Seafloor Mineral Carbonation as a Guide to Improved Geological Carbon Dioxide Storage

This research is focused on

1. Constraining suitable locations for stable carbon dioxide trapping conditions in deep-sea basalts¹ and
2. Understanding the geochemical potential of oceanic rock for carbon sequestration by conducting a series of batch-type experiments in a CO₂-seawater-rock system.

The figure on the right depicts the global carbon budget shown as average values. The CO₂ fluxes are expressed in Gt/yr with both red (anthropogenic flux) and blue (natural flux) arrows. The sum of these exchanges leads to an annual growth of 16 Gt of CO₂ into the atmosphere. The natural and anthropogenic storages of Gt of CO₂ in the earth are shown in black and pink, respectively. Anthropogenic emissions of CO₂ into the atmosphere are currently 36 Gt per year.

¹(Marieni et al., 2013)

²[Canadell et al., 2007; IPCC, 2007; Le Quere et al., 2009; Le Quéré et al., 2014; Le Quéré et al., 2015; Sabine et al., 2004]

 

The rise of atmospheric CO₂ due to the burning of fossil fuels is a key driver of anthropogenic climate change. Mitigation strategies include improved efficiency, using renewable energy, and capture and long-term sequestration of CO₂. Most sequestration research considers CO₂ injection into deep saline aquifers or depleted hydrocarbon reservoirs. More unconventional proposals include CO₂ storage in the porous volcanic lavas of the oceanic crust. In fact, there is strong evidence that, in the past, the basaltic seafloor has acted as a major sink for CO₂ through the release of divalent cations (Ca2+, Mg2+ and Fe2+) and the consequent formation of abundant carbonate veins.

In the figure on the left we see global map GDH1 (from Marieni et al. 2013) which is an equal area map showing locations for stable geological sequestration of CO₂. Shading shows the difference in density between CO₂ and seawater in areas where the sediment thickness is between 200 and 700 m and the CO₂ is denser than seawater. Five potential reservoirs (insets a–e) have been identified. The red box indicates the area required to store 100 yrs of current anthropogenic emissions of CO₂, assuming a pillow lava thickness of 300 m and 10% porosity³. Yellow boxes show unsuitable regions previously suggested by other authors as having potential.

 

³[Carlson and Herrick, 1990; Jarrard et al., 2003; Johnson and Pruis, 2003].

 

 

Clean Carbon member - Chiara Marieni.

 

Chiara is a PhD student at the National Oceanography Centre, Southampton working under the supervision of Clean Carbon members, Professor Damon Teagle, Dr Juerg Matter, and Professor Martin Palmer. During her PhD research, Chiara has been involved with the Marie Curie Initial Training Programme, CO₂REACT and has collaborated with Professor Andri Stefansson at the University of Iceland and Dr Edda Sif Aradóttir & Ingvi Gunnarsson of the geothermal company, Reykjavik Energy.