Part Load Operation Research Articles

Exergoeconomic study of reheat combined cycle configurations using steam and ammonia-water mixture for bottoming cycle parameters

The use of combined cycle power plants though had led the pathway to maximize the fuel en-ergy utilization but the part-load operation of these plants is of concern. In this work, an exer-goeconomic comparison of 11 different reheat combined cycle arrangements hasbeen carried out under their part-load operations for varying bottoming cycle parametersnamely steam-bleedfraction, deaerator pressure,separator temperature, absorber pressure, and condenser pressure.The results depict that the absorber has the highest exergy destruction with second law efficiency of 23.55% at thepart load of 25% for the combined cycle power plant having high pressure drum with steam as working fluid and low pressure drum with ammonia-wa-ter as working fluid. The comparison also shows the highest cost of electricity production as 0.1243USD/kWh for the combined cycle power plant having ammonia-water as working fluid in bottoming cycle and operating at part load of 25%. While the minimum price of electricity produced is 0.05USD/kWh at 25% part load for CCPP having double pressure HRVG’s at condenser pressure of 0.09 bar.

Optimum design of bivariate operation strategy for a supercritical/ transcritical CO2 hybrid waste heat recovery system driven by gas turbine exhaust

Gas turbines are always operated under part-load conditions to participate in the frequency regulation of power grids; therefore, the exhaust gas has fluctuating temperature and mass flow rate parameters. For better utilization of the waste heat in gas turbine exhaust under part-load conditions, a supercritical/transcritical carbon dioxide (CO2) hybrid waste heat recovery system with different operation strategies was studied. The turbine inlet pressure and mass flow rate were considered as the dominant factors affecting the system part-load performance, which formed a bivariate operation strategy. A solution procedure was proposed to optimize the bivariate operation strategy for a hybrid waste heat recovery system. The results indicate that the mass flow rate of the transcritical CO2 cycle has a greater effect on its net power than the turbine inlet pressure whereas these two regulation variables should be controlled cooperatively. The net power of the hybrid waste heat recovery system increased with an increase in the inlet valve opening of the supercritical CO2 turbine under a specific gas turbine load. Generally, the optimal bivariate operation strategy has the advantage of enhancing the part-load performance of a hybrid waste heat recovery system driven by gas turbine exhaust.

System Design, Optimization and 2nd Law Analysis of a 100 MWe Double Reheat s-CO2 Power Plant at Full Load and Part Loads

Super-critical Carbon dioxide (s-CO2) power plants are considered to be efficient and environmentally friendly compared to the traditional Rankine cycle-based steam power plants and Brayton cycle-based gas turbine power plants. In this work, the system design of a coal-fired 100 MWe double reheat s-CO2 power plant is presented. The system is also optimized for efficiency with turbine inlet pressures and the recompression ratio as the variables. The components needed, mass flow rates of various streams and their pressures at various locations in the system have been established. The plant has been studied based on 1st and 2nd laws at full load and at part loads of 80%, 60% and 40%. Operating parameters such as mass flow rate, pressure and temperature have considerably changed in comparison to full load operation. It was also observed that the 1st law efficiency is 53.96%, 53.93%, 52.63% and 50% while the 2nd law efficiency is 51.88%, 51.86%, 50.61% and 48.1% at 100%, 80%, 60% and 40% loads, respectively. The power plant demonstrated good performance even at part loads, especially at 80% load, while the performance deteriorated at lower loads. At full load, the highest amount of exergy destruction is found in the main heater (36.6%) and re-heaters (23.2% and 19.6%) followed by the high-temperature recuperator (5.7%) and cooler (4.1%). Similar trends were observed for the part load operation. It has been found that the recompression ratio should be kept high (>0.5) at lower loads in order to match the performance at higher loads. Combustion and heat exchange due to finite temperature differences are the main causes of exergy destruction, followed by pressure drop.

Reducing the Energy Penalty of Retrofit Decarbonization in Combined Cycle Power Plants

Abstract This study is a continuation of previous work aimed at elucidating the effect of hydrogen-cofiring and exhaust gas recirculation (EGR) on combined cycle (CC) performance. The thermodynamic analysis was expanded to include postcombustion capture (PCC) by means of mono-ethanolamine (MEA). Attention was paid to net power output and thermal efficiency. Part-load operation of the CC without carbon capture was taken as a reference. Decarbonization solutions, in ascending order of complexity, included the following: (1) adding a PCC unit; (2) combining EGR with PCC, so as to exploit the increase in the flue gas CO2 concentration while reducing the exhaust gas flow delivered to the absorber; (3) including hydrogen cofiring at the largest capability dictated by the gas turbine (GT) combustion system, with the opportunity to explore a wider range of EGR rates, while still relying on PCC of the residual CO2 in flue gas, before discharge into the environment. Scenarios were first discussed under the same GT load for consistency with the published literature, thus enabling the validation of the modeling procedure. Then, CC net power production was assumed as the basis of comparison. The third solution was found to be the most promising thus minimizing both the energy penalty due to carbon capture and CO2 emission intensity (EI).

Rating and sizing analysis of the solar chimney power plant considering uncertainty in solar radiation and under different load conditions

ABSTRACT The main focus of this research is on modeling and analyzing an industrial-scale solar chimney power plant (SCPP) under actual or realistic conditions. While most of earlier studies considered the steady state kind of solar radiation, this study is based on the assumption of the diffuse and erratic nature of solar energy in calculating the sizing rating of SCPP. Moreover, the use of uncertainties in solar radiations is time-consuming and difficult, and hence a theoretical approach is used to get the required results. Statistics and probability theory concerning solar radiation and weather data of Mumbai, India region are used for said analysis. The best generator rating and daily energy output are determined by taking into consideration variables like chimney height, collector radius, and storage thickness below the absorber plate of SCPP. Based on the aforementioned characteristics, one may construct SCPP sizing curves to yield 136, 435, and 945 kWh energy generation in 24 h period. It is essential to consider the full load and part load operations of the generator in order to prevent the unused kinetic energy linked to low velocity and increased velocity. While the majority of the past research by various researchers was carried out under full-load conditions, this study also addresses half-load situations. The current effort will help manufacturers and the scientific community develop sizing and rating taking into account different sun radiation statistics.

Effect of water jet area on mitigation of vortex rope in a Francis turbine

The rotating vortex rope (RVR) is normally formed at part load operating conditions, which develops flow instability in the draft tube (DT) cone of a Francis turbine. The detrimental effects of RVR reduce the life and performance of the turbine. The present work mitigates RVR through axial water jet injection in the DT cone. This paper extends the author's previous work on water injection with a 50% reduction in the water jet area through two nozzles with a diameter of 12.7 mm. The effect of area reduction is analyzed by spectral analysis like power spectrum density and spatial harmonic decomposition of the pressure field measured at the wall of the cone. The effect of water jet injection on synchronous and asynchronous pressure pulsations is analyzed at both measurement planes of the cone. The improvement in pressure recovery in the cone and turbine efficiency due to water jet injection is also analyzed. The water is injected at 0.5%–2% of the turbine inlet flow at 22.10° guide vane opening.

Synergetic performance of gas turbine combined cycle unit with inlet cooled by quasi-isobaric ACAES exhaust

Gas power generation units are challenged with peak regulation in the new power system characterized by high proportion of renewables. In aim to enhance the part-load performance and the peak-regulation capacity of gas turbine combined cycle (GTCC) power units, a synergetic power system of GTCC integrated by an isobaric and adiabatic compressed air energy storage (IACAES) was proposed, where the compressor inlet air in the gas turbine was directly mixed and cooled by the ACAES exhaust. Based on the demand load distribution of a GTCC unit and the off-design performance, the parameters of the IACAES were designed for the proposed synergetic system (SS), and comparatively for the benchmark integrated system (BS) without compressor inlet cooling. The peak-regulation performances of the proposed synergetic system were investigated and compared with those of the standalone GTCC as well as the benchmark system. The case study in a 67.3 MW GTCC indicates that, in the range of the ambient temperature from 283.15 to 308.15 K, the GTCC operative efficiency considerably enhances by averagely 0.943% resulting from the power shifting. The IACAES discharging power and roundtrip efficiency in SS are 10.5% lower than those in BS. An average negative gap of system efficiency in SS reaches 0.199% versus BS. However, GTCC inlet cooling by IACAES exhaust enhances the power capacity of the unit averagely by 1330.88 kW, and the peak-regulation capacity increases averagely by 10.59% compared to that in the standalone GTCC. The peak-regulation capacity enhances by 1.98% versus BS. The synergetic cooling effect weakens with the reduction in the ambient temperature and the charging air pressure.

Improving the partial-load performance and emission of GDI engine by combining injection strategy and exhaust variable valve timing technology

Improving the partial-load performance and emission of GDI engine by combining injection strategy and exhaust variable valve timing technology

Significant impacts of injection parameters on marine diesel engines

Nowadays, over 90% of the shipping industry mainly relies on marine transportation. The ability of 2-stroke low-speed diesel engines to consume heavy fuel and even crude oil makes them occupy an important position in the main propulsion power market. Also, it is quite convenient for them to operate reversely, which is needed for the astern situation. Compared with other propulsion power sources such as gas turbines or electro-propulsion, low-speed diesel engines have relatively better part-load performance and long-time stability, making them stand out. Most importantly, their efficiency can reach up to 60% when combined with exhaust boilers and turbine-driven alternators. The majority of those advantages are gained from the delicately designed fuel injection system and the governor system. This article discusses 2-stroke low-speed marine diesel engines' fuel injection systems and how some important parameters influence engine performance. Future opportunities and key challenges in this exciting field are also highlighted.

Experimental study on hydro- thermal behavior of journal bearing oil film profile in a slow speed diesel engine

Utilizing universal journal bearing test rig, the performance of a heavy-loaded main journal bearing has been investigated based on tracing operational behavior of oil film temperature and pressure profiles. Test trials were conducted observing the loading program of slow speed diesel engine. Examining the effect of different oil grades, it turned out that oil grade of higher viscosity index enhances journal bearing performance and maintains oil film temperature profile stability at both maximum speeds and heavy loads. Further, medium viscosity grade oil reduces fuel consumption and costs from power production for all operational conditions. Regarding the impact of heavy loads on shaft power performance with medium viscosity oil grade, the differences between optimal and heavy loads get lower as the shaft speed increases. Those were 22 %, 9.7 % and 2.1 % corresponding to the shaft speeds of 43 rpm, 90 rpm and 104 rpm respectively. Additionally, the lower the value of the maximum oil film pressure Pmax difference between optimal and heavy load, the higher the ability of the lubricant to promote performance and provide enhanced operating condition stability. Yet, at part load operating conditions entailing running journal shaft at slow speeds during ship maneuverability, it cannot be considered as the best selection due to the heavy loads often applied in such critical operating conditions. Finally, the test-trial based experimental outcomes can provide useful guidance regarding the proper selection of a lubricant for enhanced performance, cost saving and prolonged journal bearing working life.

Uncertainty in the numerical prediction of the tangential velocity in axial turbines at part load operations: A parametric study

Numerical simulations of axial hydraulic turbines away from the best efficiency point are challenging. Previous studies especially show difficulties predicting the tangential velocity at Part Load (PL) operating conditions, where the swirl is high, in comparison to experiments. This is a reoccurring problem, and it is essential to understand, as the high tangential velocity is a fundamental characteristic of the flow in hydraulic turbines and is directly related to the swirling flow stability and the turbine’s power output. The objective of this study is to numerically investigate and understand the origin of the tangential velocity deviation from experimental results by performing simulations with the finite volume method of an axial turbine operated at PL. A parametric study is performed to address the abovementioned. Specifically, the effects of the blade clearance, blade angle, flow rate, and different turbulence models are studied on this issue. Results are analyzed by comparing the predicted axial and tangential velocity profiles and torque to experimentally obtained values. Primarily the runner inter-blades flow is studied as there is a knowledge gap. In addition, the physical phenomena responsible for head losses are studied in detail. Results show that the model can predict the flow relatively well at optimal flow conditions with low swirl but has problems at part load; the tangential velocity between the runner blades is underestimated by ∼20%. The undervalued head losses are the root cause. They result in an overestimated torque and an underestimated tangential velocity as the runner extracts too much energy from the fluid. A small modeling error of 0.5° in the blade angle and a change of 3% in the flow rate significantly affect the tangential velocity and torque prediction. The studied parameters must be considered carefully when building a numerical model.

Innovative desalination system driven by a solar micro gas turbine for off-grid applications

Past work by the authors has suggested that Solar micro Gas Turbines (SmGTs) can be used cost-effectively to produce electric power and heat for freshwater production through desalination, mainly in off-grid locations. This is further studied in this work, providing an exhaustive modelling procedure and methodology. Additionally, a comprehensive analysis of system performance under both design and part-load conditions is provided along with the complete set of characteristics of the components of the SmGT and the desalination unit. To this end, the SmGT is assessed first, incorporating innovative solutions that enable better off-design performance: Variable Inlet Guide Vanes (VIGVs) in the compressor and Variable Nozzle Guide Vanes (VNGVs) in the turbine. The implementation of these features brings significant advantages in part-load operation, leading to a considerable increase in solar-to-electric efficiency and rangeability, particularly under certain ambient conditions; in particular, using these features yields 5% higher efficiency at the minimum load of the original engine (without variable geometry) and, from this load setting downwards, 15% lower minimum stable load is enabled. Furthermore, a sensitivity analysis to control strategies and ambient conditions has been included, exploring their impact on system performance.The water treatment system is comprised of two elements. A Reverse Osmosis (RO) desalination unit is driven by the electric power produced by the SmGT. Considering the emphasis on flexibility and part-load operation enhancement addressed in this work, a moderate recovery rate is proposed for this unit. The RO unit produces brine with high salt concentration to be partially treated further in a Zero Liquid Discharge (ZLD) unit driven by the exhaust gases of the microturbine (at about 250–300 °C), where the sensible heat of this stream is harvested by the ZLD unit to “dry” and concentrate the effluent. Finally, the potential and the operational limitations of the ZLD system are discussed, complemented with results from an experimental proof of concept where the feasibility of the concept is verified.

Vibro-Acoustic Responses and Pressure Signal Analysis for Early Surge Detection in a Turbocharger Compressor

Abstract High-speed centrifugal compressors may be exploited to pressurize fuel cell systems. Nonetheless, due to fuel cells significant interposed volumes, compressor behavior can lead to severe vibrations related to fluid-dynamic instabilities during part load operating conditions. In particular, surge strongly limits centrifugal compressors stable operating region when moving toward low mass flow rates due to a change in system working point. Therefore, compressor dynamic response must be adequately characterized for early surge detection. To this aim, a dedicated experimental activity was conducted on a vaneless diffuser turbocharger coupled to a solid oxide fuel cell emulator plant; compressor evolution toward surge was investigated. Several signal processing techniques were applied to pressure signals as well as vibro-acoustic responses to better predict compressor behavior and classify its status as stable or unstable. Cepstrum, cross-correlation, and wavelet transform have been identified as suitable techniques to define precursors able to early detect surge. By means of cross-correlation function, propagation phenomena in the ducts can be investigated to assess how they interact near compressor low-mass flowrate unstable conditions. Cepstrum provides a convenient way to determine pressure signal spectrum distortion in terms of further periodic components onset. These harmonic components are due to complex system responses generated by transient phenomena; indeed, cepstrum allows to identify hidden anomalous contributions in system response spectra which may arise in incipient surge conditions. Wavelet transform was performed on both structural and pressure response signals to observe their dominant energy contents temporal evolution; indeed, such spectral pattern time-dependent variation can detect the rise of unstable conditions. By exploiting all these techniques, a complete system identification is performed which allows a deeper investigation of the physical phenomena involved; moreover, a more complete set of surge precursors extracted from different probes' physical signals were defined. The results obtained provide original diagnostic insights for monitoring systems suited to perform early surge detection. Compressor instability prevention can extend its operating range, performance, and reliability to allow better integration with other plant components. Finally, cepstrum application for compressor instability identification can be regarded as a novel method in the fluid machinery field.

Transient Solid Oxide Cell Reactor Model Used in rSOC Mode-Switching Analysis and Power Split Control of an SOFC-Battery Hybrid

Defossilization of the global energy system requires a transition towards intermittent renewable energy sources and approaches that enable efficient conversion of primary energy sources into electrical energy. Due to their high efficiency in converting chemical into electrical energy and vice versa, solid oxide cell (SOC) systems provide solutions for both of these aspects. Within this contribution, two researched cases utilizing SOC's are presented, based on simulation studies and experiments.Characteristically, SOC reactors produce hydrogen from steam in solid oxide electrolysis (SOE) mode, or electricity from reformates in solid oxide fuel cell (SOFC) mode. An application of both modes as reversible solid oxide cell (rSOC) is to balance a renewable power supply with storage and power production, leading to high utilization of the same equipment. An application in SOFC mode is the maritime transportation powertrain. In both cases, transient operation is needed whenever mode transitions occur. In particular, switching between rSOC modes implies transitioning exothermal SOFC, endothermal, thermoneutral and exothermal SOE operation. Similarly, supplying the power demand of a maritime drivetrain in SOFC mode leads to various exothermic levels, as pertinent to part or full load operation. Operating strategies are needed to suppress potentially damaging thermal stresses during these transitions in the electrochemical SOC reactors. In order to identify such operating strategies, experiments have been carried out and a transient model has been developed for the analysis of rSOC mode-switching and SOFC drivetrain power supply, which are presented in this study. The 1D+1D SOC dynamic multi-reactor model includes the individual SOC reactors, piping and insulation, and is implemented in the in-house developed transient energy process system simulation framework TEMPEST [1,2]. The model couples the transient balances of mass and energy with electrochemistry, internal reforming kinetics, heat transfer, and flow distribution. As a result, temperature and voltage characteristics at cell, stack, and module levels are obtained to analyze for e.g. unwanted thermal stress. In the EU project SWITCH [3], experiments were performed at DLR with a Large Stack Module (LSM) from SolydEra (formerly SOLIDpower) to validate the model in transient 75 kW electrolysis mode, 25 kW fuel cell mode and mode-switching operation between electrolysis and polygeneration mode. The so called polygeneration mode refers to simultaneous generation of hydrogen and electricity at partial fuel utilization with natural gas, biogas or e-methane. Simulative studies of mode-switching procedures from SOE to SOFC-mode polygeneration show that drawing fuel cell current soon after reaching open circuit voltage and sufficiently in advance of the methane ramp completion leads to a reduced temperature decrease at the inlet of the cell without reaching oxygen to carbon ratios low enough to favor carbon deposition. In the EU project NAUTILUS [4], the mismatch between the transient response possibilities of SOFC systems and the power demand of a ship is addressed by connecting Li-ion batteries to the powertrain. Batteries respond to highly transient ship load demand changes, while the SOFC’s provide base part load to full load, according to a power split control strategy. A battery model developed and parametrized by the Chair for Electrochemical Energy Conversion and Storage Systems of RWTH Aachen University [5] was added to TEMPEST and validated using DLR experiments with a 40 kWh Li-ion battery. Simulation results of the SOFC-battery hybrid in Figure 1 show that a rule-based power split control strategy [6] ensures that the power demand of the ship is met at all times while the battery state of charge (SoC) remains within specified range, and the SOFC power is drawn at one of three fixed power levels for reduced thermal stress. An experimental campaign to test this and other control strategies with a 32 kW LSM from SolydEra and the 40 kWh battery is in progress at DLR. Acknowledgements Project SWITCH has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 875148. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research. Project NAUTILUS has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 861647.

Studying the Influence of Variable Inlet Guide Vane with the Physical Faults on the Performance of Industrial Gas Turbine at Part-Load Operation

Studying the Influence of Variable Inlet Guide Vane with the Physical Faults on the Performance of Industrial Gas Turbine at Part-Load Operation

Simultaneous Fault Diagnostics for Three-Shaft Industrial Gas Turbine

The study focused on the development of -gas turbine full- and part-load operation diagnostics. The gas turbine performance model was developed using commercial software and validated using the engine manufacturer data. Upon the validation, fouling, erosion, and variable inlet guide vane drift were simulated to generate faulty data for the diagnostics development. Because the data from the model was noise-free, sensor noise was added to each of the diagnostic set parameters to reflect the actual scenario of the field operation. The data was normalized. In total, 13 single, and 61 double, classes, including 1 clean class, were prepared and used as input. The number of observations for single faults diagnostics were 1092, which was 84 for each class, and 20,496 for double faults diagnostics, which was 336 for each class. Twenty-eight machine learning techniques were investigated to select the one which outperformed the others, and further investigations were conducted with it. The diagnostics results show that the neural network group exhibited better diagnostic accuracy at both full- and part-load operations. The test results and its comparison with literature results demonstrated that the proposed method has a satisfactory and reliable accuracy in diagnosing the considered fault scenarios. The results are discussed, following the plots.

Characterizing the Wake Effects on Wind Power Generator Operation by Data-Driven Techniques

Wakes between neighboring wind turbines are a significant source of energy loss in wind farm operations. Extensive research has been conducted to analyze and understand wind turbine wakes, ranging from aerodynamic descriptions to advanced control strategies. However, there is a relatively overlooked research area focused on characterizing real-world wind farm operations under wake conditions using Supervisory Control And Data Acquisition (SCADA) parameters. This study aims to address this gap by presenting a detailed discussion based on SCADA data analysis from a real-world test case. The analysis focuses on two selected wind turbines within an onshore wind farm operating under wake conditions. Operation curves and data-driven methods are utilized to describe the turbines’ performance. Particularly, the analysis of the operation curves reveals that a wind turbine operating within a wake experiences reduced power production not only due to the velocity deficit but also due to increased turbulence intensity caused by the wake. This effect is particularly prominent during partial load operation when the rotational speed saturates. The turbulence intensity, manifested in the variability of rotational speed and blade pitch, emerges as the crucial factor determining the extent of wake-induced power loss. The findings indicate that turbulence intensity is strongly correlated with the proximity of the wind direction to the center of the wake sector. However, it is important to consider that these two factors may convey slightly different information, possibly influenced by terrain effects. Therefore, both turbulence intensity and wind direction should be taken into account to accurately describe the behavior of wind turbines operating within wakes.

Part load operation analysis of a biomass steam generator integrated with a Linear Fresnel solar field

Hybrid systems involving the use of biomass and solar energy have been proposed as a promising alternative to reduce greenhouse gas emissions and provide a way to overcome the inherited shortcomings of solar energy, such as intermittent and instability. Nevertheless, some plant components will operate in the off-design condition once solar energy is added to the cycle. In this regard, the objective of this work is to evaluate the performance of an existing biomass steam generator at partial loads, integrated with a Fresnel solar field in fuel-saving mode. The equipment consists of a biomass steam generator with a capacity to produce up to 50 t/h of superheated steam at 420 ℃/45 bar(a) to feed a cogeneration power plant. Measurement data were collected on-site to calculate the boiler efficiency at part loads according to the ASME PTC4 standard. The main components of the boiler were modeled using the OpenModelica® tool and the ThermoSysPro® library. The model accuracy was verified at different loads with the available measurement data and manufacturer datasheets. In conclusion, the implemented model allowed to reproduce the boiler performance in different loads, being able to evaluate the impact of the solar field integration and the hybrid boiler operation.

The thermodynamic and life-cycle assessments of a novel charging station for electric vehicles in dynamic and steady-state conditions

The current study performs the thermodynamic and life-cycle assessments (LCA) of a novel charging station in two system designs. The goal is to design an efficient charging station for electric vehicles with high efficiencies and low environmental impacts using Solid Oxide Fuel Cell (SOFC) technology. SOFC is considered a sustainable and environmentally friendly technology to generate electricity compared to combustion engines. To ameliorate the performance, the exhaust heat of the SOFC stacks will be recovered for hydrogen production in an electrolyzer. The system uses four SOFCs to charge the electric vehicles while the output heat is recovered by an Organic Rankine Cycle (ORC) to generate further electricity for hydrogen production in an electrolyzer. In the first design, it is assumed that the SOFC stacks will work full-load during the 24 h of the day, while the second design considers full-load operation for 16 h and part-load (30%) operation for 8 h. The second design of the system analyzes the possibility of integrating a {mathrm{LiMn}}_{2}{mathrm{O}}_{4} lithium-ion battery stores the excessed electricity once the power load is low and acts as a backup in high power demands. Results of the thermodynamic analysis calculated the overall efficiencies of 60.84% and 60.67% for the energy and exergy, respectively, with the corresponding power and hydrogen production of 284.27 kWh and 0.17 g/s. It was observed that higher current density would increase the output of SOFC while reducing the overall energy and exergy efficiencies. In dynamic operation, the use of the batteries can well balance the change of the power loads and improve the dynamic response of the system to the simultaneous changes in the power demand. LCA results also showed that the 284.27kWh system leads to global warming (kg {mathrm{CO}}_{2} eq) of 5.17E+05, 4.47E+05, and 5.17E+05 using Solid Oxide Electrolyzer (SOE), Proton Exchange Membrane Electrolyzer (PEME), and Alkaline Electrolyzer (ALE), respectively. In this regard, the usage of PEME has the lowest impact on the environment in comparison to SOEC, and ALE. A comparison between the environmental impacts of different ORC’s working fluids also suggested against the usage of R227ea while R152a showed promising results to be used in the system. The size and weight study also revealed that the battery benefits from the lowest volume and weight in comparison to the other components. Among the considered components in this study, the SOFC unit and the PEME have by far the highest volume.

Heat pumps and thermal energy storages centralised management in a Renewable Energy Community.

This paper examines a Renewable Energy Community (REC) made up of 10 dwellings that collectively self-consume energy produced by a photovoltaic field connected to a water purifier. Each dwelling heat demand is satisfied by means of Heat Pump (HP) coupled with Thermal Energy Storage (TES), which can be managed to perform load shifting and increase collective-self-consumption (CSC). Techno-economic analyses are performed accounting for HPs' COP variation with temperature and part load operations, as well as TES heat dispersion. A new centralised control strategy for HPs is proposed and a sensitivity analysis is performed to assess the impact of varying TES system capacity. The results show that the centralised strategy can increase the CSC by 12-30%, with TES sizes of 100-1000 litres respectively. But the electricity consumption of HPs increases by 2-5% due to higher storage system temperatures causing worse average COPs by 2.3-0.6% and higher thermal losses by 29-58%. As a result, REC's energy independence rise, as does the amount of CSC incentives, but electricity bills also increase. Comparing these trends shows that CSC incentives should be adjusted according to energy prices to ensure cost-effective outcomes for all stakeholders and encourage the adoption of similar centralised control strategies.