Hydrogen Energy

　Hydrogen is attracting attention as a clean secondary energy with a small environmental load. When hydrogen is combusted, only water and energy are generated but any harmful elements are not released. It is also expected as an effective storage method for surplus energy. There are several technologies to utilize hydrogen energy such as hyderogen engine and fuel cells. A hydrogen engine is a way to use hydrogen like gasoline. A fuel cell is a method to generate thermal energy and electrical energy by chemically reacting hydrogen and oxygen. By utilizing heat and electricity, high efficiency can be expected. There are various types of fuel cells such as solid polymer type and solid oxide type.
　In our laboratory, we have conducted "Study on fundamental transport phenomena in proton conductive solid oxides" and "Study on water vapor behavior in electrolyte membranes for polymer electrolyte fuel cells". Going back further, we have actively carried out researches relating to hydrogen utilization, such as "Heat pumps using hydrogen storage alloys" and "Hydrogen isotope separation using hydrides". Recently, we are working on research related to hydrogen production.
　
　　　　　　　　　　　　 Noriko Behling et al., Economic Analysis and policy, 48 (2015) 204-221.

Related research in our Lab.

• Advancement of hydrogen production by steam reforming method

　In a typical hydrogen production method, nickel is used as one of the catalysts in the steam reforming method. Nickel is known to have the property of allowing hydrogen to permeate relatively quickly, in addition to its catalytic properties. In the existing hydrogen production system, hydrogen production and separation are performed by another device. If the production and separation are performed at the same time by taking advantage of the properties of nickel, the reaction can be expected to be promoted by Le Chatelier's principle. However, the research from this point of view has not been sufficiently advanced. In this research, we are evaluating the effect of hydrogen permeation on the efficiency of hydrogen production as a whole, while proceeding with the accumulation of basic data such as the reaction characteristics of nickel catalysts and the hydrogen permeation characteristics of nickel plates.

• Hydrogen producton by plasma direct decomposition method

　We are conducting research and development on a method for producing hydrogen directly from hydrocarbon gas by igniting plasma using surplus electricity such as at night. The principle is extremely simple: by introducing a hydrocarbon gas into a plasma, carbon and hydrogen are generated by the collision of hydrocarbon molecules and high-energy electrons．Ideally, when natural gas is introduced into the inlet of a plasma reactor, hydrogen will come out from the outlet. It would be nice if industrially useful high-purity carbon black could be produced at the same time as hydrogen production. So far, we have manufactured a plasma decomposition device and formulated the hydrogen production rate in this device as a function of plasma applied power, gas flow rate, and inlet hydrogen concentration.

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• Hydrogen production from high temperature steam by solid oxide electrolytic cell

　Due to its characteristics, hydrogen energy can solve for the problem of "difficulty in storage" of electrical energy. Solid oxide fuel cell electrolysis and hydrogen production using a high-temperature heat source such as a high-temperature gas-cooled reactor and a molten salt reactore is expected as carbon-free hydrogen production methods. In particular, regarding the water electrolysis technology, the higher the temperature, the lower the theoretical decomposition voltage, so that highly efficient hydrogen production becomes possible. Its method is the high temperature steam electrolysis method. In hydrogen production using a high-temperature heat source, it is expected that the production cost will be reduced not only by high-temperature heat but also by coexistence with renewable energy.
　In this research, hydrogen by high-temperature steam electrolysis is aimed at understanding mass transfer phenomena through material characteristics and performance evaluation of solid oxide electrolysis cells (SOEC) using high-temperature heat sources toward the realization of carbon-free hydrogen production technology. Recently, we built the experimental setup and tried to acumulate experimental data at high temperature conditions. Manufacturing electrodes and gas seals that can withstand high temperatures conditions is not easy and our challenge is continued.

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