How to store CO2 safely
It is expected that we shall continue using fossil fuels for several decades to come. In the case of large "point sources" such as power stations, it is possible to prevent the carbon dioxide that is released during the combustion process from finding its way back into the atmosphere by capturing and storing it − for example in empty (i.e. depleted) gas fields.
CO2 is then injected into the earth's surface. The CO2 migrates through the network of pores in the rock, which is naturally capped by a further, non-porous layer. This layer ensures that the injected gas cannot leak back to the surface. The most appropriate storage sites for CO2 are depleted gas fields, saline aquifers (deep-lying layers of porous rock) or deep coal beds. In the case of the coal beds, CO2 injection can often pave the way for extraction of methane gas, since carbon dioxide and methane exchange places in the coal layer.
In global terms, underground storage of CO2 is still only used on a limited scale, for example at the Sleipner field off Norway. However, CO2 injection has been used to assist in the recovery of oil and gas for several decades (e.g. in the USA and Turkey).
To ensure the safety of this process, large-scale testing is needed for possible interaction between CO2 and reservoir rock (also known as mineralisation). This interaction can cause rock to dissolve and result in pore blockage due to remineralisation. The phenomenon is dependent on the composition of the rock. It will also be necessary to develop cost-effective, seismic methods whereby a storage reservoir can be continuously monitored.
How is TU Delft contributing?
Underground storage in aquifers, coal beds and empty gas reservoirs in the Netherlands
Models of coal beds and porous rock (together with their properties) are needed in order to predict how quickly the carbon dioxide will migrate through these formations. Using high-pressure equipment, simulations are conducted under specific temperature and pressure conditions in order to establish what happens at depths of up to two kilometres below the surface. Aside from storage in coal seams and injection into depleted gas fields, TU Delft is investigating geophysical methods for monitoring the behaviour of CO2.
In addition, researchers in Delft are developing seismic measurement techniques that can be used for measuring and tracing any leakage. Read more about the research.
CATO
TU Delft has joined forces with the Universities of Utrecht, Twente and Amsterdam, ECN (Netherlands Energy Research Foundation), TNO (Netherlands Organisation for Applied Scientific Research), Shell, E.on and other partners in a knowledge consortium (CATO-1, CATO-2), which aims to develop a form of CO2 Capture, Transport and Storage that is suitable for the Netherlands. The programmes have been initiated by the Dutch government.
Plus:
- CO2 sequestration in gas hydrates
- Converting CO2 into fuel
- CO2 capture
- CO2 infrastructure
Links and contact
- Read the press release: "Storing CO2 like Mother Nature does".
- Contact the Delft Energy Initiative for further information about the research into CO2 capture and storage.
