Thermal power plants will be a promising power source even in the 2050s, because they can generate a vast amount of electricity with low cost, high reliability, and stability. The plants will also have strong flexibility and controllability to compensate the gap between power demand and supply with coexistence of a certain amount of unstable renewable power sources. Coal, oil, and liquefied natural gas (LNG) are mainly used for thermal power generation in the electricity business and are evenly mixed because of energy security, the so-called best mix. After the Great East Japan Earthquake, thermal power generation of all electric companies drastically increased by 164 TWh (+33.9 %), to compensate their nuclear power generation. Japan now has world-class, excellent thermal power technologies with heavyduty steam turbines under the ultra-supercritical (USC) steam condition and highefficiency 1600 AC class LNG-fired gas turbines. By 2030, if technical development projects of “advanced USC” and 1700 AC class gas turbines are completed successfully, 46 and 57% net thermal efficiencies at the sending end (higher heating value, HHV) will be achieved in commercial power plants, respectively. By 2050, the integrated coal gasification fuel cell combined cycle (IGFC) is expected to appear, and CO2 capture and storage (CCS) will move forward with full-scale implementation. However, introduction costs of these cutting-edge technologies are uncertain, and another technology for mitigation of operating restriction or life extension of aging plants may be preferable, depending on the situation after unbundling and electricity market liberalization by the “Electricity System Reform” in a few years.

In Tanegashima, the sugar mill, which is the main industry recycles sugarcane bagasse as a fuel but concurrently generates the massive amounts of unused heat at 200℃. Raw sugar is shipped to a sugar-refinery in Osaka where the sugar products are produced. The sugar-refinery uses a city gas boiler to generate a massive quantity of heat at 150℃ for refining. In order to resolve this spatial and temporal mismatch, we propose the application of chemical heat storage. Steam adsorption and desorption cycle of zeolite was employed in this work. Process flow diagram of the sugar mill was developed and potential heat storage capacity, the transport capacity for zeolite and reduction rates of city gas consumption at Osaka were calculated. From the results, it was revealed that the transport capacity for zeolite was restricting factor in the heat storage and transport system. In fact, heat storage capacity depends on desorption amount and regeneration rates, so potential heat storage capacity, the transport capacity for zeolite and fuel reduction rates at Osaka were recalculated using the results of the adsorption/regeneration tests.

Japanese iron and steel manufacturing industries import a significant amount expensive coking coal (coke); reduction of coke consumption is a great challenge for the industry. In this paper, we propose an in-plant CO recycling system which supplements coke with gaseous CO as a reducing agent in the blast furnace. Process flow diagrams including a blast furnace with CO recycling, coke oven, and hot blast stove were built in Aspen Plus and the effect of CO recycling on coal conservation, exergy efficiency, and CO_2 emission were quantitatively evaluated. In the blast furnace the input exergy, effective exergy ratio, overall CO_2 emissions, and the input coke decreased as the degree of CO circulation was increased. The recirculated CO gas was separated from the Blast Furnace Gas (BFG), the coke oven gas, and the converter gas. The separation and recycling of CO into the blast furnace resulted in the decrease of input coke, and input exergy by 13.0% and 10.3%, respectively. On the other hand, overall CO_2 emissions increased by 2.6%

The use of the Active Carbon Recycling Energy System in ironmaking (iACRES) has been proposed for reducing CO2 emissions. To evaluate the performance of iACRES quantitatively, a process flow diagram of a blast furnace model with iACRES was developed using Aspen Plus, a chemical process simulator. The CO2 emission reduction and exergy analysis was predicted by using the mass and energy balance obtained from the simulation results. iACRES used a solid oxide electrolysis cell (SOEC) with CO2 capture and separation (CCS), an SOEC without CCS, and a reverse water-gas shift reactor as the CO2 reduction reactor powered by a high-temperature gas-cooled reactor. iACRES could provide a CO2 emission reduction of 3-11 % by recycling carbon monoxide and hydrogen, whereas the effective exergy ratio decreased in all cases.

Reducing coking coal consumption and CO2 emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO2 electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H-2 produced by iodine-sulfur process. Both reduction of the coking coal consumption and CO2 emissions were greater in the RWGS system than those in the SOEC system. It was the reason of the result that excess H-2 not consumed in the RWGS reaction was used as reducing agent in the blast furnace as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H-2 production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO2 emissions more efficiently by comparing CO2 emissions reduction per unit heat of the HTGR.

Reducing coking coal consumption and CO2 emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO2 electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H-2 produced by iodine-sulfur process. Both reduction of the coking coal consumption and CO2 emissions were greater in the RWGS system than those in the SOEC system. It was the reason of the result that excess H-2 not consumed in the RWGS reaction was used as reducing agent in the blast furnace as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H-2 production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO2 emissions more efficiently by comparing CO2 emissions reduction per unit heat of the HTGR.

The use of the Active Carbon Recycling Energy System in ironmaking (iACRES) has been proposed for reducing CO2 emissions. To evaluate the performance of iACRES quantitatively, a process flow diagram of a blast furnace model with iACRES was developed using Aspen Plus, a chemical process simulator. The CO2 emission reduction and exergy analysis was predicted by using the mass and energy balance obtained from the simulation results. iACRES used a solid oxide electrolysis cell (SOEC) with CO2 capture and separation (CCS), an SOEC without CCS, and a reverse water-gas shift reactor as the CO2 reduction reactor powered by a high-temperature gas-cooled reactor. iACRES could provide a CO2 emission reduction of 3-11 % by recycling carbon monoxide and hydrogen, whereas the effective exergy ratio decreased in all cases.

It has been an important target to realize a sustainable energy usage in the future, regardless of the country. Japan is now compelled to consider a new paradigm of energy policy due to the nuclear power plant failures after March 11, 2011. To discuss the ideal or a favorable future of Japan's energy, understanding the present status as well as the available energy options in the future will be an initial step, followed by discussion of the issues related to each option. The aim of this article is to summarize the present status of Japan's energy systems and to clarify the major points of discussions for the realization of future sustainable energy systems. In addition, the major options of both energy supply and demand sides are summarized. The issues for realizing the future energy systems are discussed from the large-scale penetration of renewable systems, the demand side energy management and savings, the mobility, and the centralized electricity grid viewpoints, to provide a common basis for the discussion of future energy systems in Japan.

Lithium ortho-silicate (Li4SiO4) is a suitable solid sorbent for capturing CO2 from solid oxide fuel cells. CO2 absorption reactors packed with porous-solid spherical pellets of Li4SiO4 show unsteady temperature distribution and capture ratio behavior owing to the unsteady CO2 absorption rate and highly exothermic process. The CO2 absorption rate of this sorbent reportedly depends on temperature, CO2 concentration, and CO2 accumulation, expressed as the weight change of the sorbent. Nevertheless, discussions of detailed mechanisms of CO2 absorption by this sorbent are rare. In this study, the modified unreacted core model is proposed to explain the mechanism of CO2 absorption of a porous-solid spherical pellet, and numerical analysis was conducted to simulate the unsteady behavior of the sorbent. Important properties such as the reaction rate constant, the gas film mass transfer coefficient, and the coefficient for effective diffusion through the product layers were empirically derived using thermogravimetry and a diluted packed-bed reactor. Numerical analysis by applying these parameters to the modified unreacted core model adequately explained the complicated CO2 absorption and regeneration behaviors.

It has been an important target to realize a sustainable energy usage in the future, regardless of the country. Japan is now compelled to consider a new paradigm of energy policy due to the nuclear power plant failures after March 11, 2011. To discuss the ideal or a favorable future of Japan's energy, understanding the present status as well as the available energy options in the future will be an initial step, followed by discussion of the issues related to each option. The aim of this article is to summarize the present status of Japan's energy systems and to clarify the major points of discussions for the realization of future sustainable energy systems. In addition, the major options of both energy supply and demand sides are summarized. The issues for realizing the future energy systems are discussed from the large-scale penetration of renewable systems, the demand side energy management and savings, the mobility, and the centralized electricity grid viewpoints, to provide a common basis for the discussion of future energy systems in Japan.

Lithium ortho-silicate (Li4SiO4) is a suitable solid sorbent for capturing CO2 from solid oxide fuel cells. CO2 absorption reactors packed with porous-solid spherical pellets of Li4SiO4 show unsteady temperature distribution and capture ratio behavior owing to the unsteady CO2 absorption rate and highly exothermic process. The CO2 absorption rate of this sorbent reportedly depends on temperature, CO2 concentration, and CO2 accumulation, expressed as the weight change of the sorbent. Nevertheless, discussions of detailed mechanisms of CO2 absorption by this sorbent are rare. In this study, the modified unreacted core model is proposed to explain the mechanism of CO2 absorption of a porous-solid spherical pellet, and numerical analysis was conducted to simulate the unsteady behavior of the sorbent. Important properties such as the reaction rate constant, the gas film mass transfer coefficient, and the coefficient for effective diffusion through the product layers were empirically derived using thermogravimetry and a diluted packed-bed reactor. Numerical analysis by applying these parameters to the modified unreacted core model adequately explained the complicated CO2 absorption and regeneration behaviors.

This article has no abstract.

Electrochemical partial oxidation (EPOx) of methane can convert exhaust heat into electricity as much as difference between change of Gibbs free energy and change of enthalpy. To quantify recuperated heat and converted electric power of EPOx, we simulated the performance of EPOx in the microtubular Solid Oxide Fuel Cell (SOFC) using Gadolinium Doped Ceria as electrolyte. The quasi-two dimensional and non-isothermal model applied to this SOFC simulation, which consisted of three solid layers and two gas layers, considering with mass, energy and chemical species conservation equations as well as detailed electrochemical reaction. The simulation computed temperature and current density distributions, and evaluated energy flow in SOFC. The simulation code was validated by consistency between the simulation result of power generation using H2 as fuel and the result of previous experimental report. The results showed that EPOx could convert 40% of theoretically recuperated heat into the electric power at the operation condition maximizing total regenerated heat. © 2013 The Japan Society of Mechanical Engineers.

The cost of PEFC (Polymer Electrolyte Fuel Cell) vehicle should be reduced to spread widely, and to realize cost reduction, high current density operation under the condition of high temperature and low humidification is required. It is important for reduction of ohmic loss at the severe operating conditions to evaluate properly electron transport phenomena derived electric resistance of cell components such as GDL (Gas Diffusion Layer). This research approached to explain difference in electrical resistances among commercially available GDLs made of fabricated carbon fibers from both macroscopic and microscopic viewpoints, which are bulk density of GDLs and graphitization of carbon fibers and binders measured by Raman spectroscopy. The results of measurements indicated that electrical resistivity significantly correlated with both characteristics.

Decreasing the contact resistance between components with high sensitivity of the contact pressure in the Polymer Electrolyte Fuel Cell improves the cell performance accompanied with the complex interaction between the transport phenomenon of heat, reactants and electrons, especially, under the high current density operation of Fuel Cell Vehicles. This work aims to establish the method of measuring pressure distribution in the cell by quantifying the discoloration level of irreversible temperature-sensitive paint which also has pressure sensitivity. Three paint samples, which discolor at 95, 100 and 105 °C, were prepared in uniform thickness and pressurized during the fixed time under the condition of constant temperature and humidity. The discoloration level was quantified with the peak value of the brightness spectrum which is obtained by image processing of the sample picture of the microscope. A linear correlation between pressure and discoloration level was obtained in some paints, and at 70°C and relative humidity of 70 %, one of paints could quantify pressure range from 0.5 to 2.5 MPa and one of the other paints could quantify the lower pressure range.

This article discusses the directions for energy systems based on an urgent proposal to counter the energy crisis in eastern Japan, published from the Society of Chemical Engineers, Japan. We first illustrate the situation Japan faces, highlighting the urgency and seriousness of the consequences of power outages in industry and daily life. Then, we elaborate on the necessity for policy support to trigger collective actions to temporarily practice countermeasures that would not necessarily save resources or that could disrupt society's established routines. In this way, Japan can choose technologies without regret based on society-wide discussions on the future energy supply. Finally, we warn of the drawbacks induced by shortsighted decisions e. g., avoiding power outages by depending on less-efficient gas turbines. We conclude that Japan should commence a transition of its energy systems rather than compromising resource efficiency and grid robustness over the next decades.

Electrochemical partial oxidation (EPOx) of methane can convert exhaust heat into electricity as much as difference between change of Gibbs free energy and change of enthalpy. In this paper, we considered 30kW power generation system combined Micro Gas Turbine and the Partial Oxdation Solid Oxide Fuel Cell using Gadolinium Doped Ceria as the electrolyte that has high oxide ion conductivity below 600℃. The cylindrical-shaped POSOFC is operated at 572℃ recovering turbine exhaust heat of 593℃ and accompanying production of hydrogen and carbon monoxide. According to the result of process simulation coupling with SOFC simulation including detailed polarization models, only addition of 16 liter POSOFC can increases the power generation efficiency by 8.5 points at fuel utilization of 80.1%.

The pressure losses at manifold junctions in a molten carbonate fuel cell (MCFC) stack depend on the stacking positions of the cells and the flow rate in the manifold. These pressure losses affect the uniformity of gas flow rate in each stacked cell and consequently also affect the cell performance. In this study, the pressure losses at dividing and combining junctions in a plate heat-exchanger type MCFC stack were examined by numerical analysis. A stack consisting of 100 cells was assumed, and the junction pressure losses at various stacking positions of cells were calculated under various flow rate conditions ranging from the minimum possible flow rate (80% utilization of fuel gas) to the maximum possible flow rate (10% utilization of oxidant gas). The results were arranged according to the equations for loss coefficients, and were compared with the experimental results of previous studies. (C) 2001 Elsevier Science B.V. All rights reserved.

The purpose of the present work is to establish the design method of methanol steam. reformer for application to chemical recuperation in a gas turbine system. The reaction rate of the methanol steam-reforming was measured with a small amount of catalyst using the gaseous mixture of methanol, water, hydrogen, and carbon dioxide as a simulated product gas. The reaction rate equation could be expressed by power law of methanol m the catalyst-packed bed mole fraction and total pressure. The reaction and heat transfer was analyzed numerically using the reaction rate equation. The analytical results of temperature distribution and conversion were compared with the experimental results using a reforming tube, These results agreed well except for the region of high methanol conversion.

An investigation is made of the relationships between the gas channel height, the gas-flow characteristics, and the gas-diffusion characteristics in a plate heat-exchanger type molten carbonate fuel cell stack. Effects of the gas channel height on the uniformity and pressure loss of the gas flow are evaluated by numerical analysis using a computational fluid dynamics code. The effects of the gas channel height on the distribution of the reactive gas concentration in the direction perpendicular to the channel flow are evaluated by an analytical solution of the two-dimensional concentration transport equation. Considering the results for uniformity and pressure loss of the gas flow, and for distribution of the reactive gas concentration, the appropriate gas channel height in the molten carbonate fuel cell stack is investigated. (C) 1999 Elsevier Science S.A. All rights reserved.

Molten carbonate fuel cells (MCFCs) are expected to be large-scale, highly efficient energy sources in the future. A reactant gas seal is one of the critical issues in achievement of reliability of the MCFC stack, which is a key piece of equipment in an MCFC power plant. At present, the wet gas seal with carbonate molten at the operating temperature (650℃) is generally considered to be suitable as such a seal. On the other hand, to be cost-competitive with existing power plants, the MCFC stack must consist almost entirely of thin sheet metal parts. In this report, a wet gas seal configuration composed of thin sheet metal parts is proposed. Then, the long-term performance of the wet gas seal in an actual MCFC is evaluated.