Part Load Operation Research Articles

CFD analysis of Part-Load operation of an Open-Circuit Induced-Draft cooling tower

Evaporative towers are the most widely used systems for cooling water in industrial processes. These systems, however, are characterized by high energy and water consumptions. Therefore, technologies and operating strategies for optimization of these devices are highly recommended. The heat exchange, which takes place inside an evaporative tower is very complex and not easy to model. In this work, an induced-draft evaporative tower is modelled by means of computational fluid dynamics (CFD), which is relatively new in this field of application. A numerical model, based on the adoption of sub-models for the heat exchange between the water droplets and humid air in the filling region, is developed and validated with experimental data, laying the foundation for further analysis in the future. The achieved results can be considered reliable and accurate as the numerical uncertainty is approximately 4 %. The study aims at evaluating and analyzing the thermo-fluid-dynamic quantities that characterize the heat exchange, with reference to water outlet temperature, cooling capacity, and evaporated water flow rate. In particular, partial load operation are analyzed. The conditions refer to the simultaneous reduction of water and air flow rates. The study shows that both at full load operation and by reducing water and air flow rates to 60 % of the design value while maintaining a constant water/air ratio, the tower process parameters are kept very close to the design ones. Under these conditions, the evaporated water is halved (∼0.05 kg/s instead of ∼ 0.1 kg/s maintaining air flow at full load). Moreover, by adopting lower water and air flow rates a significant reduction of the electric power requested by the fan, from 15 kW at full load to about 8 kW at part load, is achieved.

Green hydrogen to tackle the power curtailment: Meteorological data-based capacity factor and techno-economic analysis

Hydrogen production through water electrolysis stands as a potential remedy for the problem of curtailment, which refers to the deliberate downward adjustment of output power below capacity for the purpose of balancing supply and demand. This study demonstrates how comprehensive system modeling can be used to a priori assess the economics of producing green hydrogen from curtailed renewable energy of solar and wind. A case study is presented to demonstrate how actual meteorological data are utilized to anticipate the quantity of renewable energy throughout the year, which in turn is used to estimate the capacity factor and LCOH (Levelized Cost of Hydrogen) of a renewable energy/water electrolysis system. The base case of a renewable energy source of 100 MW capacity coupled with a 20 MW hydrogen production system and 20 MW transmission to the grid shows an LCOH of 5.9 USD/kg with a capacity factor of 25%. Sensitivity analysis is carried out to examine the impact of electrolyser size and the composition of renewable energy source on its capacity factor and economic feasibility. The results demonstrate that the capacity factor of an electrolysis system is not directly proportional to the renewable energy capacity but depends on the its designed capacity as well as the climate pattern and the mix ratio between solar and wind energy. Though the effect of the electrolyser’s operating range is found insignificant in a part-load operation but not in an overload operation. In addition, the effects of the capital cost, system efficiency, and electricity price on LCOH are assessed.

Electrode Separators for the Next-Generation Alkaline Water Electrolyzers.

Multi-gigawatt-scale hydrogen production by water electrolysis is central in the green transition when it comes to storage of energy and forming the basis for sustainable fuels and materials. Alkaline water electrolysis plays a key role in this context, as the scale of implementation is not limited by the availability of scarce and expensive raw materials. Even though it is a mature technology, the new technological context of the renewable energy system demands more from the systems in terms of higher energy efficiency, enhanced rate capability, as well as dynamic, part-load, and differential pressure operation capability. New electrode separators that can support high currents at small ohmic losses, while effectively suppressing gas crossover, are essential to achieving this. This Focus Review compares the three main development paths that are currently being pursued in the field with the aim to identify the advantages and drawbacks of the different approaches in order to illuminate rational ways forward.

Experimental assessment of a pilot-scale gasification plant fueled with olive pomace pellets for combined power, heat and biochar production

This research work examines the performance of an experimental gasification plant fueled with exhausted olive pomace pellets for the concurrent production of electricity, heat and biochar in the olive oil industry. The gasification plant consists of an air-blown downdraft fixed-bed gasifier that generates a lean fuel gas, termed producer gas, in a self-sustaining autothermal process. After conditioning of the producer gas in a cooling and cleaning unit, a four-stroke spark-ignition engine coupled to an electric generator is eventually used as power generation unit. An extensive experimental assessment of this facility was performed under partial and nominal load operation and was supplemented by a physicochemical analysis of the carbonaceous solid material discharged from the gasifier. The mass and energy balances of the gasification plant were calculated, including the carbon conversion efficiency and diverse energy conversion efficiencies. The results revealed an overall stable operation of the gasification plant in terms of composition and heating value of the producer gas and cogenerative production of electricity and heat in the engine–generator set. Under nominal operating conditions, the net electrical efficiency of the gasification plant was 12%–13%, with an average carbon conversion efficiency of the biomass feedstock into producer gas just above 80% and an average cold gas efficiency close to 70%.

A strategy to extend load operation map range in oxy-fuel compression ignition engines with oxygen separation membranes

The possibility of applying oxy-fuel combustion to a compression ignition engine (CIE) at different operating points regarding engine speed and load is studied in this work. To do so, a strategy is proposed to extend the load operation map range of a 2.2L turbocharged and direct-injection CIE under oxy-fuel combustion conditions using mixed ionic-electronic conducting membranes (MIEC) to acquire oxygen (O2) from the air. As nitrogen is not present in the intake flow, nitrogen oxide (NOx) emissions are eliminated, and carbon capture is allowed. The strategy consists of modifying exhaust gas temperature and oxygen-fuel ratio , generating temperature-lambda maps to decide the optimal combination in terms of engine performance. Thus, the system behavior is analyzed at three engine speeds (1250rpm, 2500rpm and 3500rpm) with different load levels and compression ratio (CR) of 20. The baseline engine model is calibrated with experimental data within part-load operation ranges, and an apparent combustion time model calibrated with computational fluid dynamics data is applied to simulate the combustion process under oxy-fuel combustion conditions. Finally, specific parameters are researched to verify whether the system produces enough energy to heat up the MIEC, generating the necessary oxygen. Indeed, a few of them have been found very useful as design parameters for finding out oxy-fuel engine operation limits and estimating MIEC design features.

Energy prosumerism using photovoltaic power plant and hydrogen combustion engine: Energy and thermo-ecological assessment

Renewable Energy Sources (RES) represent an attractive way to save natural resources and improve the overall impact of power systems on the environment. A continuous increase of share of RES in national energy mixes is observed, and due to the energy policy of the European Union and many other countries, further increase is expected. A disadvantage of RES is their random, weather-dependent availability, which requires energy storage. A promising method of integrating RES with the energy system is the use of hydrogen as an energy carrier (e.g. coupling RES with electrolyzers in order to directly use the renewable electricity for production of hydrogen). In the present work, a simulation of cooperation of a photovoltaic power plant with a gas piston engine fueled by hydrogen was performed, with and without the presence of energy storage. The aim of the analysis is twofold. First, the “compensation losses” due to forced part-load operation of the engine coupled with RES are evaluated and compared with “storage losses” resulting from the thermodynamic imperfectness of the storage; this allows to calculate the minimum round-trip efficiency of storage required for positive energy effect. The “compensation losses” have been determined to be of the order of magnitude of 2%, and the minimum round-trip efficiency of storage to be at the level of 85%. Second, a thermo-ecological analysis was carried out to determine the impact of the source of hydrogen on the overall ecological effectiveness of the system. Contrary to the commonly used measure of “energy efficiency” describing a local balance boundary, thermo-ecological cost (TEC) evaluates the consumption of non-renewable exergy within a global balance boundary. The analysis confirmed that comparing various hydrogen production methods (especially renewable and non-renewable) in terms of local energy efficiency is inadequate, because it does not tell much about their sustainability. For a hydrogen energy system basing on the water electrolysis – hydrogen transport/storage – combustion in a gas piston engine pathway to be considered sustainable, the input electricity to the electrolysis process should be characterized by TEC lower than ∼0.15 J∗/J, a value which even some renewable energy sources fail to achieve.

Heat Transfer Analysis Using Thermofluid Network Models for Industrial Biomass and Utility Scale Coal-Fired Boilers

Integrated whole-boiler process models are useful in the design of biomass and coal-fired boilers, and they can also be used to analyse different scenarios such as low load operation and alternate fuel firing. Whereas CFD models are typically applied to analyse the detail heat transfer phenomena in furnaces, analysis of the integrated whole-boiler performance requires one-dimensional thermofluid network models. These incorporate zero-dimensional furnace models combined with the solution of the fundamental mass, energy, and momentum balance equations for the different heat exchangers and fluid streams. This approach is not new, and there is a large amount of information available in textbooks and technical papers. However, the information is fragmented and incomplete and therefore difficult to follow and apply. The aim of this review paper is therefore to: (i) provide a review of recent literature to show how the different approaches to boiler modelling have been applied; (ii) to provide a review and clear description of the thermofluid network modelling methodology, including the simplifying assumptions and its implications; and (iii) to demonstrate the methodology by applying it to two case study boilers with different geometries, firing systems and fuels at various loads, and comparing the results to site measurements, which highlight important aspects of the methodology. The model results compare well with values obtained from site measurements and detail CFD models for full load and part load operation. The results show the importance of utilising the high particle load model for the effective emissivity and absorptivity of the flue gas and particle suspension rather than the standard model, especially in the case of a high ash fuel. It also shows that the projected method provides better results than the direct method for the furnace water wall heat transfer.

Part-load performance prediction of a novel diluted ammonia-fueled solid oxide fuel cell and engine combined system with hydrogen regeneration via data-driven model

This paper proposes a novel diluted ammonia-fueled solid oxide fuel cell and X-type rotary engine (SOFC-XRE) combined system with hydrogen regeneration sub-system to realize high energy conversion efficiency. The combined system key design parameters and geometric parameters are optimized. The influences of SOFC inlet temperature, stack fuel utilization ratio, stack excess air ratio and pressure ratio across membrane for permeating hydrogen on system off-design performance are investigated. Meanwhile, the improved off-design performance of combined system is revealed by comparing with standalone SOFC. The data-driven neural network model (NNM) is established for predicting system part-load performance based on the off-design performance datasets. The optimal system operation parameter combinations and performances in a wide power load range are obtained by combining data-driven NNM with particle swarm optimization (PSO) algorithm. The results show that the cell stack temperature gradient decreases with decreasing fuel flow rate coefficient. The stack fuel utilization ratio has a larger effect on combined system energy efficiency than the fuel flow rate coefficient. The optimal membrane pressure ratio and fuel flow rate coefficient decrease with decreasing power load. The combined system energy efficiency is increased by 5.94% as the power load is decreased by 75%, while it is decreased by 2.1% as the power load is increased by 20%. The combined system energy efficiency is 10.9–12.2% higher than standalone SOFC in a wide combined system power load range of 120–25% without carbon emission.

Tradeoff between the efficiency penalty and load depth in a coal-fired power plant with CO2 capture under partial load conditions

With the penetration of renewable energy increasing rapidly in the power system, flexible operation of coal-fired power plants with CO2 capture is expected to play a key role in grid peak-regulating in China. However, studies on the interactions between power generation and CO2 separation units under partial load are still limited. Accordingly, in this paper, the factors that affect the system performance were investigated based on a 1000-MW post-combustion power plant under partial load. The results indicate that minimizing the difference between the quality of the steam extracted from the turbine and the minimum steam quality required for the reboiler, meanwhile resulting in no extra work losses, is the essential target for system integration. Under the IP-LP-PMV (Pressure Maintaining Valve) scheme, the irreversible loss caused by PMV led to an extra system efficiency penalty of 3.31% points under 30% load. However, for the IP-interstage-PMV scheme, the system efficiency could be improved by 0.7% and 1% points under loads of 30% and 40%, respectively, because the work losses caused by splitting and throttling under low load conditions could be reduced by adjusting the extraction location. Therefore, the system performance could be improved by altering the extraction position under partial load operation. By investigating the optimal extraction location under variable loads, it is disclosed that the IP-interstage-PMV scheme and the IP-LP-PMV scheme are the most efficient steam extraction schemes under 40% or 70% loads respectively. Therefore, the theoretical optimal steam extraction position varied under the different loads, and the extraction position should be selected based on the average operating load from the perspective of all the working conditions. This integration principle provides the highest performance improvement potential of 2% points for partial load operation. This study will be helpful to promoting the further deployment of large-scale post-combustion capture projects.

Part-load performance analysis of a dual-recuperated gas turbine combined cycle system

To undertake peak shaving tasks, gas turbine combined cycle (GTCC) units often deviate from the design operating point. In order to improve the off-design performance of GTCCs, a dual-recuperated gas turbine combined cycle (DRGTCC) system based on partial recuperation and compressor inlet air heating is proposed in this paper. The operating characteristics of the novel system using the proposed operation strategy are investigated, and the effects of pressure drop in recuperators and ambient temperature on system performance are discussed. The results indicate that, compared with the GTCC system, the DRGTCC system has higher turbine inlet temperature (TIT) and turbine expansion ratio at the same power output, and the performance has been improved especially at lower power outputs. When the inlet temperature of the compressor is increased from 0 °C to 45 °C, the air mass flowrate can be regulated between 46.0% and 100% of the design value. The combined cycle efficiency of the DRGTCC system is improved by 2.55 percentage points at 45.5% design combined cycle load. Moreover, the sensitivity analysis shows that the system performance decreases with the increase of the pressure drop in recuperators, and the ambient temperature affects the load regulation range and efficiency.

Impact of power supply fluctuation and part load operation on the efficiency of alkaline water electrolysis

Contrary to traditional electrolysers which operate continuously at their nominal load, future alkaline electrolysers need to be able to operate over a wide load range due to the variability of renewable electricity supply. We have investigated how the residual ripples from thyristor-based power supplies are influenced by the operating load of the system, and how these ripples affect the efficiency of alkaline electrolysers. For this, a simulation tool was developed which combines a six-pulse bridge thyristor rectifier model with closed-loop current control and semi-empirical electrolysis models. The electrolysis models can simulate the potential response to both direct and high amplitude alternating currents for lab-scale and industrial electrolysers. The electrolysis model of the lab-scale electrolyser was validated with experiments with a square wave current input. The models show that without filters the ripples result in a total system efficiency loss of 1.2–2.5% at full load and of 5.6–10.6% at a part load of 20% depending on the type of electrolyser. The implementation of an optimized L-filter suppresses residual ripples and reduces the efficiency losses to 0.5%–0.8% at full load and to 0.8–1.2% at the minimum load.

A self-oscillating series-none inductive power transfer system using a matrix converter

Power density and conversion efficiency are two critical parameters of inductive power transfer (IPT) systems. These parameters are related to the number of components in the power conversion circuit as well as its modulation method. The combination of Midpoint Matrix Converter and pulse-density modulation (PDM) has a potential to improve these parameters, due to a low number of semiconductor switches utilization as well as constant efficiency at the maximum output and partial load operations . In this context, this paper analyzes the performance of a three-phase to single-phase Midpoint Matrix Converter using a Free-wheeling Switch (MMCFS) and the PDM in a high coupling factor series-none IPT application. This converter utilizes on–off control to manage power transfer, which automatically tracks the load resonant frequency. Dynamic and steady-state mathematical equations were derived to represent the converter and the IPT system characteristics. These equations show a relationship between the link efficiency, the link gain, the damping ratio and the coupling factor. A kick-start method and a multistep switching strategy were developed to start and operate the converter, respectively. Additionally, a 150 W MMCFS-based IPT prototype was built to verify the improvement, which demonstrated an efficiency of around 80% at the maximum output and partial load operations.

Experimental and theoretical evaluation of a 60 kW PEM electrolysis system for flexible dynamic operation

Electrolysis systems based on low temperature PEM cells have fast ramp rate and load-following capability that makes them suitable to provide services to the power grid, whose reliability is hindered by the increasing deployment of dynamic and non-controllable renewable energy sources. Flexible operation of the complete electrolysis unit is influenced by system design and auxiliaries: this work provides an insight on the dynamics of integrated components, aiming at the enhancement of the flexible operation of an industrial-scale PEM electrolysis system. A numerical dynamic model of a complete electrolysis unit is implemented with the software Simulink, combining customized dynamic models of the main balance of plant components. Mass and energy balances are solved during variable load operation, while PI–type and on–off controllers are included for system operation control. The electrolysis stack performance depends on semi-empirical polarization curves, reflecting voltage dependance on temperature, pressure, and current density. The solved transients of the device provide original indications for increasing the dynamic performance of the system.A 60 kWe commercial unit is tested to validate the model, assessing its nominal and partial load performance. The experimental data confirm the capability of the system to work at partial load without relevant deviations in the stack temperature and pressure. Despite the lower specific consumption of the stack at partial load, the system shows an increase in the average net specific consumptions when the load decreases toward its minimum (from 67 kWhe/kgH2 above 1A/cm2 to 140kWhe/kgH2 at 0.3A/cm2).The simulation results and the experimental data are in good agreement, confirming the prediction capacities of the model with a good accuracy. Among the different investigated operation strategies, the strongest reduction in average net specific consumption at partial load is given by the control of water flowrate to the stack (110 kWhe/kgH2 at 0.3 A/cm2) or of the hydrogen dryer regeneration (70 kWhe/kgH2 at 0.3 A/cm2). These are the suggested points to be investigated for further improvements of fast-changing load systems.

Dynamic Simulation of Partial Load Operation of an Organic Rankine Cycle with Two Parallel Expanders

The parallel expander ORC system is one of the solutions for providing an additional power output by improving the partial-load performance of an ORC. The parallel expander system corresponds to partial-load conditions by switching between various combinations of the expanders. During this process, the dynamic behavior occurs, which have not been characterized well in the open literature according to the best of the authors’ knowledge. In this study, we developed a dynamic modeling of an ORC system using dual expanders (DE-ORC) to study the dynamic responses during its mode changes. System components were simulated using an open-source library of ThermoCycle written in Modelica language. For each component, empirical parameters were implemented based on the experimental results. Furthermore, during the mode change that involved going from dual expander mode to singular expander mode, and to prevent the formation of the droplet in the expanders, a control strategy was proposed and simulated. The strategy involved lowering of the mass flow rate and then shifting the mode. Several timings between flow rate lowering and shifting the mode were analyzed, and the optimum shifting time was found to be in between 40 to 50 s.

Experimental investigation of saturated fogging and overspray influence on part-load micro gas turbine performance

• Part-load MGT performance with water spray at the inlet is studied experimentally. • The ambient temperature impact on MGT performance is varied with its load. • The benefits of inlet fogging and overspray systems deceases with loads. • MGT performance is enhanced with water injection with fixed fuel consumption. • Inlet fogging and overspray reduce NO but increase CO concentrations. Micro gas turbines (MGT) are promising power sources for modern industries, especially in the distributed energy generation market, due to their relatively high projected energy densities. Nevertheless, they suffer from lower thermal efficiency due to the inherent constraint of high- exhaust temperature and the relatively high compression work, especially during hot days and partial load operation. Water injection into gas turbine inlet air is a possible route to improve the MGT performance. As a result of the lack of previous experimental studies related to the study of fog and overspray on turbines at partial load operations, the current study aims to evaluate the influence of saturated fogging (inlet fogging) and overspray on the MGT part-load performance experimentally. Two test benches were installed to implement inlet fogging and overspray on a 10 kW MGT. Droplet size and injected water mass flow were measured at varied spraying pressures and nozzle diameters to determine optimum spray conditions. The output power and specific fuel consumption were measured at different overspray ratios for various MGT loads. The results showed that the enhancement in power output due to inlet fogging and overspray varied according to the applied load. After applying saturated fogging, the output power augmentation corresponding to a 14℃-temperature drop was 9.32% at a load of 30%, while this value decreased to 6.86 and 4.91% for loads 50 and 70 %, respectively. It was also observed that a continuous boost in net power output with an increased overspray ratio. Increasing the load from 30 to 70% reduced the power enhancement by about 42 and 39% for overspray ratios of 1 and 2%, respectively. The maximum output power and specific fuel consumption improvement were achieved at a 2% overspray ratio. Inlet fogging and overspray reduced NO concentrations for all loads, and vice versa for CO concentrations, and emission slop decreased with the load.

Dynamics and control implementation of a supercritical CO2 simple recuperated cycle

Interest in supercritical CO2 power cycles is constantly increasing, showing good efficiency, and promising competitive costs and enhanced flexibility with respect to competing systems. Some project within the EU Horizon 2020 program have studied these systems and aim to demonstrate them in large scale, following the example of the STEP project in US. This work is part of the effort of the SOLARSCO2OL project to build a sCO2-CSP power demo plant at MW scale. A dynamic model of a simple recuperated sCO2 cycle is developed in TRANSEO, using miniREFPROP to compute fluid properties, and table of properties are implemented, when possible, to enhance the performance of the code. Control logics is described and simple controllers implemented. Finally, controllers are tested showing the response of the main parameters of the plant to a ramp variation of the load. Stable compressor inlet pressure is achieved with an inventory control, while a stable turbine inlet temperature allows a high efficiency in part-load operation.

Dynamic analysis of single–double-effect absorption chiller with variable thermal conductance during partial-load operation

• This study presents the dynamic analysis with variable thermal conductance. • Resistance ratio method is introduced to capture the variable thermal conductance. • The field test and simulation results have a good agreement. • An effective operation strategy that can improve the system performance is proposed. • The proposed operational approach increases the COP by as much as 32%. A numerical model for the dynamic analysis and control of a solar-assisted single–double-effect absorption chiller is presented. The mathematical model relies on energy and mass balances, which consider the heat and mass storage in each component. The resistance ratio method is introduced to capture the variation in the thermal conductance representing system disturbances and load variations according to the internal and external flow rates. The model was validated with reference to the outlet temperatures of hot, cooling, and chilled water from field test data for a given gas flow rate and corresponding inlet temperatures. The agreement between the field test and simulation results demonstrates the reliability of the model. Deviations between simulated and experimental temperatures mostly stays below 0.5 °C. The model was used to establish an effective operating strategy capable of minimizing the primary energy consumption without affecting the stability of the cooling output capacity and to verify the corresponding beneficial effect. The proposed operational approach increases the coefficient of performance by as much as 32 % compared with the previously implemented operation strategy, reaching up to a maximum value of 10.7 at 60 % cooling capacity.

Carbon Capture Performance Assessment Applied to Combined Cycle Gas Turbine Under Part-Load Operation

Abstract The growing share of renewable energies in our electricity production, together with the still lacking storage capacity, strongly reinforces the need for more flexible electricity production units. In this context, combined cycle gas turbines (CCGTs) have a role to play, both in the current and future electricity production system due to their high efficiency, high load flexibility, and low CO2 emissions compared to other conventional thermal power plants. Nevertheless, bearing in mind our current challenges concerning climate change, the CO2 emissions of these CCGTs need to be reduced drastically. The amine-based absorption carbon capture (CC) process is currently the most mature and applicable CC technology. This process is known to require a considerable amount of thermal energy, degrading plant performance. However, to back-up renewable production, CCGTs will operate most of the time under part-load conditions. The impact of these part-load operations on the CC is still relatively unknown. Within this framework, this study aims to assess the performance of the CC process applied to a typical CCGT under part-load operation using specific simulation models. The CC plant model has been successfully validated against experimental data from a pilot-scale capture facility. Then, the CC plant has been scaled-up to the CCGT scale and the process has been optimized for each operating condition. The simulation results show that the specific reboiler duty increases for part-load operation, while the specific cooling requirements decrease. Moreover, the analysis of the yearly CCGT operation highlights a relative increase in CC energy penalty of 21% for an annual CCGT load factor of 0.5, impacting significantly plant performance. The next step will involve reducing this energy penalty.

Modelling the Wind Turbine by Using the Tip-Speed Ratio for Estimation and Control

The development of dynamic models for control purposes is characterised by the challenge of finding a compromise between the minimum necessary information about the system dynamics contained in the model and a model with a low level of complexity such that the model-based control system design becomes comfortable. To achieve this balance, a modified dynamic model for the drivetrain of a wind turbine is proposed in this contribution. The main idea is to introduce the tip-speed ratio as a state variable so that an interval observer can be designed in such a way that its estimates can be used in the torque control during the partial load operation as well as for the estimation of the effective wind speed. During the runtime, the observer’s matrix gain is recalculated to adapt the behaviour to the current operational state, which changes all the time with the wind speed. Besides the theoretical formulation, a numerical example of a 20 MW reference wind turbine illustrates the utility of the method. The results show good control performance concerning the tip-speed ratio control loop and a satisfactory estimation of the effective wind speed.

Challenges in part load operation of biogas-based power-to-gas processes (part I)

Direct methanation of biogas enables the storage of electrical energy in carbon-neutral (bio-)methane and subsequent injection into the national gas distribution grid. The intermittent availability of renewable electricity, as well as the varying nature of biogas production by e.g. anaerobic digestion, necessitate enhanced operational flexibility of such a Power-to-Gas process and intermediate buffer storage. This work provides experimental data of dynamic part load operation of a TRL 5 methanation plant with gas upgrading to grid-ready biomethane. Full recycling of unreacted H2 could be achieved by a commercial biogas upgrading membrane (Evonik SEPURAN® Green). Using real biogas, a sequence of load levels down to 45% of the full load capacity were tested. Stable operation of the plant could be demonstrated and grid injection limitations could be fulfilled after equilibration of the system. Additionally, an idealised PtG process chain was simulated with the focus on a sensitivity analysis of the H2 storage capacity on the methanation operation hours. It was shown that increasing the hydrogen storage capacity decreases the number of start-up and shut down procedures of the methanation plant. It could be shown that by using an equally sized electrolyser and methanation unit, allowing part load operation of the methanation only during the emptying of the H2 tank leads to longer activity phases of the methanation unit, while allowing part load operation of the methanation reactor during filling of the H2 storage tank had a negative effect.