Cogeneration Power Research Articles

Design and thermodynamic analysis of a novel structure utilizing coke oven gas for LNG and power cogeneration

Coke oven gas is a by-product of the process of producing coke from coal and contains valuable compounds such as hydrogen and methane. In this study, an improved process was proposed for co-generation of power and LNG from COG with low CO2 emissions and high energy and exergy efficiency. This proposed process includes: LNG Recovery Unit, Organic Rankin Cycle, and the power plant. The results of simulation showed that the exergy and energy efficiencies for this proposed process are 77.9% and 70.29%, respectively, which are considerably higher than other studies. It is found that the total exergy destruction of the proposed process is 4272.95 kW, and the power plant with 3118.1 kW exergy destruction has the largest share in total exergy destruction. Additionally, outcomes showed that ORC recovered 1205 kW of waste heat from compressor exhaust gases and produced 167.4 kW of power. Environmental analysis shows indirect carbon emissions for the proposed process is zero. The CO2 emissions for the total energy and electric power generation were 0.0034 kgCO2/MJ and 406 gCO2/kWhel, respectively which are lower than coal or natural gas power plants.

Performance evaluation of bagasse-based cogeneration power generation plant utilizing IFLT, IF-FMEA and IF-TOPSIS approaches

PurposeTo meet energy demand and tackle the challenges posed by global warming, Bagasse-based Cogeneration Power Generation (BCPG) plant in sugar mills have tremendous potential due to large-scale supply of renewable fuel called bagasse. To meet this goal, an integrated framework has been proposed for analyzing performance issues of BCPG.Design/methodology/approachIntuitionistic Fuzzy Lambda-Tau (IFLT) approach was implemented to compute various reliability parameters. Intuitionistic Fuzzy Failure Mode and Effect Analysis (IF-FMEA) approach has been implemented for studying risk issues results in decrease in plant's availability. Moreover, IF- Technique for Order Performance by Similarity to Ideal Solution (IF-TOPSIS) is implemented to verify accuracy of IF-FMEA approach.FindingsFor membership and non-membership functions, availability decreases to 0.0006% and 0.0020% respectively for spread ±15% to ±30%, and further decreases to 0.0127% and 0.0221% for spread ±30% to ±45%. Under risk assessment failure causes namely Storage tank (ST3), Valve (VL6), Transfer pump (TF8), Deaerator tank (DT11), High pressure heater and economiser (HP15), Boiler drum and super heater (BS22), Forced draft and Secondary air fan (FS25), Air preheater (AH29) and Furnace (FR31) with Intuitionistic Fuzzy Hybrid Weighted Euclidean Distance (IFHWED) based output scores – 0.8988, 0.9752, 0.9400, 0.8988, 0.9267, 1.1131, 1.0039, 0.8185, 1.0604 were identified as the most critical failure causes.Research limitations/implicationsReliability and risk analysis results derived from IFLT and IF-FMEA approaches respectively, to address the performance issues of BCPG is based on the quantitative and qualitative data collected from the industrial experts and maintenance log book. Moreover, to take care of hesitation in expert's knowledge, IF theory-based concept is incorporated so as to achieve more accuracy in analysis results. Reliability and risk analysis results together will be helpful in analyzing the performance characteristics and diagnosis of critical failure causes, which will minimize frequent failure in BCPG.Practical implicationsThe framework will help plant managers to frame optimal maintenance policy in order to enhance the operational aspects of the considered unit. Moreover, the accurate and early detection of failure causes will also help managers to take prudent decision for smooth operation of plant.Social implicationsThe results obtained ensure continuous operation of plant by utilizing the bagasse as fuel in boiler and also mitigate the wastages of fuel. If this bagasse (green fuel) is not properly utilized, there remains a dependency on coal-based power plants to meet the power demand. The results obtained are useful for decreasing dependency on coal, and promoting bagasse as the green, and alternative fuel, the emission by burning of these fuels are not harmful for environment and thereby contribute in preventing the environment from harmful effect of GHGs gases.Originality/valueIFLT approach has been implemented to develop reliability modeling equations of the BCPG unit, and furthermore to compute various reliability parameters for both membership and non-membership function. The ranking results of IF-FMEA are compared to IF-TOPSIS approach. Sensitivity analysis is done to check stability of proposed framework.

Sustainable analysis of Waste-to-Energy systems in cities by eco-efficiency assessment using DEA approach: A case study of Iran's municipalities

Municipal Solid Waste (MSW) management has become a pressing global issue due to population growth, urbanization, and changing consumption patterns, especially in developing countries. This study develops a comprehensive framework to evaluate the sustainability of MSW management systems. Also, the sustainability of Anaerobic Digestion (AD) and landfill systems with/without various Cogeneration of Heat and Power (CHP) technologies in different conditions using the framework in the municipalities of Iran. The eco-efficiency index, which considers environmental and economic aspects, is used to assess the systems sustainability. The Data Envelopment Analysis (DEA) method is applied to assess and rank the performance of the systems based on their eco-efficiency indices considering parameters such as energy production, costs, emissions, land occupation, water consumption, and employment. The results indicate that the landfill and AD systems with/without CHP have the highest priority for all provinces when the food, paper, and cardboard wastes entering the systems are at their maximum and minimum amounts. However, the systems without CHP have the lowest efficiency when the share of the wastes is 50%. Although the findings can help decision-makers in improving MSW management, there may be limitations to the research, such as data availability and assumptions made during the analysis.

Electrochemical generator based on solid oxide fuel cell and alumina reactor for hydrogen production

A cogeneration power plant based on a solid oxide fuel cell with an aluminum-hydrogen reactor in which hydrogen is obtained from aluminum and water in the presence of alkali is described. The efficiency of such a reactor is 43,7%. The fuel utilization rate at a power plant with an electric capacity of 10 kW is 42,3%. The electrical efficiency of the fuel cell is 77.2%, the proportion of hydrogen oxidized in the anode is 80.5%. The specific consumption of conventional fuel for the production of electric energy is 0.283 kg reference fuel/kW·h, and for the production of thermal energy 78.7 kg reference fuel/GJ.Specific indicators are higher compared to similar indicators for cogeneration power plants running on hydrocarbon fuel, but less than in the Russian energy system – 0.33 kg reference fuel/kW·h.

Design optimization of compact gas turbine and steam combined cycles for combined heat and power production in a FPSO system–A case study

This case study aims to cover a wide range of relevant aspects related to combined cycle design, mechanical integrity and operational reliability for cogeneration of heat and power in FPSO systems. The methods consist of combined optimization of combined cycle thermodynamic design and geometry of steam generator; vibration analysis for flow induced vibrations; and thermal stress estimation of casings during cold start-stop scenarios. Challenges and opportunities for reliable water treatment systems are explored. The results show that small tubes, a compact tube bundle and a low condensation temperature reduces the once-trough steam generator (OTSG) weight. The vibrations numerical simulations in this work support the standard recommendations of using 35 times tube OD as upper limit for the unsupported tube length, which could be used as a reasonable design criterion. Thermal stresses analysis indicates that the design of beam arrangement, location, and stiffness of beams has a major impact on thermal stresses, and can be optimized to different plate thicknesses in order to avoid fatigue damage. Focus should be on reducing leaks of deaerator, steam turbine and condenser. It is recommended to add Na sensors after condenser and investigating the use of Electrodeionization (EDI) technology for make-up water production from seawater.

Design, multi-aspect analyses, and multi-objective optimization of a biomass/geothermal-based cogeneration of power and freshwater

Proposing an effective multi-source plant is a promising approach to achieving higher performance in energy systems. By utilizing multiple energy sources, such as renewable and conventional sources, synergistically, a multi-source plant can enhance system efficiency, reliability, and sustainability. This paper presents a novel combination of a gas turbine cycle and a geothermal system for power and freshwater production, where the gas turbine cycle is an integration of modified methane and biomass-based systems. The proposed plant aims to improve the performance of conventional systems by considering thermodynamic, economic, and multi-objective optimization perspectives. Energy, exergy, and economic analyses are applied to assess the system's performance. Two double-objective optimizations are carried out to obtain the system's operation mode at the optimum state. The results reveal that the combustion chamber has the highest exergy destruction rate by 2967 kW. At the base operation conditions, the design system provides 5601 kW of net power, a freshwater production rate of 10.05 kg/s, and 39.5% of exergy efficiency. Furthermore, considering the net power-freshwater production rate as the optimization scenario, the optimum of 7070.52 kW net power and 41.16% exergy efficiency. While, considering exergy efficiency-exergy destruction as the objective scenario, the best payback period is obtained to be 5.71 years.

Hydrogen Sulphide and Carbonyl Sulphide Removal from Biogas for Exploitation in High-Temperature Fuel Cells

Fuel cells powered by biogas for decentralised cogeneration of heat and power are an attractive alternative to combustion technologies. However, biogas contains sulfur-based compounds (H2S, COS, DMS, siloxanes), which are harmful to fuel cells. This work was carried out in the framework of the European project Waste2Watts, involving the laboratories of Politecnico di Torino, ENEA, and PSI. The aim is to design and test a flexible and cost-effective cleaning unit to remove impurities for the use of biogas in high-efficiency fuel cell systems. The focus is on small- to medium-sized farms for which deep cleaning of biogas by adsorption materials is a suitable techno-economic solution to avoid intensive gas processing treatments. The ability of commercial adsorption materials (activated carbons, metal oxides, and metal hydroxides) to remove hydrogen sulphide and carbonyl sulphide was tested under different biogas compositions (oxygen and humidity). After evaluating the results, three plant configurations were proposed to optimally utilise the potential of the sorbents. Indeed, the RGM3 sorbent has proven to be an effective solution for removing H2S and COS under humid conditions (50% RH), whilst R7H and R8C sorbents are better suited for removing H2S and COS, respectively, in dry biogas conditions.Graphical abstract

Optimum design point exploration and performance analysis of a novel CO2 power generation system for LNG cold energy recovery: Considering the temperature fluctuation of heat source

Optimum design point exploration and performance analysis of a novel CO2 power generation system for LNG cold energy recovery: Considering the temperature fluctuation of heat source

Thermodynamic analysis and parameter optimization of a hybrid system based on SOFC and graphene-collector thermionic energy converter

The exhaust heat released from SOFCs (solid oxide fuel cells) possesses tremendous energy that can be recovered for energy cascade utilization. Nevertheless, low conversion efficiency or power density limits the SOFC’s high-grade waste heat recovery capabilities for the cogeneration of electric power. To address this challenge, a novel hybrid system coupling a SOFC with a GTEC (graphene-collector thermionic energy converter) is proposed, where the GTEC harvests the high-grade exhaust heat produced by the SOFC and generates extra electricity. It is found that the maximum power density of the hybrid system can reach 0.774 W/cm2 at 1073 K, which is 1.20 times higher than that of the sole SOFC, indicating that the hybrid system offers a considerable improvement in output performance. Additionally, the optimal operating conditions and major parameter designs of the hybrid system are determined from the perspective of finite-time thermodynamics. Choosing the optimal area ratio, increasing the SOFC operating temperature, enhancing the heat transfer coefficient, decreasing the thermal emissivity, and fabricating the perfect optical reflector can further improve the optimal performance of the hybrid system. Compared with other SOFC-based hybrid systems, the SOFC-GTEC provides better output performance, proving that the GTEC can more efficiently utilize the exhaust heat produced by SOFC than other energy harvesting devices. This work provides crucial theoretical guidance on the optimal designs and parametric analysis of SOFC-GTEC hybrid systems, thus paving the way towards developing high-performance SOFC cogeneration systems.

Techno-economic assessment of co-pyrolyzed kitchen waste and rice straw for co-generation of heat and power

Increasing concerns relating to depletion of fossil fuels and global warming coupled with significant growth in waste-to-energy markets have propelled the need for ingenious and flexible technologies that can effectively transform waste biomass into fuels and power at high efficiency. In this study, a comprehensive techno-economic investigation was undertaken to investigate the economic potential of utilizing co-pyrolyzed kitchen food waste and rice straw in a waste to heat and power facility based on microwave pyrolysis and a combined heat and power system. The study involved microwave pyrolysis experiments to investigate the effects of blending proportions of kitchen food waste and rice straw on the evolution of synthetic gas components based on gas chromatography analysis. The optimal blending proportion was then used to run the Aspen Plus heat and power plant simulation. Boiler efficiency, steam cycle thermal efficiency, electrical efficiency, and overall system efficiency were 96.30 %, 36.46 %, 41.61 %, and 35.11 %, respectively. The model had an estimated annual power production of 744,576 kWh/year, hot water production capacity of 1,727,649 L/year, and annual biochar production of 162,045 kg/year. A positive net present value was observed for the project after the second year, coupled with an internal rate of return of 0.62 and a profitability index of 3.85 over ten years. The heat generated can meet rapidly increasing urban heating needs and the power will contribute to grid stabilization. Sensitivity analysis revealed that the greatest potential performance improvements can be achieved by increasing biochar selling price and reducing total investment costs and total annual operating costs. Overall, the study shows scaled-up microwave-based heat and power technology to be a profitable and effective waste management and renewable energy solution.

Biomass power plants

Biomass power plants

Total site targeting with the simultaneous use of intermediate utilities and power cogeneration at the polymer plant

Maximizing heat recovery in the process industry is important to cut primary energy targets. It is always the trade-off between saved energy and spent capital investment. This issue became more important in the transition to a low-carbon economy. Inter-plant integration can be a source of clean energy, which does not need to be produced but proper targeting gives its economic feasibility and attraction to investments. This paper provides a new extension of the Total Site method accounting optimal amount of energy that can be saved on the inter-plant level. The approach utilises the construction of the Total Site Profiles with real temperature considers heat transfer with intermediate utility and finds cogeneration potential within enthalpy blocks of Total Site heat recovery. Merging of intermediate utilities and optimisation of its temperature were considered together with CHP optimisation. Targeting of the total annual cost was performed based on Total Site Pinch concept finding the optimum temperature approach between site temperature profiles. The case study for monomer production of polymer plant was investigated and 6 different options of Total Site heat recovery were assessed. The minimum total annualised cost of 45.3 mils. EUR was accounted for option with maximum cogeneration potential and the minimum number of heat exchangers. The heat recovered is 160.7 MW, CHP potential is 32.9 MW, and the number of heat exchangers is 144 for a total site minimum temperature approach of 20 °C. The results were compared with the traditional Total Site approach and the advantages were highlighted. The sensitivity analysis of the results was performed by applying energy price changes of ± 50% of the base level. The results can be used for the detailed design of the site energy system and further development of Total Site methods.

A comparative co-simulation analysis to improve the sustainability of cogeneration-based district multi-energy systems using photovoltaics, power-to-heat, and heat storage

For an extensive decarbonization of district multi-energy systems, efforts are needed that go beyond today’s cogeneration of heat and power in district multi-energy systems. The multitude of existing technical possibilities are confronted with a large variety of existing multi-energy system configurations. The variety impedes the development of universal decarbonization pathways. In order to tackle the decarbonization challenge in existing and distinct districts, this paper calculates a wide range of urban district configurations in an extensive co-simulation based on domain specific submodels. A district multi-energy system comprising a district heating network, a power grid, and cogeneration is simulated for two locations in Germany with locally captured weather data, and for a whole year with variable parameters to configure a power-to-heat operation, building insolation/refurbishment, rooftop photovoltaic orientation, future energy demand scenarios, and district sizes with a temporal resolution of 60 s, in total 3840 variants. The interdependencies and synergies between the electrical low-voltage distribution grid and the district heating network are analysed in terms of efficiency and compliance with network restrictions. Thus, important sector-specific simulations of the heat and the electricity sector are combined in a holistic district multi-energy system co-simulation. The clearly most important impact on emission reduction and fuel consumption is a low heat demand, which can be achieved through thermal refurbishment of buildings. Up to 46% reduction in CO2 emissions are possible using the surplus electricity from photovoltaics for power-to-heat in combination with central heat storage in the district’s combined heat and power plant. Domestic hot water heated by district heating network in combination with power-to-heat conversion distributed in the district reduces the load on the distribution power grid. Even though the investigated measures already improve the sustainability significantly, providing the energy needed for the production of synthetic fuels remains the crucial challenge on the further path towards net-zero.

Thermodynamic analysis of a sorption-enhanced gasification process of municipal solid waste, integrated with concentrated solar power and thermal energy storage systems for co-generation of power and hydrogen

A system of coupled CO2 capture and gasification has led to a new concept entitled sorption-enhanced gasification (SEG) which can increase H2 concentration in the syngas composition. This study proposed a novel configuration of the SEG system comprising concentrated solar power and thermal energy storage systems. Calcium looping (CaL) is utilized as the CO2 capture process. Unlike conventional SEG systems in which calcination heat demand is supplied by an oxy-combustion process, this study considers a heliostat field to provide heat for sorbent regeneration. The solar and thermal energy storage systems are simulated dynamically to achieve accurate results. A steam Rankine cycle is also designed to recover the released heat sources through the SEG system. The overall system performance is explored through energy and exergy analyses. Based on the results, the proposed system managed to produce 0.58 kg/s pure hydrogen in addition to 13.96 MW of net electrical power. Meanwhile, CO2 is captured from syngas composition with capturing efficiency of 95%. The energy analysis shows cold gas efficiency and the annual total energy efficiency of 87.76 and 70.74%, respectively. Based on exergy analysis results, the carbonator reactor exhibits the highest permeance compared to the gasifier and calciner reactors, with an exergy efficiency of 88.74%. Parametric study results show an increase in the cold gas efficiency, hydrogen production rate, and electrical energy efficiency with enhancing steam-to-biomass ratio. An increase in CO2 capture efficiency also improves both the electrical energy efficiency and H2 concentration of the syngas composition. CO2 capture efficiency and S/B ratio are inversely related to the exergy efficiency of the system.

Integration of CaO/CaCO3-CaCl2 thermochemical energy storage system with solid oxide iron-air redox battery

In this paper, a CaO/CaCO3-CaCl2 thermochemical energy storage system (TCES) is integrated with a solid oxide iron-air redox flow battery (SOIARB) by utilization of Aspen Plus. In this system, since calcination is an endothermic reaction, outlet Fe of the charge cycle of the battery is heated by exhausted heat from the calcination reactor. On the other hand, carbonation is an exothermic reaction and with the usage of this reactor’s heat load the inlet Fe for the discharge cycle of the battery can be preheated. The amount of energy stored in the charge mode of TCES and SOIARB are 11.09 MW and 0.38 MW respectively. Furthermore, a Fortran calculator block is applied to calculate the voltage, current density and power of the battery which are 1.78 V and 845 Am−2 for the charge cycle respectively and the amount of these parameters for the discharge process are 1.7 V and 900 Am−2 correspondingly. Besides, the battery system is capable of generating 52566 kW of power. On the other hand, the released heat load of the discharge cycle of TCES and battery, are 8.5 MW and 0.084 MW correspondingly. 42 % of the heat released in the carbonator reactor can be used to preheat the input Fe of 9 batteries and CO2 power generation. The round-trip efficiency (RTE) for the TCES system, the battery and for the whole system are presented as results which are 77 %, 22 % and 74 % respectively. Sensitivity analyses in terms of the influence of the temperature of the inlet ambient air on the heat load of the battery in both charge and discharge cycles are investigated. Also, the impact of changing the molar ratio of CaCl2/CaCO3 on the amount of energy of the charge and discharge sections is analyzed.

Performance evaluation of CO2 pressurization and storage system combined with S–CO2 power generation process and absorption refrigeration cycle

Performance evaluation of CO2 pressurization and storage system combined with S–CO2 power generation process and absorption refrigeration cycle

Study the Investment Opportunity of Hybrid Energy Resources (Biomass and Solar) System; Iraq as a Case Study

The increasing world population and demand for fossil fuels for energy generation have defect the environment due to pollution and global warming. Therefore, it provoked the world to focus on renewable energy resources. Solar power and Biomass are among the good available renewable energy sources in most parts of the world. Combining both sources is a promising way to reduce greenhouse gas emissions and a reliable investment in energy. However, this type of energy has yet to be considered seriously in Iraq. This research uses theoretical and experimental studies to evaluate the energy production from hybrid energy sources (Biomass and solar) in Diyala province, Iraq. The practical part focused on creating a small-scale prototype to verify the success of Biomass in Iraq and then expand on a large scale. Moreover, the gas generated has a more economically viable and helpful heat source for cogeneration power plants. The expected electricity production from wasted food in Iraq is about 38.5 MWh. Finally, this study can be a good advantage in investigating the feasibility of operating a hybrid solar-biomass power plant in Iraq.

Development of a novel framework for the analysis of Technological Innovation Systems by Causal Layered Analysis (CLA) in energy systems

ABSTRACT Greenhouse gas emissions from the burning of fossil fuels, as one of the main sources of anthropogenic climate change accounts for two-third of the global emissions. In this issue, Iran has adopted a set of policies and goals to consider related technology development. One of these technologies around which several national programmes have launched is the Cogeneration of Heat and Power (CHP). Nevertheless, the national goals have not been fulfilled as expected. The aim of this paper is therefore to provide a framework in order to identify the bottlenecks hindering CHP development in Iran. This framework is based on the Technological Innovation System (TIS) along with the Causal Layered Analysis (CLA) to decipher the profound and latent factors causing these problems. The results reveal a significant role of the discourses and visions both directly on the failure of the CHP innovation system functions and indirectly through affecting structural problems. A notable policy suggestion is to change the discourse of centralised power generation and to make more effort to legitimate the energy efficiency in the society. The developed framework can also be beneficial to policy-makers to formulate and analyse the future visions for the CHP plants.

Influence of Carbonated Bottom Slag Granules in 3D Concrete Printing.

This study investigates the possibility of utilising bottom slag (BS) waste from landfills, and a carbonation process advantageous for the use of artificial aggregates (AAs) in printed three-dimensional (3D) concrete composites. In general, the main idea of granulated aggregates is to reduce the amount of CO2 emissions of printed 3D concrete objects (wall). AAs are made from construction materials, both granulated and carbonated. Granules are made from a combination of binder (ordinary Portland cement (OPC), hydrated lime, burnt shale ash (BSA)) and waste material (BS). BS is a waste material left over after the municipal waste burning process in cogeneration power plants. Whole printed 3D concrete composite manufacturing consists of: granulating artificial aggregate, aggregate hardening and sieving (adaptive granulometer), carbonation of AA, mixing 3D concrete, and 3D printing. The granulating and printing processes were analysed for hardening processes, strength results, workability parameters, and physical and mechanical properties. Printings with no granules (reference 3D printed concrete) were compared to 3D printed concretes with 25% and 50% of their natural aggregate replaced with carbonated AA. The results showed that, theoretically, the carbonation process could help to react approximately 126 kg/m3 CO2 from 1 m3 of granules.

Energy and Exergy Analyses of a PWR-Type Nuclear Power Plant Coupled with an ME-TVC-MED Desalination System

Electricity–water cogeneration power plants are an important tool for advancing sustainable water treatment technologies because they provide a cost-effective and environmentally friendly solution for meeting the energy and water needs of communities. By integrating power and water production, these technologies can reduce carbon emissions and help mitigate the impact of climate change. This work deals with the energy and exergy analysis of a cogeneration plant for electrical power generation and water desalination using real operational data. The power side is a pressurized water reactor (PWR) nuclear power plant (NPP), while the desalination side is a multi-effect distillation (MED) system with a thermo-vapor compressor (TVC) plant coupled with a conventional multi-effect plant (ME-TVC-MED). A mathematical model was implemented in MATLAB software and validated through a comparison with previously published research. The exergy analysis was carried out based on the second law of thermodynamics to evaluate the irreversibility of the plant and the subsystems. In this study, the components of the sub-systems were analyzed separately to identify and quantify the component that has a high loss of energy and exergy. According to the energy and exergy analyses, the highest source of irreversibility occurs in the reactor core with 50% of the total exergy destruction. However, turbines, steam generators, and condensers also contribute to energy loss. Further, the thermodynamic efficiency of the cogeneration plant was obtained as 35.38%, which is more effective than other systems. In the ME-TVC-MED desalination unit, the main sources of energy losses are located in the evaporators and the thermo-compressor (about 50% and 36%, respectively). Moreover, the exergetic efficiency of the ME-TVC-MED unit was found to be low at 6.43%, indicating a high degree of technical inefficiency in the desalination process. Therefore, many opportunities exist to improve the performance of the cogeneration system.