Scientists propose cold storage of CO2

When it comes to fighting climate change, bioenergy has one major advantage over carbon ‘neutral’ renewables such as solar, wind, geothermal or tidal energy: it can be used as the foundation stone of a radical carbon negative energy system. Scientists call such a system ‘Bio-Energy with Carbon Storage’ (BECS) and it consists of the following ‘geo-engineering’ strategy: plant energy crops at strategic locations around the globe; allow the biomass to capture CO2 from the atmosphere; use the crops as a biofuel in coal or biomass power plants; and then capture and store the CO2 emissions underground. The result is a carbon-negative cycle, which can take us back to pre-industrial CO2 levels in a matter of decades.

The viability of this geo-engineering option depends on the development of reliable carbon capture and storage (CCS) techniques.

The coal industry is investing heavily in CCS and has been looking at storage sites as diverse as salt tables, depleted gas and oil fields, and warm sediments in oceans. But doubts remain over the long-term stability of this type of sequestration; the risk of CO2 leakage remains a major obstacle.

Cold storage

Researchers from the University of Leicester and the British Geological Society (BGS) have now come up with a new proposition: CO2 can be stored as a liquid or a solid in huge, cool underground geological aquifers or reservoirs and stay there harmlessly for many thousands of years. They have already identified sites in Western Europe that would be suitable. Their research is to be published in the journal Planet Earth.

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