Developments since 2005 in understanding potential environmental impacts of CO2 leakage from geological storage

Abstract

This paper reviews research into the potential environmental impacts of leakage from geological storage of CO 2 since the publication of the IPCC Special Report on Carbon Dioxide Capture and Storage in 2005. Possible impacts are considered on onshore (including drinking water aquifers) and offshore ecosystems. The review does not consider direct impacts on man or other land animals from elevated atmospheric CO 2 levels. Improvements in our understanding of the potential impacts have come directly from CO 2 storage research but have also benefitted from studies of ocean acidification and other impacts on aquifers and onshore near surface ecosystems. Research has included observations at natural CO 2 sites, laboratory and field experiments and modelling. Studies to date suggest that the impacts from many lower level fault-or well-related leakage scenarios are likely to be limited spatially and temporarily and recovery may be rapid. The effects are often ameliorated by mixing and dispersion of the leakage and by buffering and other reactions; potentially harmful elements have rarely breached drinking water guidelines. Larger releases, with potentially higher impact, would be possible from open wells or major pipeline leaks but these are of lower probability and should be easier and quicker to detect and remediate.

Thermodynamic and Kinetic Response of Microbial Reactions to High CO2

“…Note that in our simulation, the increase of the ionic strength is due to calcite dissolution. Other factors, such as sorption reactions and mixing with deep reservoir fluids, can also raise groundwater ionic strength (Jones et al, 2015). …”

Impacts of CO2 leakage on plants and microorganisms: A review of results from CO2 release experiments and storage sites

“…Plant stress response was visible within very short periods of exposure to high CO 2 levels at the field experiments (Figs , and ), and thus plants can be useful indicators of potential CO 2 leakage from a CCS facility . Especially, species‐specific responses of plants to differing soil CO 2 concentrations could be useful in monitoring CO 2 leakage at the vegetated areas of CO 2 storage sites .…”

“…Previous studies have examined the influences of high concentrations of soil CO 2 near natural CO 2 vent on vegetation . Ecosystems at these environments have been exposed to high levels of CO 2 over long periods of time, and thus the vegetation may have adapted to such conditions . Therefore, plant responses studied at these natural CO 2 vents may not represent the effects of potential CO 2 leakage from CCS sites on plants .…”

“…Airborne hyperspectral imagery allows the rapid collection and processing of spectral measurements at a large areal scale. Hyperspectral instruments thus can be employed in monitoring and detection of potential CO 2 leaks from CCS sites but some drawbacks also exist . Further investigations are needed to clarify whether plant stress responses that are visible can be detected and compared with normal and seasonal alterations in leaf pigmentation and other plant physiological parameters.…”

Progress in monitoring strategies for risk reduction in geologic CO2 storage

“…Technical challenges at geologic CO 2 storage (GCS) sites include assuring that injectivity and capacity predictions are reliable, fate and configuration of the CO 2 plume is acceptable, regulatory permitting and compliance is accomplished in a timely manner, needed business assurances are supported by technical data, and that the storage operation is acceptable to stakeholders (Friedmann and Hovorka, 2004;DOE, 2012;Annetts et al, 2012;CSLF, 2013;Dixon and Romanak, 2015;Jones et al, 2015). There is risk, defined as the product of hazard probability and hazard impact, associated with all of these challenges (DOE, 2013a).…”