2023 Fiscal Year Final Research Report
Highly efficient water electrolysis by superimposing boiling
| Project/Area Number |
21H04665
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Medium-sized Section 31:Nuclear engineering, earth resources engineering, energy engineering, and related fields
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| Research Institution | Kyushu University |
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Principal Investigator |
ITO KOHEI 九州大学, 工学研究院, 教授 (10283491)
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| Co-Investigator(Kenkyū-buntansha) |
森 昌司 九州大学, 工学研究院, 教授 (10377088)
林 灯 九州大学, 水素エネルギー国際研究センター, 教授 (60443214)
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| Project Period (FY) |
2021-04-05 – 2024-03-31
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| Keywords | 沸騰重畳 / 非平衡効果 / 溶存ガス |
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| Outline of Final Research Achievements |
The applicant aims to improve the efficiency of water electrolysis by 10%, by superimposing boiling. When the water electrolysis operates at 100 C, boiling occurs on electrodes. It is expected that the boiling bubbles cause a local, short-term decrease in oxygen activity (dissolved oxygen concentration and oxygen partial pressure in the bubbles), leading to a decrease in electrolysis voltage via the Nernst voltage, resulting in a non-equilibrium effect. This hypothesis was tested using a three-electrode cell with a heater-embedded working electrode and a practical cell with a reference electrode. When the temperature was swept from room temperature to near the boiling point, both the OER voltage and HER voltage decreased sharply. These experimental results suggest that superimposing boiling reduces electrolysis voltage due to the non-equilibrium effect. The efficiency improvement due to the voltage drop was around 5%, but with further optimization, the target of 10% can be achieved.
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| Free Research Field |
電気化学システム
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| Academic Significance and Societal Importance of the Research Achievements |
本研究の沸騰重畳水電解技術が社会実装されれば、国内CO2を2.8%削減（2018年度基準）できる。沸騰重畳水電解は、実質電解電圧を下げ、あるいは電解電圧低下分を高電流密度化に転化すれば、水電解装置のOPEX、CAPEXを各段に低下することが可能である。このような沸騰重畳水電解セル（BS-PEMEC）を余剰電力が大きい九州内の工場に設置し、余剰再エネ電力と工場排熱によりBS-PEMECを運転し、製造した水素で水素ボイラーを運転し、高温熱源を工場に供給する、いわゆる産業用高温熱源の脱炭素化により、2050年のカーボンニュートラルの（国内）実現に対して、本技術は2.8%分寄与できると試算している。
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