Cogeneration Of Electricity Research Articles

Cogeneration of Fresh Water and Electricity with High-Temperature Power Cycles: Comparative Assessment of Multi-Effect Distillation and Reverse Osmosis

The pressing problems of water scarcity in many parts of the planet make water desalination one of the technological solutions for guaranteeing the fresh water supply. However, desalination processes require high energy consumption, mainly provided by fossil fuels. The integration of renewable energy sources into desalination processes is a promising option for decarbonizing the desalination sector. As most water-scarce regions with access to seawater frequently have high solar irradiation levels, it seems appropriate to exploit the sun to power the desalination process. This work presents the assessment of two integrated solar power and desalination systems regarding efficiency and water production. Two desalination processes (multi-effect distillation and reverse osmosis) are studied for potential coupling with the combined cycle of a central receiver solar plant to produce electricity and freshwater. In the case of the multi-effect distillation plant, it is integrated by replacing the Rankine cycle condenser of the combined cycle. In the case of the reverse osmosis plant, it is powered by the electricity generated from the combined cycle. For this comparison, the 21st of March has been considered as the design point and Almería (in the Southeast of Spain) as the plant location. The results show that the thermal cogeneration option renders a worse outcome (thermal efficiency of 50.2% for LT-MED case) than the decoupled generation of electricity and water (thermal efficiency of 53.3% for RO case), producing 18% less fresh water than the RO configuration (3831 m3/d vs. 4640 m3/d), due to the 6% penalty in the efficiency of the Rankine power cycle in the MED configuration as a result of increasing the condensation temperature from 42.6 °C to 70 °C.

4E multi-objective optimization of cold electricity co-generation system based on supercritical CO2 Brayton cycle

Reheat Brayton cycle has advantages of compact layout and high efficiency, and heat recovery from cooler in Brayton cycle by ammonia absorption refrigeration cycle can achieve efficient cold electricity co-generation. In this paper, evaluation models based on energy, exergy, economy and environment (4E) are established and multi-objective optimization are carried out for combined cycle. The reliability and accuracy of TOPSIS, MO and LINMAP decision methods are analyzed. Cycle performance, economy and environment benefits are compared and analyzed under two refrigeration conditions before and after optimization. Temperature difference distribution of printed circuit heat exchanger under different cycle layouts is analyzed. The results show that TOPSIS and LINMAP are reliable, and MO is not suitable for selection of optimum points in Pareto diagram; after optimization, economic and environment costs of top cycle are reduced by 11.21% and 6.68%, refrigeration capacity of bottom cycle under two refrigeration conditions is improved by 28.75% and 15.46%, and economic costs are reduced by 28.3% and 3.7%; for combined cycle, thermal efficiency is increased by 1.11% on average, total investment cost is reduced by 16.21% on average, overall performance of combined cycle is significantly improved; compared with basic and reheat cycle before optimization, temperature difference in high temperature section of recuperator is significantly reduced in reheat Brayton cycle after optimization, which is good for reducing exergy loss and heat stress, helping to match high temperature and pressure environment of top cycle; temperature difference in low temperature section of subcooler is increased in bottom cycle after optimization, which helps to reduce heat exchanger volume and improve compactness.

Killing Two Birds with One Stone: Upgrading Organic Compounds via Electrooxidation in Electricity-Input Mode and Electricity-Output Mode.

The electrochemically oxidative upgrading reaction (OUR) of organic compounds has gained enormous interest over the past few years, owing to the advantages of fast reaction kinetics, high conversion efficiency and selectivity, etc., and it exhibits great potential in becoming a key element in coupling with electricity, synthesis, energy storage and transformation. On the one hand, the kinetically more favored OUR for value-added chemical generation can potentially substitute an oxygen evolution reaction (OER) and integrate with an efficient hydrogen evolution reaction (HER) or CO2 electroreduction reaction (CO2RR) in an electricity-input mode. On the other hand, an OUR-based cell or battery (e.g., fuel cell or Zinc-air battery) enables the cogeneration of value-added chemicals and electricity in the electricity-output mode. For both situations, multiple benefits are to be obtained. Although the OUR of organic compounds is an old and rich discipline currently enjoying a revival, unfortunately, this fascinating strategy and its integration with the HER or CO2RR, and/or with electricity generation, are still in the laboratory stage. In this minireview, we summarize and highlight the latest progress and milestones of the OUR for the high-value-added chemical production and cogeneration of hydrogen, CO2 conversion in an electrolyzer and/or electricity in a primary cell. We also emphasize catalyst design, mechanism identification and system configuration. Moreover, perspectives on OUR coupling with the HER or CO2RR in an electrolyzer in the electricity-input mode, and/or the cogeneration of electricity in a primary cell in the electricity-output mode, are offered for the future development of this fascinating technology.

New Process Combining Fe-Based Chemical Looping and Biomass Pyrolysis for Cogeneration of Hydrogen, Biochar, Bio-Oil and Electricity with In-Suit CO2 Separation

Fe-based chemical looping gasification is a clean biomass technology, which has the advantage of reducing CO2 emissions and the potential of self-sustaining operation without supplemental heating. A novel process combining Fe-based chemical looping and biomass pyrolysis was proposed and simulated using Aspen Plus. The biomass was first subjected to pyrolysis to coproduce biochar, bio-oil and pyrolysis gas; the pyrolysis gas was subjected to an Fe looping process to obtain high-purity hydrogen and carbon dioxide. The influences of the pyrolysis reactor operating temperature and fuel reactor operation temperature, and the steam reactor and air reactor on the process performance are researched. The results showed that, under the operating condition of the established process, 23.07 kg/h of bio-oil, 24.18 kg/h of biochar, 3.35 kg/h of hydrogen and a net electricity of 3 kW can be generated from 100 kg/h of rice straw, and the outlet CO2 concentration of the fuel reactor was as high as 80%. Moreover, the whole exergy efficiency and total exergy loss of the proposed process was 58.98% and 221 kW, respectively. Additionally, compared to biomass direct chemical looping hydrogen generation technology, the new process in this paper, using biomass pyrolysis gas as a reactant in the chemical looping hydrogen generation process, can enhance the efficiency of hydrogen generation.

Technoeconomic Analysis of a Small-Scale Downdraft Gasification-Based Cogeneration Power Plant Using Green Wastes

Abstract In this work, the technoeconomic assessment of a small-scale gasification-based cogeneration plant (25–50 kWe) fed with green wastes (fallen leaves, spent coffee grounds, and paperboard) is presented. The cogeneration power plant is modeled using Thermoflex software under thermochemical equilibrium and steady-state assumptions. Subsequently, the performance of the cogeneration plant is numerically analyzed as a function of the feedstock moisture content (6–30%), air–waste equivalence ratio (0.20–0.55), and the system load (6.25–25 kWe). The results show that the best energy performance of the cogeneration plant is achieved with a feedstock moisture of 6.05%, an equivalence ratio of 0.358, and a load of 25 kWe. At this best performance mode, the electric generation and cogeneration efficiencies are 19.33% and 49.71%, respectively, with a specific biomass consumption of 1.19 kg/kWh. Two scenarios are established for the economic assessment. The baseline scenario considers a 25-kWe cogeneration plant, while, in the second one, the generation capacity of the system was assumed to be doubled (50 kWe). The financial results show that the power generation has an energy levelized cost of 11.7 ¢$/kWh and 8.4 ¢$/kWh for 25 kWe and 50 kWe, respectively. Nevertheless, none of the proposed scenarios were found to be economically feasible based on the negative net present value obtained. Therefore, further energy laws and regulations are required seeking to support the small-scale auto-generation units based on biomass gasification.

Valorization of biogas from the anaerobic co-treatment of sewage sludge and organic waste: Life cycle assessment and life cycle costing of different recovery strategies

Nowadays, biogas produced from the anaerobic digestion of biowaste is considered a valuable renewable energy source to implement the transition to a climate-neutral society. Recently, biogas upgrading to biomethane, instead of the usual co-generation of heat and electricity (CHP), has been an attractive option, as biomethane can be used for different purposes. This study performed the life cycle assessment (LCA) and life cycle costing (LCC) of different scenarios for the valorization of the biogas produced from the anaerobic co-digestion (AcoD) of secondary sewage sludge (SS) and organic fraction of municipal solid waste (OFMSW), pre-treated by an anaerobic dark co-fermentation (DF) process. Four configurations were compared, exploring the recovery of one or more of the following: heat, electricity and biomethane. Furthermore, two sensitivity analyses were performed on LCA analysis, considering the use of the produced biomethane as a fuel for transport and the European electricity mix expected by 2050, respectively. The use of biogas for CHP was the most environmentally friendly solutions in 8 out of 11 impact categories provided by the CML-IA baseline method; however, biogas upgrading-based scenarios showed less impacts in relevant categories, such as global warming potential (up to −1.14E+05 kg CO2 eq. y−1) and ozone layer depletion potential (up to −4.73E-01 kg CFC-11 eq. y−1). Sensitivity analyses confirmed that the biogas upgrading processes should have generally a lower impact on climate change than CHP systems. Furthermore, the use of biomethane to replace petrol resulted to be the best option in terms of global warming potential (up to −5.67E+05 kg CO2 eq. y−1). All the proposed configurations represented economically sustainable projects, as they reported positive net present values (NPV) in 20 years (up to 10,518,291 €). Biogas upgrading-based scenarios showed the highest NPVs; nevertheless, the combined production of heat, electricity and biomethane was the most cost-effective option, thanks to biomethane revenues and electricity sales, despite the latter being modest. In conclusion, contrary to most of the previous studies in the literature, we found that CHP should not be neglected, as the optimal configuration may lie in the combined recovery of biomethane, electricity and heat.

Modeling of an Energy-Diverse Embedded Grid for Microreactor Integration

Microreactors present an opportunity to revolutionize the role of nuclear energy via the development of these technologies in a diverse and distributed energy network for a clean energy future. Because of the limited output of these novel systems, the deployment of microreactors should be focused on high-value applications in order to realize their full potential. This involves understanding the microreactor performance and how it interacts with the preexisting infrastructure. In this work, an energy-diverse embedded grid is modeled using OpenModelica in order to study the impact of microreactor integration under several distinct deployment approaches. The University of Illinois at Urbana-Champaign (UIUC) is used as a prototypic market due to its well-characterized energy ecosystem with available extensive real-time and historical data. The UIUC model recreates the existing chilled-water, steam, and electricity infrastructure, including wind, solar, and cogeneration sources. The infrastructure model simulates the interplay between the three utilities and how different microreactor integration approaches would impact UIUC’s embedded grid. From this study, the deployment of a single microreactor under electric load-conditioning, steam production retrofit, or a hybrid of both is found to be the most appropriate in consideration of their unique advantages toward cost savings and grid resilience. Meanwhile, if grid resiliency is not a main objective, the greatest emissions reduction and cost-savings benefits can be obtained by operating the reactor in a base-loading configuration. This study employed historically low coal and gas prices and provided a conservatively low estimate for the benefits from a microreactor. Given the price volatility of fossil fuels, the benefits of the microreactor are expected to be greater than this estimate. Finally, the modular nature of the modeling framework allows for an extension of the analysis to other similar embedded grids.

Production of Substitute Natural Gas Integrated with Allam Cycle for Power Generation

The accumulation of energy from non-programmable renewable sources is a crucial aspect for the energy transition. Using surplus electricity from renewable energy sources, power-to-gas plants allow to produce a substitute natural gas (SNG) that can be injected in the existing infrastructure for large-scale and long-term energy storage, contributing to gas grid decarbonisation. The plant layout, the method used for carbon dioxide capture and the possible cogeneration of electricity can increase the efficiency and convenience of SNG synthesis plants. In this work, a system for the simultaneous production of SNG and electricity starting from biomass and fluctuating electricity from renewables is proposed, using a plant based on the Allam thermodynamic cycle as the power unit. The Allam power cycle uses supercritical CO2 as evolving fluid and is based on the oxycombustion of gaseous fuels, thus greatly simplifying CO2 capture. In the proposed system, oxycombustion is performed using biomass syngas and electrolytic oxygen. The CO2 generated by means of oxycombustion is captured, and it is subsequently used together with renewable hydrogen for the production of SNG through thermochemical methanation. The system is also coupled with a solid oxide electrolyser and a biomass gasifier. The whole plant was analysed from an energy-related point of view. The results show overall plant efficiency of 67.6% on an LHV basis (71.6% on an HHV basis) and the simultaneous production of significant amounts of electricity and of high-calorific-value SNG, whose composition could be compatible with the existing natural gas network.

Wind energy potential assessment for co-generation of electricity and hydrogen in the far North region of Cameroon

The fast increase of Cameroon population growth rate and the actual shortage of electricity plaguing the country, particularly in remote areas, give rise to great challenges in the energy generation sector. Nowadays, renewable and clean energy sources are used to foster and improve electricity production via hydrogen generation with water electrolysis. This paper therefore scrutinizes the wind energy potential alongside the electricity and hydrogen generation from wind energy for the cities of Kousseri, Kaele, Maroua, Mokolo, Mora and Yagoua in the Far North Region of Cameroon using wind speed data recorded at 10 m, 40 m and 70 m heights for the years 2011–2021. Several performance indicators including the wind power density, wind turbines power output, wind turbines capacity factor, hydrogen production, cost of produced electricity and hydrogen and payback period are utilized to evaluate the techno-economic viability of the system. This assessment was carried out employing twenty-two commercially accessible wind turbines. Our findings revealed that, Kousseri displays the best hydrogen output with yearly hydrogen production ranging from 3.5054 to 53.232 tons of hydrogen. The annual compressed hydrogen to be saved in this region was found to be in the range of 92.5049 to 1404.70 m3. Enercon E-48/800 turbine records the highest capacity factor in all the chosen locations with the lowest cost of energy varying from 0.0578 $/kWh at Kousseri to 0.0838 $/kWh at Mora. The lowest cost of hydrogen was found to be 4.3865 $/kg for Kousseri, 5.5284 $/kg for Kaele, 5.7160 $/kg for Maroua, 5.9439 $/kg for Mokolo, 6.5065 $/kg for Mora and 6.3354 $/kg for Yagoua employing GE 1.5SL turbine. The highest annual energy output of 3193.9, 2738.1, 2488.4, 2393.9, 2153.3 and 2323.1 MWh was acquired at Kousseri, Kaele, Maroua, Mokolo, Mora and Yagoua, respectively. The shortest payback period was found to be 2.9 years which was related to the case where Enercon E-48/800 wind turbine was assumed to be installed at Kousseri. Finally, the maximum CO2 emission minimization to be achieved if electricity produced by wind turbine is utilized in place of oil burning power plant and power plant that burns natural gas as fuel was 885.36 tons of CO2 and 641.60 tons of CO2, respectively.

Co-Generation of Electricity and Chemicals via Solid Oxide Fuel Cells Using Li-Doped LSGM and LSF Composite Anodes

In this work, co-generation of C2+ hydrocarbons and electricity in solid oxide fuel cells (SOFCs) was realized using methane as fuel. The SOFCs were prepared with Li-La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM)/Lr0.7Sr0.3FeO3 (LSF) as the composite anode and LSGM and (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ (LSCF)/Sm0.2Ce0.8O2−δ (SDC) as the electrolyte and cathode, respectively. Among the anode materials, Li-LSGM has higher C2+ product selectivity. It can be seen from the XPS data that the doping of Li introduces a strong alkaline active center Li+O–, changes the lattice and electronic structure, and increases the surface absorption of oxygen species, which is more conducive to the improvement of the selectivity of C2+ products. LSF has strong electron-conducting ability and high catalytic activity for methane. After mixing with Li-LSGM, XPS data show that more oxygen vacancies are generated, which is beneficial to the electrochemical reaction of the anode and effectively reduces carbon deposition. The maximum power density of the composite anode can reach 188.15 mW/cm–2 with H2 as the fuel at 850 °C, and a C2+ product selectivity of 57.48% is achieved with CH4 as the fuel at 800 °C and the current density is 40 mA/cm–2. In addition, the change of C2+ product selectivity with current density and temperature during cell operation was further investigated, providing enlightenment on how to adjust the output ratio of chemicals and electricity.

Eco-Environmental Uncertain Management of Various Energy Hubs within a Microgrid Concentrated on Demand Response, Intelligent Parking Lots, and Power-to-Gas Unit Effects

Nowadays, consumption of different energy carriers is increasing due to the division of community activities in various sectors such as residential, commercial, and industrial. The energy hub concept is used to meet the demands of different energy carriers in these sections. In this paper, a new method for energy management of a microgrid is presented in an intelligent network based on three types of commercial, residential, and industrial energy hubs. In the energy hubs, a wide range of components, including renewable and nonrenewable generation units, converters, storage devices, intelligent parking lots consisting of electric vehicles, P2G units, and cogeneration units, are used to supply electrical, heating, cooling, and natural gas energies. Some parameters like renewable generations, energy demands, and arriving and departure time of electric vehicles are considered to be uncertain, and a relevant method is applied to provide a near-realistic profile for them. In addition, a demand response paradigm has also been proposed for three types of electrical, heating, and cooling demands at the hub output side. Therefore, in this method, a mixed integer linear programming model is proposed based on benefit and reduction of emission caused by the activity of gas-burning units for short-term planning and obtaining an optimal solution for generation and sending loads in a distribution network containing energy hubs. To evaluate the performance of the proposed modeling and structure, the presented approach is applied on a modified 33-bus IEEE test network. According to the results of the energy management model, it is possible to significantly increase benefits and also obtain a smoother consumption pattern in consumption with financial incentives.

Time-Transient Optimization of Electricity and Fresh Water Cogeneration Cycle Using Gas Fuel and Solar Energy

In this study, a cogeneration cycle in a time-transient state is investigated and optimized. A quasi-equilibrium state is assumed because of the small time increments. Air temperature and solar power are calculated hourly. The cycle is considered in terms of energy, exergy, and economic and environmental analyses. Increasing the net present value (the difference between the present value of the cash inflows and outflows over a period of time) and reducing exergy destruction are selected as two optimization objective functions. The net present value is calculated for the period of 20 years of operation according to the operation parameters. The optimization variables are selected in such a way that one important variable is selected from each system. To optimize the cycle, the particle swarm optimization method is used. The number of particles used in this method is calculated using the trial-and-error method. This cycle is optimized using 13 particles and 42 iterations. After optimization, the energy efficiency increased by 0.5%, the exergy efficiency increased by 0.25%, and the exergy destruction decreased by 1% compared to the cycle with existing parameters.

Hydrophilic candle wastes microcapsules as a thermal energy storage material for all-day steam and electricity cogeneration

On-site reclamation of freshwater from seawater is urgently desired to combat freshwater scarcity, in which solar-driven interfacial evaporation has been realized as a promising strategy. However, solar desalination has been facing the negative influence of intermittent solar radiation alternating day and night; thus, incorporating a material recommended as thermal energy storage material into the photoabsorber is a profitable strategy to supply the heat for 24-h steam generation. Herein, graphene oxide (GO) was incorporated with the candle waste to store the thermal energy and encapsulated into the SiO2 shell to prevent the leakage of the paraffine wax and enhance the membrane hydrophilicity. A collaborative device including the evaporator and a commercial thermoelectric (TE) module was designed for steam-electricity cogeneration which exhibits a simultaneous evaporation rate of 1.09 kg m−2 h−1 and power density of 6.8 W m−2 under one sun irradiation. Besides, the paraffin component can store thermal energy, enabling the device to maintain a certain steam and electricity cogeneration of 0.35 kg m−2 h−1 and 2.8 W m−2 after light-off. This work may provide a cost-effective strategy for the fabrication of potential photoabsorbers from environmental wastes for all-day water evaporation and power cogeneration device to mitigate freshwater and electricity shortages.

Using machine learning approaches to model and optimize a combined solar/natural gas-based power and freshwater cogeneration system

Problems of sustainable development and environmental protection pose a challenge to humanity unprecedented in scope and complexity. Whether and how the problems are resolved have significant implications for human and ecological well-being. Accordingly, this work proposes an electricity and freshwater cogeneration system using solar energy and natural gas dual sources. The proposed system is a combination of a heliostat field with a gas turbine cycle as the top systems and thermal vapor compression-multi effect desalination, steam Rankine cycle, organic Rankine cycle, and thermoelectric generator as subsystems. For performance analysis, energy, exergy, exergoeconomic, economic, and environmental analyses were performed. To optimize the system, a coupled model of the support vector regression, multi-objective grey wolf optimization algorithm, multi-objective Grasshopper optimization algorithm, and two different decision-making methods were suggested. According to obtained results, the best swirling number and pressure ratio were 0.95 and 7, respectively. Moreover, the exergy efficiency, total product cost rate, and CO2 emission were chosen as the best optimization scenario, which led to 45.6 % of exergy efficiency, 2.716 $/GJ of total product cost rate, and 30.26 kg/s of freshwater. Moreover, the total exergy destruction rate decreased from 15153 kW to 14820 kW after the optimization of the system.

Integration of desalination and energy conversion in a thermo-osmotic system using low-grade heat: Performance analysis and techno-economic evaluation

Freshwater and electricity cogeneration systems, using renewable energy sources, can play a crucial role at the water-energy nexus. By placing a hydrophobic, porous membrane between a hot saline water flow and a pressurized cold freshwater flow, thermal-osmotic energy conversion and thermal-osmotic desalination can be implemented simultaneously. A novel open-loop freshwater and electricity cogeneration system is proposed and evaluated, which consists of a hydrophobic membrane module, a seawater pump, two heat exchangers, and a hydraulic turbine. In the base case designed for a daily freshwater production of 3.9 × 104 m3/day, the net power output is estimated to be 2.15 MWe and the energy efficiency of power generation is 0.24%. Considering the economic benefits brought by the electricity production, the water production cost is 0.36 $/m3 with a global average industrial electricity price of 0.11 $/kWh. Compared with the commercial reverse osmosis desalination technology, the desalination cost of the hybrid system is reduced by over 28%. The parameter analysis is carried out and reveals that optimizing membrane properties and operating conditions can greatly improve the energy efficiency and reduce the water production cost. Improving the liquid entry pressure and permeability coefficient and reducing the thermal conductivity of the membrane are the key to improving the application prospect of the system.

A hybrid system coupling spiral type solar photovoltaic thermal collector and electrocatalytic hydrogen production cell: Experimental investigation and numerical modeling

The sustainable cogeneration of hydrogen and electricity is one of the promising strategies to boost the world’s energy demand. This work introduces a detailed numerical modeling and experimental study for a small-scale tri-production of heat, electricity, and hydrogen via an electrocatalytic hydrogen production cell (EHPC) powered by a solar photovoltaic thermal collector (SPVTC). A novel type of spiral fluid SPVTC integrated with small-scale Hoffman's EHPC is designed and tested. The effect of type and flow rate of cooling fluid on the performance parameters of the hybrid SPVTC-EHPC; including PV electric power, surface cell temperature, cooling fluid exit temperature, electrical and thermal efficiency, and produced hydrogen yield is studied. The experimentations are carried out for the hybrid SPVTC-EHPC operating with two various cooling fluids, namely, water and air at various mass flow rates (20 and 40 L/h), and their results are compared with a standalone PV module without cooling. Moreover, CFD modeling of the water SPVTC, air SPVTC, and PV module designs is also conducted at different operating conditions. ANSYS software is applied to attain maximal efficiency from the collector by choosing the optimal spiral flow structure and determining the PV panel surface and coolant temperatures of the three proposed systems. The CFD simulation verification ensured a good fit between the computational and experimental results. The findings show that the reduction in the daily average PV surface temperature is obtained as 16.60% (54.46 °C) and 8.50% (59.75 °C) for the SPVTC-EHPC, compared to reference PV-EHPC system, when water and air are utilized as a coolant at flowrate of 40 L/h, respectively. Moreover, the daily hydrogen productivity is found as 4.41 kgH2/d for water-cooled SPVTC-EHPC (40 L/h), 4.03 kgH2/d for water SPVTC-EHPC (20 L/h), 3.60 kgH2/d for air-cooled SPVTC-EHPC (40 L/h), 3.24 kgH2/d for air SPVTC-EHPC (20 L/h), and 3.07 kgH2/d for the conventional PV module EHPC, respectively. This study offers an effective means to experimental and numerical aspects of both water and air-cooled SPVTC for the simultaneous production of electricity and hydrogen.

Stable polyethylene glycol/biochar composite as a cost-effective photothermal absorber for 24 hours of steam and electricity cogeneration.

Seawater desalination powered by solar energy is the most environmentally and economical solution in responding to the global water and energy crisis. However, solar desalination has been negatively impacted by intermittent sun radiation that alternates between day and night. In this study, sugarcane bagasse (SCB) was recycled via the pyrolysis process to biochar as a cost-effective solar absorber. Besides, polyethylene glycol (PEG) as a phase change material was encapsulated in the abundant pore structure of biochar to store the thermal energy for 24 hours of continuous steam generation. The BDB/1.5 PEG evaporator exhibited an evaporation rate of 2.11 kg m-2 h-1 (98.1% efficiency) under 1 sun irradiation. Additionally, the BDB/1.5 PEG evaporator incorporated by the TEC1-12706 module for continuous steam and electricity generation with a power density of 320.41 mW m-2. Moreover, 10 continuous hours of evaporation were applied to the composite demonstrating outstanding stability. The composite exhibited high water purification efficiency through solar desalination due to the abundant functional groups on the biochar surface. Finally, the resulting low-cost and highly efficient PCM-based absorber can be used on a wide scale to produce fresh water and energy.

Improving the efficiency of solar-driven trigeneration systems using nanofluid coolants

This article is intended to evaluate methods to improve the efficiency of trigeneration plants, which are designed for the co-generation of heat, electricity, and cold. The possibility of using nanofluids with the addition of oxides of aluminum, silicon, magnesium, and copper, as well as copper itself in the concentration range of 1–6% has been analyzed. The results show that the use of nanofluids can increase the exergic efficiency of the system to 22.9–27.8% and increase thermal efficiency by 23.2–26.7%. It was found that nanofluids have low heat capacity, which may be one of the factors that increase the overall efficiency of trigeneration plants up to 43–60%. Magnesium oxide proved to be the most efficient for generating electricity, with 212.8 kW, aluminum oxide (197.5 kW) for cooling, and copper oxide for generating 98 kW of heat. The Pearson criterion was χ2 = 0.87, Student’s t-test 0.07–0.09, statistical significance of results p ≤ 0.005.

Highly efficient solar driven cogeneration of freshwater and electricity

The integration of solar steam generation (SSG) and hydrovoltaic effect provides an ideal strategy for solving the water and energy shortage crisis.

Hybrid thermochemical process for storage and conversion into cold and electricity based on a low temperature thermal source

This paper presents a hybrid thermochemical process concept for the cogeneration of cold, electricity and thermal storage based on low temperature sources. Several innovative architectures of the process were defined at PROMES-CNRS and the ‘simultaneous mode’ architecture was chosen to be under study. It provides both cold and electricity productions in the discharging step of this storage system. A numerical model was developed at PROMES simulating the simultaneous mode of the hybrid cycle. Based on the results of the model, an experimental prototype was developed at the lab. The thermochemical reactor was tested and operated properly in the charging and discharging phase of the cycle, before its hybridization. The expander was set under the first experimental characterization using nitrogen before integrating it with the thermochemical reactor in the hybrid system to analyze the real performance of the cycle.