Nations, pore space owners, and CCUS project developers around the world are rapidly advancing their efforts to be part of this solution to the decarbonization equation. The International Energy Agency estimates that by 2050, CCUS could be responsible for reducing a significant 12% of global greenhouse gas emissions. That said, engaging in geological sequestration (the process of storing CO₂ underground) is a complex, multidimensional engineering challenge spanning technical, environmental, economic, and societal spheres. Significant investments are required to progressively evaluate the associated risks while qualifying a site as suitable for development.  

So, where do you start? Well, the first step for any CCUS project is identifying potential locations where captured CO₂ can be stored underground. Those locations must satisfy three important requirements: 

1. They must be safe (integrity)
2. They must be economical
3. They must be large enough to hold the volume to be injected. 

For these requirements to be validated, carbon storage site selection must be driven by science and data—making all decision points more traceable and, therefore, more transparent. It’s a challenging journey that asks us to merge science, innovative tech, and inclusive policymaking into a pragmatic solution for accelerating CCUS project development.  

The first step in any carbon storage initiative: Screening

Screening for potential storage sites is the first step a carbon storage site developer must take when embarking on their CCUS journey. While an increasing number of host authorities (i.e., nations) worldwide are preparing to license their subsurface pore space for carbon storage, the proper identification, screening, and ranking of these sites is a critical step at the beginning of the process.

Undertaking this first step necessitates significant financial investment in both tech and infrastructure, alongside a solid regulatory framework to ensure safe and efficient operations. The geological formations (i.e., sites) chosen must not only be capable of holding large amounts of CO₂ for long periods of time, but they must also be conveniently located near emission sources to reduce transportation costs and logistical issues.

Choosing the right place (one or many that check off the three-point list above) requires a scientific approach to both screening potential sites and ranking them. When we say scientific, we mean the approach is not only backed by unbiased data but also by experience. Because even when a potentially suitable site is identified, we must foresee and model possible events that could undermine our sequestration efforts, either through undesired economic outcomes due to poor storage performance or potential containment breaches leading to environmental damage.

The latter is why, on a societal level, building acceptance for underground CO₂ storage demands transparent communication of the associated risks and benefits. An open approach fosters trust and a cooperative spirit among communities residing near these storage sites. It harmonizes the urgent need to reduce the effects of climate change with the potential environmental impact and concerns regarding property values and land usage rights.

The right to use subsurface areas for carbon storage usually resides with governments and pore space owners (where applicable). Governments, for example, need to ascertain that the areas they offer as possible carbon storage sites have:

• Economic potential
• The right surface infrastructure
• A policy framework that incentivizes carbon sequestration projects
• Environmental regulations established for permitting and ongoing monitoring.

Typically, due to data limitations, selecting the most suitable location is no small task. This stage generally utilizes publicly available data. Leveraging this data optimally, however, and ensuring that all pertinent factors are carefully considered requires an integrated, multidisciplinary, and holistic view of both subsurface and surface information.

Add tech and experience, remove the bias

Subsurface analysis requires assessing a range of elements including but not limited to:

• Site porosity
• Permeability
• Thickness
• Depth
• Pressure
• Displacement
• Trapping mechanisms
• Homogeneity
• Risk of faulting
• Risk of fracturing
• And stress patterns.

The factors above should be considered in a detailed subsurface geological model—a challenging practice during the early phases of site screening when multiple sites are still being considered. To create a comprehensive analysis, however, other non-technical factors should be considered, as well. These include:

• Data availability
• CO₂transportation logistics
• Monitoring protocols
• Funding avenues
• Permitting procedures
• And ownership structures.

The challenge remains data. In carbon storage site screening and ranking, data regarding the areas of interest is often available in limited amounts. This is where expertise, experience, and technical advances play an important role. They allow you to connect existing information, extrapolate to fill in gaps, and make sense of large volumes of uncorrelated data to glean new insights.

It’s important to note that screening for potential storage sites is performed on the basis of both technical and non-technical criteria. Technical criteria are challenging because they are often estimates based on reference data that may not fully represent the sites being evaluated. Non-technical criteria, on the other hand, include elements that can impact cost, timing (e.g., permitting), and the likelihood of success—all of which can be somewhat subjective.