Tadahiko MIZUNO
Plasma Electrolysis
Japanese Journal of Applied Physics
Vol. 44, No. 1A, 2005, pp. 396-401
http://jjap.ipap.jp/link?JJAP/44/396/
Hydrogen Evolution by Plasma Electrolysis in Aqueous Solution
Tadahiko Mizuno*, Tadashi Akimoto, Kazuhisa Azumi (1), Tadayoshi Ohmori (2), Yoshiaki Aoki (3) and Akito Takahashi (4)
( Division of Quantum Energy Engineering, Graduate School of
Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku,
Sapporo 060-8628, Japan )
*E-mail address: mizuno@qe.eng.hokudai.ac.jp
1. Division of Molecular Science, Graduate School of
Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku,
Sapporo 060-8628, Japan
2. Catalysis Research Center, Hokkaido University, Kita 11 Nishi
10, Kita-ku, Sapporo 060, Japan
3. Center for Advanced Research of Energy Technology of Hokkaido
University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628, Japan
4. Department of Nuclear Engineering, Graduate School of
Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka
565-0871, Japan
Abstract: Hydrogen has recently attracted attention as a possible solution to environmental and energy problems. If hydrogen should be considered an energy storage medium rather than a natural resource. However, free hydrogen does not exist on earth. Many techniques for obtaining hydrogen have been proposed. It can be reformulated from conventional hydrocarbon fuels, or obtained directly from water by electrolysis or high-temperature pyrolysis with a heat source such as a nuclear reactor. However, the efficiencies of these methods are low. The direct heating of water to sufficiently high temperatures for sustaining pyrolysis is very difficult. Pyrolysis occurs when the temperature exceeds 4000°C. Thus plasma electrolysis may be a better alternative, it is not only easier to achieve than direct heating, but also appears to produce more hydrogen than ordinary electrolysis, as predicted by Faraday's laws, which is indirect evidence that it produces very high temperatures. We also observed large amounts of free oxygen generated at the cathode, which is further evidence of direct decomposition, rather than electrolytic decomposition. To achieve the continuous generation of hydrogen with efficiencies exceeding Faraday efficiency, it is necessary to control the surface conditions of the electrode, plasma electrolysis temperature, current density and input voltage. The minimum input voltage required induce the plasma state depends on the density and temperature of the solution, it was estimated as 120 V in this study. The lowest electrolyte temperature at which plasma forms is ?75°C. We have observed as much as 80 times more hydrogen generated by plasma electrolysis than by conventional electrolysis at 300 V.
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http://jjap.ipap.jp/link?JJAP/39/6055/
Production of Heat during Plasma Electrolysis in Liquid
Tadahiko Mizuno, Tadayoshi Ohmori (1), Tadashi Akimoto and Akito Takahashi (2)
( Division of Quantum Energy Engineering, Research Group of Nuclear System Engineering, Laboratory of Nuclear Material System, Graduate School of Engineering, Hokkaido University, Kita 13 nishi 8, Kita-ku, Sapporo 060-8628, Japan )
1 Catalysis Research Center, Section of Interfacial Energy
Conversion, Hokkaido University, Kita 11 nishi10, Kita-ku,
Sapporo 060, Japan
2 Department of Nuclear Engineering, Graduate School of
Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka
565-0871, Japan
Abstract: Plasma was formed on the surface of an electrode in a liquid solution when metal cathodes underwent high-voltage electrolysis. A real-time heat calibration system was designed for detecting the amount of heat generated during plasma electrolysis. The measured heat exceeded the input power substantially, and in some cases 200% of the input power. The heat generation process depended on the conditions for electrolysis. There was no excess heat at the beginning of plasma electrolysis. However, after plasma electrolysis for a long time, a large amount of heat was generated. The reproducibility would be 100% if all factors such as temperature, voltage and duration were optimized. Based on the heat and the products, we hypothesize that some unique reaction occurs on the cathode surface. This reaction may not occur at energy levels available during electrochemical electrolysis.
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Citing Article(s) :
1. Jpn. J. Appl. Phys. Vol. 40 (2001) L989-L991 : Neutron Evolution from a Palladium Electrode by Alternate Absorption Treatment of Deuterium and Hydrogen; Tadahiko Mizuno, Tadashi Akimoto, Tadayoshi Ohmori, Akito Takahashi, Hiroshi Yamada and Hiroo Numata
METHOD AND APPARATUS FOR GENERATING HYDROGEN GAS
JP2004059977
[ PDF ]
( 2004-02-26 )
MIZUNO, Tadahiko
Applicant: MIZUNO TADAHIKO; ARAKI MASAO
Classification: - international: C01B3/04; C25B1/04; C25B11/02; C25B15/02; C01B3/00; C25B1/00; C25B11/00; C25B15/00; (IPC1-7): C25B1/04; C01B3/04; C25B11/02; C25B15/02
Abstract --- PROBLEM TO BE SOLVED: To provide a method for generating a hydrogen gas with a high efficiency by continuously and directly pyrolyzing water with a satisfactory controllability. SOLUTION: This gas-generating method comprises a step of accommodating an aqueous solution of an acid, an alkali or a metal salt in a reaction vessel, and heating it to 70[deg.]C or higher but less than 100[deg.]C, a step of applying a voltage of 100-2,000 V to the above heated solution with pulse widths of 0.1-10 s and pulse intervals of 0.01-5 s to generate plasma, and a step of electrolyzing the above aqueous solution with the above plasma.
