Background

Following the Kyoto Protocol, the EU is committed to a reduction of 8% in greenhouse gas emissions in the implementation period 2008-2012. One way of reducing CO₂ emissions is to capture CO₂ from industrial point-sources and store it underground.

Approximately one-third of anthropogenic emissions arise from transport, one-third from industrial and domestic sources and one-third from power generation. While achieving substantial reductions in emissions from either of the first two will be a long-term process, the technology to capture CO₂ from power plant is already available and could lead quickly to significant reductions in emissions —provided mechanisms are available to dispose of the CO₂ thus captured. The capture and underground storage of industrial quantities of carbon dioxide is currently being demonstrated at the Sleipner West (http://www.statoil.com/statoilcom/svg00990.nsf/web/sleipneren?opendocument) gas field in the Norwegian sector of the North Sea. It has been suggested that such geological sequestration could offer potential long-term storage of significant quantities of CO₂ that would otherwise be emitted to the atmosphere.

However, if geological sequestration of CO₂ is to become acceptable, certain key issues must be addressed. These include the long-term safety and stability of storage underground and the potential effects of leakage from an underground storage reservoir. Natural CO₂ fields, and places where CO₂ is actively migrating from underground to the Earth's surface, are widespread in Europe and elsewhere in the world. These are direct natural analogues for the geological storage (and leakage) of anthropogenic CO₂. They therefore provide natural laboratories in which to address key issues for geological sequestration.

EU policies are focussed on sustainable energy production and afforestation but can these achieve necessary reductions? The EU TERES report estimated the overall potential renewable energy to be over 200 million tonnes of oil equivalent of final energy consumption for the 12 member states. It is predicted that changing energy production practices (switching to natural gas and nuclear energy from coal and oil) and increased efficiency in the transport sectors will contribute significantly to the EU's target reduction for the Kyoto protocol. Nevertheless, by 2010 renewable energy is only expected to represent 15% of all primary energy use. Within the EU there are still significant reserves of fossil fuels (some 200 years supply of coal, 50 years supply of natural gas). Further, Kyoto is widely recognised as only the first step towards achieving the necessary large-scale reductions in GHG emissions. Other mechanisms are therefore proposed that involve different sinks for the emitted CO₂. Sleipner and Weyburn indicate that underground sequestration can be a cost-effective measure on the short-term. Do we know it is a viable option in the medium to long term?