[H-SC06] CCUS (Carbon Dioxide Capture, Utilization, and Storage) for Climate Mitigation

[HSC06-P01] A decision analysis under uncertainties for the site selection stage of geological CO₂ storage

*Takahiro Nakajima^1,2, Takashi Goda³, Ziqiu Xue^1,2 (1.Research Institute of Innovative Technology for the Earth, 2.Geological Carbon Dioxide Storage Technology Research Association, 3.School of Engineering, The University of Tokyo)

Keywords:Geological CO2 storage, Decision-making under uncertainty, Value of Information, Expected Monetary Value

For the implementation of Carbon Capture and Storage (CCS), there are large uncertainties, such as amount of storable CO₂ and injectivity, in the storage part compared to the capture and the transport parts. If expected amount of CO₂ cannot be stored at a site, the development cost including surface facilities would be wasted. On the other hand, in the field of decision analysis, various methods have been proposed to assist optimal decision-making under uncertainties. We applied one of these methods to the decision-making at the early stage of geological storage of a site.

We introduced a simple decision-making model at a candidate site. The nature of state was settled as two states; “Possible” and “Impossible” to store CO₂. There assumed to be an inexpensive measurement method to obtain information on whether the storage is “Possible” or “Impossible” with some errors defined by probability. The action must be chosen from “Go”, “Re-exam”, and “Discard”. We also assumed the precision of the measurement method and payoff of every state. We evaluated Expected Monetary Value (EMV) of all possible decision methods in this model. From the decision analysis, we could obtain the optimal action as the function of the probability of “Possible” state. At extreme cases where the probability of “Possible” state is very high/low, the optimal action were “Go”/”Discard”. Furthermore, we examined the optimal action at the continuous probability of “Possible” state. The value of information by the measurement method was also calculated. This represents that the simple measurements method is needed to probe the site. We will discuss the effect of the precision of the measurement method and the payoff of each state following the cost estimation for CCS. This kind of analysis provide quantitative insight into the optimal decision-making at the early stage of geological storage.