Solar hydrogen production with cerium oxides thermochemical cycle

This paper discusses the hydrogen production using a solar driven thermochemical cycle. The thermochemical cycle is based on nonstoichiometric cerium oxides redox and the solar concentration system is a solar dish. Detailed optical and redox models were developed to optimize the hydrogen production performance as function of several design parameters (i.e. concentration ratio, reactor pressures and temperatures) The efficiency of the considered technology is compared against two commercially available technologies namely PV + electrolyzer and Dish Stirling + electrolyzer. Results show that solar-to-fuel efficiency of 21.2% can be achieved at design condition assuming a concentration ratio around 5000, reduction and oxidation temperatures of 1500°C and 1275 °C. When moving to annual performance, the annual yield of the considered approach can be as high as 16.7% which is about 43% higher than the best competitive technology. The higher performance implies that higher installation costs around 40% can be accepted for the innovative concept to achieve the same cost of hydrogen

Preliminary Assessment of sCO2Power Cycles for Application to CSP Solar Tower Plants

This work presents a preliminary thermodynamic assessment of three different supercritical CO2(sCO2) power cycles integrated in a high temperature solar tower system, working up to 800°C. An indirect cycle configuration is considered with KCl-MgCl2molten salt as heat transfer fluid (HTF) in the solar receiver and a two tanks thermal energy storage (TES) system. The most promising cycle configuration is selected, optimizing the cycle turbine inlet temperature to achieve the best compromise between cycle and receiver efficiency. An estimate of the yearly energy yield of the proposed power plant is finally performed, indicating the possibility of reaching solar-to-electric efficiency of about 17.5%

The role of simulation in neonatal and pediatric training and research

From a pediatric perspective, the two main types of simulation-based research are: studies that assess the efficacy of simulation as a training methodology and studies where simulation is used as an investigative methodology. Aim of the study. Overall, the aim of the research activity is to inquire the use of simulation as investigative methodology in pediatric and neonatal settings. Study design: Previously, we investigated the current use of simulation in pediatric fellowships in Italy in order to understand the state of the art and the expectations of pediatric residents with regard to simulationbased training and research. Furthermore, we developed suitable simulated scenarios for pediatric training and research. As second step, we evaluated technical (TS) and non-technical (NTS) skills in a sample of Italian pediatric residents using a neonatal resuscitation scenario; Finally, we aimed to evaluate the accuracy of NeoTapAS in reliably determining HR from auscultation in a high-fidelity simulated newborn resuscitation scenario. Results and future perspectives: Firstly, we highlighted that an extremely high percentage of pediatric italian residents spent less than 5 hours/year in simulation-based education. Secondly, the mean compliance to last ILCOR recommendations about neonatal resuscitation was 59 % and a very low compliance (< 30%) was observed for a number of important technical items. Finally, NeoTapAS showed a good accuracy in estimating HR and it could be an important resource for neonatologists in delivery room resuscitation As future perspective, we designed a new simulation-based multi-center research (\u201cSimarrest \u201d) in collaboration with University of Padua in order to identify gaps about in-hospital pediatric cardiac arrest management in a standardized setting

Achievements of European projects on membrane reactor for hydrogen production

Membrane reactors for hydrogen production can increase both the hydrogen production efficiency at small scale and the electric efficiency in micro-cogeneration systems when coupled with Polymeric Electrolyte Membrane fuel cells. This paper discusses the achievements of three European projects (FERRET, FluidCELL, BIONICO) which investigate the application of the membrane reactor concept to hydrogen production and micro-cogeneration systems using both natural gas and biofuels (biogas and bio-ethanol) as feedstock. The membranes, used to selectively separate hydrogen from the other reaction products (CH4, CO2, H2O, etc.), are of asymmetric type with a thin layer of Pd alloy (<5 μm), and supported on a ceramic porous material to increase their mechanical stability. In FERRET, the flexibility of the membrane reactor under diverse natural gas quality is validated. The reactor is integrated in a micro-CHP system and achieves a net electric efficiency of about 42% (8% points higher than the reference case). In FluidCELL, the use of bio-ethanol as feedstock for micro-cogeneration Polymeric Electrolyte Membrane based system is investigated in off-grid applications and a net electric efficiency around 40% is obtained (6% higher than the reference case). Finally, BIONICO investigates the hydrogen production from biogas. While BIONICO has just started, FERRET and FluidCELL are in their third year and the two prototypes are close to be tested confirming the potentiality of membrane reactor technology at small scale.The research leading to these results has received funding from the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreements No 621181 (FERRET), No 621196 (FluidCELL). BIONICO has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 671459. This Joint Undertaking receives support from the European Union's Horizon 2020 research and innovation programme, Hydrogen Europe and N.ERGHY

Optimization of the integration of fluidized bed particle heat exchanger in sCO2-based solar tower plants

Next generation solar tower plants aim at increasing the maximum achievable temperature thanks to the adoption of advanced heat transfer media and sCO2 cycles. In this context, the Horizon Europe Powder2Power project aims at demonstrating at MW-scale the adoption of fluidized particles as heat transfer medium in CSP plants. This work focuses on the numerical model for the sizing and simulation of the sCO2-particles multistage heat exchanger to be used for the overall plant analysis. The developed model adopts reliable heat transfer correlations available in the literature to size the heat exchanger based on the target thermal duty and pressure losses. A sensitivity analysis is presented to study the effect of the main design parameters on the component size and efficiency. The model is then used in a case study for the complete techno-economic optimization of fluidized particle based CSP plants. Results show that the temperature differences at the cold- and hot-end of the heat exchanger greatly influences the minimum number of stages and that an increase in the number of stages leads to a reduction in the total heat transfer surface. The economic optimization highlights that the fluidized bed heat exchanger represents a marginal share of the plant overall cost and thus that there is no convenience to adopt a component with a little number of stages and penalize the efficiency and that the stage number in real plants would be likely more constrained by other technical aspects related to components manufacturing

Techno-economic assessment of small-scale solar tower plants with modular billboard receivers and innovative power cycles

This work investigates performances and costs of various configurations of 5 MWel solar tower CSP plants, located in Sicily. The design of the plants aims at comparing two solar towers concepts (i.e., a single tower and modular towers), both adopting billboard receivers. A sensitivity on various heat transfer fluids (i.e., solar salt and sodium), storage fluids (solar salt and NaCl-MgCl2) and power block technologies (i.e., steam Rankine and sCO2 cycles) is also proposed. For each investigated plant configuration, tailored numerical models are presented to assess the performances of each plant subsystem (e.g., solar field, receiver, piping system, power cycle). The results show very competitive LCOE (between 160 and 180 $/MWhel), achievable with satisfactory capacity factors (around 55%), while suggesting good profitability levels for such investments in small scale CSP plants

Part-load analysis and preliminary annual simulation of a constant inventory supercritical CO2 power plant for waste heat recovery in cement industry

The present work investigates the part-load performance of a MW-scale sCO2 2 power plant designed as waste heat recovery unit for an existing cement plant located in Czech Republic, in the framework of the H2020 funded project CO2OLHEAT. The study first presents the selected power plant configuration and then focuses on the evaluation of its part-load operation due to variation of flue gas mass flow rate and temperature. The range of flue gas conditions at the outlet of the upstream process is retrieved from a preliminary statistical analysis of historical trends obtained through the cement plant monitoring. The numerical model developed for this study aims at providing realistic results thanks to the adoption of turbomachinery performance maps provided by the turbomachinery manufacturer of the project. Moreover, heat exchangers have been modelled through a discretized approach which has been validated against manufacturer data, while piping inventory and pressure losses have been assessed through a preliminary sizing that considers the actual distances to be covered in the cement plant. Performance decay is estimated for the whole range of flue gas conditions, reporting the most significant power cycle parameters, and identifying the main causes of efficiency loss. The part-load analysis is carried out considering a constant CO2 2 inventory, in order to reduce the system complexity and capital cost and simplify plant operation. Results show that the operation entails minor variation of the compressors operative points in the whole range of operating conditions of the cement plant, avoiding the risk of anti- surge bypass activation. Moreover, the plant is able to work close to the nominal thermodynamic cycle efficiency (20.5 %-23.0 - 23.0 %) for most of the year and benefits from part-load operation in terms of overall performance. In the last part of the work, a preliminary techno-economic analysis of the plant is also presented to highlight the potential advantages of sCO2 2 technology for waste heat recovery applications. The results of the part-load performance of the plant are combined with the flue gases data obtained from the preliminary statistical analysis and the cement plant historical monitoring. An annual electricity production equal to 13 ' 909.7 ' 909.7 MWh is obtained, corresponding to 6560 equivalent hours and a system capacity factor of 74.9 %. The investment cost of each CO2OLHEAT plant component is estimated by means of cost correlations obtained from literature and the non-discounted payback time is computed as a function of the electricity selling price. The results show that, even considering electricity prices before 2022, the payback time of the CO2OLHEAT plant is estimated to be lower than 8 years, justifying the industrial interest in the proposed technology

Thermal Desalination Through Forward Osmosis Coupled With CO2-Mixture Power Cycles for CSP Applications

This work, performed in the framework of the H2020 EU project “DESOLINATION”, analyses the coupling between CSP plants using transcritical power cycles with CO2-mixtures and an innovative thermal desalination technique based on Forward Osmosis. Calculations are presented for a large scale CSP plant with central tower receiver and direct storage with solar salts in Dubai, adopting the mixtures CO2+SO2 and CO2+C6F6 in the power cycles. The heat rejected from the cycle condenser is recovered directly by the FO plant, where the draw solute is heated up from 40 °C to 76 °C, to allow for the regeneration of the draw solution used in the forward osmosis membrane. The thermo-responsive polymer adopted is PAGB2000, already considered in literature as a promising option. Results show a very effective synergy between the electricity and the freshwater production: high yearly solar to electric efficiencies are possible (around 19%), with a low freshwater specific thermal consumption (around 100 kWhth/m3). The proposed desalination method is more effective than a conventional MED system (with + 50% of yearly freshwater produced), while a larger solar field (+ 28% in surface area) is necessary for a PV+RO plant to produce annually both the energy and freshwater produced by the CSP+FO plants

CONDICIONAMENTO FISIOLÓGICO COM DIFERENTES FONTES E CONCENTRAÇÕES DE GLICÍDIOS EM SEMENTES DE BRAQUIÁRIA

Seed priming is a practice for improving the expression of seed physiological potential. Such technique consists of synchronizing and reducing the time of seed germination by controlled hydration. The aim of this study was to evaluate the effect of seed-priming with different sugar sources and concentrations on the physiological quality Urochloa brizantha seeds and initial seedling performance. Before treating, seeds were scarified chemically with concentrated sulphuric acid (H2SO4) for 5 minutes to overcome physical dormancy. The experimental design was completely randomized in a 3 x 6 factorial scheme consisting of priming using three sugar sources (glucose, sucrose, and maltose) and six concentrations (zero [water control], 2%, 5%, 10%, 15%, and 20%), with four replicates. The seeds were primed by direct immersion for 2 hours at 25 ºC and, after hydration, they were dried for moisture equilibrium recovery. Seed germination, vigor, viability, and initial seedling growth were evaluated. The results showed that glucose was the source able to promote beneficial effects on the germination of U. brizantha cv. MG-5 seeds. Moreover, the supply of glucose at the concentrations of 2 and 5% for physiological conditioning increased seedling dry phytomass.O condicionamento em sementes é uma prática capaz de possibilitar maior expressão do potencial fisiológico das sementes. Esta técnica permite a sincronização e redução do tempo de germinação das sementes através da hidratação controlada. O objetivo foi avaliar o efeito do condicionamento fisiológico em sementes de Urochloa brizantha com diferentes fontes e concentrações de glicídios na qualidade fisiológica de sementes e desempenho inicial das plântulas. Anterior a aplicação do priming as sementes foram submetidas a escarificação química com ácido sulfúrico concentrado (H2SO4) por 5 minutos para remoção da dormência primária. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 3 x 6, constituído por condicionamento fisiológico utilizando três fontes de glicídios (glicose, sacarose e maltose) e seis concentrações (zero [controle em água], 2%, 5%, 10%, 15% e 20%), com quatro repetições. O condicionamento fisiológico utilizado foi via imersão direta por 2 horas a 25 ºC e, posteriormente a hidratação das sementes, foi realizada a secagem para a retomada da umidade de equilíbrio. Foi realizado teste de germinação, vigor, viabilidade das sementes e crescimento inicial de plântulas. A glicose como fonte de glicídio promoveu efeitos benéficos na germinação de sementes de U. brizantha cv. MG-5. O fornecimento de glicose nas concentrações de 2 e 5% pelo condicionamento fisiológico propiciaram incremento na fitomassa seca de plântulas