| 1. |
- Mehr, A. S., et al.
(author)
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Polygeneration systems based on high temperature fuel cell (MCFC and SOFC) technology : System design, fuel types, modeling and analysis approaches
- 2021
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In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 228
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Research review (peer-reviewed)abstract
- No one can disagree the growing attention to developing and utilizing high temperature fuel cells partly due to their potential for multi-service applications. Recently, much focus can be observed on examination of the integration of solid oxide fuel cell (SOFC) or molten carbonate fuel cell (MCFC) systems with other subsystems to propose polygeneration plants. Literature review prove that, to propose a poly generation concept based on SOFC and MCFC systems, there is not a typical way commonly used by researchers. So it is tried to categorize and survey the current challenges of the high temperature fuel cell polygeneration plants. In this regard, the most common concepts and some unique system designs are reviewed and investigated in terms of fuel type, plant scale, electrical efficiency, overall efficiency and other performance indicators. It is figured out that similar to the typical CCHP system, the most common polygeneration designs are those utilizing the potential of exhaust gases from the natural gas fed fuel cell system in a heat recovery unit and a refrigeration system. A notable observed trend in recent years is the coupling of biofuels with polygeneration concepts. We found that there are still great challenges regarding how to predict the fuel cell actual cell voltage influencing the overall efficiency of poly generation plants. It is also observed that attendance of researchers to analyze the polygeneration systems from the viewpoints of economic and environmental is less in comparison with the investigation of the systems from the thermodynamics point of view.& nbsp;
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| 2. |
- Gandiglio, M., et al.
(author)
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Enhancing the energy efficiency of wastewater treatment plants through co-digestion and fuel cell systems
- 2017
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In: Frontiers in Environmental Science. - : Frontiers Media S.A.. - 2296-665X. ; 5
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Research review (peer-reviewed)abstract
- The present work provides an overview of technological measures to increase the self-sufficiency of wastewater treatment plants (WWTPs), in particular for the largely diffused activated sludge-based WWTP. The operation of WWTPs entails a huge amount of electricity. Thermal energy is also required for pre-heating the sludge and sometimes exsiccation of the digested sludge. On the other hand, the entering organic matter contained in the wastewater is a source of energy. Organic matter is recovered as sludge, which is digested in large stirred tanks (anaerobic digester) to produce biogas. The onsite availability of biogas represents a great opportunity to cover a significant share of WWTP electricity and thermal demands. Especially, biogas can be efficiently converted into electrical energy (and heat) via high temperature fuel cell generators. The final part of this work will report a case study based on the use of sewage biogas into a solid oxide fuel cell. However, the efficient biogas conversion in combined heat and power (CHP) devices is not sufficient. Self-sufficiency requires a combination of efficient biogas conversion, the maximization the yield of biogas from the organic substrate, and the minimization of the thermal duty connected to the preheating of the sludge feeding the anaerobic digester (generally achieved with pre-thickeners). Finally, the co-digestion of the organic fraction of municipal solid waste (OFMSW) into digesters treating sludge from WWTPs represent an additional opportunity for increasing the biogas production of existing WWTPs, thus helping the transition toward self-sufficient plants.
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| 3. |
- MosayebNezhad, M., et al.
(author)
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Technology review and thermodynamic performance study of a biogas-fed micro humid air turbine
- 2019
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In: Renewable energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0960-1481 .- 1879-0682. ; 140, s. 407-418
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Research review (peer-reviewed)abstract
- Biogas is a proven and valuable energy source today for the combined production of heat and electricity (CHP). One of the most reliable and efficient technologies for the CHP application using biogas is represented by microturbine (MT). This prime mover not only shows a very flexible behavior towards change in the fuel composition, but it also sticks out for its reliability, small size, and low weight. Moreover, micro humid air turbine (mHAT) cycle, which is still under development, provides a relatively simple and inexpensive solution to increasing the power output of the microturbines. In this paper, the thermodynamic model of a novel CHP system based on a 500 kW micro humid air turbine (mHAT) in a wastewater treatment plant (WWTP) is presented and discussed. Furthermore, some considerations regarding an appropriate biogas treatment system and heat recovery module are discussed. The results presented in this paper show how the proposed biogas-fed plant can achieve an electrical efficiency of 46.6% together with a CHP efficiency of 81.2%. The impact of integration with WWTPs is beneficial where both biogas and required water for inlet air humidification are available.
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| 4. |
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| 5. |
- D'Andrea, G., et al.
(author)
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Dynamic model with experimental validation of a biogas-fed SOFC plant
- 2017
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In: Energy Conversion and Management. - : Elsevier. - 0196-8904 .- 1879-2227. ; 135, s. 21-34
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Journal article (peer-reviewed)abstract
- The dynamic model of a poly-generation system based on a biogas-fed solid oxide fuel cell (SOFC) plant is presented in this paper. The poly-generation plant was developed in the framework of the FP7 EU-funded project SOFCOM (www.sofcom.eu), which consists of a fuel-cell based polygeneration plant with CO2 capture and re-use. CO2 is recovered from the anode exhaust of the SOFC (after oxy-combustion, cooling and water condensation) and the Carbon is fixed in the form of micro-algae in a tubular photobioreactor. This work focuses on the dynamic operation of the SOFC module running on steam-reformed biogas. Both steady state and dynamic operation of the fuel cell stack and the related Balance-of-Plant (BoP) has been modeled in order to simulate the thermal behavior and performance of the system. The model was validated against experimental data gathered during the operation of the SOFCOM proof-of-concept showing good agreement with the experimental data. The validated model has been used to investigate further on the harsh off-design operation of the proof-of-concept. Simulation results provide guidelines for an improved design of the control system of the plant, highlighting the feasible operating region under safe conditions and means to maximize the overall system efficiency.
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| 6. |
- Gandiglio, M., et al.
(author)
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Large stationary solid oxide fuel cell (SOFC) power plants
- 2018
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In: Green Energy and Technology. - Cham : Springer Verlag. ; , s. 233-261
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Conference paper (peer-reviewed)abstract
- This chapter presents the current status of large-size stationary solid oxide fuel cell (SOFC) systems and provides guidelines based on initial European experience in this sector. The authors refer to non-residential systems, usually in the range of tens of kW to MW size. Both commercial buildings and industrial applications are found within this sector. Even if Asia is the most active area for stationary SOFCs (due to widespread residential SOFC projects), the analysis on large SOFC stationary plants picks out the USA as the homeland of the market, with a large number of completed installations from Bloom Energy in the last 7 years, especially in California, thanks to the “fuel cells” dedicated program (State of California Self-Generation Incentive Program, SGIP). California has now more than 200 MW of fuel cell-based systems and world-renowned companies like Apple, eBay, IKEA, and Coca-Cola have installed the Bloom Energy SOFC system. Pacific Asia is also trying to enlarge the market by pushing research on pressurized hybrid plants (LG Fuel Cell Systems and Mitsubishi-Hitachi Heavy Industries): recent installations and projects confirm the interest in this technology. The chapter’s first section shows the current status of large-size stationary SOFC companies and installations across the world, based on the most recent declarations and news from the industry. In Europe, the first industrial size biogas-fed SOFC system was installed in 2017 within the framework of the DEMOSOFC project. The chapter provides a complete description of the plant layout, including the biogas purification system, the 58 kWe SOFC module, the heat recovery section, and the electrical layout. Preliminary results from the first thousand hours of operation are presented in terms of purification outcomes, SOFC efficiency and emissions and island mode operation. The chapter ends with a summary of criticalities, strengths, and guidelines for the large-size SOFC systems market.
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| 7. |
- Kupecki, J., et al.
(author)
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Numerical model of planar anode supported solid oxide fuel cell fed with fuel containing H2S operated in direct internal reforming mode (DIR-SOFC)
- 2018
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In: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 230, s. 1573-1584
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Journal article (peer-reviewed)abstract
- Experimental analysis of a planar 100 mm × 100 mm SOFC cell was conducted during operation at 1173 K in direct internal reforming (DIR) mode. In the first phase the rate of direct internal reforming was varied from 0 to 100% what corresponds to complete external reforming and complete DIR, respectively. In the second phase 1.2 ppm(v) of H2S was introduced to the feeding gas and the variation of the rate of direct internal reforming was repeated. Following the experimental analysis the numerical model was proposed to determine the correlation between the presence of the poisoning agent and the electrochemical performance. The effect on the resistance of the cell was studied. The lumped volume model was applied to predict the cell voltage. With the use of the experimental data it was possible to determine the relative change of the model parameters which describe the ionic and electronic conductivity of the SOFC. Model was adopted for predictive modeling of the solid oxide fuel cell, operated in DIR-SOFC mode with and without the presence of hydrogen sulfide. Additionally, literature data measured for a cell operated in complete internal reforming mode with variation of the sulfur content in the feeding gas were analyzed to define the effect of H2S content on the performance drop. Relative change of the resistance of a cell was correlated with the rate of internal reforming and the content of sulfur. Results of the analysis show that the degradation of the performance of SOFC due to sulfur poisoning during operation in DIR mode can be modelled with high fidelity. Change of the ionic and electronic resistance of a cell accounted for the maximum of 34 and 53%, respectively when the rate of DIR was altered between 0 and 100%. The contribution of the sulfur poisoning accounts for 69 and 79% when the H2S content varies in the range of 0.001–5 ppm(v). With average relative prediction error below 3%, the proposed approach finds good application in simulating the performance of a cell exposed to different gas mixtures with different levels of sulfur in the fuel stream.
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| 8. |
- Lanzini, A., et al.
(author)
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Dealing with fuel contaminants in biogas-fed solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) plants : Degradation of catalytic and electro-catalytic active surfaces and related gas purification methods
- 2017
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In: Progress in Energy and Combustion Science. - : Elsevier. - 0360-1285 .- 1873-216X. ; 61, s. 150-188
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Research review (peer-reviewed)abstract
- Fuel cell and hydrogen technologies are re-gaining momentum in a number of sectors including industrial, tertiary and residential ones. Integrated biogas fuel cell plants in wastewater treatment plants and other bioenergy recovery plants are nowadays on the verge of becoming a clear opportunity for the market entry of high-temperature fuel cells in distributed generation (power production from a few kW to the MW scale). High-temperature fuel cell technologies like molten carbonate fuel cells (MCFCs) and solid oxide fuel cells (SOFCs) are especially fit to operate with carbon fuels due to their (direct or indirect) internal reforming capability. Especially, systems based on SOFC technology show the highest conversion efficiency of gaseous carbon fuels (e.g., natural gas, digester gas, and biomass-derived syngas) into electricity when compared to engines or gas turbines. Also, lower CO2 emissions and ultra-low emissions of atmospheric contaminants (SOX, CO, VOC, especially NOX) are generated per unit of electricity output. Nonetheless, stringent requirements apply regarding fuel purity. The presence of contaminants within the anode fuel stream, even at trace levels (sometimes ppb levels) can reduce the lifetime of key components like the fuel cell stack and reformer. In this work, we review the complex matrix (typology and amount) of different contaminants that is found in different biogas types (anaerobic digestion gas and landfill gas). We analyze the impact of contaminants on the fuel reformer and the SOFC stack to identify the threshold limits of the fuel cell system towards specific contaminants. Finally, technological solutions and related adsorbent materials to remove contaminants in a dedicated clean-up unit upstream of the fuel cell plant are also reviewed.
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