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[Display omitted] • Thermal decoupling of methanation and electrolysis is an effective solution. • Power-to-Gas feasibility is strictly related on oxygen selling and local grants. • Highly efficient natural gas production with 75% conversion efficiency. • Optimization suggests reducing the capacity of the methanation reactor. This work presents a numerical analysis of a fully renewable Power-to-Gas system driven by photovoltaic and anaerobic digestion technologies, to produce synthetic renewable natural gas. The anaerobic digester is supplied by municipal wastes and it produces biogas, including about 35 % of carbon dioxide. This carbon dioxide is separated by means of an upgrading unit and it is combined in a three stage multi-tubular methanation reactor with the hydrogen produced by solid oxide electrolysis. A novel control strategy is developed to achieve a stable, safe, and efficient operation of the reactor. Suitable zero-dimensional and one-dimensional steady state models are developed in MatLab for the solid oxide electrolyzer and the methanation reactor. Such MatLab models are subsequently integrated into TRNSYS environment to perform the dynamic simulation for one year of operation of the whole system. A suitable thermoeconomic analysis is also implemented, also considering the possibility of selling the oxygen produced by the electrolyzer for industrial purposes. The results show that the proposed system achieves a primary energy saving of 30.33 GWh per year with 6,330 t CO2eq per year saved. The economic profitability of the is also very good, showing a Simple Payback of 2.63 years. The income due to the selling of oxygen plays a crucial role in this result. The overall efficiency of the system is equal to 0.75, that is extremely high when compared to similar layouts. The results from the thermoeconomic optimization show that the lowest Simple Payback value, i.e. less than 2 years, is obtained when the capacity of the methanation reactor is reduced by five times. [ABSTRACT FROM AUTHOR]

• Novel layout to be easily adopted by existing residential districts. • The novel layout can reduce the primary energy consumption of the residential district. • A primary energy saving index of 38 % and payback period of 2.2 years is achieved. • Power to heat strategy increases the district self-consumed electricity by 15%. • The power to heat strategy is able to further exploit the excess renewable electricity. This paper aims at reducing both electricity and space heating demands of residential districts. It specifically investigates the emerging paradigm, based on renewable energy communities, for existing residential districts. In particular, a novel renewable energy community layout is analyzed. This layout integrates a district heating network and the power to heat control strategy. The proposed system is designed to prevent any major refurbishment inside the apartments, using the existing high temperature space heating system. This arrangement is compared with more conventional renewable energy community layouts. Detailed dynamic models for both the residential district and the proposed layouts are developed using the TRNSYS software. Results show that renewable energy community is an extremely profitable paradigm for promoting the use of renewables at residential buildings scale. Moreover, the layout integrating energy community, district heating network, and Power-to-Heat strategy achieves the best results with a payback period of 2.2 years and a primary energy saving of 38 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nonlinear dynamic model of a green ammonia synthesis system is developed. • Start-up of H 2 and N 2 subsystems and warm start-up of ammonia reactor are studied. • System dynamic responses under fluctuations of renewable energy are also analyzed. • Bed temperature, H 2 /N 2 ratio and pressure are well maintained by PID controllers. • Buffer tank decreases the reactor variation and is important for pressure control. Green ammonia production system driven by renewable electricity will be under frequent dynamic operation due to the fluctuation of renewable energy. The nonlinear dynamic model of a green ammonia synthesis system is developed and the dynamic responses of PEM (proton exchange membrane) electrolysis subsystem, PSA (Pressure swing adsorption) subsystem and ammonia synthesis subsystem during the start-up process and under the fluctuation of renewable electrical current are analyzed. The start-up dynamic results show that the hydrogen production rate of PEM electrolysis system is positively correlated to the current. The nitrogen output of PSA system is affected by the adsorption time, adsorption pressure, bed length, and air velocity. A start-up period of 300 min from the warmed-up state to the design state can maintain the temperature rise rate of the ammonia synthesis reactor at approximately 40 K/h. The dynamic results under step fluctuations of electrical current show that the PEM electrolysis subsystem and the PSA subsystem response fast compared to the ammonia synthesis reactor and buffer tanks. Using large buffer tanks to smooth the fluctuation allows the system to slide with the variation of renewable current to some extent, resulting in a higher outlet ammonia fraction when the current increases. Different volume ratios of the hydrogen tank to the nitrogen tank volume can lead to different variations of the hydrogen/nitrogen ratio. PID controllers can effectively maintain the bed temperatures, hydrogen/nitrogen ratio, and pressure of the ammonia synthesis reactor at their set points despite fluctuations in renewable electrical current. Buffer tanks are necessary to compensate for the imbalance between the flow rate fluctuation caused by current change and the flow rate regulation caused by PID controllers. [ABSTRACT FROM AUTHOR]

scheme of the on-grid photovoltaic HVAC system. [Display omitted] • Modeling of split-type HVAC systems, VRF, and Chiller with thermoaccumulation; • Energy performance analysis of photovoltaic air conditioning systems; • Compatibility between thermal load and photovoltaic generation in offices; • Energy thermoaccumulation systems contribute to an increase in energy performance; • Photovoltaic air conditioning systems proposed reduced grid dependence by 87%; This article presents the air-conditioning performance analysis of an office building with thermal zones for the transient simulation of photovoltaic solar systems in a tropical climate. The study focuses on the correlation between air conditioning consumption and photovoltaic generation. The objective is to maximize the self-consumption of locally produced photovoltaic energy. The simulation and numerical analysis of the annual energy flow using a time interval resolution of 2 min was introduced as a novelty of the work to demonstrate the implementation of the proposed climatization technologies. The procedure developed was tested through 4 case studies where photovoltaic energy generation was scaled to meet the annual consumption demand of different air conditioners and considering the southern hemisphere climate conditions. The performance of the cases studied was evaluated considering an energetic point of view through metering of self-sufficiency and self-consumption of conditioners and a financial vision through indicators of Net Present Value, Internal Rate of Return, and Payback Period. It was possible to reduce energy by 96% at peak hours compared to the reference scenario using energy demand side management. From the energy point of view, the proposed cases proved to be viable. Regarding the economic aspects, the instances with the renewal of the splits and the central Variable Refrigerant Flow system presented the best financial indexes between 6 and 7 years of payback and internal rate of return of 22% and 21%, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D dynamic models for rSOC and methanol synthesis are developed in COMSOL. • Dynamic models are run jointly by MATLAB call with fluctuating PV power supply. • Multi-physics analysis and operation optimization on full PMPS are conducted. • Techno-economic comparison of PMPS and PHPS is conducted. • The roundtrip efficiency and levelized cost are 78% and 0.49 $/t CH 3 OH, respectively. Power-to-Methanol-to-Power System (PMPS) has a great potential for fluctuating renewable power storage and flexible power generation. In this study, a dynamic-cycle model of PMPS is developed by coupling reversible solid oxide cells with methanol synthesis process. The system stores energy from fluctuating photovoltaic power in the form of methanol during the day and generates electricity at night using the methanol fuel generated in the daytime. It is found that reducing the CO 2 ratio in co-electrolysis from 60% to 30% increases CH 3 OH production by 64% and doubles electricity efficiency due to the increased H 2 supply to methanol synthesis section. While in the fuel cell, reducing methanol supply rate from 500 to 200 SCCM increases power generation capacity by 110% with longer generating duration, and the electricity efficiency is improved from 30% to 61%. Besides, the optimized PMPS presents a round-trip efficiency of 78%, along with high conversion rates of carbon (97%) and hydrogen (84%), significantly exceeding that of the Power-to-Hydrogen-to-Power System (PHPS, the round-trip efficiency of 45%) under similar cell's inputs. Furthermore, our techno-economic analysis shows that the levelized fuel cost (0.49 $ t−1 CH 3 OH) and levelized generating capacity cost (0.22 $ /kWh) of PMPS are about 10% (4.8 $ t−1 H 2) and 74% of the PHPS, mainly due to the 16% lower capital expenditure of PMPS. [ABSTRACT FROM AUTHOR]

• Thermal performance of the proposed hot water storage was evaluated experimentally. • Proposed solution shows a 19% less total thermal loss than the centralised system. • Circulating pump in this solution consumes 11 times lower energy than centralised one. • The LCC of proposed solution is 6.1% lower than that of the centralised system. • Centralised system requires higher operating costs but a lower control system cost. The retrofit solution for domestic hot water (DHW) system in existing buildings requires to ensure the long-term energy security and efficiency as well as to minimise occupants' disturbance, construction works and installation costs. In this regard, the present study performs a techno-economic evaluation on a novel retrofit solution for DHW production in a pilot building. The proposed solution appoints a substantial role to the thermal energy storage through a 2-pipe hot water network utilisable for both DHW and heating purposes. The first storage level is provided by a centralised buffer storage supplied by a PV-BESS-driven heat pump while the second level consists of decentralised modular tanks installed in each dwelling for the production and storage of hot water. Firstly, experimental thermal performance of the proposed decentralised storages is investigated. By developing a dynamic simulation code, the energy efficiency of the proposed solution is compared to that of the existing system in the pilot building as well to that of a typical centralised system as a benchmark solution. Finally, economic analysis of the retrofit solution is performed to address capital expenditures of the system, including purchasing and installation costs, as well as its life cycle cost (LCC). The obtained results indicate that the proposed system reduces the annual energy consumption for DHW production more than 7,200 kWh, with respect to the existing DHW system. Furthermore, it is shown that, in the proposed system, the fraction of thermal loss from piping network decreases by 31.5%, compared to a typical DHW centralised system. Economic assessment of the proposed solution implies that this system, in terms of both mechanical and electrical components, requires 13.7% lower initial investment than a typical centralised system. However, the cost of control systems in this system is higher since it is inherently a control-based system. [ABSTRACT FROM AUTHOR]

• It is the basis for integrated energy system scheduling based on flow-regulation. • A hydraulic-thermal coupling dynamic model for heating network is proposed. • The modified forward–backward iteration is proposed for model calculation. • The exact hydraulic and thermal dynamic processes of heating network are obtained. • A data-driven hydraulic-thermal dynamic model is proposed for fast calculation. The district heating is expected to play a crucial role in the decarbonization of integrated energy systems within the context of attaining carbon neutrality. The literature review reveals a research gap in the investigation of models that account for the hydraulic-thermal coupling dynamic characteristics of heating networks in integrated energy systems, particularly those based on the flow-regulation mode. This discrepancy may affect the safety of the heating networks and contribute to the inefficient scheduling of integrated energy systems, which motivates this study. In this study, it refutes the harsh hypotheses in previous studies, making it more closely related to the real hydraulic and thermal conditions of heating networks. A mechanism-driven model is proposed, which involves the coupled hydraulic and thermal dynamic characteristics of heating networks. The modified forward–backward iteration as a calculation method is carried out, which is embedded with the method of characteristic and upwind difference. A data-driven hydraulic-thermal dynamic model is proposed for fast calculations. For model validation and case analysis, three heating networks in the integrated energy systems are utilized. The simulation results indicate that 1) The hydraulic and thermal average relative errors between the measured data and the simulation results are 0.396% and 0.091%, respectively, validating the effectiveness of the proposed dynamic mechanism model; 2) Compared to the current quasi-dynamic model, the proposed dynamic mechanism model could reflect the characteristics of heating networks more accurately and simulates the dynamic processes with higher resolution. These results demonstrate that the fluctuations of water head and pipe flow can reach 61.24 ∼ 237.53 m and −4.26 ∼ 32.16 kg/s, respectively. The average temperature difference between the two models is around 0.264 °C; 3) Compared to the forward–backward iteration, the modified forward–backward iteration has a superior convergence performance and calculation accuracy; 4) Compared to the quasi-dynamic model, the proposed data-driven model increases the overall accuracy of hydraulic-thermal calculations and significantly reduces the amount of time required. The average calculation time of the data-driven model is 0.0349 s, while those of the quasi-dynamic model and the proposed mechanism model are 352.92 s and 624.13 s, respectively. In conclusion, the proposed mechanism model of hydraulic-thermal coupling calculation and the related data-driven model are suitable for the dynamic simulations of heating networks in integrated energy systems. [ABSTRACT FROM AUTHOR]

• Micro heat pipe array-based BIPVT module enables efficient heat utilization. • A novel model of the BIPVT module and energy supply system was established. • Highly efficient combination of BIPVT and heat pump utilization is achieved. • Summarized the energy-saving features of BIPVT building in different seasons. • The novel BIPVT buildings achieve nearly zero energy standards. Building integrated photovoltaic–thermal (BIPVT) technology is an efficient form of solar energy utilization, which realizes self-energy supply and holds good development prospects. In this paper, a novel BIPVT module based on micro heat pipe array and BIPVT near-zero energy building are proposed. A matching multi-energy complementary energy supply system is also proposed for this building. The building and energy supply system models were built using TRNSYS. The load characteristics of BIPVT buildings were studied by analyzing the heat transfer process of BIPVT components. The energy-saving rate of the building was also calculated using the method of near-zero energy building evaluation index. The accumulated cooling load and heating load of the buildings throughout the year show that those of the BIPVT buildings are 8.6% higher than those of the benchmark building. Comparison of the energy consumption results shows that the annual cumulative energy consumption of the BIPVT building is 32.3% lower compared to the benchmark building's. In addition, 61.2% of the energy required for year-round refrigeration, heating, and electricity can be supplied by this system. The energy consumption index of the BIPVT building is 70.26 kWh / (m2 • a). Compared with the benchmark building, the BIPVT building energy saving rate is 76.6% and the building energy efficiency improvement rate is 32.3%. [ABSTRACT FROM AUTHOR]

Participants of the COP 26 summit have agreed to limit global temperature rise to 1.5 K by 2050. Out of the many strategies envisaged to meet the targets of COP 26, the 'Sector Coupling' process aims to use renewable electricity in residential heating, chemical industry, and transportation sectors. Several studies predict that de-central energy systems will play a significant role in the future. Among the proposed sector coupling strategies in de-central energy systems, the Power to Gas (PtG) process producing chemical energy carriers like Substitute Natural Gas (SNG) from renewable power is gaining acceptance. Numerical models of de-central energy systems are needed to analyse sector coupling under fluctuating renewable energy generation and changing gas demand. This study introduces a numerical model of a decentral energy system that includes a novel methanation concept developed at the Engler Bunte Institut of KIT called 3 Phase Methanation. Here, H 2 from electrolysis and CO 2 from DAC or other biomass-based sources are passed through a slurry bubble column reactor. The slurry is a suspension of the catalyst in a liquid heat transfer medium where the heat of the reaction is dissipated. The 3-Phase methanation process is modelled in this study using the axial dispersion method. Earlier studies describing experimental campaigns conducted on the pilot plant in KIT have proven that the reactor core is nearly isothermal with stable product gas compositions even if the load changes are instantaneous. In this study, it is shown that the numerical model can replicate the experimental results. Following modelling and validation, the numerical model of the PtG plant is integrated with the other components to simulate the de-central energy system. The simulation results demonstrate the dynamic output of all the components and, in particular, the response provided by the PtG plant. This model can be adapted to simulate sector coupling in future de-central energy systems and analyse aspects like long-term energy storage, GHG minimisation and cost-optimal operation. • The power to gas (PtG) process helps in decarbonisation through sector coupling. • Dynamic simulation of energy systems with PtG plants is the focus of this work. • A novel 3 Phase methanation capable of dynamic operation is introduced. • A numerical model is developed for decentral energy systems with dynamic PtG plants • The model can be customised for future decentral energy systems. [ABSTRACT FROM AUTHOR]

• Dynamic model of SOFC-Engine hybrid system was developed. • Individually developed components were integrated into one system. • The model was simulated based on the start-up scenario. • The dynamic behavior of components was analyzed. A dynamic simulation model of a hybrid power generation system of a solid oxide fuel cell and a homogeneous charge compression ignition engine was developed to investigate the behavior of the system during the start-up process. The stack, reformer, catalytic burner, and heat exchanger were implemented as dynamic models based on physical equations. For the engine, an experimental data-based mapping model was developed. The dynamic model was simulated on a Matlab/Simulink platform. Individually developed component models were assembled as an integrated system model and operated at the system level. The hybrid system was designed to generate approximately 4 kW of electricity from the SOFC stack and 1 kW from the engine, resulting in a total system power of 5 kW, with an electrical efficiency of 50.6%. The integrated model was operated using a four-step start-up procedure for 50 h, during which the temperature and composition of the stream were observed in time. Based on this, the dynamic behavior of the system was analyzed at each stage throughout the entire start-up process from ambient to high operating temperature. Validation of key results suggests a close resemblance between the model and an actual system. Therefore, the proposed model is expected to exceed the limitations of the existing static model analysis method. [ABSTRACT FROM AUTHOR]

• A new energy system is developed and examined using dynamic modelling to meet the needs of a two-story structure. • To decrease the size of the plant, including the PVT size and fuel consumption, the PCM is incorporated into the building. • Fuel consumption and prices are reduced by 17.24% and 8.57%, respectively, using the suggested approach. • Exergy efficiency, unit product cost, and CO 2 emission of 64.3 %, 0.26 $/kWh, and 0.21 kg/kWh are obtained respectively at optimum point. The buildings energy sector is expected to account for 40% of total world energy consumption and 40% participation on total carbon dioxide emissions, according to the International Energy Agency reports. The present study proposes a novel integrated system to meet all loads of the house's energy requirements. The system employs a heat storage tank rather than pricey batteries, which helps to keep the total cost of the system as low as feasible. Also, the system is developed for an on-grid operation, being capable to sell surplus energy to the grid helping to reduce the payback time. Dynamic modeling is conducted to analyze the system performance to provide heating, cooling and power demands of a case study building, for which two scenarios of with and without Phase Change Material (PCM) incorporation is considered. The influence of critical design factors is investigated, after which a tri-objective optimization is carried out. It was found that, the integration of PCM energy storage would reduce the annual heating and cooling demands of the building by 25.6%. As a result, the exergy efficiency of the proposed system increases by 13 % and the product cost is reduced by 8.57%. Based on the obtained yearly average results, the proposed building energy system yields exergy efficiency, unit product cost, and CO 2 emission of 64.3 %, 0.26 $/kWh, and 0.21 kg/kWh, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hierarchical coupled method reduces the computational cost of co-optimization. • Synergistic planning of supply and demand further enhances economic and environmental benefits. • Consider dynamic features of the thermal load to further exploit energy-saving potential. • Excessive insulation of building envelope may lead to opposite effect for energy saving. In the low-carbon transition process of urban energy systems, synergistic planning with different sectors faces challenges in terms of modeling complexity, optimization accuracy and computational cost due to inconsistent granularity of models and methods. This study proposes a hierarchical coupled optimization method for cross-sectoral synergistic planning for supply and demand sides of urban energy systems. It integrates thermal load simulation of different demand-side energy-saving retrofits based on state space method with mixed integer linear programming of whole energy systems. This method enables reduced-order description of the time-varying multidimensional process while preserving the dynamic characteristics of demand-side to solve the problems of precision and scale difference in simulation and optimization. The case study shows that the optimal demand-side strategy enables 48.20% building energy-saving, while the optimal supply-side technology enables 36.77% emission reduction throughout the year. The emission reduction rate of the whole systems can be further increased by 6.16%∼30.42% after the combination of passive and active energy-saving means. Meanwhile, compared with the baseline scenario, the synergistic optimization solutions in this case results in a 24.22% decrease in net present value of cost and a 50.35% decrease in total carbon emission. This means that the energy-saving and emission reduction potential of the integrated systems can be further exploited through the integration of multiple building retrofit strategies and renewable technologies. This hierarchical approach helps to design effective cross-sector synergistic solutions that achieve a reasonable trade-off of economic benefits and environmental sustainability of the whole systems. Overall, this study integrates different models and approaches of the supply and demand sectors to provide flexible and integrated solutions for low-carbon design and operation management of urban energy systems with building energy-saving retrofit. [ABSTRACT FROM AUTHOR]

• The system analysis program for the 5 MW Small Modular Supercritical CO 2 Brayton-Cycle Reactor System is established and validated. • When the reactor power decreases, the power decrease percentage of the regenerator is the largest and the heat transfer may deteriorate. • At the case of the reactor rod ejection accident, the reactor system is with the good ability of the negative feedback regulation and certain self-stability. • When the temperature of cooling water only increases by 1 °C, the system output power can reduce about 10%. Ensuring the sufficient cooling capacity of the cooler is significant. • The compressor is more sensitive to the input parameter disturbance caused by the reactor and cooler. Small nuclear reactor system (SMR) has good development prospect in energy supply because of its flexible arrangement, wide application, and low cost. Among many small nuclear reactor systems, the Brayton cycle reactor system with supercritical CO 2 (SCO 2) as a working medium stands out. It has the advantages of high conversion efficiency, simple design, compact structure, high inherent safety, and is suitable for almost all nuclear power systems, especially small modular reactors (SMR). However, due to the unique thermophysical properties of SCO 2 , the transient operation characteristics of the system and the coupling effect between the main equipment are not precise. In this study, a dynamic model of the 5 MW modular SCO 2 Brayton cycle reactor system was established, and the system's dynamic operation characteristics and off-design control strategy were evaluated. Firstly, the steady-state simulation of the system is carried out to verify the physical model of the main equipment. Secondly, the typical transient operating conditions such as the reactor power fluctuation, reactor reactivity insertion, cooling water flow rate and temperature fluctuation, and loss of the external load are calculated. The dynamic characteristics of the system and the coupling effect between the main equipment are analyzed. The simulation results show that the control system is with good control effect and regulation ability under the condition of the reactor control rod ejection accident. The system is quite sensitive to the change of the cooling water temperature and flow rate. When the external load is lost, the turbine bypass control method can quickly match the system output power and keep the rotor speed reasonably. The dynamic modeling of the system is beneficial for the analysis of the operation characteristics and control effect of the system under variable conditions. It can provide the basis for the design, evaluation, and control strategy formulation of the system. [ABSTRACT FROM AUTHOR]

• A storage system to recover energy during startups of combined cycles is proposed. • Low payback period 3–3.4 years and energy recovery efficiency up to 80 % • The optimum solutions present a net present value between 2.53 and 4.45 M€. • The net present value grows up to 60% considering the benefits from carbon credits. • Between 2 175–3 640 tons of CO 2 emissions per year can be avoided. This work presents a novel steam accumulator and concrete-block storage system (SACSS) to recover part of the energy lost through the steam cycle side during startups of combined cycle power plants (CCPPs). The steam accumulators are integrated with sensible-heat concrete storage to provide superheated steam resulting then to a higher efficiency and safer steam turbine operation compared with systems based only on saturated steam. An economic analysis is performed considering two different scenarios: i) a CCPP able to execute fast startups using a Benson-type heat recovery steam generator (HRSG) and ii) a CCPP operated with conventional startups which employs a typical drum-type HRSG. It is worth mentioning that the second scenario is based on measured data. The economic optimization of the SACSS is carried out focusing in four design variables: number of steam accumulator units, storage pressure, concrete-block length and outer concrete diameter. The optimum solution presents a net present value of 4.45 M€ and a payback period of 3 years for the CCPP suitable for fast startups. For the CCPP operated with conventional startups, a net present value of 2.53 M€ and a payback period of 3.4 years are obtained. The net present value grows around 60 % in both cases if the benefits from carbon credits are considered. In addition to the efficiency improvement, the SACSS could be used to preheat critical sections of the heat recovery steam generators, reducing the thermal stress and the fatigue damage during fast startups. Finally, the emissions avoided thanks to SACSS are estimated to be around 3 640 and 2 175 tons of CO 2 per year, for fast and conventional startup cases, respectively. [ABSTRACT FROM AUTHOR]

In the present work, water desalination by solar energy is investigated based on life cycle cost. In the first step, regions under consideration are prioritized for solar energy utilization applying an appropriate ranking method based on desalinated water demand, saline water availability, annual average solar irradiation, and local water tensions. TRNSYS software is used for simulation and a multi-stage flash desalination system is defined in this software as a new component type by employing the Fortran program. Solar troughs and natural gas are used for solar energy extraction and heater, respectively. The considered system is investigated in seven different cities with high solar potential from the economic point of view. Also, an economic comparison is conducted in order to assess the multi-stage flash desalination system utilizing solar collector, auxiliary heater, and the system using natural gas without solar system. In this regard, the life cycle cost method is applied. The results of the study showed that using solar energy is more economical in comparison with natural gas for all of the case studies and the highest saving is obtained for Port Hedland in Australia. The lowest cycle cost of the system, utilizing solar energy and natural gas, is observed in Hurghada. In Hurghada, 88% of the energy required by the system is supplied by sun, and this city benefits the most from solar energy compared to other cities. Los Angeles and Manzanillo had the lowest share of solar energy at 59% and 57%, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biomass power plant model integrated with thermochemical heat storage was created. • Fluidized bed using Ca(OH) 2 /CaO stores surplus electricity from renewable energy. • Overall energy efficiency was 9.79% for the base case (output: 1 MW el). • Steam flow rate is most important parameter for flexible power generation. • Energy storage efficiency is dramatically improved by recycling steam. In this study, a biomass power plant integrated with thermochemical heat storage (TCS) using Ca(OH) 2 /CaO particles reacted in a fluidized bed reactor was proposed. In the strategy of power generation, organic Rankine cycle (ORC) was worked by the heat from biomass combustion in normal operation. In charging time, the electricity from the power grid was stored by dehydration reaction in the daytime although the turbine output was not changed, and the amount of biomass combustion decreased compared to normal operation time. In discharging time, the heat from hydration reaction was converted to electricity through the ORC in the evening and the turbine output increased to respond to the increase of the electricity demand. The designed process was evaluated from energy efficiencies and the flexibility of the power generation by dynamic simulation. Results show energy storage efficiency and overall energy efficiency equaled 58.5% and 9.79% (only ORC: 11.4%) for base case, respectively. The energy storage efficiency increased by increasing the heat recovery from steam after a reactor, and it led to the decrease of the biomass combustion in charging time. It was found that the inlet gas flow rate into the reactor had the largest influence on energy efficiencies by changing the parameters such as fluidized bed volume, inlet gas conditions into the reactor, and heat supply into the reactor. In addition, the increase of the turbine output and discharging time were flexibly changed in discharging time by changing operational parameters. Therefore, it is possible to add flexibility to biomass power plants by integrating TCS. [ABSTRACT FROM AUTHOR]