Performance assessment of Adiabatic Compressed Air Energy Storage (A-CAES) power plants integrated with packed-bed thermocline storage systems

Among energy storage technologies, compressed air energy storage (CAES) systems have undergone a real development since the 70s, although only two large-size commercial plants are operating worldwide. CAES systems allow very large energy storage to be performed, accumulating compressed air to be used for electrical energy generation. In recent years, A-CAES (Adiabatic Compressed Air Energy Storage) plants have had an important role. This technology allows the storage of the thermal energy released during air compression to be used for heating the compressed air during electricity generation, avoiding the consumption of fossil fuels. The main objective of this paper is to propose an innovative system solution for large-size A-CAES plants. The proposed configuration is characterized by: (i) a compression train based on two axial compressors constantly operating at design conditions and a centrifugal compressor fully devoted to managing the pressure variation, (ii) a thermocline thermal energy storage (TES) system based on a packed bed of solid material located between the low-pressure and high-pressure compressors, (iii) an expansion train based on a high-pressure radial turbine and a low-pressure axial turbine. TES performance was evaluated with integration with the A-CAES plant through a dedicated numerical simulation model. Operating modes for managing the high-pressure and low-pressure turbines through air throttling and high-pressure turbine bypassing were also studied. Finally, an in-depth analysis of the off-design behaviour of the different A-CAES components was carried out. Globally the A-CAES round trip efficiency exceeds 0.7â0.75

Numerical investigation on a packed-bed LHTES system integrated into a micro electrical and thermal grid

Currently, energy storage systems are considered a key solution when mismatch occurs between energy supply and demand, allowing a more ecient energy deployment and use. The present paper is focused on the study of a latent heat thermal energy storage (LHTES) system based on a packed bed of encapsulated phase change material (PCM) of spherical shape, conceived as an auxiliary component of a micro-grid to be built in a Research Center located in southwestern Sardinia (Italy). The main purpose of this work was to perform numerical simulations for predicting the performance of the TES system, designed to store the surplus thermal energy produced during the weekend by a heat pump fed by a photovoltaic (PV) plant. The stored energy would then be utilized during the weekdays to integrate the air-conditioning system supply. The numerical simulations were based on a one-dimensional (1-D) two-equation transient model, able to return the thermocline profile of the water and the PCM separately. The behavior of the LHTES device during charge and discharge phases was reproduced, as well as during the standby periods. Finally, two characteristic indexes of the PV system were evaluated, to investigate the eect of TES on grid interchanges, self-consumption, and self-suciency

ACAES systems to enhance the self-consumption rate of renewable electricity in sustainable energy communities

This paper aims to evaluate the optimal configuration of an Adiabatic Compressed Air Energy Storage (ACAES) system designed to achieve the best matching between power production from non-programmable Renewable Energy Sources (RES) power plants and power demand from final users. The electrical energy demand of a small town, with a maximum power load of about 10 MW, has been considered as case study. The electrical energy can be supplied by both a photovoltaic (PV) power plant and the grid. For the ACAES system, different sizes for compressor, turbine, thermal energy storage (TES) system and air storage reservoir have been evaluated by varying the air mass flow rate of turbomachines and the charging and discharging duration times, to enhance the share of the PV energy supplied to the end user. The best performance is achieved with a PV power plant rated at about 35 MW and an ACAES section characterized by a compressor/turbine rated power of about 25-35% of the maximum power load of the end user, with a charging time of about 10 hours and a discharging time of about 20 hours. The average round-trip efficiency of the ACAES system is around 70%. On the overall, the integrated PV-ACAES system allows to cover 66% of the yearly electrical energy demand

CO2-free coal-fired power generation by partial oxy-fuel and post-combustion CO2capture: Techno-economic analysis

Among the carbon capture and storage (CCS) technologies suitable for power generation plants, partial oxy-combustion coupled with post combustion CO2capture is gaining interest, since such a hybrid configuration could allow to reduce the size and enhance the performance of post-combustion CO2capture by operating combustion with air enriched with oxygen and reducing the dilution of flue gas. Moreover, partial oxy-combustion is a potential candidate for the retrofit of existing steam plants because it could be based on an almost conventional boiler and requires a smaller CO2capture section. This work presents the results of a comparative techno-economic analysis of a 1000 MWthpartial oxy-combustion plant based on an ultra-supercritical pulverized coal combustion power plant integrated with a post-combustion CO2capture system and geological storage in saline aquifer. In particular, plant performance is assessed by using simulation models implemented through Aspen Plus 7.3 and Gate Cycle 5.40 commercial tools, whereas economic performance are evaluated on the basis of the expected annual cash flow. The analysis shows that, for new plants, this hybrid approach is not feasible from the economic point of view and full oxy-combustion potentially remains the most profitable technology even if, in the short-term period, the lack of commercial experience will continue to involve a high financial risk

Integration of pumped thermal energy storage systems based on Brayton cycle with CSP plants

In this paper, the integration of Brayton cycle PTES systems with Concentrating solar power (CSP) plants is proposed and investigated. Specific mathematical models were developed to simulate the PTES and CSP sections as well as to calculate the thermal profiles of the different TES storage tanks during the charging and discharging phases. As case study, an integrated PTES-CSP system using argon as working fluid and characterized by a nominal power of 5 MW and a nominal storage capacity of 4 equivalent hours of operation is considered. The influence of the main design parameters on two performance indexes, namely, the charge-to-discharge efficiencies of the sole PTES section and the integrated PTES-CSP plant, have been investigated. The results demonstrate that the use of high values of pressure ratio is beneficial for the charge-to-discharge efficiency of the integrated plant, even if too high operating pressures could be detrimental for the design of the solar receiver and the high temperature storage tank. The low temperature TES is a critical component due to its cryogenic operating conditions, but an increase in the minimum temperature should be achieved by increasing the inlet temperature of the LP compressor. A sensitivity analysis on the compressor and turbine efficiencies, maximum and minimum temperatures, circuit pressure drop and working fluid has been carried out. Finally, a feasible design of the PTES-CSP system with a PTES roundtrip efficiency of nearly 52% and a charge-to-discharge efficiency of the integrated PTES-CSP plant of about 36% was proposed

Exploring the Viability of Utilizing TreatedWastewater as a Sustainable Water Resource for Green Hydrogen Generation Using Solid Oxide Electrolysis Cells (SOECs)

The European Union aims to achieve carbon neutrality by 2050, prompting substantial investments in sustainable energy research, particularly in the realm of renewable sources (RESs). Italy, anticipating an energy demand of 366 TWh by 2030, is obligated by the EU to fulfill 75% to 84% of this demand through RESs1. A promising solution to meet this requirement is the production of green hydrogen through water electrolysis, specifically employing Solid Oxide Electrolysis Cells (SOECs). SOECs offer advantages over Alkaline Electrolyzers (AEs) and Proton Exchange Membranes (PEMs) since they can utilize treated wastewaters, eliminating the necessity for pure water, which is already scarce. This study centers on exploring the potential of SOECs to operate effectively in high-temperature conditions and utilize water in its gaseous form as the inlet source, commencing with treated wastewaters derived from municipal wastewater treatment plants

Assessing the use of Treated Wastewater for Green Hydrogen via SOEC

The European Union's goal of achieving carbon neutrality by 2050 has led to significant investments in sustainable energy research, particularly from renewable sources (RESs). Italy, with a projected energy demand of 366 TWh by 2030, is mandated by the EU to satisfy 75% to 84% of this demand using RESs1. Green hydrogen production through water electrolysis, particularly using Solid Oxide Electrolysis Cells (SOECs), is seen as a promising solution. SOECs have an advantage over Alkaline Electrolyzers (AEs) and Proton Exchange Membranes (PEMs) as they can use treated wastewaters, eliminating the need for pure water, which is already in short supply. This study focuses on the potential of SOECs to operate effectively in high temperature conditions and use water in its gas form as the inlet source, starting with treated wastewaters from municipal wastewater treatment plants

Pregnancy and fetal outcomes after Glatiramer Acetate exposure in patients with multiple sclerosis: a prospective observational multicentric study.

BACKGROUND: Only few studies have assessed safety of in utero exposure to glatiramer acetate (GA). Following a previous study assessing the safety of interferon beta (IFNB) pregnancy exposure in multiple sclerosis (MS), we aimed to assess pregnancy and fetal outcomes after in utero exposure to GA, using the same dataset, with a specific focus on the risk of spontaneous abortion. MATERIALS AND METHODS: We recruited MS patients, prospectively followed-up in 21 Italian MS Centres, for whom a pregnancy was recorded in the period 2002–2008. Patients were divided into 2 groups: drug-exposed pregnancies (EP: suspension of the drug less than 4 weeks from conception); non-exposed pregnancies (NEP: suspension of the drug at least 4 weeks from conception or never treated pregnancies). All the patients were administered a structured interview which gathered detailed information on pregnancy course and outcomes, as well as on possible confounders. Multivariate logistic and linear models were used for treatment comparisons. RESULTS: Data on 423 pregnancies were collected, 17 were classified as EP to GA, 88 as EP to IFNB, 318 as NEP. Pregnancies resulted in 16 live births in the GA EP, 75 live births in the IFNB EP, 295 live births in the NEP. GA exposure was not significantly associated with an increased risk of spontaneous abortion (OR = 0.44;95% CI 0.044-4.51;p = 0.49). Mean birth weight and length were not significantly different in pregnancies exposed to GA than in non exposed pregnancies (p = 0.751). The frequency of preterm delivery, observed in 4 subjects exposed to GA (25% of full term deliveries), was not significantly higher in pregnancies exposed to GA than in those non exposed (p > 0.735). These findings were confirmed in the multivariate analysis. There were neither major complications nor malformations after GA exposure. CONCLUSIONS: Data in our cohort show that mother’s GA exposure is not associated with a higher frequency of spontaneous abortion, neither other negative pregnancy and fetal outcomes. Our findings point to the safety of in utero GA exposure and can support neurologists in the therapeutic counselling of MS women planning a pregnancy

Epidural analgesia and cesarean delivery in multiple sclerosis post-partum relapses: the Italian cohort study

BACKGROUND: Few studies have systematically addressed the role of epidural analgesia and caesarean delivery in predicting the post-partum disease activity in women with Multiple Sclerosis (MS).The objective of this study was to assess the impact of epidural analgesia (EA) and caesarean delivery (CD) on the risk of post-partum relapses and disability in women with MS. METHODS: In the context of an Italian prospective study on the safety of immunomodulators in pregnancy, we included pregnancies occurred between 2002 and 2008 in women with MS regularly followed-up in 21 Italian MS centers. Data were gathered through a standardized, semi-structured interview, dealing with pregnancy outcomes, breastfeeding, type of delivery (vaginal or caesarean) and EA. The risk of post-partum relapses and disability progression (1 point on the Expanded Disability Status Sclae, EDSS, point, confirmed after six months) was assessed through a logistic multivariate regression analysis. RESULTS: We collected data on 423 pregnancies in 415 women. Among these, 349 pregnancies resulted in full term deliveries, with a post-partum follow-up of at least one year (mean follow-up period 5.5±3.1 years). One hundred and fifty-five patients (44.4%) underwent CD and 65 (18.5%) EA. In the multivariate analysis neither CD, nor EA were associated with a higher risk of post-partum relapses. Post-partum relapses were related to a higher EDSS score at conception (OR=1.42; 95% CI 1.11-1.82; p=0.005), a higher number of relapses in the year before pregnancy (OR=1.62; 95% CI 1.15-2.29; p=0.006) and during pregnancy (OR=3.07; 95% CI 1.40-6.72; p=0.005). Likewise, CD and EA were not associated with disability progression on the EDSS after delivery. The only significant predictor of disability progression was the occurrence of relapses in the year after delivery (disability progression in the year after delivery: OR= 4.00; 95% CI 2.0-8.2; p<0.001; disability progression over the whole follow-up period: OR= 2.0; 95% CI 1.2-3.3; p=0.005). CONCLUSIONS: Our findings, show no correlation between EA, CD and postpartum relapses and disability. Therefore these procedures can safely be applied in MS patients. On the other hand, post-partum relapses are significantly associated with increased disability, which calls for the need of preventive therapies after delivery

Process analysis and performance evaluation of updraft coal gasifiers

Coal gasification is becoming commercially even more import due to its potential application in hydrogen, ammonia, methanol and other chemicals and clean fuels production, other than power generation, together with carbon dioxide capture and sequestration. In this framework the technological development is also addressed, with a renewed interest, to simplified processes and plant solutions based, for example, on gasification with air (or air enriched with oxygen) and on moving or fluidised bed gasifiers, of interest for small and medium scale plants. The design, analysis and performance evaluation of the overall system (gasification, gas clean-up, desulphurisation, CO-shift conversion, CO2 and hydrogen separation, etc.) require a preliminary estimation of gasifier mass and energy balances and raw gas composition, which influence the whole downstream gas clean-up and treatment systems. The present study reports a process analysis and performance evaluation of updraft moving bed gasifiers, which have been carried out by a computer simulation model developed using the Aspen Plus 12.1 software, The model schematises the gasifier in several different zones: coal preheating and drying, devolatilization, gasification, combustion and oxidant preheating, under the hypothesis of char gasification at thermodynamic equilibrium. The model allows to appraise the mass and energy balance of the gasifier and the main characteristics of the syngas produced by the gasification process (composition, mass flow, temperature, lower heat value, etc.), being assigned coal composition and coal, steam and oxidant (air eventually enriched with oxigen) mass flows. In this paper the model is applied to predict the performance of two updraft moving bed gasifiers (sized respectively for 35 kg/h and 700 kg/h of low sulphur coal and high sulphur coal (Sulcis). The gasifiers are part of a small pilot gasification and gas treatment plant for hydrogen production under construction at the Sotacarbo Research Centre in Sardinia