The economics of a fuel cell cogeneration system using a by-product hydrogen stream

A site-specific fuel cell cogeneration study was conducted. A molten carbonate fuel cell (MCFC) system, sized at a nominal 25 MW (d.c.) to use an available by-product hydrogen stream, was compared with the alternative of purchased electricity and the use of natural gas to produce steam. The economic analysis objectives were to determine; the savings due to the reduced amount of purchased energy; the cost/benefit ratio; and the payback period for the MCFC cogeneration system. Another objective was to determine if the high capital cost of the first prototype MCFC plant would require a commercialization subsidy to make it attractive to an industrial owner. It was found that a commercialization subsidy would be required for the initial high cost prototype plant, but this technology promises an energy utilization of 84% of the input fuel heating value which represents a strong incentive for commercialization.     

A review of polymer electrolyte membrane fuel cells: Technology,applications, and needs on fundamental research

Polymer electrolyte membrane (PEM) fuel cells, which convert the chemical energy stored in hydrogen fuel directly and efficiently to electrical energy with water as the only byproduct, have the potential to reduce our energy use, pollutant emissions, and dependence on fossil fuels. Great deal of efforts has been made in the past, particularly during the last couple of decades or so, to advance the PEM fuel cell technology and fundamental research. Factors such as durability and cost still remain as the major barriers to fuel cell commercialization. In the past two years, more than 35% cost reduction has been achieved in fuel cell fabrication, the current status of $61/kW (2009) for transportation fuel cell is still over 50% higher than the target of the US Department of Energy (DOE), i.e. $30/kW by 2015, in order to compete with the conventional technology of internal-combustion engines. In addition, a lifetime of ∼2500 h (for transportation PEM fuel cells) was achieved in 2009, yet still needs to be doubled to meet the DOE’s target, i.e. 5000 h. Breakthroughs are urgently needed to overcome these barriers. In this regard, fundamental studies play an important and indeed critical role. Issues such as water and heat management, and new material development remain the focus of fuel-cell performance improvement and cost reduction. Previous reviews mostly focus on one aspect, either a specific fuel cell application or a particular area of fuel cell research. The objective of this review is three folds: (1) to present the latest status of PEM fuel cell technology development and applications in the transportation, stationary, and portable/micro power generation sectors through an overview of the state-of-the-art and most recent technical progress; (2) to describe the need for fundamental research in this field and fill the gap of addressing the role of fundamental research in fuel cell technology; and (3) to outline major challenges in fuel cell technology development and the needs for fundamental research for the near future and prior to fuel cell commercialization.     

Metal foams as a gas diffusion layer in direct borohydride fuel cells

Renewable energy sources have become an important issue due to global warming and the diminishing of fossil fuel resources that have become a major problem for the world. Fuel cells are one of the most important renewable energy systems. The use of metal foams within the scope of commercialization and cost reduction of fuel cells attracts attention today. Metal foams are a material that provides excellent performance in many engineering applications, especially in fuel cells, thanks to the high permeability provided by the porous structure, narrow flow channels, large specific surface area, capillary, and diffusive forces. Among the metallic foams, the focus is on the use of aluminum foam, due to its low cost, superior strength, and thermal conductivity performance properties as well as ease of production. As an alternative to gas diffusion layers, the use of different metallic foam materials in fuel cell systems and performance improvements were analyzed. The use of aluminum foams as flow distributors and electrodes in the anode diffusion layer, which is one of the DBHYP components, provides significant increases in cell performance, cell weight, and volume. It has been found that open-cell metallic foams used in fuel cell systems cause an increase in performance due to their positive effects on the amount of catalyst coating, flow characteristics, and electrical properties.     

MOLTEN SALT FUEL CELLS: Diversity and convergence,cycles and recycling

The development of the Molten Carbonate Fuel Cell, now 65 years old in its pure molten-salt cell embodiment, has spawned a remarkable variety of designs and technologies (gas-fed fuel cells, direct carbon fuel cells, solid oxide FC hybrids, CO₂ concentrating/capture and hydrogen generating systems). Sometimes these new subsets are recycling ideas from earlier stages of fuel cell exploration - which extend quite far back. Since Grove's discovery in 1840, diversification of the fuel has been a persistent lure and challenge – which led to exploration of ionic melts. Much later, after the isolation and identification of solid-oxide conductors, the path to a purely carbonate cell became conceptually clear. Its history since then has had several critical points, of diversification and convergence. Like all energy technologies, it is forever at the mercy of the economics, and politics, of primary energy resources – the balance between fossil and renewable. Is MCFC a technology whose time has come … and gone? Such a view would ignore its strong chemical fundamentals, intrinsic to a future including biofuels. But controlling and stabilizing the morphology and wetting properties of MCFC materials is vital for another cycle of re-birth and flowering.     

Review on dye-sensitized solar cells (DSSCs): Fundamental concepts and novel materials

The prosperity of human society largely relies on safe energy supply, and fossil fuel has been serving as the most reliable energy source. However, as a non-renewable energy source, the exhaustion of fossil fuel is inevitable and imminent in this century. To address this problem, renewable energy especially solar energy has attracted much attention, because it directly converts solar energy into electrical power leaving no environment affect. In the past, various photovoltaic devices like organic, inorganic, and hybrid solar cells were fabricated in succession. In spite of high conversion rate of silicon based solar cells, the high module cost and complicated production process restricted their application solely to astronautic and aeronautic technology. For domestic and other commercial applications, research has been focused on organic solar cells for their inherent low module cost and easy fabrication. In addition, organic solar cells have their lightweight and flexibility advantage over conventional silicon-based crystalline solar cells. Among all the organic solar cells, dye-sensitized solar cells (DSSCs) are the most efficient and easily implemented technology. Here, this study examines the working principle, present development and future prospectus for this novel technology.     

Microfluidic microbial fuel cells: Recent advancements and future prospects

Over the years, there has been a substantial increase in the demands of a portable, green source of energy for powering microelectronics to be used as sensors, medical implants and other lab-on-chip devices. Microfluidic microbial fuel cells have been identified as a genuine option to address these requirements. These cells operating at microscale level are characterised by laminar flow of fuel and oxidant which eradicates the requirement of a membrane ensuring higher performance and improved reaction rates than conventional fuel cells. Owing to these advantages, microsized microbial fuel cells have been extensively used to design micro power sources for environmental biosensors, point-of-care diagnostics, medical implants. However, the microfluidic microbial fuel cell technology suffers from some noteworthy disadvantages which need to be addressed before the commercialization of technology. The review comprehensively discusses the development, and advancements in microfluidic microbial fuel cell technology followed by their current applications, challenges, the possible solutions and future prospects.     

Steady state simulation of energy production from biomass by molten carbonate fuel cells

This paper presents an integrated approach to the steady state simulation of biomass gasification, fuel cells and power generation processes. Attention is devoted to molten carbonate fuel cells (MCFC) due to the relative low cost, simpler construction and flexibility in the use of fuel. A steady state model simulating a global MCFC power plant based on real plants data is described and the simulations are selected according to real operating conditions. The software developed allows to study ‘ìn silico’ the effect of variations of the process conditions as well as modification of the input fuel, thus providing a useful tool for supporting technical decisions and feasibility study on the use of fuel cells in developing countries. The paper reports results of computer simulation focusing on macroscopic quantities of interest such as stack efficiency, global process electrical efficiency, cogenerative efficiency. The computer simulation is applied to a feasibility study of a MCFC coupled with a biomass gasification module focusing on the energy consumption of the process and reporting comparison of the energy efficiency for three kinds of biomass.     

An overview of hydrogen as a vehicle fuel

As hydrogen fuel cell vehicles move from manifestation to commercialization, the users expect safe, convenient and customer-friendly fuelling. Hydrogen quality affects fuel cell stack performance and lifetime, as well as other factors such as valve operation. In this paper, previous researcher's development on hydrogen as a possible major fuel of the future has been studied thoroughly. Hydrogen is one of the energy carriers which can replace fossil fuel and can be used as fuel in an internal combustion engines and as a fuel cell in vehicles. To use hydrogen as a fuel of internal combustion engine, engine design should be considered for avoiding abnormal combustion. As a result it can improve engine efficiency, power output and reduce NO_x emissions. The emission of fuel cell is low as compared to conventional vehicles but as penalty, fuel cell vehicles need additional space and weight to install the battery and storage tank, thus increases it production cost. The production of hydrogen can be ‘carbon-free’ only if it is generated by employing genuinely carbon-free renewable energy sources. The acceptability of hydrogen technology depends on the knowledge and awareness of the hydrogen benefits towards environment and human life. Recent study shows that people still do not have the sufficient information of hydrogen.     

Economic analysis of hydrogen production from wastewater and wood for municipal bus system

The levelized cost of hydrogen for municipal fuel cell buses has been determined using the DOE H2A model for steam methane reforming (SMR), molten carbonate fuel cell reforming (MCFC), and wood gasification using wastewater biogas and willow wood chips as energy feedstocks. 300 kg H₂/day was chosen as the design capacity. Greenhouse gas emissions were calculated for each for the three processes and compared to diesel bus emissions in order to assess environmental impact. The levelized cost per kilogram for SMR, MCFC, and gasification is $5.12, $8.59, and $10.62, respectively. SMR provided the lowest sensitivity to feedstock price, and lowest levelized cost at various scales, with competitive cost to diesel on a cost/km basis. All three technologies provide a reduction in total greenhouse gases compared to diesel bus emissions, with MCFC providing the largest reduction. These results provide preliminary evidence that small scale distributed hydrogen production for public transportation can be relatively cost-effective and have minimal environmental impact.     

Review: Direct ethanol fuel cells

Direct ethanol fuel cells have attracted much attention recently in the search for alternative energy resources. As an emerging technology, direct ethanol fuel cells have many challenges that need to be addressed. Many improvements have been made to increase the performance of direct ethanol fuel cells, and there are great expectations for their potential. However, many improvements need to be made in order to enhance the potential of direct ethanol fuel cells in the future. This paper addresses the challenges and the developments of direct ethanol fuel cells at present. It also presents the applications of DEFC.     

Electrochemical performances of NANOCOFC in MCFC environments

The electrochemical performances of fuel cells using nano-ceria-salt composites electrolyte (NANOCOFC) have been investigated at different temperatures in molten carbonate fuel cell (MCFC) environment. The maximum output power density increased with the temperature, and reached 140 mW/cm² at 650 °C. After operating for 200 h, the open circuit voltage (OCV) can keep the same value and the output power density only deceased 0.08%. It demonstrated that the NANOCOFC possessed the perfect stability of electrochemical performance in the MCFC environment. However, it was found that the output power density of the fuel cell in MCFC environment was much lower than that of fuel cell in SOFC environment. It was implied that the carbonate transfer would hinder the conduction of both proton and oxygen ion, which result in the poor output power density of fuel cells.     

Distributed generation—Molten carbonate fuel cells

High efficiency and ultra-clean molten carbonate fuel cell (MCFC) technology development by FuelCell Energy, with support from the U.S. Department of Energy (DOE), has progressed to commercial power plants for stationary applications such as distributed generation. Lessons learned from this development will also be valuable to DOE for the ongoing Solid State Energy Conversion Alliance (SECA) solid oxide fuel cell (SOFC) development and cost reduction, for fuel cell turbine hybrids, and for hydrogen economy development with FutureGen.     

MCFC-并联TTEG混合系统的性能优化

为有效回收熔融碳酸盐燃料电池产生的余热,提出一种由熔融碳酸盐燃料电池(MCFC)、两级并联温差发电器(TTEG)和回热器组合而成的混合系统模型.考虑MCFC电化学反应中的过电势损失和混合系统中的不可逆损失,通过数值分析得出混合系统的输出功率和效率的数学表达式,获得混合系统的一般性能特征,讨论MCFC电流密度与温差发电器...     

Comparison by the use of numerical simulation of a MCFC-IR and a MCFC-ER when used with syngas obtained by atmospheric pressure biomass gasification

In order to realize biomass potential as a major source of energy in the power generation and transport sectors, there is a need for high efficient and clean energy conversion devices, especially in the low-medium range suiting the disperseness of this fuel. Large installations, based on boiler coupled to steam turbine (or IGCC), are too complex at smaller scale, where biomass gasifiers coupled to ICEs have low electrical efficiency (15-30%) and generally not negligible emissions.This paper analyses new plants configurations consisted of Fast Internal Circulated Fluidized-Bed Gasifier, hot-gas conditioning and cleaning, high temperature fuel cells (MCFC), micro gas turbines, water gas shift reactor and PSA to improve flexibility and electric efficiency at medium scale. The power plant feasibility was analyzed by means of a steady state simulation realized through the process simulator Chemcad in which a detailed 2D Fortran model has been integrated for the MCFC. A comparison of the new plant working with external (MCFC-ER) and internal (MCFC-IR) reforming MCFC was carried out. The small amount of methane in the syngas obtained by atmospheric pressure biomass gasification is not enough to exploit internal reforming cooling in the MCFC. This issue has been solved by the use of pre-reformer working as methanizer upstream the MCFC. The results of the simulations shown that, when MCFC-IR is used, the parameters of the cell are better managed. The result is a more efficient use of fuel even if some energy has to be consumed in the methanizer. In the MCFC-IR and MCFC-ER configurations, the calculated cell efficiency is, respectively, 0.53 and 0.42; the electric power produced is, respectively, 236 and 216 kW_e, and the maximum temperature reached in the cell layer is, respectively, 670 °C and 700 °C. The MCFC-ER configuration uses a cathode flowrate for MCFC cooling that are 30% lower than MCFC-IR configuration. This reduces pressure drop in the MCFC, possible crossover effect and auxiliaries power consumption. The electrical efficiency for the MCFC-IR configuration reaches 38%.     

Quantum mechanical interpretation and analysis of perovskite material based single layer fuel cells (SLFCs)

Fossil fuels are unable to meet the current energy demands and polluting the environment with the emission of harmful gases. Therefore, clean energy technology is need of the modern era. One of the energy conversion devices is fuel cell which utilized fuel from renewable sources and convert into electricity in an efficient and clean way. However, for commercialization of this technology high operating temperature, degradation of electrodes and manufacture cost is the key challenges in conventional three layer fuel cell. Significant improvements have been made to reduce the cost and operating temperature by selecting suitable materials. Therefore, single layer fuel cell (SLFC) has been got much attention due to simple geometry. The mechanism inside the SLFC is still mystery which has been explained in this paper using quantum mechanical parameters like band gap and effect of particle size on charge transportation.In this research work, nanocomposite materials for single layer fuel cell have been synthesized by chemical routes. The x-ray diffraction shows the cubic perovskite structure with average crystallite size in the range of 23–37 nm. The particle size and surface area is found to be 23 nm and 86.42 m² g^?1, respectively. Raman spectrum of LBSCF-SDC shows a red shift compared to LBSCF and band gap of the composition 3LBSCF-7SDC is found to be 2.51 eV. Moreover, the conductivity of the sample 3LBSCF-7SDC has been found to be 0.02 Scm^?1 at 750 °C. The quantum mechanical effects governing the working of single layer fuel cells are observed by different analyses. Photon confinement and Fano-Interactions phenomena resulted in a red shift using Raman analysis technique. The red shift in Raman spectrum is referred to a photon confined in a single layer fuel cell system. These effects are studied in single layer fuel cell for the first time with no previous analyses done in this newly field.     

Review: Enhancement of composite anode materials for low-temperature solid oxide fuels

Solid oxide fuel cell (SOFC) technology is attractive for its high-energy efficiency and expanded fuel flexibility. It is also more environmentally benign than conventional power generation systems. Recently, increasing attention has been paid to intermediate-to-low-temperature solid oxide fuel cells, which operating at 400–800 °C. Reducing its operating temperature can render SOFC more competitive with other types of fuel cells and portable energy storage system (EES) over a range of applications (eg: transportation, portable, stationary) and more conducive for commercialization. The high-performance composite anode requirements for low operating temperature (400–600 °C) demand microstructural and chemical stability, high electronic conductivity, and good electrochemical performance. The current high-temperature anode, Ni-YSZ (nickel-yttria stabilized zirconia) is generally reported with high interfacial resistance at reduced temperatures. This review highlights several potential composite anode materials (Ni-based and Ni-free) that have been developed for low-temperature SOFCs within the past 10 years. This literature survey shows that most of these anodes still exhibit relatively high polarization resistance. Focus is also given on reducing polarization resistance to maintain the cell power density. In literature, common approaches that have been adopted to enhance the performance of anodes are (i) selecting high-performance electrolyte, (ii) exploiting nanopowder properties, and (iii) adding noble metals as electrocatalysts.     

燃料电池发电的电站应用

燃料电池作为一种高效稳定的分布式清洁能源,其发电技术在电站领域的应用备受关注,而国内燃料电池电站尚在起步阶段,因此对这一领域的研究和实践经验具有重要意义。基于韩国燃气轮机联合循环电站中燃料电池发电项目的实施,介绍了燃料电池的选型,并通过模拟运行确定了最佳余热回收方案。MCFC燃料电池额定发电效率为47%,余热回收后效率提高3.5%。这些经验将对国内未来燃料电池电站的建设起到参考和借鉴意义。     

An overview of unsolved deficiencies of direct methanol fuel cell technology: factors and parameters affecting its widespread use

Direct methanol fuel cells (DMFCs) have evolved over the years as a potential candidate for application as a power source in portable electronic devices and in transportation sectors. They have certain associated advantages, including high energy and power densities, ease of fuel storage and handling, ability to be fabricated with small size, minimum emission of pollutants, low cost, ready availability of fuel and solubility of fuel in aqueous electrolytes. However, in spite of several years of active research involved in the development of DMFC technology, their chemical‐to‐electrical energy conversion efficiencies are still lower compared with other alternative power sources traditionally used. This review paper will focus on the existing issues associated with DMFC technology and will also suggest on the possible developmental necessities required for this technology to realize its practical potentials. Copyright © 2014 John Wiley & Sons, Ltd.     

Numerical modeling of an automotive derivative polymer electrolyte membrane fuel cell cogeneration system with selective membranes

Cogeneration power plants based on fuel cells are a promising technology to produce electric and thermal energy with reduced costs and environmental impact. The most mature fuel cell technology for this kind of applications are polymer electrolyte membrane fuel cells, which require high-purity hydrogen.The most common and least expensive way to produce hydrogen within today's energy infrastructure is steam reforming of natural gas. Such a process produces a syngas rich in hydrogen that has to be purified to be properly used in low temperature fuel cells. However, the hydrogen production and purification processes strongly affect the performance, the cost, and the complexity of the energy system.Purification is usually performed through pressure swing adsorption, which is a semi-batch process that increases the plant complexity and incorporates a substantial efficiency penalty. A promising alternative option for hydrogen purification is the use of selective metal membranes that can be integrated in the reactors of the fuel processing plant. Such a membrane separation may improve the thermo-chemical performance of the energy system, while reducing the power plant complexity, and potentially its cost. Herein, we perform a technical analysis, through thermo-chemical models, to evaluate the integration of Pd-based H₂-selective membranes in different sections of the fuel processing plant: (i) steam reforming reactor, (ii) water gas shift reactor, (iii) at the outlet of the fuel processor as a separator device. The results show that a drastic fuel processing plant simplification is achievable by integrating the Pd-membranes in the water gas shift and reforming reactors. Moreover, the natural gas reforming membrane reactor yields significant efficiency improvements.     

MCFC versus other fuel cells—Characteristics, technologies and prospects

Characteristics of molten carbonate fuel cell (MCFC) were critically compared to these of polymer electrolyte membrane fuel cell (PEMFC), alkaline fuel cell (AFC), phosphoric acid fuel cell (PAFC) and solid oxide fuel cell (SOFC). In comparison to the other fuel cells, the MCFC operates with the lowest current densities due to limited zones of effective electrode reactions and low solubilities of oxygen and hydrogen in molten carbonates; also it has a thickest electrodes–electrolyte assembly. In consequence, the applications of MCFC are almost limited to stationary power generators. Although the MCFC stationary power generators have now approached high technological level of precommercialization, in the future they may face a serious contest from SOFC and PEMFC, for which improvement of operational parameters is believed to be achieved easier.