Ash-free coal as fuel for direct carbon fuel cell

This work describes the performance of the direct carbon fuel cell (DCFC) fuelled by ash-free coal. Employing coal in the DCFC might be problematic, mainly because of the ash deposition after the cell reactions. In the study, the carbonaceous ash-free component of coal is obtained, which is then evaluated as the DCFC fuel and compared with raw coal, active carbon, carbon black, and graphite. The electrolyte-supported SOFC structure is adapted to build the DCFC. The DCFC based on the ash-free coal fuel exhibits good performance with regard to the maximum power density, day-by-day measurements, and durability at continuous run. When the carbon fuels are internally gasified to H₂ and CO, the power density is generally much improved, compared to N₂ pyrolysis environment. The power generation is most likely related to the concentration of pyrolyzed gases as well as the electrochemical reactivity of the solid carbon.     

Cellulosic fuel ethanol

Iogen (Canada) is a major manufacturer of industrial cellulase and hemicellulase enzymes for the textile, pulp and paper, and poultry feed industries. Iogen has recently constructed a 40 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. The integration of enzyme and ethanol plants results in significant reduction in production costs and offers an alternative use for the sugars generated during biomass conversion. Iogen has partnered with the University of Toronto to test the fermentation performance characteristics of metabolically engineered Zymomonas mobilis created at the National Renewable Energy Laboratory. This study focused on strain AX101, a xylose- and arabinose-fermenting stable genomic integrant that lacks the selection marker gene for antibiotic resistance. The “Iogen Process” for biomass depolymerization consists of a dilute-sulpfuric acid-catalyzed steam explosion, followed by enzymatic hydrolysis. This work examined two process design options for fermentation, first, continuous cofermentation of C₅ and C₆ sugars by Zm AX101, and second, separate continuous fermentations of prehydrolysate by Zm AX101 and cellulose hydrolysate by either wildtype Z. mobilis ZM4 or an industrial yeast commonly used in the production of fuel ethanol from corn. Iogen uses a proprietary process for conditioning the prehydrolysate to reduce the level of inhibitory acetic acid to at least 2.5 g/L. The pH was controlled at 5.5 and 5.0 for Zymomonas and yeast fermentations, respectively. Neither 2.5 g/L of acetic acid nor the presence of pentose sugars (C₆:C₅ = 2:1) appreciably affected the high-performance glucose fermentation of wild-type Z. mobilis ZM4. By contrast, 2.5 g/L of acetic acid significantly reduced the rate of pentose fermentation by strain AX101. For single-stage continuous fermentation of pure sugar synthetic cellulose hydrolysate (60 g/L of glucose), wild-type Zymomonas exhibited a four-fold higher volumetric productivity compared with industrial yeast. Low levels of acetic acid stimulated yeast ethanol productivity. The glucose-to-ethanol conversion efficiency for Zm and yeast was 96 and 84%, respectively.     

Urine utilisation by microbial fuel cells; energy fuel for the future

This communication reports for the first time the direct utilisation of urine in MFCs for the production of electricity. Different conversion efficiencies were recorded, depending on the amount treated. Elements such as N, P, K can be locked into new biomass, thus removed from solution, resulting in recycling without environmental pollution.     

Nuclear oxide fuel analysis

As a rule the analysis of nuclear oxide fuel includes the determination of uranium, plutonium, their isotopic composition, cation impurities, carbon, nitrogen, chlorine, fluorine, oxygen coefficient. In this paper we discuss different methods for the a analysis of unirradiated uranium and plutonium oxide fuelds used in the laboratories of the Analytical Chemistry Department: coulometry, emission analysis, chromatography, X-ray analysis. Much consideration is being given to the analysis of uranium and plutonium oxide samples and uranium-plutonium mixed fuels irradiated in the BOR-60 using mass-spectrometric (isotope dilution method) and radiometric techniques. The results of uranium and plutonium determination by these methods are compared. The main analytical characteristics of the methods are given.     

Zeolite micro fuel cell

Microfabricated HZSM-5 micromembranes were successfully employed as a proton-exchange membrane in a micro fuel cell and the energy generation is strongly dependent on the Al-content of the HZSM-5.     

Solid oxide fuel cells

Despite being first demonstrated over 160 years ago, and offering significant environmental benefits and high electrical efficiency, it is only in the last two decades that fuel cells have offered a realistic prospect of being commercially viable. The solid oxide fuel cell (SOFC) offers great promise and is presently the subject of intense research activity. Unlike other fuel cells the SOFC is a solid-state device which operates at elevated temperatures. This review discusses the particular issues facing the development of a high temperature solid-state fuel cell and the inorganic materials currently used and under investigation for such cells, together with the problems associated with operating SOFCs on practical hydrocarbon fuels.     

Towards biochemical fuel cells

A biochemical fuel cell is a device which converts chemical energy into electrical power. The catalysts used in this process can be either inorganic or organic type giving rise to ‘inorganic fuel cells’ or ‘biochemical fuel cells’, respectively. Biochemical fuel cells use either micro-organism or enzymes as active components to carry out electrochemical reactions. The efficiency of such a device theoretically can be as high as 90%. The difficulty in attaining these values arises due to sluggishness of electron transfer from active site to conducting electrode. This can be overcome by using mediators or by immobilizing active components on conducting electrode. We have immobilizedfad-glucose oxidase on a graphite electrode using a semiconducting chain as a bridge. At the present stage of development, such a device tacks high current densities, which is essential for commercial power generation but can be used in applications such as pacemakers and glucose sensors.     

Large-scale fuel ethanol from lignocellulose

Applied Biochemistry and Biotechnology - Ethanol produced from lignocellulose is considered as a largescale transportation fuel in the United States. Five key issues are identified and considered...     

Alpha-spectrometry in nuclear fuel analysis

A survey is given of the analysis of actinide nuclides by means ofa-spectrometry in high-level radioactivity process solutions resulting from reprocessing of spent U-Th fuel. Separation of fission products and isolation of the nuclides²²⁸Th,²³¹Pa,²³²U,²³⁷Np and²³⁸Pu are performed by adsorption, ion-exchange, extraction chromatography and extraction techniques. After separation, samples for quantitative determination are prepared by electrodeposition and measured using a silicon-surface barrier detector combined with a multichannel analyzer. An error estimation is given.     

X-ray absorption spectroscopic studies on solid oxide fuel cells and proton-conducting ceramic fuel cells

X-ray absorption spectroscopy (XAS) is one of the best techniques to obtain the information on the electronic and local structures of materials. In the last few decades, XAS becomes a common analytical technique for the investigation of solid oxide fuel cells and proton-conducting ceramic fuel cells. In particular, operando and/or advanced XAS measurements can be recently available with the increased accessibility of synchrotron radiation. In this article, recent trends of solid oxide fuel cell and proton-conducting ceramic fuel cell researches using XAS are overviewed.     

以椰壳生物质炭为燃料的直接炭固体氧化物燃料电池

通过热裂解制得椰壳炭,表征了其结构和组成,并将其用于电解质为钇稳定化氧化锆（YSZ）、电极材料为银和钆掺杂氧化铈（Ag-GDC）的固体氧化物燃料电池（SOFC）的燃料,对所构成的直接炭固体氧化物燃料电池（DC-SOFC）的性能进行了测试研究。结果表明,所制得的椰壳炭颗粒粒径在微米级别,具有介孔结构,而且椰壳炭中含有K、Ca等元素,可用作Boudouard反应催化剂。当使用椰壳炭作为DC-SOFC燃料时,在800 ℃下电池最大功率密度为255 mW/cm²;负载Fe催化剂后,最大功率密度提升为274 mW/cm²。以0.5 A/cm²的恒电流放电,0.5 g负载Fe椰壳炭燃料电池能够连续工作17.6 h,燃料利用率为39%,表明椰壳炭作为DC-SOFC燃料具有优异的性能和潜力。     

Catalysis in high-temperature fuel cells

Catalysis plays a critical role in solid oxide fuel cell systems. The electrochemical reactions within the cell--oxygen dissociation on the cathode and electrochemical fuel combustion on the anode--are catalytic reactions. The fuels used in high-temperature fuel cells, for example, natural gas, propane, or liquid hydrocarbons, need to be preprocessed to a form suitable for conversion on the anode-sulfur removal and pre-reforming. The unconverted fuel (economic fuel utilization around 85%) is commonly combusted using a catalytic burner. Ceramic Fuel Cells Ltd. has developed anodes that in addition to having electrochemical activity also are reactive for internal steam reforming of methane. This can simplify fuel preprocessing, but its main advantage is thermal management of the fuel cell stack by endothermic heat removal. Using this approach, the objective of fuel preprocessing is to produce a methane-rich fuel stream but with all higher hydrocarbons removed. Sulfur removal can be achieved by absorption or hydro-desulfurization (HDS). Depending on the system configuration, hydrogen is also required for start-up and shutdown. Reactor operating parameters are strongly tied to fuel cell operational regimes, thus often limiting optimization of the catalytic reactors. In this paper we discuss operation of an authothermal reforming reactor for hydrogen generation for HDS and start-up/shutdown, and development of a pre-reformer for converting propane to a methane-rich fuel stream.     

Fire safety on fuel containers

Fire safety on fuel containers can be improved at its initial stage if flame spreading can be controlled. Therefore, the understanding of the fundamental processes that control flame spreading will help us to determine a few control parameters that could be useful to improve security in fuel deposits. A series of experiments have been conducted in different fuel containers that helped to understand the basic mechanisms involved. A new phenomenon of convection ahead of the flame is observed in liquid fuels that do not appear in solid fuels. Finally, two control factors have been found useful to control fire spread: the initial fuel surface temperature and the convection zone observed in front of the flame. The first experimental results observed controlling these two factors led flame to spreading velocities of order 1 cm s^–1 and, in some cases, flame extinguishes.     

A new modified low-energy emulsification method for preparation of water-in-diesel fuel nanoemulsion as alternative fuel

In this research, 24 of water-in-diesel fuel nanoemulsions were prepared using mixed nonionic surfactants of sorbitan monooleate and polyoxyethylene sorbitan trioleate (MTS). The emulsions were formed using a new modified low-energy method at hydrophilic-lipophilic balance (HLB) value of 10 and a working temperature of 20°C. Five HLB values of 9.6, 9.8, 10, 10.2, and 10.4 were prepared to identify the optimum value that gives low water droplet size at working conditions as: 5 wt% of water contents, 10 wt% of mixed surfactant concentration, and a temperature of 20°C. The effect of mixed surfactant concentration and water content on the droplet size for 0, 15, 30, 60, and 90 days has been studied. Droplet size of the prepared nanoemulsions was determined by dynamic light scattering and the nanoemulsion stability was assessed by measuring the variation of the droplet size as a function of time. Results show that the mean droplet sizes were formed between 26.23 and 277.1 nm depending on the surfactant concentrations, water contents, and storage time.     

A membrane electrode assembly with high fuel coulombic efficiency for passive direct borohydride fuel cells

Here, we report the development of a new membrane electrode assembly (MEA) structure for passive direct borohydride fuel cells (DBFCs). The anode of this type of MEA includes upper and lower parts for the electro-oxidation of borohydride and hydrogen, respectively. In comparison to conventional MEAs, the maximum power of this MEA is increased by 28.1%, and the anode polarization is decreased due to the current contribution of hydrogen electro-oxidation. The hydrogen generated from borohydride hydrolysis can be oxidized inside the cell, and the fuel coulombic efficiency reaches 100%. Therefore, high fuel utilization and cell safety can be obtained by employing this novel MEA in DBFCs.     

Prospects of low-temperature platinum-free fuel cells

Results of research on the development of platinum-free cathode PdM (M = Co or Fe) and anode catalysts PdM (M = Ru, Mo, Au) and RuM (M = Co, Ni, Fe), deposited onto disperse carbon material, are presented. The developed catalysts are shown to be practically feasible for membrane electrode assemblies for low-temperature hydrogen-air and ethanol-air fuel cells. A platinum-free alkaline ethanol-air fuel cell is first developed.     

Proton-exchange membranes for hydrogen-air fuel cells

The review is devoted to recent advances in the development of polymer electrolytes for low-temperature (operating temperatures ～80°C) and medium-temperature (operating temperatures 160–180°C) fuel cells. At present the most used are perfluorinated polymer membranes, such as Nafion®, Aciplex®, Flemon®, and Dow®, owing to their high chemical stability and proton conductance, as well as good machinability. However, successful commercialization of fuel cells with such membranes is prevented by their high cost, as well as low proton conductance at low humidities and temperatures above 100°C. Much effort is underway to develop membranes alternative to perfluorinated ones, with emphasis on aromatic hydrocarbon polymers.