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Microbial Dolomites PDF Print E-mail
Written by david brunnen   
Tuesday, 01 May 2007 00:00

A new technique to help rid the world’s atmosphere of excess CO2. 

ImageThe build-up of greenhouse gases in the atmosphere, especially carbon dioxide (CO2), is linked to global warming, sea-level rise, changing weather patterns and a multiplicity of associated problems ranging from food production to massive social displacement and human survival.

 

International schemes to reduce atmospheric CO2 levels are difficult to implement and monitor.   Emissions can be reduced, but not eliminated, by increasing the efficiency of power-producing equipment, by carbon capture and storage, and by harnessing wind, solar, hydro, tidal and wave power.  These approaches, along with actions to curb fossil fuel consumption are, however, not yet sufficient, and atmospheric levels of CO2, already too high, will continue to rise.

 

Kyoto Protocol signatories can meet part of their obligations to reduce greenhouse gas emissions from fossil fuel consumption by increasing land carbon sinks. However, there are serious concerns about the permanence of current carbon sinks (typically involving afforestation), and the accuracy with which carbon sequestration can be quantified and verified.  Our Microbial Dolomite (MD) Global research project offers the potential for significant sequestration of atmospheric carbon in a system that is sustainable and can satisfy Kyoto criteria for permanence, quantification, verification and additionality.

 

MD production can use land unsuitable for agriculture and is a low-energy/low-cost technique for removing substantial quantities of CO2 from the atmosphere.   As an example of operational scale, a rain forest, such as that in SE Australia, delivers an annual sequestration of around 45m tonnes of atmospheric carbon.  Cautious model projections indicate that replication at this scale of sequestration is both practical and economically viable given sufficient engineered MD systems; it can potentially act as a carbon management tool.   The solid carbonate (dolomite) output is also expected to become a valued resource for construction and land engineering.

 

This MD process already happens in nature

The Coorong distal lakes of South Australia provide examples of relatively rare modern primary precipitation of carbonates in an annual cycle, where the kinetic inhibitors to carbonate precipitation are removed by microbial mediation of ambient waters in evaporative, hypersaline conditions.    Our published research has shown that this natural process can now be replicated in the laboratory.  Microbial Dolomites Global – an expert group of leading researchers, environmental economists and investors – seeks to develop and scale the process to make a major contribution towards off-setting atmospheric carbon dioxide levels.  

MD processes – essential Techniques/Technologies

A full understanding of how the anaeorobic microbial ecosystem mediates saline water chemistry to facilitate the precipitation of carbonate minerals, in particular dolomite, is an essential prerequisite to the project. The fundamental microbiogeochemical processes and controls operating in such a system are now known to us, and have been proven in experiments, but in order to maximise potential we need to scale up operations and create the necessary conditions to sustain the appropriate microbial ecosystems in open tanks. The research programme includes:

  • sampling and RNA-sequencing techniques to more precisely quantify and identify many of the constituent anaerobic microbes in the responsible microbial ecosystems;
  • analysis of gas flux and techniques for managing CO2 absorption into saline solutions to maintain sustainable balance with precipitated outputs.
  • sampling and monitoring the chemistry of lake water and lake-sediment pore-waters using meters, ion-selective microprobes and titration equipment;
  • sequestering of by-product hydrogen sulphide using e.g. iron salts;
  • quantification and verification techniques for measuring the volume or mass of dolomite precipitated.
  • civil engineering studies for technology transfer, initial development of pilot bio-reactors and analysis of potential sites.

For details of Dr Wright's publications click here 

 

See also 'Climate Change - digesting the problem'.

 

 

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