A reforming system for co-generation of hydrogen and mechanical work from methanol

The paper describes a reforming system for converting methanol into pure hydrogen. The system is based on an autothermal reforming reactor operating at elevated pressures followed by membrane-based hydrogen separation. The high-pressure membrane retentate stream is combusted and expanded through a turbine generating additional power. Process simulation illustrates the effects of the system operating parameters on performance and demonstrates system reforming efficiency up to ∼90%. When coupled with a PEM fuel cell and an electrical generator, overall fuel to electricity efficiency can be >48% depending upon the efficiency of a PEM fuel cell stack.     

Evaluation of a wind energy based system for co-generation of hydrogen and methanol production

A novel idea of wind energy based methanol and hydrogen production is proposed in this study. The proposed system utilizes the industrial carbon emissions to produce a useful output of methanol. There are several pros of manufacturing the methanol as it has the capability to be employed as conventional automotive fuel as it carries the advantages of efficient performance, low emissions and low flammability risk. The designed system comprises of the major subsystems of wind turbines, proton exchange membrane fuel cell (PEMFC), methanol production system and distillation unit. The Engineering Equation Solver (EES) and Aspen Plus are utilized for system modeling and comprehensive analysis. The proposed system is also investigated to operate under different wind speeds and different wind turbine efficiencies. The proposed integration covers all the electric power required by the system. The industrial flue gas including CO₂ reacts with hydrogen to produce methanol. The designed system produces both methanol and hydrogen simultaneously. For the performance indicator, efficiencies of the overall system are calculated. The exergetic efficiency is found to be 38.2% while energetic efficiency is determined to be 39.8%. Furthermore, some parametric studies are conducted to investigate the distillation column performance, methanol and hydrogen capacities and exergy destruction rates.     

Performance investigation of an integrated wind energy system for co-generation of power and hydrogen

In this paper, a wind turbine energy system is integrated with a hydrogen fuel cell and proton exchange membrane electrolyzer to provide electricity and heat to a community of households. Different cases for varying wind speeds are taken into consideration. Wind turbines meet the electricity demand when there is sufficient wind speed available. During high wind speeds, the excess electricity generated is supplied to the electrolyzer to produce hydrogen which is stored in a storage tank. It is later utilized in the fuel cell to provide electricity during periods of low wind speeds to overcome the shortage of electricity supply. The fuel cell operates during high demand conditions and provides electricity and heat for the residential application. The overall efficiency of the system is calculated at different wind speeds. The overall energy and exergy efficiencies at a wind speed 5 m/s are then found to be 20.2% and 21.2% respectively.     

Performance of hydrogen and power co-generation system based on chemical looping hydrogen generation of coal

An integrated hydrogen and power co-generation system based on slurry-feed coal gasification and chemical looping hydrogen generation (CLH) was proposed with Shenhua coal as fuel and Fe₂O₃/MgAl₂O₄ as an oxygen carrier. The sensitivity analyses of the main units of the system were carried out respectively to optimize the parameters. The syngas can be converted completely in the fuel reactor, and both of the fuel reactor and steam reactor can maintain heat balance. The purity of hydrogen produced after water condensation is 100%. The energy and exergy analyses of the proposed system were studied. Pinch technology was adopted to get a reasonable design of the heat transfer network, and it is found pinch point appears at the hot side temperature of 224.7 °C. At the given status of the proposed system, the hydrogen yield is 1040.11 kg·h⁻¹ and the CO₂ capture rate is 94.56%. At the same time, its energy and exergy efficiencies are 46.21% and 47.22%, respectively. According to exergy analysis, the degree of exergy destruction is ranked. The gasifier unit has the most serious exergy destruction, followed by chemical looping hydrogen generation unit and the heat recovery steam generator unit.     

Evaluation of syngas-based chemical looping applications for hydrogen and power co-generation with CCS

This paper evaluates hydrogen and power co-generation based on coal-gasification fitted with an iron-based chemical looping system for carbon capture and storage (CCS). The paper assess in details the whole hydrogen and power co-production chain based on coal gasification. Investigated plant concepts of syngas-based chemical looping generate about 350–450 MW net electricity with a flexible output of 0–200 MW_th hydrogen (based on lower heating value) with an almost total decarbonisation rate of the coal used.     

Investigation of hydrogen and power co-generation based on direct coal chemical looping systems

This paper evaluates hydrogen and power co-generation based on direct coal chemical looping systems with total decarbonization of the fossil fuel. As an illustrative example, an iron-based chemical looping system was assessed in various plant configurations. The designs generate 300–450 MW net electricity with flexible hydrogen output in the range of 0–200 MW_th (LHV). The capacity of evaluated plant concepts to have a flexible hydrogen output is an important aspect for integration in modern energy conversion systems. The carbon capture rate of evaluated concepts is almost total (>99%). The paper presents in details evaluated plant configurations, operational aspects as well as mass and energy integration issues. For comparison reason, a syngas-based chemical looping concept and Selexol^®-based pre-combustion capture configuration were also presented. Direct coal chemical looping configuration has significant advantages compared with syngas-based looping systems as well as solvent-based carbon capture configurations, the more important being higher energy efficiency, lower (or even zero) oxygen consumption and lower plant complexity. The results showed a clear increase of overall energy efficiency in comparison to the benchmark cases.     

小型热电联产蒸汽供热系统的能耗分析

目前,有些小型热电联产系统运行不合理、冷源损失大、节能效果不理想.通过对某小型热电联产系统全年运行状况的凋查,计算了热电机组的发电效率、热效率及汽机冷源能量损失,分析了小型热电联产系统能耗大的主要原因,提出了提高热电联产系统能源利用效率、改进热电联产集中供热形式等措施,为热电联产系统改造和扩建工作提供参考.     

A computer-aided planning (CAP) system for the gas engine co-generation plant

The objective of this study is to develop a computer-aided optimal planning (CAP) system for the initial design of the cogeneration plant composed of combining a gas engine-driven generator, electric and gas refrigerators, gas engine- and electric-driven heat pumps, gas boiler, single effect refrigerator, heat exchanger, etc. In the CAP system, it is first necessary to effectively determine the energy demand categorized by electric power, space heating and cooling, and hot water supply, together with the configuration of the plant's equipment and the tariff of fuel by utilizing the man-machine interactive ability of a personal computer. Then to calculate the optimal operation of the co-generation plant; the load allocation problem is investigated based on the mixed-integer linear programming method by adopting zero-one integer variables indicating the on/off status of operation, together with continuous variables indicating the operational level of each equipment. By using the branch and bound algorithm, the optimal operational policy is determined by a large computer. Lastly, the economical comparison of some alternative plants is made based on the annual cost method obtained on the above results.     

CO2-promoted hydrolysis of KBH4 for efficient hydrogen co-generation

Hydrolysis of metal borohydrides in the presence of CO₂ has not been studied so far, although carbon dioxide contained in air is known to accelerate hydrogen generation. KBH₄ hydrolysis promoted by CO₂ gas put through an aqueous solution was studied by time-resolved ATR-FTIR spectroscopy, showing a transformation of BH₄⁻ into B₄O₅(OH)₄²⁻, and a drastically accelerated hydrogen production which can be completed within minutes. This process can be used to produce hydrogen on-board from exhaust gases (CO₂ and H₂O). We found a new intermediate, K₉[B₄O₅(OH)₄]₃(CO₃)(BH₄)·7H₂O, forming upon hydrolysis on air via a slow adsorption of the atmospheric CO₂. The same intermediate can be crystallized from partly hydrolyzed solutions of KBH₄ + CO₂, but not from the fully reacted sample saturated with CO₂. This phase was studied by single-crystal and powder X-ray diffraction, DSC, TGA, Raman, IR and elemental analysis, all data are fully consistent with the presence of the three different anions and of the crystallized water molecules. Its crystal structure is hexagonal, space group P-62c, with lattice parameters a = 11.2551(4), c = 17.1508(8) Å. Formation of the intermediate produces 16 mol of H₂ per mole of adsorbed CO₂ and thus is very efficient both gravimetrically and volumetrically. It allows also for an elimination of carbon dioxide from exhaust gases.     

Reforming catalysts for hydrogen generation in fuel cell applications

The objective of this review paper is to present a summary of the specific contributions in the field of fuel processing, particularly, outlines various developments involving catalytic reforming of a range of fuels for the development of an efficient fuel-processing unit for syngas production in fuel cell applications. Two major topics are discussed (i) the basic reactions involved in each of the processes and (ii) various catalyst systems that have been tested. A final short section offers some new possible routes for future research.     

HAT循环构成热电冷三联产总能系统的可行性分析

对国内外在提高能源利用率方面的研究现状和发展趋势进行了综述，在前人研究的基础上提出以湿空气透平湿空气透平（HAT）循环构成热、电、冷三联产总能系统的能量利用形式，详细分析了构成该系统的相关技术、可行性及需要加以解决的几个问题。     

Catalyst-free low temperature conversion of n-dodecane for co-generation of COx-free hydrogen and C2 hydrocarbons using a gliding arc plasma

In this study, plasma reforming of n-dodecane for the co-generation of CO_x-free hydrogen and C₂ hydrocarbons at low temperature and ambient pressure has been investigated in a gliding arc discharge (GAD) reactor. The selective synthesis of H₂, C₂H₂ and C₂H₄ and the energy efficiency for n-dodecane conversion can be tuned by changing different processing parameters including the gas flow rate, n-dodecane concentration and input voltage. The highest selectivities of H₂ (76.7%), C₂H₂ (41.4%) and C₂H₄ (12.0%) were achieved with an n-dodecane conversion of 68.1%. The generation of mixed hydrogen, acetylene and ethylene offers the possibility for in-situ hydrogenation to enhance the selectivity of light olefins (e.g., ethylene) without prior gas separation. The plausible reaction mechanism and pathways in the plasma cracking of n-dodecane have been discussed through plasma emission spectroscopic diagnostics coupled with a comprehensive analysis of gas and liquid products. A strong correlation between the yield of C₂ hydrocarbons and the relative intensity of C₂ Swan bands was found, which suggests that C₂ Swan bands could be used as a valuable probe to understand the generation of C₂ hydrocarbons in the plasma reforming of hydrocarbon oils.     

Policy schemes,operational strategies and system integration of residential co-generation fuel cells

This study presents a holistic approach for the commercialisation of fuel cells for stationary applications. We focus our analyses on microCHP based on SOFC units fired with natural gas. We analyse the interaction of operational strategies under different ownership arrangements, required support levels and system integration aspects. The operational strategies, support mechanisms and ownership arrangements have been identified through actor analysis involving experts from Denmark, France and Portugal. With regard to operational strategies, the actor analyses led us to distinguishing between a heat-driven strategy, with and without time-differentiated tariffs, and an electricity price driven strategy for the operation as a virtual power plant. The corresponding support schemes identified cover feed-in tariffs, net metering and feed-in premiums. Additionally, the interplay of the microCHP units with the national energy systems has been analysed. Our main findings are that net metering would be an appropriate tool to support FC based microCHP in Denmark, whereas a price premium would be the preferable tool in France and Portugal.     

Reforming options for hydrogen production from fossil fuels for PEM fuel cells

PEM fuel cell systems are considered as a sustainable option for the future transport sector in the future. There is great interest in converting current hydrocarbon based transportation fuels into hydrogen rich gases acceptable by PEM fuel cells on-board of vehicles. In this paper, we compare the results of our simulation studies for 100 kW PEM fuel cell systems utilizing three different major reforming technologies, namely steam reforming (SREF), partial oxidation (POX) and autothermal reforming (ATR). Natural gas, gasoline and diesel are the selected hydrocarbon fuels. It is desired to investigate the effect of the selected fuel reforming options on the overall fuel cell system efficiency, which depends on the fuel processing, PEM fuel cell and auxiliary system efficiencies. The Aspen-HYSYS 3.1 code has been used for simulation purposes. Process parameters of fuel preparation steps have been determined considering the limitations set by the catalysts and hydrocarbons involved. Results indicate that fuel properties, fuel processing system and its operation parameters, and PEM fuel cell characteristics all affect the overall system efficiencies. Steam reforming appears as the most efficient fuel preparation option for all investigated fuels. Natural gas with steam reforming shows the highest fuel cell system efficiency. Good heat integration within the fuel cell system is absolutely necessary to achieve acceptable overall system efficiencies.     

Reforming of vegetable oil for production of hydrogen: A thermodynamic analysis

The vegetable oils are one of the promising renewable feedstock for production of hydrogen suitable for application in hydrogen based fuel cells for electrical power generation. In the present work, a thermodynamic equilibrium analysis of steam reforming (SR) and autothermal steam reforming (ATSR) of vegetable oils to synthesis gas was investigated by Gibbs free energy minimization method. The thermodynamic equilibrium analysis was performed considering the vegetable oils as a mixture of triglycerides containing three same fatty acid groups in the structure. The property method used for equilibrium analysis was first regressed using available physical and chemical properties of the considered triglycerides. The regressed property method was then used to calculate the equilibrium products composition. The effects of various parameters of SR of vegetable oils, temperature and steam-to-carbon ratio (SCR), on hydrogen yield and selectivity of CO and methane was studied in a broad range of temperature (573-1273 K) and SCRs (1-6). The optimum conditions for SR of vegetable oils were then determined for maximum hydrogen yield with very low selectivity of methane. The thermodynamic equilibrium analysis of ATSR of vegetable oils was then performed at different oxygen-to-carbon ratios and thermoneutral conditions were then determined for various operating conditions.     

Protonic membrane for fuel cell for co-generation of power and ethylene

Yttrium-doped barium cerate, BaCe_0.85Y_0.15O_3−α (BCY15), membranes are proton-conducting electrolytes for intermediate-temperature protonic ceramic fuel cells (IT-PCFC), useful for, among other processes, co-production of power and ethylene by dehydrogenation of ethane. BCY15 membranes showed good conductivity at intermediate temperatures, 15 and 20 mS cm⁻¹ at 700 and 750 °C, respectively. Maximum power density was 174 mW cm⁻² at 700 °C, with a corresponding current density of 320 mA cm⁻², using a C₂H₆,Pt/BCY15/Pt,O₂ fuel cell, with a ca. 0.5 mm thick membrane, producing 34% ethane conversion with 96% ethylene selectivity Comparison of performances using vertical and horizontal set-ups showed that horizontal set-ups are subject to torsional strain, causing reduced cell performance resulting from even minor leakage at the glass seal.     

Biogas upgrading for on-board hydrogen production: Reforming process CFD modelling

Hydrogen production through fuel reforming can be used to improve IC (internal combustion) engines combustion characteristics and to lower vehicle emissions. In this study, a computational fluid dynamics (CFD) model based on a detailed kinetic mechanism was developed for exhaust gas reforming of biogas to synthetic gas (H₂ and CO). In agreement with experimental data, the reactor's physical and chemical performance was investigated at various O₂/CH₄ ratios and gas hourly space velocities (GHSV). The numerical results imply that methane reforming reactions are strongly sensitive to O₂/CH₄ ratio and engine exhaust gas temperature. It was also found that increasing GHSV results in lower hydrogen yield; since dry and steam reforming reactions are relatively slow and are both dependent on the flow residence time. Furthermore, the hot spot effect, which is associated to oxidation reforming reactions, was investigated for catalyst activity and durability.     

Thermalhydraulic analysis and heat transfer correlation for an intermediate heat exchanger linking a SuperCritical Water-cooled Reactor and a Copper-Chlorine cycle for hydrogen co-generation

This paper presents the development of a new heat-transfer correlation for the flow of SuperCritical Water (SCW) in bare circular tubes, and its applicability to thermalhydraulic analysis for Heat eXchanger (HX) designs, linking a SuperCritical Water-cooled nuclear Reactor (SCWR) and a Copper-Chlorine (Cu–Cl) cycle-based hydrogen co-generation facility.     

Techno-economic analysis of e-waste based chemical looping reformer as hydrogen generator with co-generation of metals,electricity and syngas

Chemical looping reforming (CLR) is an efficient technology to convert hydrocarbon fuels into CO₂ and H₂ using metal oxide based oxygen carriers. The novelty of the present study is to utilize electronic waste such as printed circuit board (PCB) to generate high quality syngas and metallic components for the CLR process. A portion of the syngas generated during e-waste pyrolysis is used with coal and polypropylene for effective combustion. A techno-economic analysis is performed for the production of hydrogen and electricity in the CLR method. The levelized costs for electricity (LCOE), hydrogen (LCOH), syngas (LCOS), and metal (LCOM) production using e-wastes are estimated as 92.28 $/MWh, 3.67 $/kg, 0.0034 $/kWh, and 24.32 $/ton, respectively. The LCOH is found to be the least of 2.90 $/kg under the co-feed conditions of PCB syngas-PP. The integration of the e-waste based CLR with a steam turbine system achieved a net efficiency of 50%.     

The effect of hydrogen on the mechanical properties of FeTi for hydrogen storage applications

In this paper, the density functional theory (DFT) within the generalized gradient approximation (GGA) was used. The single crystal elastic constants for the intermetallic FeTi and its hydrides FeTiH and FeTiH₂ are successfully obtained from the stress–strain relationship calculations and the strain energy-strain curves calculations, respectively. The shear modulus, Young's modulus, Poisson's ratio and shear anisotropic factors are also calculated. The bulk moduli derived from the elastic constants calculations of the cubic FeTi, orthorhombic P222₁ FeTiH and Cmmm FeTiH₂ are calculated. For cubic FeTi compound, the bulk modulus is in a good agreement with both theoretical results and experimental data available in the literature. More importantly, it is found that, the insertion of hydrogen into the FeTi crystal structure causes an increase in the bulk modulus. From the analysis of shear-to-bulk modulus ratio, it is found that FeTi compound and its hydrides are ductile and that this ductibility, changes with changing the concentration of hydrogen.