Defining CCS Ready: An Approach to An International Definition

Chapter 4: Storage Ready Plant Definitionassessment would focus on the most viable opportunities, and importantly would need toco-develop multiple sites in case one area is found not to be adequate or has levels ofuncertainty that are too high or cannot be easily resolved.Categories of Capacity EstimatesMost (>95%) of the values in the published literature are theoretical estimates, 98 and thusare of no practical value for planning purposes to develop Storage Ready plants. Even thedocumented storage capacity volume in Chapter 5 (Geological Storage) of the IPCC’sSpecial Report on CCS 95 are not representative of the true extent of practical storagecapacity; 96 these values probably overstate the likely practical storage capacity andunderstate the economic reality of achieving the quoted storage capacity volumes. Thevalues quoted do not describe the highly theoretical nature of the storage capacitycalculations, which are at the physical limit of the rock pore volume to accept CO 2 (seebelow regarding pressure build-up).Bradshaw et al. raised the problems with the disparate data set of local and worldwideestimates for storage capacity, and the inadequate understanding of storage efficiency. 97 In apresentation of those findings in October 2002 in Kyoto, Japan, the concept of a resourcepyramid was presented as a way to encapsulate the vagaries of CO 2 geological storagecapacity estimates. Subsequently, Bradshaw et al. 98 introduced the concept of quotingstorage capacity in terms of “theoretical,” “realistic,” and “viable” with a resource pyramid,which was later modified by Bachu et al. as “theoretical,” “effective,” “practical,” and“matched.” 99 (See Exhibit 4-2.) The UK CCR Guidance note uses the terms in the earlierBradshaw et al. paper, and recommends that the capacity estimates be in the category of“realistic” or “viable”—which could require significant effort in terms of exploration.The qualifying terms in Exhibit 4-2 need to be quoted alongside any numerical capacityestimate so it is clear whether the values are theoretical estimates or have some degree ofscience, modelling, and realistic validation and quantification behind them. To reach StorageReady, the estimates will have to progress up the resource pyramid definitions, withincreasing certainty from technical, commercial, legal, and regulatory perspectives. Thus,conceptually in this scheme, as more information is used in an assessment, the smaller andmore certain the resource value estimate becomes. However, new information andexploration data will affect the prospectivity assessment and can alter the absolute capacityvalues as better knowledge and more data are produced. Normally, as each phase in thework plan is reached (Exhibit 4-1), a more refined capacity estimation can be produced, thusstepping through the storage capacity levels shown in Exhibit 4-2.95 Intergovernmental Panel on Climate Change (IPCC). (2005a). IPCC Special Report on Carbon Dioxide Capture andStorage. New York, NY: Cambridge University Press.96 Holloway, S.. (2008). Advances in global and regional capacity assessment. Paper presented in Session 1A of GHGT-9:9 th international conference on greenhouse gas control technologies, Washington, DC.97 Bradshaw, J. et al.. (2003). Australia’s CO2 geological storage potential and matching of emission sources to potentialsinks. Energy, 29, 1623-1631. doi:10.1016/j.energy.2004.03.064.98 Figure 2 in Bradshaw, J., et al.. (2007). CO2 Storage Capacity Estimation: Issues and development of standards.International Journal Greenhouse Gas Control 1,1, 62-68. doi:10.1016/S1750-5836(07)00027-8.99 Bachu, S., et al. (2007).CO2 storage capacity estimation: Methodology and gaps. International Journal of GreenhouseGas Control, 1, 4, 430-433. doi:10.1016/S1750-5836(07)00086-2.23 February 2010 54