Cogeneration Of Electricity Research Articles

Life cycle environmental benefits of recycling waste liquor and chemicals in production of lignocellulosic bioethanol

In recent decades, numerous bioconversion processes and techniques have been developed to utilize lignocellulosic biomass as feedstock in the production of bio-based fuels and materials. However, waste treatment, an important sub-system, is seldom considered in the life cycle assessment of lignocellulose derived products. This study comprehensively investigated the environmental impacts of bioethanol and electricity cogeneration from sugarcane bagasse, with a focus on recycling techniques adopted in waste treatment. A life cycle assessment indicated that high recycle rate of black liquor, acid and waste washing water can substantially reduce the consumption of fresh water, related chemicals and energy by 70–80%. Environmental impacts relating to global warming, acidification potential and primary energy demand can be decreased by 5–10 times or even entirely eliminated. These study outcomes demonstrate significant environmental benefits of integrating waste recycling techniques into lignocellulose biorefinery process, providing a solid foundation for future industrial development.

Performance investigation on a concentrating photovoltaic thermal system integrated with spectral splitter and absorption heat pump

To alleviate the energy consumption crisis and environmental pollutant problems, a concentrating photovoltaic thermal system integrated with spectral splitter and absorption heat pump is proposed. Through solar spectral splitting, the photo-electric and photo-thermal processes are decoupled, which facilitates the cogeneration of electricity and high-temperature heat. Through absorption heat pump, the temperature of geothermal energy is improved by high-temperature solar heat for subsequent utilization. Thus, the efficient utilization of full spectrum solar energy is achieved. To further evaluate the performances, an electric-thermal coupled model is developed and the comprehensive analysis is carried out from energy, exergy and exergoeconomic viewpoints. Results indicate that for an optical window of 400–1300 nm, strong LiBr/H2O solution concentration of 64 %, concentration difference of 5 % and thermal receiver temperature of 438.15 K, the overall energy and exergy efficiency is obtained about 102.14 % and 37.49 %, respectively. Among all components, parabolic trough concentrator is the most inefficient component with energy losses of 123.86 MWh. Highest exergy destruction is observed in the solar cell, accounting for 67.51 % of the total destruction. Moreover, a total exergoeconomic factor of 79.94 % is obtained for the entire system indicating that 20.06 % of the total costs are related to exergy destruction.

Electricity and water cogeneration using a small PWR of 75 MW(th) coupled to a DCMD desalination plant with heat recovery

The use of a small PWR of 75 MW(th) coupled to a Direct Contact Membrane Distillation (DCMD) desalination plant with heat recovery, for cogeneration of electricity and water, is investigated here. Part of the heat used for desalination is waste heat from the power plant, as the desalination plant collects warm seawater from the power plant condenser instead of taking water directly from the sea. Two distinct coupling strategies are considered. In the first one, the additional heating required for the desalination process is obtained from steam extractions, taken at the low pressure turbine, after the extracted steam has already done a substantial amount of mechanical work. The second strategy is based on splitting the steam produced in the steam generator into two parallel Rankine cycles. The condenser at one of those cycles is set to operate just below atmospheric pressure in order to provide extra heating, at a higher temperature, for the desalination plant. Both strategies analysed in this work, relying on the use of waste heat and employing a DCMD desalination plant with efficient heat recovery, are shown to be competitive with other well established thermal desalination technologies currently used in nuclear cogeneration plants, such as MED and MSF.

Design and Thermo-Economic Analysis of an Integrated Solar Field Micro Gas Turbine Biomass Gasifier and Organic Rankine Cycle System

A micro gas turbine (MGT) is an advanced technology with a simple structure and fast load response. It represents a good choice for the next generation of distributed power systems, where fossil fuels are going to be largely replaced by biofuels and renewable sources. In this context, this work aims to investigate and compare the performance of gradually more complex energy systems integrating a micro gas turbine plant: simple cogenerating asset, integrating a solar field, presence of a gasifier, and the addition of a bottoming ORC. In all cases, a thermo-economic analysis has been carried out for an application in the agricultural sector. Agricultural waste can be used to create a syngas as fuel for MGT through a gasifier, promoting the utilization of carbon-neutral alternative fuels to reduce harmful emissions. The authors considered the electrical and thermal needs of a hypothetical agri-food company to build the electrical and thermal load curves. The new and more complex cogeneration plant, designed by using the Thermoflex 30 software, leads to an increase in electrical power, recovered thermal power, overall electrical efficiency, carbon neutrality, and cogeneration indexes. In particular, the presence of the solar field promotes a reduction in fuel consumption as well as greater heat input to the thermal unit. The addition of a bottoming ORC system increases the electrical power by 36.4%, without significantly penalizing the thermal unit. Moreover, thanks to the gasifier that offsets the fuel reduction costs, through an economic analysis of the entire plant, a payback time of the investment of less than 4 years is obtained.

The reusage of water and steam utilities by using the integrated fork technique and the complete circular economy

The reusage of water and steam utilities plays a key role in the mitigation of decarbonising and climate change, including reduced fossil-fuel energy consumption and reducing the dependence on natural gas. The water condensates can be used for utility and heat-recovery systems by an integrated fork technique, achieving economic benefits and a complete circular economy, presented in two steps. The main novelty of this fork technique includes the determination of a regulated heat flow rate for the integration between the dryer and evaporator, which enables an evaporation of the same water mass flow as by the existing evaporating system, which is performed in the first step. The main significance of this technique presents the manner of a fork system as a superstructure for waste condensates’ collection separately and combinedly, and sustainable reusage's alternatives of the condensates, such as steam or electricity cogeneration, presented in the second step.This technique is carried out in two steps, including real-simulated results using an Aspen Plus® simulator. This approach is illustrated using an existing sugar production, which is selected as the waste mass and energy reusage from the evaporator and dryer for low-pressure steam production, generating a possible increase profit of 1.9 MEUR/a. The saving of the heat flow rate after the integrated dryer with evaporator should be 15,816 kW, or 73 %, presenting as a percentage.

Система совместного использования обедненного метана угольных пластов и биогаза для выработки электроэнергии в угольных шахтах

Purpose: Justification and development of new resource-saving technologies aimed at utilization of coal bed methane. The problem of low efficiency of utilization of lean methane-air mixtures is primarily due to the low content of methane itself, which varies significantly depending on the type of coal or concentration. This paper discusses the concept of a co-production system that mixes low-methane methane-air mixtures and biogas to generate power. Methods: Analysis of the possible volumes of utilized methane, biogas requirements and the suitability of the primary feedstock for co-generation of heat and electricity. Selection of appropriate parameters for the processes of utilization of mine methane. Analysis of the merits of the proposed method of utilization of lean coal mine methane. Results: It is recommended that biogas produced by agriculture and forestry in the vicinity of the mines be added to the dry methane stream to obtain the necessary gas concentration for electricity generation. Potential electricity production and greenhouse gas emission reductions have also been evaluated. The result shows that the co-production system can significantly improve the efficiency of poor methane-air mixtures in coal mines. Practical significance: The joint use of lean methane and biogas from straw offers practical advantages both economically, ensuring sufficient energy supply in mines, and as a foundation for broad future prospects. It allows for energy cost reduction and environmental pollution reduction, such as decreasing carbon dioxide emissions.

A solar spectral splitting-based PVT collector with packed transparent tube receiver for co-generation of heat and electricity

Combined heating and power (CHP) systems co-generating electrical energy as well as thermal energy is indispensable for modern-day distributed applications. Photovoltaic thermal (PVT) systems are such hybrid co-generation systems. However, in a conventional PVT system, the PV module/cell temperature restricts the thermal output, making these systems unsuitable for various applications. This study offers a novel and resilient design for a spectral beam splitting-powered compound parabolic collector-based PVT system that employs a nanofluid optical filter within borosilicate glass tubes for volumetric absorption. By maximizing the “splitting effect”, the goal of this work is to disrupt the long-standing relationship between the thermal and electrical yield from a PVT collector, i.e., obtaining a higher heat transfer fluid temperature than the PV cell temperature. Several configurations with varying array width-to-receiver tube diameter ratios, i.e. bdo ratios (ranging from 3 to 8) and one, two, and three rows/layers of receiver tubes were evaluated and compared. The optical and thermal performance of the collector designs are compared using metrics such as heat flux distribution, optical efficiency, temperature distribution, receiver efficiency, and splitting ratio. This work determines how the splitting effect dictates the performances of the collector. Through the ray-tracing routine and thermal analysis, it is demonstrated that for certain bdo ratios, the developed collector attained a maximum cumulative temperature rise of >100∘ C using ZnO–water–ethylene glycol nanofluid as the optical filter. Also, the receiver and electrical efficiency of 51.81% and 18.77%, respectively, are achieved. Moreover, the packed borosilicate glass receiver tubes with a bdo ratio of 8 and two receiver rows/layers achieved the so-called “splitting ratio” (ratio of filter fluid temperature to cell temperature; THTFTcell) of >1.6. The studied configurations find their application depending on the extent of the achieved splitting ratio. Based on these findings, it is concluded that the analyzed packed glass tube receiver designs provide a viable new route towards cost-effective and dependable robust PVT collectors for distributed and other applications.

Simultaneous water production and electricity generation driven by synergistic temperature-salinity gradient in thermo-osmosis process

Low-grade heat energy is enormous and widely distributed around the world, but it cannot be effectively converted to electricity owing to the small temperature difference and fluctuating heat source. As a promising technology that can convert low-grade heat energy into electricity while obtaining additional freshwater, thermo-osmotic energy conversion has attracted attentions of numerous researchers. However, traditional thermo-osmotic energy conversion technologies lack the utilization of the accompanying variation in salinity gradients throughout the process. In this study, a hybrid system was presented to achieve simultaneous freshwater production and electricity generation by combining thermo-osmosis system with a salinity gradient power recovery module. Continuous operation of the thermo-osmosis system will naturally produce a range of salinity differences, which will then be converted into electricity by the salinity gradient power recovery module. Our results show that this hybrid system can optimally increase the electricity output by ∼0.99 W m−2 over the conventional thermo-osmotic energy conversion system. Overall, our research demonstrates a promising device to harvest low-grade waste heat for co-generation of electricity and freshwater. This innovative approach has the potential to broaden the application possibilities of thermo-osmosis technology.

Impact of the Catalyst Type and Dopant Composition on the Performance of High-Temperature PEM Fuel Cell

Increasing interest in hydrogen-powered fuel cells for electric energy generation led to the identification of serious limitations of state-of-the-art technologies. In particular, low-temperature fuel cell with a proton-exchange membrane (LT-PEM FC), which is widely considered as an optimal type for mobility, is reaching its technological limits. This is due to its operating temperature up to 90 °C, defined by properties of perfluorinated, sulfonated membranes used as PEM, requiring liquid water for ensuring their ionic conductivity. In the case of heavy duty applications, high-power LT-PEMFC stacks suffer from local overheating, which is currently solved by intensive cooling. Ineffective heat-exchange and necessity of water regime control lead to limitations in total energy utilization. Such problem can be solved by increasing operating temperature up to 180 °C, which is suitable for heat cogeneration. This requires application of appropriate PEM conducting even at an elevated temperature.Current state-of-the-art high-temperature PEM fuel cells (HT-PEM FCs) utilize PEMs based on polymer doped with phosphoric acid. Polymers, such as polybenzimidazole or pyridine aromatic polyether, act as a matrix and a bonding agent for the phosphoric acid dopant. Such PEMs can operate within the temperature range of 120 to 180 °C. In terms of the catalyst, HT-PEM FCs use Pt-based, nanoparticle catalysts on carbon support as in LT-PEM FCs. However, due to the mobile nature of phosphoric acid, which is responsible for pronounced catalyst degradation, poisoning as well as local catalytic layer flooding, Pt loading used in HT-PEM FCs is within an order of magnitude higher than in LT-PEM FCs.Due to its high operating temperature, HT-PEM FC technology offers numerous advantages, such as heat and electric energy cogeneration, simple water regime and, due to improved tolerance to catalyst poisons like CO, the possibility of utilization of contaminated H2 produced from fossil fuels and biomass. However, degradation of components, in particular the catalyst and the membrane, remain the main bottlenecks for wide HT-PEM FC commercialization. With respect to the latest advances in technology, two critical aspects were identified. Firstly, the necessity of new catalysts immobilized on durable supports, with improved stability, activity and resistance against poisoning by phosphate anions. Secondly, membrane with improved fixation of phosphoric acid and greater durability. A special case of the membrane degradation is the reduction of phosphoric acid, by hydrogen or at low potentials on the anode, to phosphorous acid. This compound can poison the anode catalyst, incorporate into the membrane as well as oxidize on the cathode to phosphoric acid, completing dopant lifecycle. Nevertheless, the exact impact of phosphorous acid on HT-PEM FC performance is still not fully understood.Accordingly, the study had two major goals. A first one was to investigate the performance and degradation of Pt-based alloy catalyst on graphene-type support using thin-film modified rotating disc electrode, half-cell and single cell setups. All experiments have been performed at HT-PEM FC relevant conditions, i.e. in concentrated phosphoric acid electrolyte within temperature range of 120 to 180 °C. On the other hand, the second one goal investigated the influence of the dopant composition in terms of phosphorous acid addition to phosphoric acid electrolyte on the activity of the catalyst.Performance of experimental catalysts based on Pt-Co on various supports, including carbon black and graphene was compared to commercial Pt/C catalyst. Experimental catalysts exhibited superior activity for oxygen reduction. The overall performance of single cells with experimental catalyst on the cathode was better than the one with the commercial catalyst, with best results obtained for the graphene supported Pt-Co. The impact of phosphorous acid on oxygen reduction on commercial Pt/C catalyst was significant, due to simultaneous oxidation of acid and reduction of oxygen, as confirmed using rotating disc electrode and half-cell setups. Using the addition of phosphorous acid after single cell break-in on the cathode, the anode or both electrodes at once, it was determined that after stabilization the performance improved. Electrochemical impedance spectroscopy showed that addition of phosphorous acid decreases cell Ohmic resistance, but the comparative I-U curves and CO stripping analysis performed on cathode indicated significant decrease of available Pt surface. This reflects the ambivalent influence of phosphorous acid on HT-PEM FC.This study was supported by the Grant Agency of the Czech Republic under project No. 22-23668K.

Experiment study on heat transfer enhancement of micro heat pipe PV/T by Reynolds number improvement

The rapid performance improvement of photovoltaic/thermal (PV/T) implies great potential application to various aspects of society. The previously developed micro heat pipe PV/T by our team has shown favorable cogeneration of electricity and heat in cold regions, while it is badly needed to improve its comprehensive performance by enhancement of heat transfer. For same working fluid as HCFC141b in micro heat pipe, higher Reynolds Number (Re) theoretically means better heat transfer. Therefore, two available micro heat pipes were developed with trapezoidal cross section and rectangular cross section respectively while with same cross section area and applied in two micro heat pipe PV/T systems. Subsequent experiment study testifies that the rectangular micro heat pipe PV/T of higher theoretical Re verily shows more favorable performance than the trapezoidal micro heat pipe PV/T when they are at 45° inclination angle. Deducting power consumption of circulating pump, the average electrical efficiency of rectangular micro heat pipe PV/T system is 12.4%, while that of trapezoidal micro heat pipe PV/T system is 11.9%. Moreover, the thermal efficiency, total energy power, and total energy efficiency of rectangular micro heat pipe PV/T system are respectively 28.1%, 472.3 W, and 40.5%, which are 10.1%, 119.8 W, and 10.8% higher than those of trapezoidal micro heat pipe PV/T system. The results are significant and valuable for the application of micro heat pipe PV/T in cold regions.

Techno-economic assessment of an autothermal poly-generation process involving pyrolysis, gasification and SOFC for olive kernel valorization

The present work elaborates on the simulation and techno-economic analysis of a proposed MW-scale hybrid scheme that enables the production of different marketable products (i.e., electric energy and bio-oil) from the thermochemical exploitation of olive kernel residual biomass. In this regard, detailed calculations for mass and energy balances, process simulation in Aspen Plus and economic analysis with complementary sensitivity scenarios were conducted, with the aim to model and assses the feasibility of an integrated process for electricity and crude bio-oil co-generation via subsequent stages of biomass pyrolysis, bio-char gasification, syngas-fed SOFC and steam turbine. Notably, it was demonstrated that the provision of 20 tn/day of raw olive kernel resulted in a net electricity generation of 1685 kWel as well as production of 3.4 tn/day of bio-oil, without the need for external heating. Equally importantly, the overall electric efficiency and the combined bio-oil/power co-generation efficiency of the integrated process were equal to 46.8% and 77.0%, respectively, being amongst the highest values reported in relevant works. Moreover, economic analysis revealed that syngas clean-up and SOFC units account for 75% of the total fixed capital investment as well as for 62% of the annual operation costs. Nonetheless, increased unit cost is largely counterbalanced by the fact that electricity generation accounts for ∼85% of total profits. Also, it was found that the proposed venture is not profitable considering current market values for electricity and bio-oil. However, sensitivity analysis revealed that a main equipment cost reduction of 70% is a prerequisite for the break-even electricity price to attain the current market values. Moreover, profitability can be marginally improved further by accounting for a state subsidization of more than half of the initial investment and by the increase of the crude bio-oil price at 700 €/tn.

A licensing plan for coupling nuclear–renewable hybrid energy systems

South Africa committed to reducing greenhouse gas emissions by 34% below "Business As Usual" levels by 2020 and 42% by 2025 at the Copenhagen climate change conference. However, global energy demand was projected to rise due to population and industrial growth, with energy usage expected to increase by 13% through 2040. In South Africa, a steady increase in electricity demand prompted the government to implement a new growth path (NGP), which prioritized job creation in all economic policies, including energy. To address the growing energy demand, an alternative energy source for combined heat and power was necessary, particularly for synthetic fuel production. The coupling of a high temperature reactor (HTR) with a chemical process plant could improve carbon and thermal efficiency, as seen in international organizations like the ARCHER (Advanced High-Temperature Reactors for Cogeneration of Heat and Electricity R&D) project. HTRs are still in their conceptual stages andaresuitable candidate forcouplingto an energy-intensiveindustrythat require process heat with sufficiently hightemperatures,with potential uses for NRHES (Nuclear-Renewable Hybrid Energy Systems). The South African team aimed to model the SASOL process, assess its financial viability, and develop a licensing plan.

A cleaner and more efficient energy system achieving a sustainable future for road transport

A novel integrated cooling system is developed for future medium to large electric vehicles by integrating the fuel cell, battery, metal-hydride, heat pump, and liquid desiccant dehumidification system to reduce power consumption and extend vehicle's driving range. The system benefits from the reuse of the normally wasted energy in the form of pressure difference and wasted thermal energy, from the hydrogen vessel, the fuel cell stack, and the battery pack. A numerical model for the proposed system and a finite element model for the dehumidifier and regenerator are developed and validated by experimental results from published data. A comprehensive evaluation of the impacts of the ambient air temperature and humidity, fuel cell current output, battery discharging C rate, and air mass flow rate on the Coefficient of Performance (COP), outlet air temperature, and cooling capacity is conducted. Two operating modes, namely non-compressive mode and heat pump supplemental mode are investigated and a detailed comparison between these two modes is undertaken. Furthermore, the proposed system under heat pump supplemental mode has been compared to other published cooling systems and dehumidification systems. Under non-compressive mode, results indicate that the proposed system can provide sufficient cooling capacity without the need of the compressor when the supply air mass flow rate is lower than 0.03 kg/s, under the specific operating situation. Under the heat pump supplemental mode, the proposed system can operate at 36 °C with a COP greater than 4, which is 56% higher than the cited published results, although the COP of the proposed system also considers battery cooling. Heat pump supplemental mode drastically reduces the 12-s insufficient cooling period that occurs at the beginning of the charging to discharging transition between the two metal hydrides to 2 s compared to non-compressed mode. Overall, this study provides a potential solution for future zero-emission vehicles by utilizing the heat and electric co-generation characteristic of the fuel cell, the isothermal characteristic of the metal hydride, and dehumidification and cooling characteristics of the liquid desiccant dehumidification system to extend the driving range of the electric vehicles and reduce energy consumption for cooling. Moreover, the proposed system can also provide domestic cooling loads and power by integrating the system into residential buildings.

Proposal and evaluation of a hydrogen and electricity cogeneration system based on thermochemical complementary utilization of coal and solar energy

In this study, an efficient and clean hydrogen and electricity cogeneration system based on thermochemical complementary utilization of coal and solar energy is proposed, and the feature is that steam-to-methane ratio in the high-temperature syngas generated by supercritical water coal gasification is more than 3:1. Thus, without injecting new steam into syngas and only further increasing the temperature will provide very suitable reaction conditions for hydrogen production by steam methane self-reforming in syngas, which has lower energy consumption relative to a conventional reforming process. Through thermochemical complementary utilization, the solid fuel coal and solar energy are first converted into methane-rich syngas by supercritical water coal gasification, then methane-rich syngas and solar energy are converted into hydrogen-rich syngas by steam methane self-reforming, realizing the cascade utilization of chemical energy. Hydrogen is separated from the hydrogen-rich syngas by pressure swing adsorption, and the purge gas is introduced into the gas turbine to generate electricity. The results show that the total energy and exergy efficiencies of the integrated system are 49.37% and 49.84%, respectively, which increased by 4.91 and 4.97 percentage points relative to the reference system. In the integrated system, the hydrogen output is 452.40 MW (13582 kg/h, 28 bar), the electricity output is 209.47 MW, and the chemical energy of the syngas is 978.49 MW, which is approximately 49.14% higher than that of 656.09 MW in the reference system. Energy utilization diagram revealed that the key to the improved performance in the integrated system lies in the reduction of exergy destruction during the fuel conversion and heat exchange, which decreased by 3.76 and 6.68 percentage points relative to the reference system, respectively. This work provides a competitive option for large-scale hydrogen and electricity cogeneration systems.

Liquid flow fuel cell with an electrodeposition-modified nickel foam anode for efficient oxidation of 5-hydroxymethylfurfural to produce 2, 5-furandicarboxylic acid with co-generation of electricity

Liquid flow fuel cells were developed as reactors for efficient conversion of 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxylic acid (FDCA) at room temperature with co-generation of electricity. Electrodeposition modification of nickel foam (NF) with CoSO4 and NaH2PO2 (Co-P@NF anode) was found to significantly increase HMF oxidation efficiency, due to the reduction of polarization resistance of NF and increased electrochemical active area. However, the active species of Co-P@NF anode for HMF oxidation actually was NiOOH rather than cobalt. By using (VO2)2SO4 as a cathodic electron carrier, peak power density of 38.9 mW/cm2 at room temperature was obtained with 100% HMF conversion and 89.0–93.4% FDCA yield. FDCA concentration reached 81.8 g/L with 90% total yield after feeding HMF for six batches. Therefore, efficient production of FDCA was achieved under mild conditions with oxygen (air) as the final oxidant via the electron transport chains constructed by active nickel species and cathode electron carriers.

Direct Ammonia-Fed Liquid Metal Anode Solid Oxide Fuel Cell for Co-Generation of Hydrogen and Electricity

Ammonia shows great promise as a carbon-free alternative fuel with high hydrogen content, nice energy density and developed supply chain. For solid oxide fuel cells (SOFCs), ammonia decomposition at the anode forms a high temperature gradient, thus exerting a negative effect on the cell durability. In this research, a liquid antimony anode (LAA) SOFC was prepared as an electrochemical partial oxidation reformer. Part of ammonia was electrochemically oxidized at the LAA for producing heat and electricity, while the rest was decomposed to H2 and N2. The single cell exhibited a current density of 128 mA/cm2 at 0.4V and 850℃. Thermodynamic calculations showed that the heat release can be balanced with the heat adsorption. LAAs with high thermal conductivity transferred ammonia oxidation heat and prevented a high temperature gradient. This work showed the potential of LAA-SOFCs for co-generation of hydrogen and electricity from ammonia.

Effects of electrode rinse solution on performance of hydrogen and electricity cogeneration system by reverse electrodialysis

A harvestable salinity gradient energy exists between the concentrated and diluted electrolyte solutions, which can be converted to the electromotive force of a reverse electrodialysis (RED) stack to drive the power generation and hydrogen production. The performance of a hydrogen and electricity (H&E) cogeneration system by RED method is significantly influenced by the characteristics of the electrode rinse solution (ERS). The study experimentally investigated the effects of ERS concentration, flow rate, electrolyte composition, and active additive on the system's output voltage, power density, and hydrogen and oxygen production. Besides, a surface-active substance with catalytic activity was applied for the first time to the H&E cogeneration system, aiming to decrease the overpotentials of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The results showed that the output voltage increased with an increase in ERS flow rate, but hydrogen production declined. Increasing the concentration of the ERS was beneficial to promoting the output voltage and power density, but an extremely high pH of the ERS was not conducive to hydrogen production. The electrical output performance of the H&E cogeneration system using NaOH solution as the ERS was generally better than that of the corresponding KOH solution. The addition of trioctylmethylammonium chloride (Aliquat-336) was detrimental to the electrical output performance but promoted evolution of hydrogen and oxygen. At a current of 0.3 A and an Aliquat-336 concentration of 0.4 mM, the system achieved a hydrogen production rate of 0.71 ± 0.002 mol·m−2·h−1.

Research on solar dish/Stirling engine driven adsorption-based desalination system for simultaneous co-generation of electricity and freshwater: Numerical investigation

Poly-production green systems are recently promising alternatives that could produce various useful energy outputs such as electricity, heat, and distilled water with higher efficiencies, lower costs, and eco-friendly benefits. Considering the superior advantages of the dish/Stirling power cycle and adsorption-based distillation system. This study investigates a detailed theoretical dynamic modeling and performance analysis of an adsorption-based distillation system powered by a solar dish/Stirling engine (ADS-SDSE) for combined electricity and freshwater dual-production. Numerical lumped models for the hybrid system components are developed using MATLAB to evaluate the electrical performance and freshwater production of the proposed ADS-SDSE. The models are considered based on opt-geometric approaches, energy balance analyses, and isotherm adsorption simulation to dynamically simulate the ADS-SDSE operation to analyze its performance under real weather conditions in Tianjin, China, for one complete year. The daily, monthly, and yearly performances of the ADS-SDSE are comprehensively evaluated in terms of net electric power, electrical efficiency, specific distilled freshwater productivity, specific cooling power, and the gained output ratio (GOR) of the hybrid system. It is found that the role of the Stirling engine rejected heat recovery remarkably enhanced the inlet feed hot water temperature feeding the adsorptions beds and became uniformly at (82.6−95 °C) throughout the day. Moreover, the proposed ADS-SDSE can produce an electrical power output of about 23.42 kW with solar to electricity efficiency of 23.40%, specific daily freshwater production (SDWP) of about 11.53 m3 per ton of silica gel, 320 W/kg of silica gel specific cooling power, and 0.62 GOR. Conclusively, it can be inferred that the proposed ADS can be powered efficiently by the waste heat of the solar dish/Stirling engine.

Modelling of a novel electricity and methanol co-generation using heat recovery and CO2 capture: Comprehensive thermodynamic, economic, and environmental analyses

The current investigation proposes a novel and efficient co-generation with a methanol production process through a power plant flue gas's captured CO2 in which an alkaline reactor supplies the methanol reactor's input hydrogen. Besides, the compressors, methanol distillation tower, and methanol reactor wasted heat are used as an Organic Rankine Cycle input energy to design a multi-layer wasted heat recovery system. The energy, exergy, economic and environmental approaches are used to assess the plant performance via an Aspen HYSYS code. Accordingly, the total energy and exergy efficiencies are obtained at about 64.13% and 76%. The CO2 capture and methanol separation unit efficiencies are estimated at 42% and 80%. Regarding exergy analysis, the methanol reactor has the highest exergy destruction of about 11302.61kW. The environmental assessment reveals that the total CO2 emission equals 0.9tonCO2/tonMeOH and the Organic Rankine Cycle utilization restricts the indirect emission to the reboilers and distillation columns. Eventually, the total annual cost and total production cost of the proposed scheme are calculated as about 5,638,060dollars and 0.73$/kgMeOH, respectively.

Hybridizing solar dish Stirling power system with single-effect desalination for sustainable electricity and freshwater co-generation: Mathematical modeling and performance evaluation

At present, poly-generation sustainable systems are highly promising pathways that could produce several beneficial energy outputs, such as electricity, heat, and freshwater, that have the potential to fulfill financial competitiveness and higher efficiencies. Considering the great advantages of the solar dish/Stirling cycle, this study introduces comprehensive theoretical modeling and performance analysis of a solar dish/Stirling-powered single effect distillation system (SDSPSEDS) for combined electricity, heat, and freshwater tri-production. A detailed mathematical model executed in MATLAB software based on energy balance and opt-geometric approaches was established to simulate the SDSPSEDS operation dynamically. In order to analyze its performance under real weather conditions of Tabuk, KSA, for four seasonal scenarios. The energetic performance of the hybrid SDSPSEDS is comprehensively evaluated in terms of net electric power, solar-to-electricity conversion efficiency, Stirling engine rejected heat, distilled freshwater productivity, and overall co-generation efficiency of the hybrid system. The simulation results show that the daily electrical energy produced by the SDSPSEDS is 234.7, 194.6, 159.8, and 190.0 kWh/day. In contrast, the daily freshwater production is obtained as 787.4, 657.3, 545.0, and 650.0 kg/day in June, September, January, and March, respectively. Moreover, it is also found that the overall daily co-generation efficiency of the hybrid SDSPSEDS is increased to 62.60%, 53.50%, 47.40%, and 52.96% compared to only daily average electrical efficiencies of 20.92%, 17.82%, 15.50%, and 17.60% attained; in the same examined seasonal days, respectively when utilizing only standalone solar dish/Stirling power system. Thus, the findings of this study proved that the hybrid SDSPSEDS is an efficient system to produce power and water in rural areas with no water piping network or electrical grid.