[H-SC05] 地球温暖化防⽌と地学（CO2地中貯留・有効利⽤、地球⼯学）

[HSC05-17] Cost analysis of CO₂ transportation in CCS deployed in Japan

*磯谷 浩孝¹、マイヤーズ コーリ²、中垣 隆雄²、名井 健³、清水 淳一³ (1.早稲田大学大学院　創造理工学研究科　総合機械工学専攻、2.早稲田大学理工学術院、3.二酸化炭素地中貯留技術研究組合 / 公益財団法人地球環境産業技術研究機構)

キーワード：パイプライン、船舶輸送、CO₂回収回避コスト、ハブアンドクラスター

Carbon dioxide capture and storage (CCS) is regarded as an integral technology to meet net CO₂ neutrality in Japan and abroad. The technology can be divided into three major activities: capture of CO₂ from emission sources, transportation of CO₂ to a storage site, and injection of CO₂ into an appropriate underground geological formation. In Japan, the transportation of CO₂ captured at a power plant in Kyoto to the existing storage site in Hokkaido is planned to be demonstrated within a few years. One of the barriers to a rapid deployment of CCS is recognized as the high costs. Discussion of cost has historically focused on CO₂ capture, primarily because CO₂ transport by onshore pipeline is a mature and relatively cheap activity. In Japan and coastal Europe area where onshore pipelines are far less deployed than US, a mixture of geology, geography, regulations, and public opinion make CO₂ transport by ship a promising method as shown in hub and cluster system. The available data on cost of transport by ship is difficult to merge with existing data on CO₂ capture and injection because of imprecise definitions of the boundaries of each activity. In this study, the cost of CO₂ transport is calculated as part of a complete CCS chain to eliminate issues of boundary selection. Transport by ship and pipeline are evaluated in the context of Japan to provide a clear comparison. The cost of transport is reported per unit of avoided CO₂.

For both the pipeline and ship-based transport methods, it is assumed that the emission source is either a GW-class supercritical pulverized coal-fired power plant (SCPC) or a natural gas combined cycle power plant (NGCC). In both cases, an amine-based CO₂ capture system is retrofitted to existing power plant. For pipeline transport, captured CO₂ is compressed to the supercritical state and is transported via onshore pipeline with intermediate boosters. The injection site is assumed to be operated from onshore though actual injection occurs at sea, similar to JCCS’ Tomakomai CCS demonstration facility. The pipeline cost estimate is broadly based on the “FE/NETL CO₂ Transport Cost Model” by NETL with various location factors modified to account for differences between the US and Japan. The results of the cost estimation are corroborated by comparison with multiple existing CO₂ pipeline projects. In all cases, pipeline transport costs are OPEX-dominated so long as the operation period is long to some extent (typically >20 years). Countries and localities with experience with pipelines show markedly lower costs due to the shorter permitting period, calling into question the applicability of pipeline transport in Japan. For transport by ship, the liquefaction of CO₂ at around triple point, intermediate storage at port, loading to the ship, transport by ship, unloading, and conditioning prior to injection are considered. It is assumed that CO₂ injection occurs at sea. The cost of ships and at-sea injection facilities are based on previously reported engineering analyses. The several conditioning steps applied to CO₂, especially conditioning chilled and liquefied CO₂, incurs a large electricity burden which means that the cost and CO₂ intensity of electricity are important factors in determining the cost per unit of avoided CO₂. At short transport distances, the cost for maintenance and repair of facilities also account for a large portion of the total cost. At longer transport distances, fuel costs become an increasingly large portion of total cost and the balance between ship speed and the number of ships gain importance. The results in this study are corroborated by comparison with cost estimates from literatures. Regardless of transport type, it was found that the SCPC case has a higher sensitivity of CO₂ transportation cost on the CO₂ avoided cost compared with NGCC case due to the difference in the amount of CO₂ captured and emission.