報告書番号

U35

タイトル（和文）

堆積岩における水封式圧縮空気貯蔵技術の成立性 - 古第三紀礫岩における評価研究 -

タイトル（英文）

Technical apsects of compressed air energy storage in unlined storage cavers in sedimentary rock -Estimation in the Palaeogene conglomerate

概要 （図表や脚注は「報告書全文」に掲載しております）

圧縮空気貯蔵ガスタービン発電システム(CAES)は有望なエネルギー貯蔵技術の一つと考えられる。CAESの貯槽の気密方式としては、地下水を利用した水封方式が経済的に有利であると考えられ、これまでに花崗岩地点では現場試験により水封機能が確認されている。立地可能性拡大の観点から、堆積岩地点におけるケーススタディとして、礫岩主体の古第三紀堆積岩中に掘削した深度600mのボーリング孔を用いた現場調査・試験ならびに数値解析を実施した。調査試験では、地質概要の把握、礫岩の力学特性に及ぼす基質部材料の影響評価、水理地質特性および岩盤力学特性の把握、水封機能評価、岩盤特性の把握を行った。また数値解析では、応力解析による貯槽の概略設計と熱解析による貯蔵空気温度の排水への影響評価を実施した。これらの結果、土木技術的に堆積岩地点が水封式CAESの立地可能性を有することを明らかにした。

概要 （英文）

Middle sized storage systems are nowadays required for efficient power supply and a system of compressed air energy storage (CAES) with a gas turbine power generator is supposed as an effective way to transfer off-peak electricity in Japan.In order to make the CAES system more economical and more feasible in Japan, a large amount of highly compressed air would be stored in deep excavated caverns without lining. In this case air leakage would be prevented by air tightness of submerged rock. Therefore in order to examine the air tightness of a rock a series of preliminary investigations using boreholes had been carried out in a plutonic rock field.From the point of view to expand the feasibility of CAES out of plutonic rock fields, Kyushu Electric Power Company and Central Research Institute of Electric Power Industry carried out a joint project of research on geotecnical aspects of CAES in unlined storage cavers in a sedimentary rock in Kita-Kyushu.In this project field investigations were performed on geological and hydrogeological features as well as mechanical charateristics of the sedimentary rock. Computational studies were also carried out on stability of underground storage caverns and thermal behavior of surrounding rock.The results are summarized as:(1) The test site in Kita-Kyushu is mainly formed by conglomerate of the Tertiary period sedimentary rock. Six formations were confirmed by newly drilled 600m-borehoe with diameter of 76mm.(2) Uniaxial strength of the conglomerate varied from about 20 to 60 MPa. Laboratory tests showed that the strength of the conglomerate depeneded on the calcite content rather than the gravel content.(3) Concerning geohydrology along the borehole the sedimentary rock had rather low permeability which was varied mainly around 10^-9 and 10^-8 m/s. Pore pressure distributed in almost static water pressure equivalent the water level in the borehole.(4) With a newly developed test apparatus air tightness was confiremd to be larger than pore pressure along the borehole. This fact was similar to the result at the previous granite test site.(5) Conceptual design of storage caverns in the sedimentary rock was proposed and the stabiliy of the caverns was assured by numerical analysis.(6) Thermal analysis showed that storage of high temperature comressed air practically caused no problem.These results lead conclusion that the CAES system with unlined storage caverns will be applicable to the sedimentary rock.

報告者

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