Diabatic Compressed Air Energy Storage Research Articles

Thermodynamic analysis of natural gas/hydrogen-fueled compressed air energy storage system

In this paper, a diabatic compressed air energy storage system fueled by a natural gas/hydrogen mixture that integrates heating and power generation is proposed. A comprehensive thermodynamic analysis has been conducted to identify the key factors influencing system performance and elucidate the detailed formation and distribution patterns of irreversible losses when utilizing a hydrogen-natural gas blend as fuel in the proposed system. The research results indicate that increasing the hydrogen blending ratio from 0.5 to 1 lead to greater enhancements in roundtrip efficiency (∼1.08% vs. ∼0.33%), exergy efficiency (∼3.88% vs. ∼1.15%), and energy density (∼1.24% vs. ∼0.42%) compared to an increase from 0 to 0.5. The combustor suffers the largest exergy destruction proportion, with a notable reduction in exergy destruction achieved through increased hydrogen blending. System performance benefits significantly from higher combustor outlet temperatures and expansion ratios at various hydrogen blending ratios. The rate of change in exergy efficiency (∼42.76% vs. ∼83.17%) and energy density (∼58.83%) demonstrates an inverse correlation with the varied parameters (1100–1500K, 4–8), except for the rate of change in energy density (∼6.76%), which displays a positive relationship with the combustor outlet temperature. Notably, a significant decrease in the rate of change in roundtrip efficiency (∼1.87% vs. ∼6.64%) is observed within a specific parameter range (1400–1500K, 5–6). Sensitivity analysis identifies the combustor outlet temperature as the most influential factor in enhancing system performance, consistently showing positive effects of the hydrogen blending ratio.

Prospects of Hydrogen Application as a Fuel for Large-Scale Compressed-Air Energy Storages

A promising method of energy storage is the combination of hydrogen and compressed-air energy storage (CAES) systems. CAES systems are divided into diabatic, adiabatic, and isothermal cycles. In the diabatic cycle, thermal energy after air compression is discharged into the environment, and the scheme implies the use of organic fuel. Taking into account the prospects of the decarbonization of the energy industry, it is advisable to replace natural gas in the diabatic CAES scheme with hydrogen obtained by electrolysis using power-to-gas technology. In this article, the SENECA-1A project is considered as a high-power hybrid unit, using hydrogen instead of natural gas. The results show that while keeping the 214 MW turbines powered, the transition to hydrogen reduces carbon dioxide emissions from 8.8 to 0.0 kg/s, while the formation of water vapor will increase from 17.6 to 27.4 kg/s. It is shown that the adiabatic CAES SENECA-1A mode, compared to the diabatic, has 0.0 carbon dioxide and water vapor emission with relatively higher efficiency (71.5 vs. 62.1%). At the same time, the main advantage of the diabatic CAES is the possibility to produce more power in the turbine block (214 vs. 131.6 MW), having fewer capital costs. Thus, choosing the technology is a subject of complex technical, economic, and ecological study.

Hydrogen application in the fuel cycle of compressed air energy storage

The development of large energy systems based on renewable energy sources is accompanied by an increase in the input capacities of large grid storages. Taking into account the vector for decarbonization and maneuverability, the use of hydrogen as a fuel in the cycle of a diabatic compressed air energy storage (CAES) is a promising scientific and technical direction. This paper analyzes the key performance indicators of a compressed air energy storage in the presence and absence of thermal energy recovery within the cycle. In addition, an assessment was made of the prospects for the use of a methane-hydrogen mixture in gas turbines. At the end of the paper, a calculation of the process of plasma pyrolysis of methane is given as one of the possible methods for the production of hydrogen for use in energy purposes.

Performance Analysis of a Diabatic Compressed Air Energy Storage System Fueled with Green Hydrogen

The integration of an increasing share of Renewable Energy Sources (RES) requires the availability of suitable energy storage systems to improve the grid flexibility and Compressed Air Energy Storage (CAES) systems could be a promising option. In this study, a CO2-free Diabatic CAES system is proposed and analyzed. The plant configuration is derived from a down-scaled version of the McIntosh Diabatic CAES plant, where the natural gas is replaced with green hydrogen, produced on site by a Proton Exchange Membrane electrolyzer powered by a photovoltaic power plant. In this study, the components of the hydrogen production system are sized to maximize the self-consumption share of PV energy generation and the effect of the design parameters on the H2-CAES plant performance are analyzed on a yearly basis. Moreover, a comparison between the use of natural gas and hydrogen in terms of energy consumption and CO2 emissions is discussed. The results show that the proposed hydrogen fueled CAES can effectively match the generation profile and the yearly production of the natural gas fueled plant by using all the PV energy production, while producing zero CO2 emissions.

Optimization-based economic analysis of energy storage technologies in a coupled electricity and natural gas market

This work presents a stochastic mixed-integer linear programming (MILP) optimization framework to investigate the optimal participation and economics of various energy storage technologies, such as pumped-hydro, advanced adiabatic and diabatic compressed air systems and li-ion battery, in a perfectly competitive coupled electricity and natural gas market. The clearing scheme pertains to energy-only markets, aiming to optimize dispatch and maximize social welfare for the integrated energy system, through a two-stage stochastic programming. The first stage presents the day-ahead market clearing procedure, while the second stage illustrates the integrated system operation in the real-time trading floor, through a set of plausible wind power generation realizations. The two markets mainly interact the bilateral operation of the diabatic compressed air energy storage system, both as an electricity producer and as natural gas consumer. The proposed algorithm is applied to a modified IEEE 24-bus power grid and a single-node gas network and provides a thorough analysis of the operational characteristics and profitability of each energy storage technology in the integrated energy system. Results illustrate that electricity storage systems can increase their overall profits under power transmission congestion and while wind power generation volatility increases from 5 % up to 52 %. In contrast, a decrease by 3.1 % in the social welfare is realized in the case of power congestion while this figure is approximately 2.54 % under wind power volatility increase.

Techno-economic evaluation of combined cycle gas turbine and a diabatic compressed air energy storage integration concept

More and more operational flexibility is required from conventional power plants due to the increasing share of weather-dependent renewable energy sources (RES) generation in the power system. One way to increase power plant's flexibility is integrating it with energy storage. The energy storage facility can be used to minimize ramping or shutdowns and therefore should lower overall generating costs and CO2 emissions.In this article, we examined the effects of a combined cycle gas turbine (CCGT) power plan and a compressed air energy storage (CAES) system integration. The main feature of the CCGT-CAES integration concept is using the CCGT installation as a heat recipient and provider for the CAES installation. This approach was applied to a real-life case study of the PGE Gorzów CCGT power plant. First, technical feasibility of itegrating a CCGT plant with a CAES system was verified and the restrictions on the operating conditions were identified. Next, the improvement in flexibility was quantified by the additional profits gained from the integration. Polish day-ahead electricity prices were used as a measure for remunerating flexibility.Two models were developed in the Python computer programming language: a thermodynamic one and an economic one. The former was buit without the use of flowsheeting software or purpose-built industry specific tool. The latter was implemented within the frame of the PuLP library and solved using its default solver (CBC). By means of mixed integer linear programming (MILP) optimal generation schedules and maximum profits were found for three cases: an independent operation of the CCGT, an integrated CCGT-CAES plant and an integrated CCGT-ES plant with 81% storage efficiency.The results of the computational simulations contradict the supposition that the integration is economically viable, even if mechanical energy storage efficiency of 81% is assumed. Regarding the impact of the integration on the optimal schedule, although it is negligible for the 56% mechanical energy storage efficiency case, a significant change in operation profiles is observed for the 81% case. The model developed here can be used either when making decisions about investment in flexibility improvements or for planning daily operation of a generating unit.

Economic assessment for compressed air energy storage business model alternatives

Compressed air energy storage (CAES) is a large-scale energy storage system with long-term capacity for utility applications. This study evaluates different business models' economic feasibility of CAES pre-selected reservoir case studies. It assesses several scenarios for each case study and analyzes two business models: one for the storage of excess renewable energy sources (RES) and another for energy arbitrage. The novelty of this work is performing the economic investment assessment using a Monte Carlo Simulation (MCS) methodology applied to CAES, considering the uncertainties associated with such types of projects and evaluating different business models for the technology.The results suggest a better performance from the CAES RES business model than the CAES arbitrage business model. Furthermore, the diabatic CAES assessed scenarios seem to have more attractive results than their equivalent adiabatic CAES systems in the CAES RES business model. However, adiabatic CAES can be economically feasible in both business models. In addition, it was observed that CAES is viable in specific scenarios and can be profitable for the storage of energy from RES, facilitating the management of their variability, decreasing their dependence on weather, and helping their integration into the grid. However, CAES does not seem a good fit for grid energy arbitrage in the generality of the scenarios evaluated.

Optimization of a diabatic compressed air energy storage coupled with photovoltaics for buildings: CO2-eq emissions vs payback time

The necessary path towards sustainable development makes increasingly crucial the role of energy storage systems because the most affordable renewable energy sources (RES) are typically intermittent In this perspective compressed air energy storage (CAES) is one of the main alternatives to batteries and pumped hydro energy storage. This study shows how an integrated system coupling RES and CAES may significantly reduce greenhouse gas emissions with acceptable payback times. The electrical load is provided by a representative building sample (RBS) located in Naples (Southern Italy), generated using the simulation-based large-scale uncertainty/sensitivity analysis of building energy performance (SLABE) methodology. A Pareto multi-objective optimization is performed via a brute-force search to minimize CO2-eq emissions and payback time. The design variables refer to a photovoltaic system design and to size and operation of an associated diabatic CAES. Two different application scenarios are envisaged: 1000 buildings and 2000 buildings. The avoided greenhouse gas emissions are about 55% and 51% with simple payback times of 14.3 years and 12.4 years, respectively. The results show that the proposed integrated framework, with the right mix of renewables, may lead to the complete satisfaction of the electrical load at reasonable costs.

Techno-Economic Comparison of Utility-Scale Compressed Air and Electro-Chemical Storage Systems

The paper deals with a techno-economic comparison between utility-scale diabatic compressed air energy storage (D-CAES) systems equipped with artificial storage and Battery Energy Storage (BES) systems based on consolidated technologies, such as Sodium-Sulfur (Na-S) and Lithium-ion (Li-Ion). The comparison is carried out on the basis of the levelized cost of storage (LCOS). Analyses have been performed by varying key inputs, such as the rated power, the storage capacity, the price of electricity absorbed from the grid during the charging phase, and the cost of fuel fed to D-CAES during the discharge phase. Na-S technology-based systems always show better techno-economic performance in respect to Li-Ion based ones. The economic performance of both D-CAES and BES improves by increasing the storage capacity. The D-CAES performance improvement rate, however, is higher than that estimated for BES based systems. Moreover, the economic performance of D-CAES systems is less sensitive to the price of electricity in respect of BES based storage facilities. As a result, D-CAES based solutions can reach a LCOS lower than that of Na-S batteries if the size of the system and the price of electricity are large enough.

Process improvements and multi-objective optimization of compressed air energy storage (CAES) system

Intermittency and high cost were the main barriers to the large-scale commercialization of renewable energy decades ago. The cost of renewable energy has decreased dramatically in the last decade. The intermittency of renewable energy, however, remains a serious challenge to be overcome. Compressed Air Energy Storage (CAES) is widely considered to be a promising energy storage technology at utility-scale and receives increasing attention from both academic and industrial communities. In this study, two novel CAES systems are proposed and a thorough investigation and comparison of the thermodynamic performance of both conventional and novel CAES systems have been performed. The turbine inlet temperature and the maximum cavern storage pressure are identified as the bottlenecks of CAES plants. The round-trip efficiency and energy density are chosen as the conflicting objectives. Pareto fronts are obtained based on the simulation-based multi-objective optimization framework developed in this study. The energy density of a diabatic CAES plant is within the range between 4.24 and 11.58 kWh/m3, while that value becomes 1.28–7.96 kWh/m3 for a conventional adiabatic CAES system. The novel two-pressure level adiabatic CAES system can improve the round-trip efficiency by at least 3.5% compared with the conventional adiabatic CAES system. The novel indirect heating diabatic CAES system can improve the round-trip efficiency by at least 2%. The Pareto fronts can be a useful tool for the grassroot design or retrofit of a CAES plant. Solutions to improve the CAES system performance have been proposed based on the optimization results of this study.

Adiabatic compressed air energy storage technology

Adiabatic compressed air energy storage technology

Comparative Study of Various Constant-Pressure Compressed Air Energy Storage Systems Based on Energy and Exergy Analysis

Abstract The balance between supply and demand for electricity is mainly disrupted by the growing contribution of renewable energy sources to the electrical grid since these sources are intermittent by nature. Therefore, the energy storage systems, mainly those of considerable size, become essential to restore the electricity balance. The compressed air energy storage (CAES) system is one of the mature technologies used to store electricity on a large scale. Therefore, this article discusses the energy and exergy analysis of different configurations of a constant-pressure CAES system to improve its overall efficiency and energy density. The exergy efficiency of our basic adiabatic configuration using water as thermal storage medium is 56.4% and the energy density is 12.17 kWh/m3. The results show that the CAES system using a packed bed of quartzite rock as thermal storage medium has the best efficiency (67.2%) and energy density (17 kWh/m3) among adiabatic systems. The diabatic CAES systems could have a net efficiency up to 70.1% and an energy density up to 31.95 kWh/m3 by using combustion chambers. Finally, the waste heat recovery from other installations such as a gas turbine power plant has the potential to improve the energy density to 20.53 kWh/m3 without using fossil fuel sources.

Analysis of diabatic compressed air energy storage systems with artificial reservoir using the levelized cost of storage method

Analysis of diabatic compressed air energy storage systems with artificial reservoir using the levelized cost of storage method

Compressed Air Energy Storage System Modeling for Power System Studies

In this paper, a detailed mathematical model of the diabatic compressed air energy storage (CAES) system and a simplified version are proposed, considering independent generators/motors as interfaces with the grid. The models can be used for power system steady-state and dynamic analyses. The models include those of the compressor, synchronous motor, cavern, turbine, synchronous generator, and associated controls. The configuration and parameters of the proposed models are based on the existing bulk CAES facilities of Huntorf, Germany. The models and performance of the CAES system are first evaluated with step responses, and then examined when providing frequency regulation in a test power system with high penetration of wind generation, comparing them with existing models of CAES systems. The simulation results confirm that the dynamic responses of the detailed and simplified CAES models are similar, and demonstrate that the simultaneous charging and discharging can significantly contribute to reduce the frequency deviation of the system from the variability of the wind farm power.

Performance comparison of different combined heat and compressed air energy storage systems integrated with organic Rankine cycle

Compressed air energy storage (CAES) is promising to enable large-scale penetration of renewable energies (REs). However, conventional diabatic CAES (D-CAES) depends largely on fossil fuels, while adiabatic CAES (A-CAES) is limited in output power. To conquer these disadvantages, concept of combined heat and CAES (CH-CAES) is proposed in this paper. The proposed system couples an electric heater with conventional A-CAES. During charging, electricity storage transforms from pure compression to partly relying on Joule heating. The stored heat in an electric heater will be used to boost turbine inlet temperature during discharging. Consequently, system charge/discharge capacity can be improved without enlarging cavern size, raising cavern pressure, and producing greenhouse gases. This paper discusses three types of CH-CAES systems with different electric heater installation positions. Off-design performance analysis for each system is conducted on the basis of turbomachinery (compressors, turbines, and the pump) characteristic maps and heat exchangers off-design models. Performance comparison is conducted between these three CH-CAES systems (called Mode II, III, and IV for simplification) and the conventional A-CAES system (Mode I). Control strategies are also given in this paper. Results show that the EVR (energy generated per unit volume of storage) increases with participation of an electric heater, while the RTE (system roundtrip efficiency) slightly decreases. Mode I has the highest RTE. The largest EVR appears in Mode III where the electrical heater is in series with the intercooler and after cooler. Mode II is a compromise solution to achieve both relatively high RET and EVR when the electrical heater is installed in series only with the intercooler. Mode IV with a paralleling electrical heater has great flexibility to adapt different user demands. The integration of the ORC has a positive effect on system RTE and EVR.

Underground coal mine workings as potential places for Compressed Air Energy Storage

The article gives a brief overview of current developments and projects of Compressed Air Energy Storage (CAES). Typical CAES configurations such as Adiabatic CAES and Diabatic CAES are described. The concept of air storage in isolated workings of closed coal mine is presented taking into account availability of such places in the Silesian Coal Basin of southern Poland. The article also discusses major challenges of such concept such as insulation of underground workings, geomechanical stability of workings and site availability. As a proof of concept examples of underground coal mines converted into natural gas storage sites are given. Types of underground workings that could serve as a part of potential compressed storage site are listed and an example of volume calculation available in coal mine for storage is given.

Thermal Design and Analysis of a Solid-State Grid-Tied Thermal Energy Storage for Hybrid Compressed Air Energy Storage Systems

Power overgeneration by renewable sources combined with less dispatchable conventional power plants introduces the power grid to a new challenge, i.e., instability. The stability of the power grid requires constant balance between generation and demand. A well-known solution to power overgeneration is grid-scale energy storage. Compressed air energy storage (CAES) has been utilized for grid-scale energy storage for a few decades. However, conventional diabatic CAES systems are difficult and expensive to construct and maintain due to their high-pressure operating condition. Hybrid compressed air energy storage (HCAES) systems are introduced as a new variant of old CAES technology to reduce the cost of energy storage using compressed air. The HCAES system split the received power from the grid into two subsystems. A portion of the power is used to compress air, as done in conventional CAES systems. The rest of the electric power is converted to heat in a high-temperature thermal energy storage (TES) component using Joule heating. A computational approach was adopted to investigate the performance of the proposed TES system during a full charge/storage/discharge cycle. It was shown that the proposed design can be used to receive 200 kW of power from the grid for 6 h without overheating the resistive heaters. The discharge computations show that the proposed geometry of the TES, along with a control strategy for the flow rate, can provide a 74-kW microturbine of the HCAES with the minimum required temperature, i.e., 1144 K at 0.6 kg/s of air flow rate for 6 h.

Thermodynamic analysis of cavern and throttle valve in large-scale compressed air energy storage system

The compressed air energy storage system has the potential to enable large-scale implementation of renewable energies. However, the exergy destruction in the throttle valve and cavern is an important factor that affects the overall performance of the system. The conventional diabatic compressed air energy storage system consisted of compressors, heat exchangers, cavern, combustion chambers and turbines was studied and parameters of the Huntorf plant were adopted for calculation. Mathematical models of the components in the compressed air energy storage system were developed based on the equation of state for the real gas and the thermodynamic laws. The models are derived on the basis of assumptions that the inlet and outlet air flow rates of the cavern are negligible and that the system is operated in steady state. The test data of the Huntorf plant during the initial test was used to validate the models. Sensitivity analyses were conducted to identify the domain parameters that affect the exergy destruction in the cavern and throttle valve. The results indicated that 18.85% of the stored exergy was lost in the cavern and throttle valve during a complete cycle. The exergy destruction in the cavern was higher than that in the throttle valve, and the exergy destruction coefficients in the cavern and throttle varied with opposite tendencies when the parameters were changed. The heat transfer coefficient, injected air temperature, and initial temperature of the cavern were found to highly affect the total exergy destruction coefficient. Higher injected air temperature and lower cavern initial temperature reduces the total exergy destruction in the cavern and throttle valve.

Induced geochemical reactions by compressed air energy storage in a porous formation in the North German Basin

A synthetic diabatic compressed air energy storage (CAES) based on an existing surface facility and using the Rhaetian sandstone formation in the North German Basin as porous storage reservoir is investigated for induced geochemical reactions. A daily storage cycle with a 6-h injection and a 6-h extraction phase in the early morning and late afternoon is applied. The chosen mineral assemblage shows the presence of pyrite in the Rhaetian sandstone, so that operating CAES in this porous formation introduces oxygen in the formation and induces geochemical reactions governed mainly by pyrite oxidation. A consistent geochemical reaction system for the Rhaetian sandstone is developed and kinetic batch simulations are used to quantify the changes due to the induced geochemical reactions in both stored air as well as storage formation.The injection of air into this geological formation leads to pyrite oxidation, changes in stored air composition, air pressure and formation properties. Results show that only a very small change up to 0.29% in the oxygen mole fraction is found within one storage cycle, which does not affect flammability of the stored air. Considering a longer residence time, the oxygen concentration in the stored air may drop below the minimum oxygen concentration for flame propagation and thus cannot be used for burning natural gas as required for a diabatic CAES. The pH of the formation fluid after 20-year cyclic daily operation can drop significantly below one near the gas wells increasing the risk of well corrosion, but with smaller effects at larger distances. However, mineral dissolution and precipitation found in the storage formation results in only minor increases of porosity and permeability with relative changes up to 1.0% and 5.0%, respectively. The uncertainties in mineral reactive surface area and pyrite oxidation kinetic strongly affect the rate of oxygen reduction and fluid acidification. Analysis of these parameters of the reservoir mineral phases from the target location, especially for pyrite, are therefore required for a reliable estimate of possible induced geochemical reactions and impacts.

Performance analysis of diabatic compressed air energy storage (D-CAES) system

Compressed air energy storage (CAES) system can storage electricity with compressed air as working medium. In this paper, the performance of the diabatic CAES (D-CAES) system based on Huntorf plant is numerically investigated by analyzing the effects of some key parameters such as the gradient utilization of the pressure in cavern and the waste heat recovery of the system. The simulation results indicate that the output power of the turbine train can be improved with gradient utilization of the pressure in cavern. More power is generated with higher entrance temperature of low pressure turbine. But the needed thermal energy from fossil fuel for heating compressed air is increased. The performance of the system is improved obviously by means of recovering the waste heat from the exhaust air from low pressure turbine to preheat the compressed air.