State of the art review of CO2 Storage Site Selection and Characterisation Methods

 
1. INTRODUCTION
 
2. GEOLOGICAL CHARACTERISATION OF THE SITE
 
3. FLOW MODELLING
 
4 REACTIVE FLOW MODELLING
 
5. COUPLED GEOMECHANICAL AND FLOW MODELLING
 
6. ENVIRONMENTAL IMPACT AND RISK ASSESSMENT
 
7. ECONOMIC ANALYSIS
 
8. PUBLIC PERCEPTION AND ACCEPTANCE
 
9. CONCLUSIONS AND RECOMMENDATIONS
 
 
7.1 Storage site selection economics
 
7.2 CO2 storage costs
 
» 7.3 Key conclusions of the ZEP report
 
 

7.3 Key conclusions of the ZEP report

The CO2 storage cost estimates reported in the ZEP report fluctuate between €1-7/tonne CO2 stored for the cheapest option (onshore DOGF with re-usable wells) to €6-20/tonne CO2 stored for the most expensive alternative (offshore SA). Uncertainty ranges within each case are in line with the natural variability of storage candidates, namely, reservoir capacity and injectivity. The effect of the learning rate was found to be negligible.

The ZEP report highlights substantial differentiators in the economics of storage, the key being:

  • Reservoir capacity (higher cost for smaller reservoirs);

  • Site location (higher costs offshore than onshore);

  • Site information level (high for DOGF, meaning lower costs; low for SA, meaning higher costs);

  • Existence of re-usable infrastructure (wells, offshore structure);

  • Reservoir quality (injectivity; poorer quality reservoirs leading to higher costs).

The cost sensitivity studies revealed that:

  • Field capacity has the highest impact on cost in four cases and the second largest effect in the other two cases. consequently, selection of appropriate storage reservoirs with respect to their capacity is a key element to cut the costs of CO2 storage. Therefore, exploration and reservoir characterisationare vital activities for CO2 storage as they allow selection of a storage reservoir of suitable dimensions. This is of particular importance in the case of offshore SA, where the use of larger reservoirs results in considerably lower costs than for smaller ones (economy of scale benefit);

  • Well capacity is the top second contributor to variations of cost for onshore cases and thus the design and placement of wells is a basic activity for such cases;

  • Well completion costs are the succeeding most important factor for offshore cases, highlighting the specificities of that offshore environment;

  • The top two items for all cases relate to storage capacity and injectivity;

  • The assumed cost of liability is equal for all cases when reported per tonne of CO2 stored. Therefore, its relative weight is the largest for cases where the total cost of storage per CO2 tonne stored is the smallest, that is to say onshore.

Finally,regarding demonstration projects, the ZEP study concludes that it is very likely that the costs per tonne of CO2 stored will be significantly higher than those of projects in the early commercial phase. Such a conclusion should be taken into account when financing demonstration projects and when comparing the actual costs of demonstration projects with those of early commercial projects.