Status of Geological Storage of CO2 as Part of Negative Emissions Strategy

Abstract:

Recent analyses show that many GHG stabilization scenarios require technologies that permanently extract CO₂ from the atmosphere –so-called “net negative emissions.” Among the most promising negative emissions approaches is bioenergy with carbon capture and storage (BECCS). The most mature options for CO₂ storage are in sedimentary rocks located in thick sedimentary basins. Within those basins, CO₂ can be stored either in depleted or depleting hydrocarbon formations or in so-called saline aquifers. In addition to the economic costs of bioenergy with CO₂ capture, key to the success of and scale at which BECCS can contribute to negative emissions is the ability to store quantities on the order of 1 Gt per year of CO₂.

Today, about 65 Mt of CO₂ per year are injected underground for the purposes of enhancing oil recovery (CO₂-EOR) or for CO₂ storage, the vast majority being for CO₂-EOR. Achieving 1 Gt per year of negative emissions will require a 15-fold scale up of the current injection operations. This paper will review the conditions necessary for storage at this scale, identify what has been learned from nearly 2 decades of experience with CO₂ storage that provides insight into the feasibility of CO₂ storage on this scale, and identify critical issues that remain to be resolved to meet these ambitious negative emissions targets.

Critical technological issues include but are not limited to: the amount of CO₂ storage capacity that is available and where it is located in relation to biomass energy resources; identification of sustainable injection rates and how this depends on the properties of the geological formation; the extent to which water extraction will be required to manage the magnitude of pressure buildup; identification of regions at high risk for induced seismicity that could damage structures and infrastructure; and selection of sites with a adequate seals to permanently contain CO₂. Social, economic and political issues are also important: including the support for and confidence in the projects by the local population; scale at which these projects are financially feasible; resolution of issues such as who pays and who benefits from these projects; and development of regulatory frameworks that are at the same time, environmentally protective and not overly burdensome.