A feasibility investigation in partnership with the University of Bristol for the CO2 sequestration within the basalt scoria deposits via induced mineralisation.

This is a three year research project which seeks to investigate the potential of basaltic scoria and lavas for mineral carbonation of anthropogenic CO2. It will use minerals already obtained from the UK's dependency of Ascension Island in the South Atlantic. The research will identify the optimum pressure, temperature and chemical conditions required to induce CO2 mineralisation, develop reactive-transport simulations to facilitate scale-up of the findings, assess readily-available mineralisation reactant quantities and locations on Ascension and potential applications where mineralisation could be applied and ascertain specific technology development needs for implementation of mineralisation CCS using basaltic rocks.

The Problem

To curb anthropogenically induced climate change there is increasing international pressure to limit future emissions of CO2 (e.g. the Kyoto Protocol) and find effective ways of permanently and safely sequestering CO2. This new technology typically referred to as "Carbon Capture and Storage" (CCS), involves a chain of technologies for capturing CO2 emitted by fixed point source fossil fuel combustion sources, and storing it long-term in geological formations such as depleted natural gas fields or deep saline aquifers. Conceptually, CCS technology can reduce CO2 emissions from large industrial sources and coal-fired power stations by ~85%, representing a potentially significant tool for curbing climate change. However, CCS is controversial, with uncertainty in ensuring safe and permanent trapping of CO2 in saline aquifer and depleted gas fields in particular, contributing to an increasing level of public hostility to CCS which may become a "show stopper" for large-scale implementation.

The Solution

Mineralisation (mineral carbonation) was identified by the Intergovernmental Panel on Climate Change (IPCC) as a promising additional technology in the CCS portfolio. Mineral carbonation is the formation of Mg, Ca and Fe carbonates from the exothermic reaction of CO2 with Mg, Ca, Fe rock silicates (and industrial slags). The end products are thermodynamically stable, inert and environmentally benign compounds sequestering CO2 permanently, avoiding security and safety concerns associated with other forms of geological sequestration. Moreover, they offer a storage solution in full alignment with the very stringent legal and regulatory exactitudes of the EU Geological Storage Directive (2009/31/EC). The IPCC highlights the "highly verifiable and unquestionably permanent" nature of this storage mechanism, likely leading to greater public acceptance than traditional CCS approaches. Though the UK appears well-served with potential sites for geological CO2 storage, these may turn out to be insufficient, uneconomic or impractical. Mineralisation is therefore an important risk mitigation strategy for the UK's CCS activities. Though less extensively researched than headline sequestration options, interest is developing. Current research has focussed on:

i. theoretical aspects of the thermodynamic and chemical reactivity of CO2, in wet and dry systems, with moderate-high Mg, Ca, Fe content rocks (e.g. basalts and peridotites).

ii. physical configuration of such systems, e.g. hydrofracturing or mining of suitable rocks.

iii. consequential adverse energy, cost and carbon footprint impacts.

Research is now moving towards first pilot implementations and this project seeks to follow suit for the UK. The research will undertake investigations of both "wet" and "dry" mineralisation techniques using basaltic scoria and lava collected from Ascension, to determine the feasibility of CO2 mineralisation in these deposits as an effective means of offsetting the UK carbon footprint.

Project Partners: Dr Keith Hallam & Dr Fiona Whitaker University of Bristol, Dr John Morris & Mr Barry Wickenden Obsidian Minerals Limited