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Geothermal energy can play a crucial role in the global energy transition towards more sustainable and renewable sources. It can contribute in numerous ways including renewable and clean energy, baseload power generation, energy independence and security, heating and cooling applications, economic benefits and transition support for fossil fuel-dependent regions. Considering the modest deployment of geothermal energy regardless of its immense potential, this study explores the better utilization of geothermal energy for multigeneration purposes that also improves the system efficiencies. In this study, a binary-type geothermal-based system is developed for multigeneration including power generation, seawater desalination and hot water production. The system incorporates an isobutane entailing organic Rankine cycle (ORC) to generate electrical power and a flash distillation system for seawater desalination. A detailed thermodynamic analysis including first and second law efficiency assessment is performed to depict the performance of the designed concept. The system entails a power output of 2262 kW and seawater desalination rate of 11.09 kg/s. The energy efficiency of the overall system is evaluated to be 23.5 %. Also, the exergy efficiency is found to be 28.9 %. In addition, the ORC energetic efficiency is determined to be 7.9 % and the exergetic efficiency is evaluated as 51.1 %. Moreover, the flash distillation subsystem has energetic and exergetic efficiencies of 9.3 % and 2.7 % respectively. Several parametric studies are performed to investigate the effects of varying system conditions and operating parameters on system efficiencies. • A binary-type geothermal-based system is developed for multigeneration. • Useful commodities incorporated include electricity, desalination, and hot water. • Overall energy efficiency of the integrated system is evaluated to be 23.5 %. • The exergetic performance is evaluated 28.9 % in terms of exergy efficiency. • Several parametric investigations and sub-component analysis are also performed. [ABSTRACT FROM AUTHOR]

• A biomass and solar energy based system is developed and comparatively evaluated. • The proposed system is analysed thermodynamically by energy and exergy approach. • Hydrogen, electricity, hot water for fish farming and cooling are major commodities. • The hydrogen production rate of 59.45 mol/s and power of 8.3 MW is produced. • The overall energy and exergy efficiencies are found to be 29.9% and 31.5%. A biomass and solar energy based system consisting of a gas turbine cycle, a reheat Rankine cycle, a solar heliostat field, four-step copper-chlorine cycle and absorption cooling system is newly proposed, analyzed and comparatively evaluated through energy and exergy approaches. The proposed system is designed for the multiple useful commodities of hydrogen, electricity, hot water for fish farming and cooling. The effects of different operating conditions and parameters, namely air flow rate, biomass flow rate, working fluid flow rate, direct normal irradiance, number of heliostats, evaporator exit temperature and ambient temperature are investigated for the performance of the designed system defined in terms of energy and exergy efficiencies, and energy and exergetic coefficients of performance. The combined system, excluding solar heliostat field and absorption cooling system, is simulated using the Aspen Plus while the subsystems are modeled using the engineering equation solver package. Heating and cooling are produced for community usage, and hydrogen can be employed for industrial purposes. Both design and cost analyses are also conducted using the Aspen Plus v9 and Aspen Plus economic analyzer v9. The energy efficiency of the overall system is determined as 29.9% while the corresponding exergy efficiency is obtained to be 31.5%. The additional findings and outcomes are also presented and discussed comprehensively. [ABSTRACT FROM AUTHOR]

A novel multi-generation integrated energy system is presented in this paper, consisting of a gas-steam combined cycle, four-step thermochemical copper-chlorine (Cu Cl) cycle, proton exchange membrane fuel cell (PEMFC) and a reverse osmosis (RO) desalination unit. Effective thermal management of waste heat is recognized as a key objective in the steel industry. Hydrogen, electricity, fresh water and heat are the useful outputs of the integrated system. The produced electricity supplies the electricity load required by the electrolyzer, compressor and pumps while the supplementary electricity is an additional system product. Aspen Plus and Engineering Equation Solver (EES) are used for modeling and simulation of the multi-generation system. The overall hydrogen production rate of the designed system is 51.8 kg/hr and the net power production is 1.7 MW. The overall energy efficiency of the multi-generation system is 63.3% and the exergy efficiency is 58.8%. Further sensitivity studies and outcomes are presented and discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper focuses on a new configuration of biomass gasification based cascaded ammonia synthesis and proposes two different configurations of ammonia synthesis system using the Stoichiometric and Gibbs reactors in the Aspen Plus V11. A new heat recovery technique from biomass gasification using syngas cooling is also proposed in this study. The proposed configuration comprises of a biomass gasifier, a heat recovery unit for syngas cooling, a combined cycle, water gas shift reactor system (WGSRS), pressure swing adsorption (PSA) and ammonia production unit. The ammonia based carbon-capturing system is incorporated to ultimately capture the CO 2 emissions. The sensitivity analyses are conducted on each significant subsystem employed in the proposed configuration. The results obtained from the Gibbs reactors show that pressure has a positive effect while very high-temperature effects negative on the ammonia synthesis. The results also reveal that the cascaded ammonia synthesis offers high ammonia conversion rates. The designed system produces 21.9 kmol/h of ammonia and 3405 kW electrical power. The results obtained from the present sensitivity analysis are further presented and discussed. • New configuration of biomass gasification based cascaded NH 3 synthesis is proposed. • New heat recovery technique is proposed using the syngas cooling. • The designed system produces 21.9 kmol/h of ammonia and 3405 kW electrical power. • Overall exergy and energy efficiencies are found to 44.2% and 42.4% respectively. [ABSTRACT FROM AUTHOR]

Hydrogen is acknowledged as a potential fuel as it can be used as an energy carrier, a storage medium, in fuel cells and as a fuel as well and offers carbon-free solutions. This paper investigates three renewable energy based configurations for hydrogen production. The renewable energy sources considered in this study are solar PV, geothermal power generation and biomass gasification. The proposed study also presents a novel configuration of biomass gasification for hydrogen production via multistage water gas shift reactors. The solar PV and geothermal energy based hydrogen production systems are analysed employing the EES software while the hydrogen production system employing biomass gasification is simulated employing Aspen Plus. All three designed configurations are proceeded through numerous parametric analyses to investigate the system behavior and effect on system efficiencies. The hydrogen production using biomass gasification technique provides with the energetic and exergetic efficiencies of 53.6% and 49.8% and the efficiencies for the geothermal power generation based hydrogen production system are found to be 10.4% and 10.2% respectively. The exergetic and energetic efficiencies of hydrogen production system employing solar PV system are found to be 17.45% and 16.95%, respectively and the system is designed to produce 1.13 mol/s of hydrogen. Furthermore, the results of the parametric studies and sensitivity analyses are presented and discussed. • This paper investigates three renewable energy techniques for hydrogen production. • The considered renewable energy sources are solar PV, geothermal and biomass. • Biomass gasification offers energy and exergy efficiencies of 53.6% and 49.8%. • The energy and exergy efficiencies of geothermal hydrogen are 10.4% and 10.2%. • The exergy and energy efficiencies of solar PV based H 2 are 16.95% and 17.45%. [ABSTRACT FROM AUTHOR]

A biomass gasification based multi-generation system integrated with thermoelectric generators is developed and proposed for cleaner applications. The paper presents, analyzes and validates a novel integration of the thermoelectric generators in the proposed biomass gasification based system and discusses the possibility of better efficiency and energy use with reduced carbon emissions. The influences of varying biomass gasification parameters are also studied against the syngas composition. The major subsystems of the integrated system, such as gasification, cryogenic air separation unit, Brayton cycle, heat recovery and domestic hot water production is simulated using Aspen plus while the Engineering Equation Solver (EES) is employed to model thermoelectric generators, proton exchange membrane electrolyzer and organic Rankine cycle. The system operating conditions and their effects on system performance are investigated. The waste heat from the thermoelectric generators is employed to the organic Rankine cycle to produce power and work generated by thermoelectric generators is employed to the proton exchange membrane electrolyzer to produce hydrogen. The amount of hydrogen produced is about 0.13 kg/day, and the amount of heating achieved by the system is 1.4 MW. Likewise, the proposed system is capable of producing 22 kg/s of hot water for the domestic purposes. The overall energy and exergy efficiencies are found to be 58.03% and 32.78%. As compared to conventional systems with thermoelectric generation, the system proposed in this study carries unique and superior characteristics. • A biomass gasification based integrated energy system is uniquely proposed. • Influence of biomass gasification parameters on syngas composition is investigated. • Operating conditions and their effects on system performance are investigated. • Power from thermoelectric generators is employed to the PEM electrolyzer. • The overall energetic and exergetic efficiencies are found to be 58.03% and 32.78%. [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]