SOFC Management in Distributed Energy Systems

2011 ◽  
Vol 8 (3) ◽  
Author(s):  
Daniele Chiappini ◽  
Andrea Luigi Facci ◽  
Laura Tribioli ◽  
Stefano Ubertini
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Energy Systems ◽  
Hot Water ◽  
Pollutant Emissions ◽  
Heating Process ◽  
Distributed Energy ◽  
Utilization Factor ◽  
Distributed Power Generation

Among the distributed generation emerging technologies, solid oxide fuel cells (SOFCs) seem to be the most promising for small and medium power (up to 1 MW) as they feature extremely high efficiency and low pollutant emissions, and the high-grade waste heat can be utilized for space heating, process steam, and/or domestic hot water demands. As their main drawbacks are high cost and relatively short lifetime, much research is devoted to solve technological problems and to develop less expensive materials and mass production processes. However, even if SOFCs are close to commercialization and several demonstration units are already running, only few researches have been performed on their integration in power plants for distributed power generation, which are complex systems made up of different components that have to satisfy energy requirements (heat, electricity, and cooling). In this paper, we investigate the behavior of SOFCs in distributed energy systems and how their operation in terms of load and fuel utilization factor could optimize fuel consumption and/or minimize energy costs. The potential advantages of SOFCs related to their excellent part-load operation and their ability to meet and follow the highly noncoincident electric and thermal loads in either grid-connected or stand-alone configurations are discussed.

Design Parameters for High-Efficiency Hybrid PV/Thermal Solar Energy Systems

2011 ◽  
Author(s):  
Jerry A. Dutreuil ◽  
Hamid A. Hadim
Keyword(s):  
Solar Energy ◽  
High Efficiency ◽  
Waste Heat ◽  
Energy Systems ◽  
Energy Performance ◽  
Hot Water ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Improved Design ◽  
T System

With recently increasing focus on solar energy, there has been increased interest in hybrid PV/thermal (PV/T) solar energy systems. In the PV/T system, a thermal energy recovery system is implemented to remove waste heat from the PV cells, thereby decreasing their operating temperature, leading to enhanced overall energy performance of the PV cells. The possibility of the utilization of waste heat recovered for hot water or space heating makes the PV/T system highly attractive for building integration. The main objective of this study is to conduct a state-of-the-art review and compare existing PV/T systems in terms of the factors limiting their electrical and thermal performance. Critical design parameters for maximum efficiency of PVT systems are identified and practical recommendations for improved design of PVT systems are provided.

Design and Optimization of Integrated Distributed Energy Systems for Off-grid Buildings

2021 ◽  
pp. 1-27
Author(s):  
Jian Zhang ◽  
Heejin Cho ◽  
Pedro Mago
Keyword(s):  
Energy Storage ◽  
Optimal Design ◽  
Power Systems ◽  
Thermal Energy ◽  
Waste Heat ◽  
Carbon Dioxide Emission ◽  
Energy Systems ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Distributed Energy

Abstract Off-grid concepts for homes and buildings have been a fast-growing trend worldwide in the last few years because of the rapidly dropping cost of renewable energy systems and their self-sufficient nature. Off-grid homes/buildings can be enabled with various energy generation and storage technologies, however, design optimization and integration issues have not been explored sufficiently. This paper applies a multi-objective genetic algorithm (MOGA) optimization to obtain an optimal design of integrated distributed energy systems for off-grid homes in various climate regions. Distributed energy systems consisting of renewable and non-renewable power generation technologies with energy storage are employed to enable off-grid homes/buildings and meet required building electricity demands. In this study, the building types under investigation are residential homes. Multiple distributed energy resources are considered such as combined heat and power systems (CHP), solar photovoltaic (PV), solar thermal collector (STC), wind turbine (WT), as well as battery energy storage (BES) and thermal energy storage (TES). Among those technologies, CHP, PV, and WT are used to generate electricity, which satisfies the building's electric load, including electricity consumed for space heating and cooling. Solar thermal energy and waste heat recovered from CHP are used to partly supply the building's thermal load. Excess electricity and thermal energy can be stored in the BES and TES for later use. The MOGA is applied to determine the best combination of DERs and each component's size to reduce the system cost and carbon dioxide emission for different locations. Results show that the proposed optimization method can be effectively and widely applied to design integrated distributed energy systems for off-grid homes resulting in an optimal design and operation based on a trade-off between economic and environmental performance.

Analysis of Extended Environomic Cost Influence on Conventional Energy Systems Design

2000 ◽  
Author(s):  
R. Borchiellini ◽  
M. Calì ◽  
M. Santarelli
Keyword(s):  
High Efficiency ◽  
Systems Design ◽  
Energy Systems ◽  
Policy Instrument ◽  
Combined Cycle ◽  
Energy Resources ◽  
Environmental Cost ◽  
Pollutant Emissions ◽  
High Investment ◽  
Economic Balance

Abstract In the paper the authors analyse how the application of an extended environomic procedure, based on charges linked to the pollutant activities of energy systems, influences the energy behaviour of energy systems. If in the economic balance of an energy plant a cost is assigned only to the pollutant emissions (Environmental Cost), it can be shown that this choice allows a good promotion of the abatement devices and of the switching fuel approach, but the efficient utilization of energy resources is not sufficiently promoted. The extended approach, here analysed, takes into account both the pollutant emissions and the inefficient use of energy resources. In the proposed method, on the basis of thermodynamic considerations, a cost is assigned to the exergy rate destroyed inside the system and to the exergy flows rejected into the biosphere with the plant wastes (Efficiency Penalty). Many calculations have been developed using different sets of both the Environmental Cost and the Efficiency Penalty; assigning different weights to them. The calculations have been applied to a 30 MWel gas turbine cogeneration power plant (CGAM), and to an existing 350 MW combined cycle, considering the pollutant emissions of CO, NOx, SOx and CO2. The obtained results show that this approach can become a real energy policy instrument: in fact it allows to stimulate high efficiency design of conventional plants and advanced high-efficiency low-pollutant energy systems, becoming an opportunity to disseminate advanced technologies that still have difficulties to compete in the energy market due to their high investment costs.

Topology Optimization of Multimaterial Thermoelectric Structures

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Xiaoqiang Xu ◽  
Yongjia Wu ◽  
Lei Zuo ◽  
Shikui Chen
Keyword(s):  
Topology Optimization ◽  
Thermoelectric Materials ◽  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Oil Refining ◽  
Numerical Verification ◽  
Temperature Range ◽  
Multiple Materials ◽  
P Type

Abstract A large amount of energy from power plants, vehicles, oil refining, and steel or glass making process is released to the atmosphere as waste heat. The thermoelectric generator (TEG) provides a way to reutilize this portion of energy by converting temperature differences into electricity using Seebeck phenomenon. Because the figures of merit zT of the thermoelectric materials are temperature-dependent, it is not feasible to achieve high efficiency of the thermoelectric conversion using only one single thermoelectric material in a wide temperature range. To address this challenge, the authors propose a method based on topology optimization to optimize the layouts of functional graded TEGs consisting of multiple materials. The multimaterial TEG is optimized using the solid isotropic material with penalization (SIMP) method. Instead of dummy materials, both the P-type and N-type electric conductors are optimally distributed with two different practical thermoelectric materials. Specifically, Bi2Te3 and Zn4Sb3 are selected for the P-type element while Bi2Te3 and CoSb3 are employed for the N-type element. Two optimization scenarios with relatively regular domains are first considered with one optimizing on both the P-type and N-type elements simultaneously, and the other one only on single P-type element. The maximum conversion efficiency could reach 9.61% and 12.34% respectively in the temperature range from 25 °C to 400 °C. CAD models are reconstructed based on the optimization results for numerical verification. A good agreement between the performance of the CAD model and optimization result is achieved, which demonstrates the effectiveness of the proposed method.

Multimaterial Topology Optimization of Thermoelectric Generators

2019 ◽  
Author(s):  
Xiaoqiang Xu ◽  
Yongjia Wu ◽  
Lei Zuo ◽  
Shikui Chen
Keyword(s):  
Topology Optimization ◽  
Conversion Efficiency ◽  
Thermoelectric Materials ◽  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Computational Simulation ◽  
Oil Refining ◽  
Temperature Range ◽  
Multiple Materials

Abstract Over 50% of the energy from power plants, vehicles, oil refining, and steel or glass making process is released to the atmosphere as waste heat. As an attempt to deal with the growing energy crisis, the solid-state thermoelectric generator (TEG), which converts the waste heat into electricity using Seebeck phenomenon, has gained increasing popularity. Since the figures of merit of the thermoelectric materials are temperature dependent, it is not feasible to achieve high efficiency of the thermoelectric conversion using only one single thermoelectric material in a wide temperature range. To address this challenge, this paper proposes a method based on topology optimization to optimize the layouts of functional graded TEGs consisting of multiple materials. The objective of the optimization problem is to maximize the output power and conversion efficiency as well. The proposed method is implemented using the Solid Isotropic Material with Penalization (SIMP) method. The proposed method can make the most of the potential of different thermoelectric materials by distributing each material into its optimal working temperature interval. Instead of dummy materials, both the P and N-type electric conductors are optimally distributed with two different practical thermoelectric materials, namely Bi2Te3 & PbTe for P-type, and Bi2Te3 & CoSb3 for N-type respectively, with the yielding conversion efficiency around 12.5% in the temperature range Tc = 25°C and Th = 400°C. In the 2.5D computational simulation, however, the conversion efficiency shows a significant drop. This could be attributed to the mismatch of the external load and internal TEG resistance as well as the grey region from the topology optimization results as discussed in this paper.

Study on the Comprehensive Program of Heat Pump Technology Recycling Thermal Power Plants Circulating Water Heat

2013 ◽  
Vol 313-314 ◽  
pp. 759-762
Author(s):  
Yun Feng Ma ◽  
Yan Xiang Liu ◽  
Tao Ji
Keyword(s):  
Heat Pump ◽  
Power Plants ◽  
Waste Heat ◽  
Thermal Power ◽  
Heating System ◽  
Hot Water ◽  
Thermal Power Plants ◽  
Domestic Hot Water ◽  
Circulating Water ◽  
Central Heating

In order to fully recycle power plant’s circulatingwater heat, improve the thermal efficiency and protect the environment, thispaper designs the comprehensive scheme of heat pumptechnology recycling power plant’s circulating water heat, including theboiler mae-up water pre-heating system, the central heating circulatingsystem and the domestic hot water circulating system, which not only run at thesame time but also function independently. Even in non-heating seasons,the waste heat of circulating water can be utilized fully. It is worthmentioning that this paper puts forward to install climate compensationdevice in the central heating system, which can perform intelligent district timesharing control to meet different users’ needs.

scholarly journals Combined Cycles Permit the Most Environmentally Benign Conversion of Fossil Fuels to Electricity

1990 ◽  
Author(s):  
Guenther Haupt ◽  
John S. Joyce ◽  
Konrad Kuenstle
Keyword(s):  
Environmental Impact ◽  
Power Plants ◽  
Fossil Fuels ◽  
Coal Gasification ◽  
High Efficiency ◽  
Waste Heat ◽  
Primary Energy ◽  
Combined Cycle ◽  
Point Of View ◽  
Steam Boiler

The environmental impact of unfired combined-cycle blocks of the GUD® type is compared with that of equivalent reheat steam boiler/turbine units. The outstandingly high efficiency of GUD blocks not only conserves primary-energy resources, but also commensurately reduces undesirable emissions and unavoidable heat rejection to the surroundings. In addition to conventional gas or oil-fired GUD blocks, integrated coal-gasification combined-cycle (ICG-GUD) blocks are investigated from an ecological point of view so as to cover the whole range of available fossil fuels. For each fuel and corresponding type of GUD power plant the most appropriate conventional steam-generating unit of most modern design is selected for comparison purposes. In each case the relative environmental impact is stated in the form of quantified emissions, effluents and waste heat, as well as of useful byproducts and disposable solid wastes. GUD blocks possess the advantage that they allow primary measures to be taken to minimize the production of NOx and SOx, whereas both have to be removed from the flue gases of conventional steam stations by less effective and desirable, albeit more expensive secondary techniques, e.g. flue-gas desulfurization and DENOX systems. In particular, the comparison of CO2 release reveals a significantly lower contribution by GUD blocks to the greenhouse effect than by other fossil-fired power plants.

scholarly journals Regeneration of Electrical Energy from Waste Geothermal Fluid in Geothermal Power Plants

2019 ◽  
Vol 2 (3) ◽  
pp. 525-531
Author(s):  
Mahmut Hekim ◽  
Engin Cetin
Keyword(s):  
Power Plants ◽  
Thermoelectric Generator ◽  
Waste Heat ◽  
Electrical Energy ◽  
Heat Energy ◽  
Hot Water ◽  
Geothermal Resources ◽  
Geothermal Fluid ◽  
Geothermal Power ◽  
Electrical Energy Production

Geothermal power plants are the plants that provide the conversion of thermal energy in geothermal fluid to electrical energy as a result of the extraction of underground hot water resources to the earth by drilling. The total installed power of geothermal power plants in the field of geothermal resources in Turkey has reached 1,336 MW. The geothermal fluid, which is used for electric power generation in geothermal power plants, is re-injected into the underground wells after electrical energy production. For efficient generation of electrical energy in geothermal power plants, it is aimed to reuse the waste heat energy within the geothermal fluid before it is sent to the re-injection well. To achieve this aim, thermoelectric generator modules which convert waste heat energy to electrical energy can be used. In this study, a thermoelectric generator-based geothermal power plant simulator that converts geothermal fluid waste heat into electrical energy is installed and commissioned in the laboratory conditions.

Using ESP Permanent Magnet Motor Technology in High-Temperature Geothermal Applications

2021 ◽  
Author(s):  
Natalia Lykova ◽  
Danila Martiushev
Keyword(s):  
High Temperature ◽  
Permanent Magnet ◽  
High Speed ◽  
Power Plants ◽  
High Efficiency ◽  
Induction Motors ◽  
Renewable Energy Sources ◽  
Hot Water ◽  
Heat Conducting ◽  
Permanent Magnet Motor

Abstract Geothermal energy is one of the more efficient renewable energy sources. It uses heat from the Earth's interior to produce electricity in geothermal power plants. In binary cycle power plants, geothermal water can often be produced naturally from high-pressure wells. But when reservoir pressure drops, these power plants need to add artificial lift to continue to produce needed quantities of hot water. The geothermal industry is looking at electrical submersible pumping (ESP) systems as a way to improve geothermal fluid production. But ESPs were designed for the conditions in oil wells and are subject to severe complicating factors in geothermal conditions that significantly reduce runlife, such as temperatures up to 200°C (390°F), highly corrosive fluid, and salt deposition (scale). At the same time, production rates need to be higher than those typical of oil production. The most commonly used geothermal pumps are driven by a transmission shaft and drive on the surface, or they use a submersible asynchronous induction motor. Surface-driven pumps, commonly called line-shaft pumps, have significant depth limitations. Submersible asynchronous induction motors cannot provide a sufficient volume of fluid supply and tend to overheat in high-temperature conditions. To compensate for the heat, induction motors must operate underloaded. Even so, they are subject to frequent premature failures with operating times of between 30 and 100 days. To solve the problem of cost-effective exploitation of geothermal fields, Novomet used its expertise with permanent magnet motors and high-speed pumps to develop an electrical submersible pumping system that would offer more reliability and runlife in geothermal conditions. A 254-mm (10-in.) geothermal submersible pumping (GSP) system was designed, manufactured, and tested with a production output of up to 12,000 m3/d (75,477 bbl/d, 139 l/s, 2201 gpm,). It featured new generation, high-efficiency pump stages and a permanent magnet motor with a capacity of up to 1.5 MW. The GSP system design was field tested in Turkey. Improvements to early system designs include the use of a heat-conducting filler in the materials used to compound the permanent magnet motor, the adoption of various high-temperature-rated components (AFLAS rubber elements, RYTON motor terminals, and heat-resistant motor oil), and the development of metal-to-metal sealing in the motor lead extension. One of the early GSP systems installed in the field performed reliably for 470 days at a frequency of 90 Hz, significantly exceeding the target runtime. More than thirty units with a total flow rate of 190,000 m3/d (1,195,000 bbl/d, 2199 l/s, 34,856 gpm) are currently in operation in Turkey. The electrical consumption savings average 25% for each GSP system with a permanent magnet motor compared to systems using asynchronous induction motors. While designed for geothermal applications, GSPs can also be used in oil and gas operations.

A SOFC-Based Integrated Gasification Fuel Cell Cycle With CO2 Capture

2010 ◽  
Author(s):  
Vincenzo Spallina ◽  
Matteo C. Romano ◽  
Stefano Campanari ◽  
Giovanni Lozza
Keyword(s):  
Fuel Cell ◽  
Co2 Capture ◽  
Heat Recovery ◽  
Power Plants ◽  
High Efficiency ◽  
Air Separation ◽  
Pollutant Emissions ◽  
Separation Unit ◽  
Power Stations ◽  
Integrated Gasification

Application of Solid Oxide Fuel Cells (SOFC) in gasification-based power plants would represent a turning point in the power generation sector, allowing to considerably increase the electric efficiency of coal-fired power stations. Pollutant emissions would also be significantly reduced in Integrated Gasification Fuel Cell cycles (IGFC) considering the much lower emissions of conventional pollutants (NOx, CO, SOx, particulate matter) typical of fuel cell-based systems. In addition, SOFC-based IGFCs appear particularly suited to applications in power plants with CO2 capture. This is evident by considering that SOFCs operate as air separators and partly oxidized fuel exiting the fuel cell does not contain nitrogen from air, like in conventional oxy-fuel processes. The aim of the present paper is the thermodynamic analysis of a SOFC-based IGFC with CO2 capture. In the assessed plant, syngas produced in a high efficiency Shell gasifier is used in SOFC modules after heat recovery and cleaning. Anode exhausts, still containing combustible species, are burned with oxygen produced in the air separation unit, also used to generate the oxygen needed in the gasifier; the product gas is cooled down in a heat recovery steam generator before water condensation and CO2 compression. The plant layout is carefully designed to best exploit heat generated in all the processes and, apart from the fuel cell, exotic components, far from industrial state-of-the-art, are not included. Detailed energy and mass balances are presented for a better comprehension of the obtained results.

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