Insights and Commentaries
Vast subsurface resources are available to support CCS deployment
15th November 2015
Topic(s): Carbon capture, CO2 storage, Engineering and project delivery, use and storage (CCUS)
The Global CCS Institute has published a major report on the latest developments in Carbon Capture and Storage (CCS). The Global Status of CCS: 2015 highlights new operational projects, policy and international climate discussions, new technology developments and further progress towards the emergence of coordinated industrial hubs and clusters. One key to the future of CCS is the availability of storage resources. A number of resource assessments have been published which confirm there is sufficient storage capacity for current mitigation goals over the coming decades. In this Insight Neil Wildgust, Principal Manager – Storage discusses one of these resource assessments, the fifth version of the US DOE/NETL Carbon Storage Atlas.
The fifth version of the Carbon Storage Atlas has been published by the US Department of Energy (DOE) National Energy Technology Laboratory (NETL). The updated Atlas details a conservative estimate of total onshore storage resources as 2,600 Gigatonnes of CO2 (GtCO2) for the US and parts of Canada – up by nearly 10% from the previous 2012 publication. The Atlas also details lessons learnt to date by the large scale (Phase III) demonstration projects being undertaken across the US by the Regional Carbon Sequestration Partnerships (RCSP) program, which have demonstrated secure geological storage across a range of subsurface settings – in deep saline formations (DSF) and in association with enhanced oil recovery (CO2-EOR).
Research and development of clean energy technologies to reduce greenhouse gas emissions is a priority for the US DOE, including the Office of Fossil Energy (FE). The Carbon Capture Program and the Carbon Storage Program (CSP) is implemented by NETL under the guidance of the FE program office. The CSP is focused on the ‘safe and permanent storage and/or utilisation of CO2 captured from stationary sources’. It is structured around activities for both ‘Core Storage R&D’ and ‘Storage Infrastructure’, the latter including the RCSP initiative, which undertakes regional characterisation and field projects to demonstrate commercial scale storage opportunities across the US. The Phase III projects (see table below) are on course to eventually have injected and stored over 10 Million tonnes of CO2 (MtCO2), with associated learnings around the advancement of monitoring technologies, predictive modelling capability and risk management procedures.
| Project | Regional Partnership | Storage Type |
CO2 injected* |
Storage depth (m) |
| Cranfield, Mississippi | Southeast (SECARB) | CO2-EOR | >5 | >3,000 |
| Bell Creek, Montana | Plains (PCOR) | CO2-EOR | 1.1 | >1,300 |
| Michigan Basin, Michigan | Midwest (MRCSP) | CO2-EOR | 0.3 | >1,600 |
| Farnsworth, Texas | Southwest (SWP) | CO2-EOR | 0.3 | >2,300 |
| Decatur, Illinois | Midwest (MGSC) | DSF | 1.0 | >2,100 |
| Citronelle, Alabama | Southeast (SECARB) | DSF | 0.1 | >3,000 |
*Injected quantity as reported in Atlas V
The Atlas lists potential storage resources associated with oil and gas fields as between 186 and 232 GtCO2. Much of this potential storage could be realised in association with CO2-EOR, and four of the Phase III projects are associated with CO2-EOR operations:
- Cranfield (SECARB partnership) http://www.secarbon.org/
- Bell Creek (PCOR partnership) http://www.undeerc.org/pcor/
- Michigan Basin (MRCSP partnership) http://www.mrcsp.org/
- Farnsworth (SWP partnership) http://www.southwestcarbonpartnership.org/
Future CO2 injection opportunities associated with CO2-EOR could provide significant additional storage resources not included in the 186 – 232 GtCO2 estimates of the Atlas. These include CO2-EOR in extensive residual oil zones, which frequently underlie conventional oil fields, and the use of CO2 to improve oil recovery from unconventional ‘tight’ oil reservoirs such as the Bakken Play in the northern US and southern Canada.
The largest potential storage resources listed by the Atlas are associated with DSF, estimated as between 2,379 and 21,633 GtCO2. These regional resource estimates are based on geological models of the accumulations of sedimentary rocks (basins) in which commercial scale storage will generally be undertaken. Calculations of resources involve the use of a storage efficiency factor, which refers to the proportion of pore space in a storage formation which is accessible to injected CO2 – allowing for technical factors but not considering regulatory or economic constraints. Atlas V lists the storage efficiency factors for DSF according to calculated confidence limits – 0.51%, 2.0% and 5.5% at the P10, P50 (mean) and P90 confidence limits respectively. In other words, there is a 90% chance that at least 0.51% of the pore space of a suitable DSF could be occupied by injected CO2 and a 10% chance that over 5.5% could be used; and the most likely scenario is that 2% of the pore space would be accessible.
The order of magnitude variation between these lower and higher estimated resources in DSF reflects a greater degree of uncertainty in comparison to oil and gas fields. Pre-existing knowledge (and data) for DSF is frequently less detailed than that available for oil and gas fields, and there is still a debate about the degree to which pressure effects could determine storage resources in DSF. However, the lower Atlas V estimate is based on conservative assumptions and yet still outlines a huge potential resource in comparison to CO2 emissions sources in the US and climate mitigation targets.
Two RCSP Phase III projects have so far injected into DSF:
- Decatur (MGSC partnership, http://www.sequestration.org/)
- Citronelle (SECARB partnership,http://www.secarbon.org/)
A third DSF project, Kevin Dome in Montana (Big Sky partnership) has not yet commenced injection.
The publication of Atlas V builds on previous editions in showing that very large storage resources are present within onshore USA and Canada, capable of supporting CCS deployment for many decades to come. The resource mapping illustrated in Atlas V, as with all such regional studies, is not however a substitute for the detailed site investigations required to characterise commercial storage projects with sufficient confidence for final investment decisions.
The RCSP Phase III large scale demonstration projects described in Atlas V further demonstrate that secure industrial scale storage of anthropogenic CO2 can be achieved with existing technology and risk management procedures.