Research press release


Nature Communications

Climate sciences: Regulated CO2 storage sites may deliver on climate mitigation



今回、Juan Alcaldeたちの研究グループは、「Storage Security Calculator」という数値プログラムを開発して、二酸化炭素の地層学的貯留が気候変動の緩和にどれほど有効なのかを評価した。この計算ソフトは、2020~2050年に地中に圧入される二酸化炭素の貯留性と、1万年間に大気中に漏れ出す二酸化炭素の総量を定量する。Alcaldeたちは、この計算を2つのシナリオについて行った。第1のシナリオは、二酸化炭素が圧入された貯留層の密度がそれほど高くなく、貯留層の管理が現在の最良の実務慣行に基づいて行われる場合、第2のシナリオは、貯留層の管理が十分でない場合だ。



Geological carbon capture and storage may be an effective climate mitigation tool, reports a study published in Nature Communications. Modelling shows that under appropriate regulation, there is a 50% probability that 98% of injected CO2 is retained in the subsurface for over 10,000 years. Under poor regulation, 78% of injected CO2 is retained in the subsurface.

Carbon capture and storage involves the injection into the subsurface of CO2 emitted from using fossil fuels in industrial processes. Despite the potential of this technology to reduce global CO2 emissions and help in achieving the Paris Agreement targets, there are concerns that the injected CO2 could leak into the atmosphere in future.

Juan Alcalde and colleagues develop a numerical program, the Storage Security Calculator, to assess the effectiveness of geological CO2 storage for climate mitigation. The calculator quantifies the immobilisation of CO2 injected into the subsurface between 2020 and 2050, and the total CO2 leakage to the atmosphere over 10,000 years. The authors perform this calculation for two scenarios, one where injection site density is modest and sites are regulated using current best practices, and another where sites are poorly regulated.

They find that if sites are appropriately regulated, yearly leak rates are lower than 0.01% per year, considered by many to be the acceptable limit for effective climate mitigation. For inadequately regulated sites, although leakage exceeds this limit for the first 100 years, after 1,000 years it is reduced to acceptable levels.

The authors caution that an incomplete understanding of CO2 behaviour in the subsurface over the thousands of years timescale is a key uncertainty in their model, which could result in an overestimation of CO2 storage.

doi: 10.1038/s41467-018-04423-1

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