Cycle (ORC) is a widely utilized technology for generating electricity from various sources, including geothermal energy, waste heat, biomass, and solar energy. Harnessing solar radiation to drive ORC is a promising renewable energy technology due to the high compatibility of solar collector operating temperatures with the thermal requirements of the cycle. The aim of this review article is to present and discuss the principles of solar-ORC technology and the broad range of solar-ORC systems that have been explored in the literature. Various solar energy technologies capable of powering ORC are investigated, including flat plate collectors, vacuum tube collectors, compound parabolic collectors, and parabolic trough collectors. The review places significant emphasis on the operating parameters of technology. Full article

A thermal efficiency analysis of an organic Rankine cycle (ORC) system enables its performance to be evaluated; for this purpose, critical system components, including the turbine and the boiler, must be scrutinized. ORC plants can operate under various regimes, such as simple, regeneration, and reheat work modes. Organic fluids such as R-245fa integrate low-temperature sources such as solar radiation. However, a literature review revealed limited research on the impact of a solar collection system on the overall thermal efficiency of an ORC system during the regeneration stage. In this study, we examined the thermal efficiency behavior of an ORC plant with a 1 kW generator operating in simple and regeneration modes with a solar collection stage. The results show that the thermal efficiency in simple mode was 35.27%, while in regeneration mode with solar collection it reached 51.30%. Improving the thermal efficiency of a thermodynamic cycle system can reduce CO₂ emissions. The operating temperature ranges facilitate the development of a methodology for industries to implement ORC systems in their manufacturing processes, thereby utilizing waste heat from industrial operations. Full article

Traditional working fluids used in direct vapor generation for solar organic Rankine cycle (DVG-ORC) systems have a high global warming potential (GWP), making it imperative to find environmentally friendly alternative working fluids for these systems. This paper evaluates the performance of the DVG-ORC system under different operating conditions. By comparing the results of traditional working fluids with those of low-GWP fluids, the feasibility of using low-GWP fluids as alternative working fluids is explored. Additionally, to screen the working fluids suitable for this system further, the system is optimized with net output power as the objective function. The results show that evaporation temperature has different impacts on system performance. R245ca and R1336mzz(Z) exhibit higher net output power at different evaporation temperatures, with R1336mzz(Z) only reducing it by 3.73–5.26% compared to R245ca. However, an increase in condensation temperature negatively affects system performance, leading to a decrease in net output power and various efficiencies. Net output power increases with an increase in mass flow rate, indicating that higher mass flow rates can enhance system performance. The optimization results show that the net output power of low-GWP working fluid R1336mzz(Z) decreases by only 3.44% compared to R245ca, which achieves the maximum net output power. Moreover, among low-GWP working fluids, R1336mzz(Z) demonstrates the highest ORC efficiency and system efficiency, making it the most suitable working fluid for the DVG-ORC system due to its environmental friendliness and safety. Full article

Libya is facing a serious challenge in its sustainable development because of its complete dependence on traditional fuels in meeting its growing energy demand. On the other hand, more intensive energy utilization accommodating multiple energy resources, including renewables, has gained considerable attention. This article is motivated by the obvious need for research on this topic due to the shortage of applications concerning the prospects of the hybridization of energy systems for electric power generation in Libya. The 283 MW single-cycle gas turbine operating at the Sarir power plant located in the Libyan desert is considered a case study for a proposed Integrated Solar Combined Cycle (ISCC) system. By utilizing the common infrastructure of a gas-fired power plant and concentrating solar power (CSP) technology, a triple hybrid system is modeled using the EES programming tool. The triple hybrid system consists of (i) a closed Brayton cycle (BC), (ii) a Rankine cycle (RC), which uses heat derived from a parabolic collector field in addition to the waste heat of the BC, and (iii) an organic Rankine cycle (ORC), which is involved in recovering waste heat from the RC. A thermodynamic analysis of the developed triple combined power plant shows that the global power output ranges between 416 MW (in December) and a maximum of 452.9 MW, which was obtained in July. The highest overall system efficiency of 44.3% was achieved in December at a pressure ratio of 12 and 20% of steam fraction in the RC. The monthly capital investment cost for the ISCC facility varies between 52.59 USD/MWh and 58.19 USD/MWh. From an environmental perspective, the ISCC facility can achieve a carbon footprint of up to 319 kg/MWh on a monthly basis compared to 589 kg/MWh for the base BC plant, which represents a reduction of up to 46%. This study could stimulate decision makers to adopt ISCC power plants in Libya and in other developing oil-producing countries. Full article

In pursuit of sustainable development and mitigation of the intermittency challenge associated with solar energy, this study proposes a hybrid solar system integrating waste heat incineration alongside solar power generation and distinct heat provision. Leveraging the superior energy efficiency of the organic Rankine cycle (ORC) in medium- and low-temperature scenarios, a parabolic trough collector (PTC) is selected for its cost-effectiveness and long-term operational reliability. Dowtherm A and toluene are identified as the optimal working fluids for the PTC and ORC, respectively. To optimize this complex system, a combination of artificial neural networks (ANNs) and multi-objective optimization via non-dominated sorting genetic algorithm II (NSGA-II) is employed, streamlining the optimization process. Thermal dynamic simulations are executed using Engineering Equation Solver (EES, V11) to validate the proposed system’s performance. TOPSIS is employed to identify the optimal solution from the Pareto frontier. The results indicate that the hourly cost of the system stands at USD 43.08, with an exergy efficiency of 22.98%. The economic analysis reveals that the solar collector constitutes the most significant portion of the total initial cost, representing 53.2%, followed by the turbine, thermoelectric generator (TEG), and waste heat incineration, in descending order of costliness. Full article

Humanity is facing the challenge of reducing its environmental impact. For this reason, many specialists worldwide have been studying the processes of production and efficient use of energy. In this way, developing cleaner and more efficient energy systems is fundamental for sustainable development. The present work analyzed the technical feasibility of a solar-driven power-cooling system operating in a particular location in Mexico. The theoretical system integrates organic Rankine and single-stage absorption cooling cycles. A parabolic trough collector and a storage system integrated the solar system. Its performance was modeled for a typical meteorological year using the SAM software by NREL. The analyzed working fluids for the organic cycle include benzene, cyclohexane, toluene, and R123, while the working fluid of the absorption system is the ammonia-water mixture. The cycle’s first and second-law performances are determined in a wide range of operating conditions. Parameters such as the energy utilization factor, turbine power, COP, and exergy efficiency are reported for diverse operating conditions. It was found that the highest energy utilization factor was 0.68 when the ORC utilized benzene as working fluid at ORC and ACS condensing temperatures of 80 °C and 20 °C, respectively, and at a cooling temperature of 0 °C. The best exergy efficiency was 0.524 at the same operating conditions but at a cooling temperature of −10 °C. Full article

Triple organic Rankine cycle (TORC) is gradually gaining interest, but the maximum thermal efficiencies (around 30%) are restricted by low critical temperatures of common working fluids (<320 °C). This paper proposes a high-temperature (up to 400 °C) TORC system to ramp up efficiency. A near-azeotropic mixture biphenyl/diphenyl oxide (BDO), which has a stellar track record in the high-temperature ORC applications, is innovatively adopted as the top and middle ORC fluid simultaneously. Four conventional organic fluids are chosen for the bottom ORC. A mixing heat exchanger connects the top and middle ORCs to reduce irreversible loss. Thermodynamic analysis hints that the optimal performance is achieved on the use of benzene as the bottom fluid. The maximum thermal and exergy efficiencies are respectively 40.86% and 74.14%. The largest exergy destruction occurs inside the heat exchanger coupling the middle and bottom ORCs, accounting for above 30% of the total entropy generation. The levelized energy cost (LEC) is 0.0368 USD/kWh. Given the same heat source condition, the TORC system can boost the efficiency by 1.02% and drive down LEC by 0.0032 USD/kWh compared with a BDO mixture-based cascade ORC. The proposed system is promising in solar thermal power generation and Carnot battery applications using phase change materials for storage. Full article

When it comes to seawater desalination in the small- to medium-electricity ranges, the organic Rankine cycle (ORC) powered by solar energy stands out as the most energy-efficient technology currently available. Various solar techniques have been developed to capture and absorb solar energy. Among them, the parabolic trough collector (PTC) has gained recognition as a low-cost solar thermal collector with a long operating life. This study investigates the thermodynamic performance and economic parameters of a PTC-powered ORC using Dowtherm A and toluene as working fluids for the solar cycle and ORC cycle, respectively. Thermo-economic multi-objective optimization and decision-making techniques are applied to assess the system’s performance. Four key parameters are analyzed for their impact on exergy efficiency and total hourly cost. Using TOPSIS decision-making, the best solution from the Pareto frontier is identified, featuring an ORC exergy efficiency of 30.39% and a total hourly cost of 39.38 US$/h. The system parameters include a mass flow rate of fresh water at 137.7 m³/h, a total output net power of 577.9 kJ/kg, and a district heating supply of 1074 kJ/kg. The cost analysis reveals that the solar collector represents approximately 68% of the total hourly cost at 26.77 US$/h, followed by the turbine, thermoelectric generator, and reverse osmosis (RO) unit. Full article

In order to lessen reliance on fossil fuels, a rise in interest in the utilization of fluctuating and intermittent heat sources derived from renewable energy (such as solar thermal, ocean thermal, and geothermal) and waste heat has been observed. These heat sources could be used to generate electricity at relatively low and medium temperatures, for example, through the organic Rankine cycle (ORC). In some case studies, various approaches have been developed to deal with and design ORCs in the desired operating condition utilizing suitable working fluids. This article aims to review some designs and integrated systems of ORC with thermal energy storage (TES) and a two-phase expansion system focusing on the utilization of medium- and low-temperature heat sources in which some subcritical ORCs are presented. Moreover, several possible control systems (both conventional and advanced ones) of ORC with TES and a two-phase expansion system are reported and compared. At the end of this article, the possible future developments of design and control systems are discussed to describe advanced ORC for utilizing low-grade heat sources. This study aims to provide researchers and engineers with an insight into the challenges involved in this process, making industrialization of ORC technology more extensive, in particular when combined with TES and a two-phase expansion system. Full article

In order to achieve efficient utilization of solar energy resources, this study combines the trans-critical organic Rankine cycle (ORC) power cycle (TORC) with the trans-critical CO₂ refrigeration cycle (TCO₂). Additionally, a comprehensive three-level index decision evaluation system is developed based on system safety and environmental protection, thermodynamics, and techno-economic performance. The evaluation focuses on typical medium- and high-temperature solar energy applications and considers six organic working gases. The evaluation results demonstrate that the R600 + CO₂ solution outperformed the others. This solution achieved a maximum net output power (P_net) of 1531.31 kW and 2306.43 kW, a maximum coefficient of performance (COP) of 3.16, a predicted payback period of 2.651 years and 2.033 years, and a benefit–investment ratio of 4.533 and 5.773. Full article

The organic Rankine cycle (ORC) exhibits considerable promise in efficiently utilizing low-to-medium-grade heat. Currently, there is a range of organic fluids available in the market, and selecting the appropriate one for a specific application involves considering factors such as the cycle’s thermodynamic performance, plant size, and compatibility with turbomachinery. The objective of our study is to examine the exergetic performance of the ORC with internal heat regeneration. We analyze 12 different organic fluids to evaluate their suitability based on parameters like exergy efficiency and heat exchange area requirements. Additionally, we investigate the need for internal heat regeneration by comparing the overall exergy performance with a simpler ORC configuration. To ensure broad applicability, we consider source temperatures ranging from 150 to 300 °C, which are relevant to industrial waste heat, geothermal sources, and solar energy. For each case, we calculate specific net power output and the UA value (heat exchanger conductance) to gain insights into selecting the appropriate organic fluid for specific source temperatures. Cyclohexane, benzene, isopropyl alcohol, and hexafluorobenzene show poor exergy efficiency due to their high boiling points. Pentane and cyclopentane provides the highest exergy efficiency of 62.2% at source temperature of 300 °C, whereas pentane is found to be the most suitable at source temperatures of 200 and 150 °C with exergy efficiency of 67.7% and 61.7%, respectively. At 200 °C source temperature, RE347mcc achieves 65.9% exergy efficiency. The choice of organic fluid for a given heat source is highly influenced by its critical properties. Moreover, the normal boiling temperature of the organic fluid significantly impacts exergy destruction during the condensation process within the cycle. Full article

Energy in microgrids (MGs) can now be generated from a variety of renewable sources, but their effective and sustainable use is dependent on electrical energy storage (EES) systems. Consequently, the expansion of MGs is greatly reliant on EES systems. The high infiltration of electric vehicles (EVs) causes some problems for the smooth functioning of the electric power system. However, EVs are also able to offer ancillary services, such as energy storage, to power systems. The research presented in this paper aims to develop a novel frequency regulation (FR) approach for biogas diesel engines (wind), the organic Rankine cycle (ORC), and solar-based two-area islanded microgrids with EVs in both areas. This article discusses the introduction of a fuzzy logic controller (FLC) for FR with scaled factors configured as proportional integral (PI) and proportional derivative with filter (PDF), i.e., a FLC-SF-PI-PDF controller. A recently created modified dragonfly algorithm is used to determine the best values for the controller parameters. To justify the effectiveness of the proposed controller with the presence of EVs, the execution of the proposed controller is associated with and without the presence of EVs. This research also looks at the different uncertain conditions, non-linearities, and eigenvalue stability analysis to validate the supremacy of the proposed approach. Full article