209 research outputs found
Gas-fired wind power and electric hydrogen
No full textIn the seemingly endless discussions about the pros and cons of wind power even its advocates have to agree that though wind can fly, with offshore wind farms soon to become reality, this only exacerbates the problem of the winds changeability. Even now the major producers of electricity and power grid companies foresee grave difficulties from the peaks and dips in supply of this green power source. Dr Kas Hemmes of the faculty of Systems Engineering, Policy Analysis, and Management at TU Delft has managed to adapt wind power for use in the current power grid system by combining a fuel cell with a wind turbine, and by better use of the heat released by a fuel cell. Wind turbines will be producing hydrogen after all, albeit mainly from natural gas.Technology, Policy and Managemen
Comparison of the solid oxide fuel cell system for micro CHP using natural gas with a system using a mixture of natural gas and hydrogen
No full textSolid oxide fuel cell systems for combined heat and power production (SOFC μCHP) fueled by natural gas are attractive because of their high electrical and total efficiency even at small scale. The development of a hydrogen economy will increase the availability of distributed hydrogen as a pure gas. Alternatively, hydrogen may be blended with natural gas in the grid. This study investigates the performance of SOFC μCHP systems, while using a fuel varying from pure hydrogen to pure methane via mixtures of hydrogen and methane called Hythane. Flowsheet models of external as well as internal reforming fuel cell systems were developed in Cycle-Tempo simulation software. Results show that both the external as well as the internal reforming system can operated on all fuel gas compositions varying from pure hydrogen to pure methane, thus allowing for a transition towards a hydrogen economy via the mixing of hydrogen into the natural gas grid. Although the natural gas based systems have a higher electrical efficiency, the introduction of hydrogen into the gas leads to a higher total efficiency of the combined heat and power system. The addition of hydrogen into the fuel minimizes the problems of thermal stress and thermal shock associated with the use of methane in internal reforming fuel cell systems. The internal reforming system showed a higher performance compared to the external reforming system for all Hythane gas mixtures in terms of not only electrical efficiency but also in terms of thermal and total efficiency.Economics of Technology and Innovatio
Coproduction with Molten Carbonate Fuel Cells: Exploring the feasibility of coproducing hydrogen and electricity from internal reforming molten carbonate fuel cells
No full textThe concept of coproduction has been explored in combined heat and power applications. It is a method of improving the efficiency of the energy generating system by utilising waste heat. In the coming years hydrogen is expected to play an important role in decarbonization as it does not emit greenhouse gas at the point of application. Hydrogen today is primarily generated from fossil fuels and the processes of producing hydrogen are energy intensive, while also emitting large quantities of greenhouse gases into the atmosphere. As the amount of hydrogen generated today is limited, it has restricted the growth of industries such as the automobile industries producing fuel cell vehicles that are to use hydrogen as fuel. In this thesis report a coproduction concept using high temperature molten carbonate fuel cell has been examined. The molten carbonate fuel cells operate at very high temperature, and it is possible to utilise the waste heat for internal reforming reaction of a fuel such as natural gas to liberate hydrogen required by the fuel cell. Excess hydrogen can also be produced from such fuel cell systems when the fuel utilisation in the fuel cell is reduced. This concept has been studied with solid oxide fuel cells and a paper published in 2008 by Hemmes et al. titled "Flexible Coproduction of Hydrogen and Power Using Internal Reforming Solid Oxide Fuel Cells System" has served as the inspiration for this thesis report. Three modes of operations have been simulated in this thesis on the Cycle-Tempo software with varying fuel utilisations, similar to what has been shown with the solid oxide fuel cells in that paper. With molten carbonate fuel cells, overall efficiency of up to 80% was obtained in terms of electricity and hydrogen coproduction. By doing so it is also possible to produce overall power output of nearly three times than what can be achieved by conventional electricity production. The results obtained have also been compared with the solid oxide fuel cells in this report. While high coproduction efficiencies for flexibly coproducing hydrogen and power have been shown to be possible, other factors would also play important roles in the success of this technology. In this report some of those factors such as the status and expected growth of the hydrogen market, molten carbonate fuel cell market, role of actors, role of policy makers have also been examined. As this technology does rely on a fossil fuel that is natural gas, the benefits of using natural gas in hydrogen production has also been highlighted along with the positive effects these systems could have on the society
Binding of small interfering RNA molecules is crucial for RNA interference suppressor activity of rice hoja blanca virus NS3 in plants
No full textThe NS3 protein of rice hoja blanca tenuivirus represents a viral suppressor of RNAi that sequesters small interfering (si)RNAs in vitro. To determine whether this siRNA binding property is the critical determinant for the suppressor activity of NS3, an alanine point mutational analysis was performed and the resulting mutant proteins were tested for both siRNA binding ability and RNAi suppressor activity in plants. Alanine substitutions of lysine residues at position 173-175 resulted in mutant proteins that lost both their affinity for siRNAs and their RNAi suppressor activity in planta. This indicates that siRNA binding of NS3 is indeed essential for the suppressor function of NS3 and that residues at position 173-175 are involved in the siRNA binding and suppressor activit
Integrating Wind And Solar With Hydrogen Producing Fuel Cells
No full textThe often proposed solution for the fluctuating wind energy supply is the conversion of the surplus of wind energy into hydrogen by means of electrolysis. In this paper a patented alternative is proposed consisting of the integration of wind turbines with internal reforming fuel-cells, capable of co- producing hydrogen and electricity from natural gas. Storage of hydrogen is not absolutely necessary, since the naturally available energy storage capacity of the gas field is effectively used. The flexibility of a fuel cell to vary electric output and/or simultanuously produce hydrogen from natural gas can be used very beneficial in an integrated windturbine fuel cell configuration. Flowsheet calculations have shown that the change in hydrogen output can be three times or more than the increase in electric input from wind energy at constant natural gas input and constant total electric power output, resulting in an apparent conversion efficiency of more than 300%.Values and TechnologyTechnology, Policy and Managemen
Method for the integrated operation of a fuel cell and an air separator
No full textThe invention relates to a system and method for integrating renewable energy and a fuel cell for the production of electricity and hydrogen, wherein this comprises the use of renewable energy as fluctuating energy source for the production of electricity and also comprises the use of at least one fuel cell, and wherein a control unit controls the operation of the at least one fuel cell such that the total production of electricity lies within chosen limitsCivil Engineering and Geoscience
Method for the production of nitrogen and hydrogen in a fuel cell
No full textThe invention relates to a method for the production of nitrogen and hydrogen in a fuel cell with an anode and a cathode, comprising the steps of inducing a combustion in a fuel cell, wherein a fuel is supplied to the anode, and air is supplied to the cathode, and with oxygen in the air being reduced. According to the invention, nitrogen from the cathodic gas stream is supplied to a natural gas stream whose calorific value and Wobbe Index are higher than a standard calorific value, so as to reduce the calorific value to the standard calorific value.Civil Engineering and Geoscience
System and method for integration of renewable energy and fuel cell for the production of electricity and hydrogen
No full textThe invention relates to a system and method for integrating renewable energy and a fuel cell for the production of electricity and hydrogen, wherein this comprises the use of renewable energy as fluctuating energy source for the production of electricity and also comprises the use of at least one fuel cell, and wherein a control unit controls the operation of the at least one fuel cell such that the total production of electricity lies within chosen limitsCivil Engineering and Geoscience
A personal retrospect on three decades of high temperature fuel cell research: ideas and lessons learned
No full textIn 1986 the Dutch national fuel cell program started. Fuel cells were developed under the paradigm of replacing conventional technology. Coal-fired power plants were to be replaced by large-scale MCFC power plants fuelled by hydrogen in a full-scale future hydrogen economy. With today's knowledge we will reflect on these and other ideas with respect to high temperature fuel cell development including the choice for the type of high temperature fuel cell. It is explained that based on thermodynamics proton conducting fuel cells would have been a better choice and the direct carbon fuel cell even more so, with electrochemical gasification of carbon as the ultimate step. The specific characteristics of fuel cells and multisource multiproduct systems were not considered, whereas we understand now that these can provide huge driving forces for the implementation of fuel cells compared to just replacing conventional combined heat and power production technology.Economics of Technology and Innovatio
Method of converting a carbon-comprising material, method of operating a fuel cell stack, and a fuel cell
No full textThe invention relates to a method of converting a carbon-comprising material at elevated temperature in the presence of a molecule that comprises at least one oxygen atom. According to the invention the carbon-comprising material in the fuel cell is converted substantially to carbon monoxide in a reaction with a negative enthalpy ( DELTA H) and a positive entropy change ( DELTA S), heat is supplied to the fuel cell, and at least one of the contributing reactions resulting in the formation of carbon monoxide is an electrochemical reaction producing electricity. This is a more efficient method of converting heat into electricity and at the same time converting the enthalpy of the gasification reaction into electricity.Civil Engineering and Geoscience
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