Engineering application of hydrogen generation in natural environments

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K19081
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Nuclear engineering, Earth resources engineering, Energy engineering, and related fields
• Research Institution: Hokkaido University
• Principal Investigator: Otake Tsubasa 北海道大学, 工学研究院, 准教授 (80544105)
• Project Period (FY): 2017-06-30 – 2020-03-31
• Keywords: 蛇紋岩化 / 水素 / 超苦鉄質岩 / 地球化学モデル / オフィオライト / M-S-H

Outline of Final Research Achievements

Hydrogen generation during low temperature serpentinization was examined using various ultramafic rocks obtained from natural environments. The experimental results showed that unaltered harzburgites produced the highest amounts of hydrogen at 90 degree C. Solution and solid analyses after the experiments indicates that the high amount of hydrogen production was caused by precipitation of low-crystalline magnesium silicates (M-S-H), which buffered the pH lower and promoted dissolution of olive and pyroxene. The precipitation of M-S-H was favored from solutions with high silica concentrations due to dissolution of pyroxene contained in unaltered harzburgites. The positive effect of dissolved silica on hydrogen production was confirmed by addition of silica into the starting materials. Geochemical modeling further suggests that efficiency for hydrogen production can be improved 100 times when an open-system (i.e., flow-through type) is applied.

Free Research Field

地球化学

Academic Significance and Societal Importance of the Research Achievements

水素は今後の需要増加が期待されるクリーンなエネルギー源である。現在の水素製造方法の多くが化石燃料を使用する一方で、本研究の手法では水と岩石のみから水素を生成することができる。今回、
実験で得られた水素生成効率では実用化には至らないが、添加物質によって水素生成量を増大することが可能であることを実験的に証明した。さらにシミュレーションによって将来的に実験系を工夫することで更なる水素生成量の増大も可能であることを示すことができた。