Steam Rankine Cycle Research Articles

Life cycle assessment and thermodynamic performance of biomass-based combined cogeneration

Abstract This study presents a thermodynamic and life cycle analysis of a biomass-based integrated energy system, comprising a biomass gasification cycle, a steam Rankine cycle, and an ammonia fluid Organic Rankine cycle. The primary objective of the system is to efficiently convert olive husk, a sustainable biomass source, into electricity and heating. The gasification process generates syngas, which fuels a gas turbine, producing high-temperature exhaust that drives a Rankine cycle. The thermodynamic analysis indicates that the overall system achieves an energy efficiency of 20.85% and an exergy efficiency of 11.70%. The Rankine cycle exhibits an energy efficiency of 23.91%, while the Organic Rankine cycle demonstrates a higher exergy efficiency of 68.87%. Parametric studies reveal that increasing the combustion chamber temperature significantly enhances system efficiency and output, with energy efficiency rising linearly as the temperature increases from 800 °C to 1000 °C. Additionally, the analysis emphasizes the importance of the compressor's compression ratio on system performance. A life cycle assessment conducted using the ReCiPe methodology evaluates the environmental impact of the system throughout its lifecycle, revealing critical insights into its sustainability. This comprehensive evaluation highlights the potential of utilizing agricultural waste, such as olive husk, to produce renewable energy, thereby supporting environmental sustainability and waste management goals. The findings underscore the viability of the proposed system for enhancing energy production while minimizing environmental impacts, making it a promising solution for renewable energy generation in regions with abundant biomass resources.

Comprehensive study on waste heat recovery from gas turbine exhaust using combined steam rankine and organic rankine cycles

Waste heat recovery technology has proven to be an effective approach for enhancing energy efficiency, reducing greenhouse gas emissions, and lowering energy costs. This study assesses the performance of different waste heat recovery systems from thermodynamic, exergy destruction, economic, and environmental perspectives. Using the DWSIM software, the study simulated a waste heat recovery cycle powered by a high-temperature heat source (508.99 °C) to maximize recovery power and determine the optimal system configuration, including standalone Organic Rankine Cycle (ORC), standalone Steam Rankine Cycle (SRC), and combined systems like SRC with series ORC (SRC + S-ORC), cascade ORC (SRC + C-ORC), and a combination of both (SRC + S-ORC + C-ORC). Among these configurations, the SRC + S-ORC + C-ORC configuration delivered the best performance, achieving a net power output of 3,532.14 kW and a thermal efficiency of 17.09 %. Economically, it demonstrated strong results with a net present value of €1.478 million, a payback period of 8.01 years, and a benefit-cost ratio of 1.32. This configuration also had the highest environmental impact, reducing CO2 emissions by 12,452.48 metric tons per year, equivalent to annual earnings of approximately €999,933.85 through carbon credits trading. The study also found that the evaporator experienced the most significant exergy destruction, suggesting opportunities for improving the highest exergy destruction area, leading to an increase in overall system efficiency. In conclusion, the SRC + S-ORC + C-ORC configuration offers the most promising combination of thermodynamic, economic, and environmental benefits for waste heat recovery systems.

Techno-economic evaluation and multi-objective optimization of a cogeneration system integrating solid oxide fuel cell with steam Rankine and supercritical carbon dioxide Brayton cycles

Developing highly efficient thermodynamic cycles is of great importance in the area of distributed energy system, there are still many non-negligible problems on feasibility assessment and performance evaluation in the application of some emerging technologies, especially involving the fuel cells and carbon dioxide power cycles. This study proposes a distributed heat and power cogeneration system composed of a solid oxide fuel cell, a gas turbine, a steam Rankine cycle, a supercritical carbon dioxide Brayton cycle, and a heat exchanger. The system mathematical model is constructed, and the investigation on system energy, exergy, economic, environmental, and techno-economic performance is performed to demonstrate the technology’s feasibility and applicability. The simulation results indicate that the system can provide 367.03 kW of power and 58.02 kW of heating at the design point, and the overall electrical, exergetic, and energy efficiencies are 68.38 %, 72.41 %, and 79.19 %. The total cost rate of system is achieved to be 11.62 $/h with the system carbon dioxide emission and payback period being 0.2829 kg/kWh and 10.87 year. It can be concluded from the sensitivity analysis that the increases of the compressor pressure ratio, fuel flow rate, and SOFC inlet temperature contribute to improving the system electrical efficiency, while the carbon dioxide emission and the payback period can be reduced. Finally, multi-objective optimization of the cogeneration system is further performed to provide a strategy of performance improvement for system designers and decision makers. The optimization result indicates that though the system carbon emission is increased by 0.25 %, the system payback period and levelized cost of energy are obtained to be 9.88 year and 0.2836 kg/kWh, which are decreased by 9.11 % and 1.47 % compared to the design point.

Multi-Thermal Recovery Layout for a Sustainable Power and Cooling Production by Biomass-based Multi-generation System: Techno-Economic-Environmental Analysis and ANN-GA Optimization

This paper presents a ground-breaking design for a multigeneration system capable of simultaneously producing electricity, hydrogen, and cooling loads. This research advances sustainable energy systems by introducing an innovative design that optimally utilizes waste heat and integrates biomass gasification with advanced thermodynamic cycles. It also provides a model for future studies on carbon emission reduction and improved efficiency. The proposed system effectively harnesses waste heat from the Brayton cycle to drive the supercritical carbon dioxide cycle, steam Rankine cycle, absorption refrigeration, and proton exchange membrane electrolyzer. This approach improves overall efficiency and offers a promising solution for integrated energy generation. Additionally, employing the sCO2 cycle provides high thermal efficiency, cost-effectiveness, and lower environmental impacts compared to traditional power generation methods. Extensive evaluations, including techno-economic and environmental analyses, confirm the system's practicality and potential for future commercial application. Additionally, a parametric investigation of five essential design parameters provides important insights into the system's performance and flexibility. Analysing the proposed system determined that the gasifier-Bryton unit has the highest irreversibility and cost rate among other subsystems. A novel approach combining artificial neural networks (ANN) with a non-dominated sorting genetic algorithm II (NSGA-II) has been developed to optimize the system, substantially reducing computational time and costs associated with system performance analysis. According to the three-objective optimization, the system in the optimal operating mode provides 45.89 kg/h of hydrogen with an exergy efficiency of 33.15% and a total cost rate of 159.5 $/h. After the optimization process, significant achievements have been observed, including a 5.02% improvement in exergy efficiency, an increase of 7.29 kg/h of hydrogen production, and a decrease of 0.1 ton/MW in the CO2 emission index.

Multi-criteria optimization next to a comparative analysis of a polygeneration layout based on a double-stage gas turbine cycle fueled by biomass and hydrogen

The significance and advantages of utilizing renewable energy sources are widely recognized. Upon examining past studies, it was revealed that there has been a lack of research on harnessing the waste energy from double-stage gas turbines powered by biomass-hydrogen hybrid fuel for polygeneration applications. Thus, a new configuration is proposed in the study for the multi-production of electricity, cooling, heating, and potable water. In the current research, a high-pressure turbine is driven by a combustion chamber fed by a biomass gasifier. Meanwhile, a low-pressure turbine is driven by a post-combustion chamber fed by hydrogen as fuel. The heat loss of the topping gas turbine cycle is recuperated by a supercritical Brayton cycle (SBC), a steam Rankine cycle (SRC), and a water heater. The waste heat of the supercritical Brayton cycle and steam Rankine cycle is recovered through an absorption refrigeration cycle and a thermoelectric generator, respectively. Thus, the heat loss of the topping system is completely recovered. The net power output of the gas turbine cycle is considered the electricity production of the system while the output power of the SBC and SRC is utilized in a reverse osmosis desalination system to produce potable water. The investigations conducted on the system are thermodynamic and exergy-economic assessments and three-objective optimization utilizing 5 gases (i.e., CO2, CO, Nitrogen, Air, and Helium) in the SBC. The final results reveal the superiority of Helium as the supercritical gas, bringing about an exergy efficiency (ηex) of 32.11 %, a total cost rate (C˙tot) of 103 $h−1, a payback period (PP) of 0.159 years, and a specific cost of polygeneration (cpoly) of 22.03 $GJ−1 for the system. Although the levelized cost of products of the configuration is high due to the freshwater production, ηex of the proposed system is higher than the previous systems based on a double-stage gas turbine cycle driven by biomass and hydrogen.

Techno-economic analysis of power-to-heat-to-power plants: Mapping optimal combinations of thermal energy storage and power cycles

To enable the widespread exploitation of intermittent, low-cost, and non-dispatchable renewable energy technologies, energy storage plays a key role in providing the required flexibility. This study introduces maps of optimal combination of Thermal Energy Storage (TES) and power cycles, supporting decision-making in power-to-heat-to-power applications. These maps span a wide temperature range from 200 to 1200 °C and are proposed for different charging costs, installed capacities, and storage durations. For thermal-to-electricity reconversion, this study explores power blocks including steam Rankine cycle, supercritical CO2 (sCO2) Brayton cycle, Organic Rankine Cycle (ORC), and combined gas turbine with Rankine and sCO2. Results highlight that, in a grid-based plant with a 50 EUR/MWh charging cost, the most cost-effective pairing involves sCO2 cycles with recompression and intercooling, with particle TES at 600–800 °C. Air packed-bed suits scenarios where TES contributes significantly to capital costs or involves low charging costs. Molten salt TES is the optimal choice when the design temperatures align with salt temperature limitations. Particle TES proves cost-effective across a broad temperature range and scales (10–200 MW). For solar-based systems, the integration of molten salt TES with simple sCO2 recuperated cycles demonstrates market potential for southern European locations.

Techno-economic process design of multi-stage flash- reverse osmosis for water and power production using solar-wind resources

This paper introduces a newly developed hybrid power plant design that combines renewable energy sources to produce both electricity and freshwater. The design offers a higher gain output ratio (GOR) and improved efficiency in power and freshwater production, all at a lower cost compared to existing research papers. To generate power, the power plant incorporates a range of technologies, such as a horizontal-axis wind turbine (WT), photovoltaic panels (PV), parabolic trough collectors (PTC), a steam Rankine cycle, a multi-stage flash (MSF) desalination unit that cleverly harnesses excess heat from the Steam Rankine cycle, and an Reverse osmosis (RO) unit. With the assistance of ASPEN Plus, ASPEN Economic, and HOMER PRO software, the process parameters undergo significant improvement. According to the results, the power plant has the capacity to generate 57.63 MW of electricity and produce 2505 m3h of freshwater. Additionally, it has a GOR of 9.09 and utilizes 7285 m3h of seawater, which has a renewability factor of 97.6 %. In addition, the efficiency of the steam Rankine cycle stands at 32 %, providing notable energy savings. The production costs for electricity and freshwater are 0.037 $kW and 1.38 $m3, respectively, indicating their affordability. The economic analysis reveals promising results for the project, with an anticipated annual profit of 41 % and a relatively short capital payback period of 2.4 years. By implementing the proposed hybrid cogeneration power plant, the region can tackle its water and energy scarcity issues with a sustainable and long-lasting solution.

A new integrated system for carbon capture and clean hydrogen production for sustainable societal utilization

Both hydrogen production and carbon dioxide removal are considered in this study as two of the critical pieces to achieve the ultimate sustainability target. This study proposes and investigates a new variation of potassium hydroxide thermochemical cycle in order to combine hydrogen production and carbon dioxide removal synergistically. An alkali metal redox thermochemical cycle is developed to utilize the potassium hydroxide uniquely through a nonequilibrium reaction. Also, the multigeneration options are explored by employing two-stage steam Rankine cycle, multi-effect distillation desalination, and Li-Br absorption chiller, which is integrated with potassium hydroxide thermochemical cycle for hydrogen production, carbon capture, power generation, water desalination, and cooling purposes. A comparative assessment under different scenarios is carried out. The energy and exergy efficiencies of the hydrogen production thermochemical cycle are found to be 44.2 % and 67.66 % when the hydrogen generation reaction is carried out at 180 °C and the separation reactor temperature is set at 400 °C. Among the multigeneration scenarios considered, a trigeneration option for producing hydrogen, power and freshwater provides the highest energy efficiency as 66.02 %.

Integrated optimization framework for a biomass supply network and steam Rankine cycle

Integrated optimization framework for a biomass supply network and steam Rankine cycle

Modelling and optimization of combined supercritical carbon dioxide Brayton cycle and organic Rankine cycle for electricity and hydrogen production

Hydrogen as a clean fuel, is key energy carrier for sustainable development, and its production via water electrolysis is most desirable for its carbon free nature. Nuclear power provides good opportunity to satisfy the huge energy demand associated with the process, in addition to electrical power generation. Modelling an efficient and cost effective nuclear based power and Hydrogen cogeneration system and optimizing it to enhance its performance is the core academic problem addressed in the present study. It proposes a power plant cycle aided by a nuclear reactor, providing 300 MW thermal power input. Supercritical CO2 Brayton cycle is used as the main cycle, instead of traditional Helium Brayton cycle or steam Rankine cycle. To increase the cycle efficiency, by reducing the compression work and by reducing the cold source loss, main compression intercooling and waste heat recovery by an Organic Rankine Cycle (ORC) is introduced together with recompression Brayton cycle arrangement. The power coming from recovered waste heat goes to a Proton Exchange Membrane Electrolyzer (PEME), which facilitates the production of Hydrogen by splitting water via electrolysis. Additional attention is given to ORC fluid selection by employing and comparing the performance of widely acknowledged R245fa together with its more eco friendly replacements, R1233Zd(E) and R1234Ze(Z). The evaluation of the system performance is conducted through the lenses of Energy, Exergy, and Economics. Essential parameters are scrutinized to gauge their impact on two pivotal objectives. Overall Exergy Efficiency(ηex) takes care of the thermodynamic performance and the economic aspect is scrutinized by Levelized Cost of Energy (LCOEn). Notably, by employing R245fa as the ORC working fluid, the system attains peak Energy efficiency of 42.13% and Exergy efficiency of 58.32%, and a minimum LCOEn of 0.063 USD/kWh. Of all the components associated with the system nuclear reactor tops the chart for maximum exergy destroyed(40.8% of total) as well as maximum investment cost(65.7% of total). Pump contributes least to exergy destruction(0.03% of the total) and heat exchangers hold least share(1.1% of total) for investment cost. Furthermore, a multiobjective optimization exercise is executed to fine-tune the system’s operational parameters. This optimization results in a 3.12% increase in Overall Exergy Efficiency and a 9.79% decrease in LCOEn compared to the base operating condition with R245fa used as the ORC fluid. The ηex & LCOEn in best possible operating condition are 58.25% & 0.0645 USD/kWh using R245fa as ORC fluid, 58.23% & 0.0645 USD/kWh using R1233Zd(E) as ORC fluid and 58.22% & 0.0644 USD/kWh using R1234Ze(Z) as ORC fluid. If same amount of electrical Power is supplied to PEME for both with and without ORC configuration, having an ORC is advantageous both in terms of superior Exergy Efficiency and lower LCOEn. The proposed configuration is also economically more lucrative with higher Net Present Value(NPV) and Benefit to Cost Ratio(BCR). For example, when PEME power input for both the cases is 10 MW, proposed system has NPV = 201.79 Million USD & BCR = 1.70 compared to NPV = 164.03 Million USD & BCR = 1.58 for without ORC configuration. Even if in without ORC configuration, no electrical power is supplied to the electrolyzer, adding an ORC to produce Hydrogen will still achieve maximum 1.57% Exergy Efficiency increment, compared to only electrical power production by sCO2 Brayton cycle. It is seen that in base condition, the NPV is still superior for the proposed configuration (203.03 to 189.32 Million USD), and the BCR dips only slightly from 1.72 to 1.71.

Optimization and exergoeconomic analysis of a biomass-driven cogeneration system for power and cooling applications

Due to the increasing population and the expansion of industry in daily life, a significant depletion of fossil fuel resources is observed, accompanied by escalating environmental concerns. In response to these challenges, this study presents an optimized cogeneration system powered by renewable biomass, designed for simultaneous power and cooling generation. The system integrates a biomass gasification unit, a steam Rankine cycle, a helium-driven gas turbine cycle, and an ammonia-water-based two-stage absorption refrigeration cycle with a bleed line. Thermodynamic and exergoeconomic analyses reveal a net power output of 5356 kW, a cooling load of 360.9 kW, and an exergetic efficiency of 29.52 %. Financially, the system shows a net present value of 11.76 $M and a payback period of 6.51 years. A multi-objective optimization utilizing the gray wolf algorithm improves system performance through the employment of three diverse scenarios, which raises power output to 5864 kW, cooling load to 372 kW, and optimize net present to 14.28 $M with a reduced payback period of 5.96 years. The studied system is well-suited for industrial applications, rural electrification, and district energy systems, and offers a sustainable and economically viable energy solution.

Comparative thermoeconomic analysis of integrated hybrid multigeneration systems with hydrogen production for waste heat recovery in cement plants

The cement industry is a widely used and energy-consuming sector, making it one of the largest CO2 emitters, primarily to meet its energy demands. Therefore, this research aims to evaluate the waste heat recovery process from a cement factory to fulfill a portion of its energy requirements. In this study, four scenarios have been evaluated, including power production scenarios, hydrogen production scenarios, methanation production process evaluation scenarios, blending hydrogen with natural gas, oxy-fuel combustion scenarios, and scenarios for producing the required freshwater for the factory and the water electrolysis process. The results show that the steam Rankine cycle with the reheating process and the organic Rankine cycle with methanol working fluid with a production capacity of 24.35 MW, and a payback period of 2.4 years with levelized cost of energy being 0.005809 $/kWh, is the most favorable scenario for the power generation cycle. Also, the process of alkaline electrolysis with a hydrogen production rate of 0.1648 kg/s, and a payback period of 5.816 years, and also with the levelized cost of hydrogen being 1.001 $/kg, happened to be the most suitable hydrogen production scenario compared to other electrolysis scenarios such as PEM and SOEC. Moreover, the process of water desalination by reverse osmosis with the energy consumption of 2.7 MW of power is capable of supplying all the required water of the factory and the water electrolysis process, and it was determined as the most suitable scenario for supplying the required water.

Zeotropic mixture as a working fluid for cascade Rankine cycle-based reverse osmosis: Energy, exergy, and economic analysis

This study investigates the cascade Rankine cycle coupled with a reverse osmosis system for brackish groundwater treatment. The proposed system integrates a steam Rankine cycle (SRC) and an organic Rankine cycle (ORC) in a looped configuration, utilizing solar energy as a heat source. Each Rankine cycle is coupled with reverse osmosis (RO) to produce approximately 1 m3/h of permeate from each RO system. The system is investigated with working fluid combinations from R1233zd(E), R1234ze(Z), and R1336mzz(Z). Through comprehensive energy, exergy, and economic analyses, the system's performance is evaluated with zeotropic mixtures compared to pure R1233zd(E). The results demonstrate reliable performance with zeotropic mixtures, particularly R1233zd(E)/R1234ze(Z) with a mass composition of 0.6/0.4, demonstrating the maximum ORC expander work output of 1.15 kW. Parametric analysis reveals remarkable performance under different ORC system parameters. Variations in SRC condensation pressure show a trade-off performance between SRC and ORC turbine work output. Exergy analysis reveals an increase in exergy destruction by evaporation-based ORC components and a reduction in exergy destruction by condensation-based components, emphasizing improved irreversibility during the condensation process. Economic analysis indicates a marginal impact on the overall system cost, with the treated water cost ranging from 0.891 to 0.919 $/m3.

Thermo-economic and environmental analyses of supercritical carbon dioxide Brayton cycle for high temperature gas-cooled reactor

The supercritical carbon dioxide (sCO2) Brayton cycle demonstrates special advantages for the high temperature gas-cooled reactor (HTGR) delivered into commercial operation recently in China, with its high efficiency, compactness, flexibility, and safety compared to the conventional steam Rankine cycle. However, the large temperature rise of 500 °C for the HTGR brings new challenges for the design of sCO2 cycle. Here, we present the first study on the thermodynamic, economic, and environmental performance of the HTGR-sCO2 system using the energy, exergy, economic, and environmental (4E) evaluation method. The cascaded sCO2 cycle made up of two independent sCO2 cycles is proposed, which are arranged in series on the cold side of reactor heat exchanger. We show that the cascaded sCO2 cycle can utilize the heat absorption from HTGR effectively by optimizing the cycle configurations of top and bottom sub-cycles. The improved cascaded sCO2 cycle minimizes the exergy loss, and increases the thermal efficiency to 43.2% when compared to the steam Rankine cycle of HTGR demonstration power plant and the single recompression cycle. By balancing the fixed-capital investment cost with the net power, the levelized cost of electricity can be reduced to 0.0283$/kWh. The life-cycle GHG emission intensity of HTGR-sCO2 systems is about 6.5gCO2,eq/kWh, which is much smaller than that of coal-fired power plants, suggesting a great potential for decarbonization of the HTGR-sCO2 system. Our study may find implications for the advancement of the sCO2 Brayton cycle in next-generation nuclear power plant.

Modeling of an advanced renewable energy system coupled with hydrogen production and liquefaction for sustainable communities

The primary objective of this study is to develop a sustainable and efficient renewable energy-based multigeneration system that is specifically designed to meet diverse energy demands, such as heat, cooling, electricity and hydrogen. The system comprises several subsystems: a digester for biomass processing, a solar energy collection system, a thermal energy storage system, a multistage Brayton cycle, a steam Rankine cycle with reheat, a double-effect absorption system, a sonic hydrogen production unit, and a multistage hydrogen liquefaction system. The methodology involves conducting energy and exergy analyses, economic evaluation, and environmental impact assessment to determine the system's performance and viability. The energy efficiency results show that the Brayton cycle, steam Rankine cycle and liquefaction system have efficiencies of 30.92 %, 30.18 %, and 64.53 %, respectively. The exergy efficiencies for these subsystems are 50.10 %, 67.21 %, and 11.29 %, respectively. The double-effect absorption system exhibits energetic and exergetic coefficients of performance of 1.68 and 0.64, respectively. The overall energy and exergy efficiencies of the system are 36.41 % and 55.74 %, respectively. The economic analysis indicates a significant revenue potential, with the project reaching its break-even point in 2031 and achieving a net present value of $6.60 million. The results of an environmental impact assessment study highlight a reduction in CO2 emissions compared to conventional systems, emphasizing the system's contribution to sustainable energy solutions.

Hybridization of Concentrated Solar Thermal With Geothermal and Biomass Power

While Geothermal Power Plants (GPPs) can be a reliable renewable energy source, this reliability can decrease over the years due to brine mass flow declining. This reduced mass flow causes extra capacity unused in the GPP turbines. This problem can be overcome by hybridizing GPPs with CST and biomass. These three thermal technologies can, in theory, complement each other if all the resources are present at the exact location. This is the scenario for this study, as the location for the case study is the Kızıldere 2 (KZD2) GPP in Denizli, Turkiye, operated by Zorlu Energy. This region has sufficient potential for all three technologies: CST, geothermal, and biomass. Furthermore, by building a topping cycle using CST and biomass, it is possible to generate additional power. This study utilizes a topping steam Rankine cycle run equally by CST and biomass, and, as a result, the 20% excess capacity in the GPP turbine is used while generating an additional 20 MWe of power.

Development of a solar-ocean based integrated plant with a new hydrogen generation system

Considering the global urgency to decrease carbon emissions and shift to sustainable energy sources, combining solar and other renewables with hydrogen generation appears to offer an appealing answer. The combination of solar and ocean energies with hydrogen production, therefore, offers a great potential to improve energy efficiency and create a feasible route towards zero-emission energy systems. A new hybrid photoelectrochemical (PEC)-conventional electrolysis system was designed and incorporated into the proposed multigeneration system. The hybridized reactor combines the benefits of PEC and conventional electrolysis by using a developed bipolar anode to produce hydrogen continuously, even when there is no solar radiation. The main aim of this research is to investigate the integrated power process that utilizes solar power for several uses, such as generating electricity, producing freshwater, and synthesizing hydrogen. The proposed research involves integrating several components, including a solar through collector system, a combination of power cycles (steam and organic Rankine cycles), a multi-effect desalination (MED) unit, a new hybrid electrolyzer system, a wave energy system, and a hydrogen storage and refuelling station. The main outputs include 2.05 kg/s freshwater production, 0.125 kg/s hydrogen production, 16,284.24 kW net work rate, and 95,068 kW solar heat input. The highest exergy destruction rates were found in the solar collector (56,194.8 kW) and turbines T1 and T2 (6019.9 and 4627.6 kW). The overall energy and exergy efficiencies of the proposed system are obtained to be 15.83 % and 16.61 %, respectively.

Implementation of a waste heat recovery prototype facility based on the Rankine cycle with a twin-screw expander

Considering the energy needs of developing countries, thermal power plant facilities are necessary for power generation. However, usable thermal energy is lost because the necessary technologies to exploit the waste heat from industrial processes have not yet been implemented. In this sense, the present analysis shows the experimental study of a prototype Steam Rankine Cycle energy system. The prototype uses the residual heat of the combustion gases from one of the generators installed in a thermal power plant as a heat source, the maximum temperature of these gases is 320 °C. This prototype is considered the first in the region to perform heat recovery with a power cycle with water as the working fluid. Considering the country’s economic constraints, the prototype was built using a 20 kW twin-screw compressor modified to function as a turbine. This prototype aims to increase the overall performance of the generating unit. For the characterization of this prototype plant, energy and exergetic efficiency analysis was carried out using the experimental data. The application showed that the measured efficiency of the twin-screw expander was low at 18.44 %. In contrast, the maximum expander work was 15.81 kW, the overall cycle efficiency was 3.52 %, and the exergetic efficiency was 5.45 %.

Optimizing a hybrid solid oxide fuel cell-gas turbine and geothermal energy system for enhanced efficiency and economic performance in power and hydrogen production scenario

Geothermal energy is utilized due to its sustainability and ability to provide a continuous low-emission source of heat, making it an ideal complement to the high-efficiency requirements of modern power plants. This study investigates a novel configuration coupling a solid oxide fuel cell-gas turbine unit with a dual-flash binary geothermal structure, enhanced by low-temperature electricity generation and hydrogen production subsystems. This configuration incorporates a regenerative steam Rankine cycle and a proton exchange membrane electrolyzer to achieve an efficient overall design. The setup is evaluated from thermodynamic and economic perspectives using a non-dominated sorting genetic algorithm-II for optimization. A complete parametric study assesses the sensitivity of critical variables. Multi-objective optimization is conducted across three scenarios considering exergy efficiency, hydrogen production rate, sum unit cost of products, and the payback period as objective functions. Results indicate an optimal exergy efficiency of 56.95% and a hydrogen production rate of 0.22 kg/h, with a product unit cost of $7.06/GJ and a payback period of 1.12 years. The parametric study underscores the significant impact of the number of solid oxide fuel cells and their existing density on key variables of the presented configuration. This study highlights the system's potential for efficient and economically feasible power and hydrogen production.

Thermo-economic optimization on a combined heat and power system with supercritical Rankine cycle for power-to-heat batteries

The global energy structure is transforming to low-carbon, and it is urgent to construct a sustainable energy system mainly based on renewables. The power-to-heat batteries (P2HBs) show great potential for large-scale energy storage by converting low-cost renewable power to heat. This paper aims to study the thermodynamic and economic advantages of the P2HB integrated with a supercritical steam Rankine cycle (RC) to achieve combined heat and power (CHP) generation. Firstly, a system model of P2HB-CHP consuming grid valley power is developed. The system includes three sub-systems: P2HB, steam generator, and CHP. Thermodynamic and economic analysis models are developed, and the average exergy efficiency (ηav) and net present value (NPV) are formulated as performance evaluation targets, respectively. The genetic algorithm is used to perform multi-parameter optimization of the system. The thermodynamic optimization results show that the maximum ηav of supercritical P2HB-CHP is 0.47 %, 1.16 %, and 1.44 % higher than that of subcritical P2HB-CHP when the high working temperature of the molten salt reaches 505 °C, 570 °C, and 640 °C, respectively. The largest proportion of anergy is generated by electric heaters, over 72 %. The next largest proportion is heat exchangers, which is related to the heat transfer temperature differences. The results of the economic analysis show that the maximum NPV of supercritical P2HB-CHP is lower by 158 M$, lower by 74 M$, and higher by 55 M$ than that of subcritical P2HB-CHP when the high working temperature of the molten salt is reached 505 °C, 570 °C, and 640 °C, respectively. The high efficiency of supercritical RC reduces the costs of electric heaters and molten salts, but sets high demands on the heat exchangers. Although high-temperature molten salt results in high energy efficiency, the increased cost of molten salt reduces the profitability of the system.