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• A novel hybrid solar-wind based system with energy storage via ammonia is developed. • Dynamic simulation and thermodynamic analyses performed to study system performance. • Overall energy and exergy efficiency vary between 46.1 and 53.3% and 34–41.5% annually. • Peak energy output potental of the ammonia based system determined to be 28,463 kWh. In this study, a new renewable energy based integrated system is developed where it stores the excess power generated in the form of ammonia. The developed system integrates both solar and wind energy resources. A dynamic simulation is performed considering the variations in solar radiation intensities as well as wind speeds across the year. The proposed methodology utilizes excess power available during periods of high solar radiation or wind speeds to synthesize and store ammonia that can be utilized for power generation during periods of low energy availability, through ammonia fed solid oxide fuel cells. Further, a reverse osmosis desalination system is also utilized for producing fresh desalinated water during periods of high energy availability. The system performance is simulated and analyzed thermodynamically on the average days of each month. The overall energy efficiency of the developed system is determined to vary between 46.1% and 53.3% across the year. Also, the overall exergy efficiency is found to vary between 34% and 41.5%. The ammonia fed solid oxide fuel cell is observed to have an energy efficiency in the range of 51.9%–80.8% and the exergy efficiency is observed to vary between 51.9% and 91.5%. The energy output potential of the proposed ammonia and solid oxide fuel cell based energy storage system is determined to be 28,463 kWh at the peak value, and the maximum daily fresh water production is evaluated to be 20891.5 tonnes/day. [ABSTRACT FROM AUTHOR]

Highlights • Development and investigation of a new direct ammonia fuel cell stack. • Open circuit voltage is found to be 1249 ± 37.5 mV. • Peak power density is observed to be 13.4 ± 0.4 W m−2. • Energy and exergy efficiencies are found to be 52.4 ± 1.6% and 49.3 ± 1.6% respectively. Abstract In the present study, the experimental investigation and performance evaluation of a newly developed direct type ammonia fuel cell stack are performed. A solid anion exchange membrane electrolyte is also utilized. The performances of a single-cell and a 5-cell stack are investigated through thermodynamic efficiencies. The open circuit voltages for a single cell and 5-cell stack are obtained as 280 ± 8 mV and 1249 ± 37.5 mV respectively. Furthermore, the peak power densities are found as 6.4 ± 0.2 W m−2 and 13.4 ± 0.4 W m−2 for a single-cell and a 5-cell stack respectively. Moreover, the effects of varying humidifier temperatures on their efficiencies are studied, and hence increasing humidifier temperatures are found to provide higher efficiencies. Both energetic and exergetic efficiencies at the peak power density are determined to be 52.4 ± 1.6% and 49.3 ± 1.6% respectively under the ambient conditions considered. [ABSTRACT FROM AUTHOR]

Abstract In the present study, the solid anion exchange membrane and molten electrolyte entailing direct type ammonia fuel cells are uniquely developed, and their performances are investigated through energy and exergy efficiencies at varying operating conditions and state properties, based on the presently conducted experiments and datasets obtained. Both energy and exergy efficiencies are determined to be 12.1 ± 0.4% and 13.8 ± 0.4% respectively at the maximum power density value of 6.4 ± 0.2 W m−2 for the membrane based cell. Higher humidifier temperatures are observed to improve the performance of the fuel cell. The energy and exergy efficiencies of the molten alkaline electrolyte based cell are found to be 20.6 ± 0.6% and 23.3 ± 0.7% respectively at a temperature of 220 °C. The open circuit voltages are found as 278 ± 8 mV and 520 ± 16 mV for the anion exchange membrane and molten alkaline electrolyte based cells respectively. The open circuit voltage decreases and the short circuit current density increases with increasing electrolyte temperatures. Highlights • Membrane and molten electrolyte based direct ammonia fuel cells uniquely developed. • Membrane based cell has energy and exergy efficiencies of 12.1% and 13.8%. • Molten electrolyte based cell has energy and exergy efficiencies of 20.6% and 23.3%. • Open circuit voltages of 520 mV and 278 mV obtained for the two cells respectively. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a direct ammonia fuel cell comprising of an anion exchange membrane‐based electrolyte is developed, built and tested in the laboratory for investigating the performance electrochemically. In this regard, the aqueous ammonia is used as a storage medium for unreacted fuel. With gaseous ammonia fuel, an open circuit voltage (OCV) of 280 ± 8 mV is obtained at an operating temperature of 25 °C and a pressure of 100 kPa (1 bar). Furthermore, the peak power density at ambient conditions with gaseous ammonia fuel is observed to be 6.4 ± 0.3 W m−2. The unreacted gaseous fuel is stored in the form of aqueous ammonia and the fuel cell performance is tested at varying storage reservoir temperatures between 25 °C and 65 °C. An OCV of 110 ± 3 mV and a peak power density of 0.72 W m−2 is observed at an aqueous fuel temperature of 25 °C. Increasing storage reservoir and humidifier temperatures are found to improve the fuel cell performance characteristics. [ABSTRACT FROM AUTHOR]

In this study, life cycle assessments and comparative evaluations are performed for different types of renewable and alternative fuels for aircrafts. The life cycle impacts of both hydrogen and ammonia fuels are primarily investigated considering conventional and renewable energy-based routes. The overall life cycle impacts of several hydrocarbon fuels including kerosene, ethanol, methanol, dimethyl ether, and biodiesel are also studied. The steam methane reforming-based route for hydrogen and ammonia fuels is found to have higher global warming potentials as compared to alternative production routes. High phosphate emissions result in a higher freshwater eutrophication potential for the solar-based route for ammonia fuel. Fossil fuel-based dimethyl ether is found to have a comparatively higher global warming potential of 1.3 kgCO 2 equivalent per tonne-km amongst the considered hydrocarbon fuels that include ethanol (1.1 kgCO 2 equivalent per tonne-km), kerosene (1.04 kgCO 2 equivalent per tonne-km), methanol (1.01 kgCO 2 equivalent per tonne-km), and biodiesel (1.07 kgCO 2 equivalent per tonne-km). Dimethyl ether is found to entail high toxicity potentials and the reduction of life cycle arsenic, barium, cadmium, chromium, cobalt, and lead emissions is recommended. However, higher photochemical ozone formation potentials of 0.0055 and 0.0046 kgNOx equivalent per tonne-km are associated with biodiesel and kerosene fuels respectively. • Comparative life cycle assessment of different alternative aviation fuels. • Solar-based hydrogen fuel found to entail higher ionizing radiation potential. • Dimethyl ether fuel found to have global warming potential of 1.3 kgCO 2eq /tkm. • Biodiesel entails photochemical ozone formation potential of 0.0055 kgNO xeq /tkm. [ABSTRACT FROM AUTHOR]

Although there has been the commercially employed and widely used Haber-Bosch ammonia synthesis process which requires the high operating pressure and temperature in addition to the relatively low conversion rates, there is a need for a more compact and modular, but more efficient and effective approach. In conjunction with this, the present study develops, tests and investigates a cascaded ammonia synthesis system to explore the room for improvement in the ammonia conversion efficiencies. A lab-scale prototype is developed to investigate the effect of cascading two ammonia synthesis reactors in series employing pre-reduced KMR catalyst and the experimental investigations revealed the improved ammonia synthesis rates using cascaded configuration. The scanning electron microscopy (SEM) results of the KMR catalyst are also presented at different magnifications of 2.00 kx and 50.0 kx. The Aspen Plus simulation results of the cascaded ammonia synthesis system have also been validated using the experimental results and validation shows the percentage difference ranging from 1.62–6.61%. The experimentally developed cascaded ammonia synthesis system is investigated under different operating temperatures and pressures. The experimental results revealed that the ammonia conversion efficiencies that range from 4.58–7.88% using the single reactor with pressure rise from 6 to 12 bar at the temperature of 370 °C, increase to the conversion efficiencies of 5.42–9.16% by employing cascaded ammonia synthesis design. [Display omitted] • A new concept of cascaded ammonia synthesis is developed experimentally. • The experimental system performance is investigated with and without cascading. • The SEM results of KMR catalyst are presented at 2.00kx and 50.0kx magnifications. • Pressure rise from 6 to 12 bar increased NH3 conversion efficiencies from 5.42–9.16%. • The validation showed the percentage difference ranging from 1.62–6.61%. [ABSTRACT FROM AUTHOR]

• New integrated ammonia synthesis and fuel cell system experimentally investigated. • Charging and discharging exergy efficiencies found to be 17% and 49.2% respectively. • Hydrogen production entails highest exergy destruction ratio of 153.6 kJ/molH 2. • Overall efficiency of the developed system found to be 8.4%. In the present study, an experimental investigation of a new integrated ammonia synthesis and fuel cell system is performed. A lab-scale clean ammonia synthesis system utilizing hydrogen produced through the water electrolysis route is integrated with a direct ammonia fuel cell system. The performance of the developed system is investigated under the two key phases of energy charging and discharging. The energetic and exergetic performances of associated subsystems are also investigated. An energy efficiency of 15.9% is found for the charging phase of the system and the system exergy efficiency for this phase is evaluated as 17%. Furthermore, the energetic and exergetic efficiencies for the discharging phase are determined as 52.3% and 49.2% respectively. The overall efficiency of the developed experimental system is evaluated as 8.4%. The exergy destruction ratios of associated subsystems are also evaluated and the proton exchange membrane-based water electrolysis subsystem entails the highest ratio of 153.6 kJ/molH 2. In addition, the exergy destruction ratio of the ammonia synthesis subsystem is found to be 5.63 kJ/molNH 3. Several parametric studies are also performed to investigate the system performances under varying operating parameters. [ABSTRACT FROM AUTHOR]

In this study, a new wind and solar energy-based system is developed for multigeneration of clean electricity, heat, hydrogen and ammonia. Two input commodities considered are air and water for producing clean hydrogen and synthesizing into ammonia. With the excess wind power, hydrogen and ammonia are further synthesized where the produced ammonia is also used as an energy storage medium. Furthermore, excess solar energy is stored and used to generate electricity as well as dissociate ammonia for fuel cell operation when low energy availability exists. A dynamic investigation of the developed system is performed to assess its performance during each month of the year through energetic and exergetic analyses. The integrated system is found to be capable of providing an 8-h maximum stable power output value of 104.5 MW from solar-based power generation. Also, a 6-h maximum stable wind-based power output of 92.2 MW is obtained for the developed system. In addition, the highest daily hydrogen and ammonia synthesis during the year entail values of 5849.3 kmol and 1949.8 kmol, respectively. The overall daily energy efficiency of the system during the year varies between 37.4% and 62.9% whereas the corresponding exergy efficiency lies between 35.1% and 55.5%. • A novel multigeneration system proposed with new waste heat recovery techniques. • A maximum solar-based stable power output of 104.5 MW obtained for 8 h. • The peak exergetic efficiency of the developed system is obtained to be 55.5%. • Hydrogen and ammonia synthesis entail peak values of 5849.3 kmol and 1949.8 kmol. [ABSTRACT FROM AUTHOR]

In the present study, a new ammonia synthesis and fuel cell system integrated with solar energy is developed. The excess energy from a solar photo-voltaic plant is utilized for ammonia synthesis, which acts as an energy storage medium. Two different locations in Canada are considered for system modelling and simulation. The thermodynamic performance of the developed system is analyzed on a transient basis taking into account the variations in solar intensities across the year. The maximum energetic performance evaluated in terms of energy efficiency is 15.72%. Also, the peak exergetic efficiency of the solar-based system is determined as 16.55%. In addition, the daily discharge time capacity is found to reach 8.9 h at the peak. Furthermore, the ammonia synthesis rate obtains a value of 64.8 mol/s at the peak synthesis rate. The daily capacity of energy discharge entails the maximum value of 8502.4 kWh. The dynamic simulation results of each subsystem are discussed comprehensively presenting the applicability of the developed system for intermittency mitigation. Image 10 • A new ammonia synthesis and fuel cell system integrated with solar energy. • Maximum energetic performance in terms of efficiency reaches 15.72%. • The peak exergetic efficiency of the solar-based system is determined as 16.55%. • Daily discharge time and energy capacity found to reach 8.9 h and 8502.4 kWh [ABSTRACT FROM AUTHOR]

• New integrated solar-based ammonia synthesis and fuel cell system developed. • Transient simulation of the developed system performed at varying solar intensities. • Overall system energy efficiency varies between 15.68 and 15.83%. • Exergy efficiency of the overall system varies between 16.44 and 16.67%. • Discharge time capacities found to vary between 2.6 and 8.3 h across the year. Ammonia is considered to be a promising energy storage medium that can address the challenges associated with hydrogen. It is essential to investigate the usage of ammonia for energy storage, especially for the applications of intermittent energy resources. Hence, in the present study, a new integrated solar-based ammonia synthesis and fuel cell system is presented. The excess power generated by a solar photovoltaic system is utilized to synthesize ammonia. Furthermore, a direct ammonia fuel cell is employed for electricity production when low solar energy is available. The system is simulated dynamically on the average day of each month and the performance is investigated through thermodynamic energy and exergy tools. The overall exergy efficiency lies in the range of 16.44%-16.67% while the overall energy efficiency during the year varies between 15.68% and 15.83%, respectively. Also, the discharge time capacity is found to vary between 2.6 and 8.3 h. Moreover, the ammonia synthesis rate reaches a peak value of 64.8 mol s−1 during high solar energy availability. In addition, the maximum energy discharge capacity of the system is evaluated to be 7924.2 kWh. Several parametric studies are also conducted, and the performances are studied comprehensively through energy and exergy efficiencies under various conditions. The developed system entails the advantages of high energy density as well as longer storage times as compared to other energy storage methods. [ABSTRACT FROM AUTHOR]

• Improvement capability of ammonia fuel cells tested with hydrogen inclusion. • Thermodynamic energy and exergy analyses performed with different fuel blends. • Energy efficiency rises by 7.9% with 40% hydrogen addition. • Exergy efficiency rises by 7.6% with 40% inclusion as compared to pure ammonia. In this study, hydrogen is investigated as a source of performance improvement for alkaline electrolyte entailing direct ammonia fuel cells via dual fuel utilization. Membrane electrolytes are utilized with anion exchange characteristics and the fuel cell performance is investigated with pure ammonia, ammonia-hydrogen blends and pure hydrogen. The power density is observed to be 1990.8 mW/m2 for pure ammonia fuel at peak point. However, this is found to increase to 2853 mW/m2 and 4471 mW/m2 when fuel blends of 80%NH 3 -20%H 2 and 60%NH 3 -40%H 2 are utilized respectively. The exergy efficiency at the maximum point power density increases from 14.2% to 22.1% and the energy efficiency rises from 15.2% to 22.8% as the fuel input is changed from pure ammonia to 60%NH 3 -40%H 2 by mass. Also, the highest exergy efficiency of 29.1% and energy efficiency of 28.7% is obtained for the pure hydrogen fueled cell. In addition, the exergy destruction rate is determined to be 16.8 mW for the pure ammonia fuel cell at the maximum point power density, which decreases to 15.1 mW and 13.6 mW for 60%NH 3 -40%H 2 and 80%NH 3 -20%H 2 fuels respectively. [ABSTRACT FROM AUTHOR]

In this study, a novel hybrid thermal energy storage and ammonia fuel cell system is developed and investigated for a solar tower based power plant. An annual analysis of the developed system is performed by considering the monthly average days. Also, the actual power demands as well as the solar intensity changes are taken into account. Thermodynamic approaches of energy and exergy analyses are utilized for system analysis. The energetic efficiency of the proposed power plant varies between 5.3% and 37% while the exergy efficiency ranges between 5.7% and 39%, depending on the corresponding power demands as well as available solar energy. The system simulation results for each month are also described in terms of the specific exergies and enthalpies at the turbine inlets. Furthermore, energy efficiency of the direct ammonia fuel cell is evaluated to be 37% and the exergy efficiency is found to be 34% at the peak power density. At a temperature of 500 °C, a specific thermal energy storage capacity of 266 kJ kg−1 is determined for the hybrid system. • A novel solar tower based power generation system is developed. • A hybrid thermal energy storage and ammonia fuel cell system is introduced. • The energy efficiency of the developed system varies between 5.3% and 37%. • The exergy efficiency of varies between 5.7% and 39%. [ABSTRACT FROM AUTHOR]