Cogeneration Of Electricity Research Articles

Integration of proton exchange membrane fuel cell with air gap membrane distillation for sustainable electricity and freshwater cogeneration: Performance, influential mechanism, multi-objective optimization and future perspective

Proton exchange membrane fuel cell (PEMFC) converts vast majority of hydrogen energy into waste heat, resulting in energy wasting, membrane drying and even lifetime shortening. Herein, air gap membrane distillation is proposed to immediately remove and harness the waste heat from PEMFC for additional freshwater production. By quantifying the irreversible thermodynamic and electrochemical losses, mathematical formulas for the water production, power generation and overall efficiency are derived to evaluate the system performance. After a rigorous model validation, the performance feature, feasibility and competitiveness of the proposed system are examined. The integration system achieves a peak power density 23.69 % higher than that of a single PEMFC at 353 K, with a corresponding increase in exergy efficiency by 3.61 %. In addition, the influential mechanisms of the PEMFC operating conditions, air gap thickness, coolant temperature, and properties of the proton exchange membrane and hydrophobic porous membrane are investigated to discern potential avenues for further performance improvement. The gradient-based local sensitivity analyses further determine the optimal parameter regulation strategies for different output targets. The economic study indicates that the levelized costs of water and electricity over the total lifecycle are 21.53 $ m−3 and 0.061 $ kWh−1, respectively. The multi-objective optimization, integrating genetic algorithm and the technique for order preference by similarity to an ideal solution, maximizes the exergy efficiency and output power density while minimizing the initial investment cost per unit area, with values of 42.84 %, 0.975 W cm−2, and 27.33 $ cm−2, respectively.

Hydrogen and electricity cogeneration driven by the salinity gradient from actual brine and river water using reverse electrodialysis

Reverse electrodialysis (RED) is a promising method for harvesting the salinity gradient energy (SGE) between the brine and river water. Many investigations are carried out by using the artificially brine and fresh water, bringing difficulties in reflecting the practical RED performance under the complex influences of feed solutions. This work explores the performance of the RED system for hydrogen and electricity co-generation that is driven by salinity gradient between the actual concentrated brine and natural river water, and compared with the simulative brines and river waters under six testing schemes. The results show both the working current and solutions influence the system performances, including the output voltage, power density, hydrogen production, and energy conversion efficiency. Besides, the effects of salinity gradient of feed solutions are greater than that of the presence of trace multivalent ions and anionic radical in brine. The effective monovalent ion ionic strength is vital. The experimental maximum hydrogen production and power density are 82.12 mL·h−1 and 0.124 W·m−2 respectively at the current is 0.2 A, and the total power reached 0.32 W with the energy conversion efficiency of 25%. The research offers recommendations for harnessing SGE from actual brines and freshwater to produce hydrogen.

Achieving solar-thermal driven dual functional device utilizing flexible PDA coated sponge integrated thermoelectric module design for water purification and power generation

The design of an efficient solar energy collector for solar-thermal-driven water purification and power generation is a promising strategy to concurrently mitigate the shortage of fresh water and energy crises. However, harvesting low-grade thermal energy in an eco-friendly and cost-effective manner through solar-thermal materials for water evaporation and electric cogeneration remains challenging. Herein, we demonstrate a dual-functional device integrating solar-thermally driven water purification and thermo-induced power generation. This typical design, fabricated via polydopamine (PDA) tightly deposited onto melamine sponges (PDA@Sponge) via H-bonds, along with a thermoelectric generator (PDA@Sponge/TEG), showcases superior solar-thermal-driven dual-functional application. The critically structurally adjustable PDA@Sponge possesses excellent homogeneity and stability, weakening interfacial hydrogen bonding between water molecules, favoring the evaporation and overflow of water molecules. The optimal serrated design achieves a water evaporation rate of up to ∼1.50 kg −2h−1, with an efficiency of ∼ 94.04 % under one sun, surpassing the most of previous reports, owing to its special tip thermal localization effect and rational water transportation management. Simultaneously, the designed PDA@Sponge/TEG yields an open-circuit voltage and short circuit current of 55 mV and 22 mA, respectively, along with a maximal output power of 162 μW (40.5 μW/cm2) at a load resistance of 7.5 Ω, under one sun and room temperature. Notably, such a device, after multiple series connections, can charge a capacitor to 1.5 V within 1 min, capable of powering low-energy electronic devices such as smartwatches and LED lights. By efficiently integrating of multiple solar-thermal-driven processes, our research promotes the design of multifunctional devices to promise an approach for desalinating seawater, purifying wastewater, and powering low-energy electronics, especially in remote areas lacking power stations and/or water treatment facilities.

Performance analysis of integrating photovoltaic-radiative sky cooling and humidification-dehumidification for combined power and all-day desalination

Although the state-of-the-art photovoltaic-thermal-driven humidification-dehumidification desalination has a high potential for electricity and freshwater cogeneration, this technology can only operate when there is sunlight and has zero output during the night. This research exploits the photovoltaic cell's nighttime radiative sky-cooling ability to achieve dehumidification of ambient humid air and subsequently nighttime desalination. By combining this with the usual daytime operation, the proposed system increases the all-day productivity while keeping the system structure simple. The proposed system is analyzed via steady-state thermodynamic models of the photovoltaic panel, radiative sky cooling, seawater flow, and humidification-dehumidification subsystems. A series of parametric studies and a time-dependent analysis are conducted to evaluate its cogeneration performance. Results reveal that the nighttime and daytime freshwater productivities are a maximum of 0.13 kg/(h m2 PV area) and 0.6 kg/(h m2 PV area), respectively. The corresponding all day productivities are 1.114 kg/(day m2) and 5.371 W h/(day m2), respectively, which demonstrate that the photovoltaic cell's radiative sky cooling ability can offer an additional 20% of productivity. Notably, desalination is weakest during the sunset and sunrise periods because the radiative cooling and solar irradiance effects cancel each other here.

Harnessing Geothermal Energy Potential from High-Level Nuclear Waste Repositories

The disposal of high-level nuclear waste (HLW) has been one of the most challenging issues for nuclear energy utilization. In this study, we have explored the potential of extracting decay heat from HLW, taking advantage of recent advances in the technologies to utilize low-temperature geothermal resources for the co-generation of electricity and heat. Given that geothermal energy entails extracting heat from natural radioactivity within the Earth, we may consider that our approach is to augment it with an anthropogenic geothermal source. Our study—for the first time—introduces a conceptual model of a binary-cycle geothermal system powered by the heat produced by HLW. TOUGHREACT V3.32 software was used to model the heat transfer resulting from radioactive decay to the surrounding geological media. Our results demonstrate the feasibility of employing the organic Rankine cycle (ORC) to generate approximately 108 kWe per HLW canister 30 years after emplacement and a heat pump system to produce 81 kWth of high-potential heat per canister for HVAC purposes within the same timeframe. The proposed facility has the potential to produce carbon-free power while ensuring the safe disposal of radioactive waste and removing the bottleneck in the sustainable use of nuclear energy.

Performance optimization of an integrated solar combined cycle for the cogeneration of electricity and fresh water

Many Arabic countries suffer water scarcity while having an energy surplus. The present work investigates and optimizes a proposed plant for the cogeneration of electricity and fresh water. This plant comprises an Integrated Solar Combined Cycle (ISCC) power plant and a Multi Stage Flash (MSF) desalination unit. The steam condenser of the ISCC acts as a brine heater of the MSF desalination unit. Thus, the waste thermal energy from the ISCC is used to desalinate the seawater. The proposed cycle produces fresh water during its part load operating conditions. Simulation programs were developed and validated using real data from the ISCC power plant in Kuraymat-Egypt. The present results show that the proposed plant is very promising for the cogeneration of electricity and fresh water. An optimum top brine temperature (To) of 80 °C was estimated based on the amount of fuel required to desalinate the seawater. The proposed plant produces up to 1140 m3/h of fresh water under the typical operating conditions of Hurghada-Egypt, 50 % of the rated output power, and To = 80 °C. It saves up to 84.7 % of the fuel required for desalination compared to a standalone MSF desalination unit that operates under the same conditions.

High efficiency electricity and gas cogeneration through direct carbon solid oxide fuel cell with cotton stalk biochar

For the first time, biochar derived from a renewable resource, cotton stalk, is used as the feedstock of direct carbon solid oxides fuel cells (DC-SOFCs) for electricity and gas cogeneration. It turns out that the cotton stalk biochar has plenty of naturally grown K and Ca, which are active catalysts for the reverse Boudouard reaction in DC-SOFCs. This natural advantage of the cotton stalk biochar enables an extremely high power density of an anode-supported DC-SOFC at 850 °C, 0.9 W cm−2, which is the highest among those of the reported DC-SOFCs. Meanwhile, high concentration of CO gas, which is an important feedstock for chemical industry, is obtained from the DC-SOFCs. The energy conversion efficiency of the electricity-gas cogeneration of DC-SOFCs reaches over 70%. A novel method, using compressed char, is proposed and carried out for continuous supply of cotton stalk char to a DC-SOFC. The present work has demonstrated the feasibility and advantages of cogenerating electricity and gas through DC-SOFCs with biochar derived from cotton stalk as the feedstock.

Formulation of billing policy for residential scale solar PV systems and its impact in the Kingdom of Saudi Arabia

Governments worldwide have introduced diverse billing methods and regulations to promote the adoption of photovoltaic (PV) systems, aiming to reduce greenhouse gas emissions. This paper aims to develop a billing policy for installing rooftop PV systems in the Kingdom of Saudi Arabia by studying policies implemented to support installing PV systems in leading countries. Initially, the system is evaluated using the tariff predetermined by Saudi Electricity Cogeneration Regulation Authority under three different policies: a Feed-in Tariff (FIT), net metering, and net billing for different sizes of solar systems 10 kW, 15 kW, and 20 kW. The findings suggest a considerable discounted payback period ranging from 14 to 20 years under the net metering framework with the current tariff structure. In contrast, investments under FIT and net billing schemes do not appear to be viable. Thus, a tariff schedule, tailored according to the consumer-preferred payback period, is proposed. For a payback timeframe of 6–10 years, the tariff should range between $0.09–0.06 $/kWh within the FIT scheme. However, in the case of a net billing policy, the tariff should vary between $0.123–0.066 $/kWh. These findings suggest the supremacy of the FIT scheme, particularly if the government determined to use the low tariff policy.

Electricity and hydrogen cogeneration: A case study simulation via the Aspen plus tool

The focus of the current study is on a cogeneration unit designed to produce both electricity and hydrogen, which is made up of a parabolic trough collectors’ field associated with a storage tank, a recuperative organic Rankine cycle module, and a proton exchange membrane water electrolyzer. The latter system operates using electricity generated by the organic Rankine cycle to produce hydrogen, which can subsequently be used as either a fuel or a storage medium for seasonal storage. The study begins with a thermodynamic investigation under both steady-state and dynamic conditions. The solar field is simulated using the Engineering Equation Solver, while the organic Rankine cycle and the electrolyzer are modeled in Aspen Plus. The analysis extends to economic and environmental evaluations, along with an optimization procedure based on techno-economic criteria. Regarding the optimum design case, the annual net electricity yield is determined at 333.8 MWh, the yearly hydrogen production amount is equal to 6236.6 kg, while the yearly energy efficiency is calculated at 14.9% and the yearly exergy efficiency at 15.9%. Finally, the economic investigation indicates the net present value is about 645,555 €, while the system contributes to saving 198.1 tnCO2-eq during the yearly operation.

Highly salt resistant composite based protonated g-C3N4@rGO/biochar for photocatalytic degradation of organic dyes through simultaneous solar steam-electricity generation

Solar steam generation (SSG) is a promising solar energy harvesting technique for addressing global freshwater scarcity. However, the high materials cost, salt accumulation, and concentration of pollutants in the brine after SSG hindered their practical applications. Herein, the recycled sawdust waste was used as a cost-effective evaporator and decorated with protonated carbon nitride and reduced graphene oxide (rGO) which was termed as P-g-C3N4 @ rGO/DB. The g-C3N4 was protonated with sulfuric acid giving P-g-C3N4, which has high salt resistance via the Donnan exclusion mechanism. Besides, P-g-C3N4 as a metal-free semiconductor with a mild band gap (2.7 eV) was utilized for the photocatalytic degradation of the organic dyes under solar illumination to prevent the concentration of pollutants in water after desalination. Coupling rGO as electron acceptors inhibits the e−/h+ pairs recombination and traps the organic dyes on the surface of the evaporator increasing the photocatalytic degradation efficiency. The composite exhibited an excellent evaporation rate of 1.98 kg m−2 h−1 with 97.2 % solar to steam conversion efficiency as well as superior photocatalytic degradation of RhB dye under 1 sun illumination. Finally, the evaporator was coupled with a thermoelectric module achieving the maximum electricity cogeneration of 13.69 mW/m2.

Laccase-Mediated Oxygen Reduction in Liquid Flow Fuel Cells for Efficient Oxidation of Biomass-Derived Aldehydes with Co-Generation of Electricity

Laccase-Mediated Oxygen Reduction in Liquid Flow Fuel Cells for Efficient Oxidation of Biomass-Derived Aldehydes with Co-Generation of Electricity

Recent Advances of Green Electricity Generation: Potential in Solar Interfacial Evaporation System.

Solar-driven interfacial evaporation (SDIE) has played a pivotal role in optimizing water-energy utilization, reducing conventional power costs, and mitigating environmental impacts. The increasing emphasis on the synergistic cogeneration of water and green electricity through SDIE is particularly noteworthy. However, there is a gap of existing reviews that have focused on the mechanistic understanding of green power from water-electricity cogeneration (WEC) systems, the structure-activity relationship between efficiency of green energy utilization in WEC and material design in SDIE. Particularly, it lacks a comprehensive discussion to address the challenges faced in these areas along with potential solutions. Therefore, this review aims to comprehensively assess the progress and future perspective of green electricity from WEC systems by investigating the potential expansion of SDIE. First, it provides a comprehensive overview about material rational design, thermal management, and water transportation tunnels in SDIE. Then, it summarizes diverse energy sources utilized in the SDIE process, including steaming generation, photovoltaics, salinity gradient effect, temperature gradient effect, and piezoelectric effect. Subsequently, it explores factors that affect generated green electricity efficiency in WEC. Finally, this review proposes challenges and possible solution in the development of WEC.

Integrated biorefinery for bioethanol and succinic acid co-production from bread waste: Techno-economic feasibility and life cycle assessment

In this study, an advanced decarbonization approach is presented for an integrated biorefinery that co-produces bioethanol and succinic acid (SA) from bread waste (BW). The economic viability and the environmental performance of the proposed BW processing biorefinery is evaluated. Four distinctive scenarios were designed and analysed, focusing on a plant capacity that processes 100 metric tons (MT) of BW daily. These scenarios encompass: (1) the fermentation of BW into bioethanol, paired with heat and electricity co-generation from stillage, (2) an energy-optimized integration of Scenario 1 using pinch technology, (3) the co-production of bioethanol and SA by exclusively utilizing fermentative CO2, and (4) an advanced version of Scenario 3 that incorporates carbon capture (CC) from flue gas, amplifying SA production. Scenarios 3 and 4 were found to be economically more attractive with better environmental performance due to the co-production of SA. Particularly, Scenario 4 emerged as superior, showcasing a payback period of 2.2 years, a robust internal rate of return (33% after tax), a return on investment of 32%, and a remarkable net present value of 163 M$. Sensitivity analysis underscored the decisive influence of fixed capital investment and product pricing on economic outcomes. In terms of environmental impact, Scenario 4 outperformed other scenarios across all impact categories, where global warming potential, abiotic depletion (fossil fuels), and human toxicity potential were the most influential impact categories (−0.344 kg CO2-eq, −16.2 MJ, and −0.3 kg 1,4-dichlorobenzene (DB)-eq, respectively). Evidently, the integration of CC unit to flue gas in Scenario 4 substantially enhances both economic returns and environmental sustainability of the biorefinery.

Biomass Photothermal Hydrogel Based on Tea Leaves Residue for Cogeneration of Clean Water and Electricity

AbstractInterfacial solar‐driven evaporation has attracted much attention due to its high photothermal conversion efficiency. The core technology of photothermal conversion is photothermal materials, biomass photothermal materials are characterized by low cost, large specific surface area, environmental friendliness, and renewability. Discarded tea leaf residue (TLR) is harmful to the environment and has good recycling potential. In this work, a high‐performance, low‐cost, environmentally friendly solar steam generation material is fabricated by combining polyvinyl alcohol hydrogels and biomass photothermal material TLR. TheTLR hydrogel utilizes solar energy as a renewable energy source for desalination. Under 1.0 kW m−2 simulated solar irradiation, the evaporation rate is 1.35 kg m−2 h−1 and the evaporation efficiency is 93.35%. The waste heat generated during solar water evaporation can be effectively used for synergistic water‐electricity cogeneration, thus achieving an evaporation rate and voltage of 0.91 kg m−2 h−1 and 58.8 mV under 1.0 kW m−2 solar irradiation, respectively. The prepared hydrogel can also be used as a good organic dye adsorbent material, which has a broad application prospect in wastewater treatment. This method for preparing solar absorbers reduces manufacturing costs environmentally friendly and guides the potential practical application using discarded waste.

Performance prediction and regulation of a tubular solid oxide fuel cell and hydrophilic modified tubular still hybrid system for electricity and freshwater cogeneration

Tubular solid oxide fuel cells (TSOFCs) are a promising technology for electricity generation; however, they also generate high-temperature waste heat, leading to reduced efficiency and energy wastage. To address this challenge and unlock the full potential, a novel geometry-matching hybrid system incorporating methane reforming TSOFC and hydrophilic modified tubular still (HMTS) is proposed and modelled. Considering various irreversible losses, vital performance indicators including power output, energy efficiency and exergy efficiency are firstly derived, through which comprehensive thermodynamic performance features of the TSOFC/HMTS hybrid system are predicted. The proposed system design demonstrates a significant advantage by achieving a maximum output power density that is 99.7 % higher and a corresponding energy efficiency that is 57.3 % higher compared to the standalone TSOFC. Extensive parametric analyses reveal that raising the operating temperature or stream/carbon ratio positively enhances the system's performance. Conversely, increasing electrode tortuosity, electrolyte thickness, wind velocity, or tubular shell diameter negatively degrades the system's performance. In addition, the anode thickness is an optimizable parameter. Local sensitivity analyses identify that the operation temperature and electrode tortuosity are, respectively, the most and least sensitive parameters for performance regulation. The findings make a significant step forward in the field of sustainable and innovative energy solutions.

Performance investigation on an agricultural photovoltaic thermal system based on spectral separation

Based on cascade utilization of full spectrum solar energy, a spectral splitting agriculture photovoltaic thermal hybrid system has been proposed in this study. The red and blue light is assigned to farmland for plant photosynthesis, while the photovoltaic active light is absorbed by solar cell for electricity generation, and the rest to thermal receiver for high temperature production. To maximize the power output of proposed system, redundant waste heat is recovered through ejector and converted into electricity in organic Rankine cycle subsequently. By such incorporation, the proposed system can not only increase the overall utilization efficiency of solar energy, but also achieve the cogeneration of crops and electricity on the same land. Energy, exergy, and economic analyses are performed to evaluate the performance of proposed system. Results show that the overall utilization efficiency of solar energy reaches 39.67 % with the highest losses of 79.65 MW in organic Rankine cycle. From the point view of exergy, photoelectric conversion in solar cell is responsible for the largest exergy destruction and finally the overall exergy efficiency of proposed system reaches 40.65 %, which is 16.13 % higher than that of equivalent agricultural and photovoltaic system with separate land use.

An efficient mixed-variable generation operator for integrated energy system configuration optimization

Energy consumption has skyrocketed as society has progressed, resulting in energy crises and environmental issues. New energy technologies are being developed to address these challenges, and technologies such as the cogeneration of electricity, heating, and cooling are being used to improve energy utilization. The configuration of an energy system has a critical impact on the economics of the system, its ability to supply energy, etc. This study establishes a multiobjective mixed-variable configuration optimization model for a comprehensive combined cooling, heating, and power energy system. The model considers equipment types (categorical variables), equipment quantities (integer variables), and critical parameters (real variables) as optimization variables, where economic performance, the proportion of renewable energy, supply shortage, and dependence on the external power grid are considered unoptimized objectives. This is a multiobjective and mixed-variable problem, and the combination of the two properties poses an excellent challenge for evolutionary algorithms in optimizing the model. Therefore, we propose an efficient generating operator based on a fully connected weighted neural network, called the FCWN operator. This operator overcomes the challenge of the discrete variable space and broken neighborhood relationships in mixed-variable problems. During the algorithm search process, search history information is used to update the fully connected weight network for distribution estimation of the variable space. Offspring are generated based on the fully connected network to improve the algorithm’s search efficiency. In the experimental section, we construct a model with 20 variables and conduct simulation-based configuration optimization for scenarios with 3, 5, and 8 available equipment types. The final obtained Pareto frontier solution set is evaluated using the hypervolume metric, a widely used multiobjective evaluation metric. The Wilcoxon rank sum test on the experimental results shows that the proposed algorithm has better results than other state-of-the-art algorithms at a 95% confidence level.

Synergistic solar-powered water-electricity generation: An integrated floating system on water

The global pursuit of sustainable development faces two critical challenges: the scarcity of clean water and the growing energy crisis. The integration of solar-powered hybrid systems that harness the photovoltaic effect and passive steam generation has emerged as a crucial strategy. While several thermally-localized multi-stage solar stills have been developed, they predominantly rely on ground-mounted designs. Herein, we present a groundbreaking integration concept that combines a floating solar panel with a five-stage membrane distillation (MD) device, enabling simultaneous clean water and electricity generation on water surfaces. Positioned on the reverse side of the photovoltaic (PV) cell, the Janus membrane-involved multi-stage architecture of the MD device passively cools the PV cell, captures and repurposes the waste heat and manages vaporization enthalpy recycling. Our research highlights the importance of optimizing heat and mass transport within each stage, boosting the photoelectronic and photothermal conversion of the whole system. As a result, the integrated system achieves an impressive water production rate of 4.14 kg m−2 h−1 while simultaneously maintaining a high electricity generation efficiency of 16.4 % under 1 sun, therefore maximizing the total solar energy conversion. The clean water production rate of 11.6 kg m−2 day−1 places our system among the best-performing solar stills operating under natural sunlight. This integrated system sets a pioneering example of clean water and electricity co-generation with minimized carbon footprint, extending the applicability of ground-mounted solar conversion systems to water bodies.

Development of a novel power and freshwater cogeneration plant driven by hybrid geothermal and biomass energy

The reliable supply of electricity and potable water has crucial importance on achieving higher level of human welfare, where the primary energy source to provide these requirements is fossil fuels at present. Since the combustion of fossil fuels has irreparable environmental impacts, thus utilization of clean and renewable energy resources is a promising alternative to overcome the energy-related environmental issues. In this regard, present research aims at development of an effective co-generation of electricity and freshwater plant driven by hybrid geothermal and biomass renewable energy sources. To make a comprehensive system assessment, thermodynamic, exergy, environmental and economic aspects are considered and appraised in detail and multi-objective optimization is used to detect the best performance of the plant. The results indicated feasibility of hybridization of biomass and geothermal resources for efficient co-production of potable water and electricity. Under optimized operation, the plant exergetic efficiency, unit product cost, exergo-environmental index, and CO2 emission are found to be 44.12 %, 66.97 $/MWh, 0.5114 and 0.7105 kg/kWh, respectively. The second law analysis revealed that, from 18302 kW of input exergy, a value of 9357 kW is destructed within the components, where the gasifier owns the largest portion with 3569 kW.

Process design, integration, and optimization of a novel compressed air energy storage for the coproduction of electricity, cooling, and water

The use of fluctuating renewable energy over a certain threshold may lead to an unmanageable mismatch between the electricity generation and demand profiles threatening the grid's stability. In this study, an innovative complex energy storage/conversion system is proposed for the cogeneration of electricity, cooling, and water by integrating the liquefied natural gas (LNG) regasification process, an organic Rankine cycle, a compressed air energy storage (CAES) system, and a multi-effect distillation unit. The study attempts to minimize the CO2 emission from the CAES technology while addressing interruptions and reductions in the grid upon the extensive use of intermittent renewables. In addition, the proposed system uses excess power and waste heat during the charging and discharging of the CAES to regasify LNG and produce fresh water. The reference system performance is analyzed considering thermodynamic, economic, and environmental perspectives. The multi-objective grasshopper optimization algorithm is used to make a trade-off between the technical, economic, and environmental performance factors of the system. The results show an exergy efficiency of 50.6 % and a total cost rate of 322.8 $/h for the proposed system at the TOPSIS optimal point. The Grassmann diagram indicates the combustion chamber is the main source of irreversibility, and the Chord diagram revealed the discharge unit was responsible for more than 55 % of the total cost.