水素電池：石炭に水素を貯蔵することで、クリーンなエネルギー経済への貢献が期待されます。(Hydrogen battery: Storing hydrogen in coal may help power clean energy economy)

2023-05-25

2023-05-24 ペンシルベニア州立大学(PennState)

◆ペンシルバニア州立大学の研究チームが、石炭が水素ガスを蓄える潜在的な方法となり得ることを発見しました。これは、電池がエネルギーを将来の使用のために蓄えるように、クリーンエネルギー供給チェーンの構築における大きな課題に対応しています。
◆石炭は水素を注入して蓄えることができる「地質学的な水素バッテリー」であり、水素の貯蔵方法を開発する上で有望な選択肢となる可能性があります。これにより、水素インフラの構築や経済的で信頼性のあるエネルギー源への発展に向けた多くの作業が残されています。

＜関連情報＞

石炭における水素の収着と拡散：水素の地中貯留への影響 Hydrogen sorption and diffusion in coals: Implications for hydrogen geo-storage

Ang Liu, Shimin Liu
Applied Energy Available online: 27 January 2023
DOI:https://doi.org/10.1016/j.apenergy.2023.120746

Abstract

A full-scale hydrogen economy requires a bulk energy storage system to store the excess energy as a buffer and to fulfill the demand constantly. Hydrogen sorption capacity and diffusion behavior in coal quantify its potential to become a well storage candidate from geological formations. In this study, the sorption and diffusion behaviors of eight coals across the major coalfields in the United States in terms of their ranks, fixed carbon content, vitrinite reflectance, vitrinite or huminite content, O/C ratio, and H/C ratio were measured and analyzed. The sorption data shown that all eight coals have considerable sorption capacities, among which the LvB coal has the maximum adsorption capacity of ∼ 1.17 mmol/g, followed by An coal with the maximum hydrogen adsorption capacity of ∼ 0.95 mmol/g and the SemiAn coal of approximately 0.82 mmol/g. The fixed carbon content and typically the O/C ratio are obviously correlated with the maximum hydrogen adsorption capacity in coals, which may be attributed to the oxygen-containing functional groups. Hydrogen has superior diffusive gas deliverability defined by hydrogen effective diffusivity. The effective diffusivities of hydrogen in SemiAn coal decreases from ∼ 0.00156 to ∼ 9.26 × 10^-41/s with pressure increases from ∼ 2.45 MPa to ∼ 10.07 MPa, among which the lowest diffusivity at ∼ 10.07 MPa is even ∼ 4 times higher than that of CH₄ at equivalent pressure. This is a vantage for a promising field candidate of hydrogen storage in coal with maximized injectivity. The results reveal that the sorption and diffusion behaviors of hydrogen in different rank coals towards the depleted coalbed methane formation with injected hydrogen can serve as a geological “H₂-Battery”.