Supported by Linde, the GFZ German Research Centre for Geosciences is investigating the feasibility of permanent underground CO2 storage.
This research takes place under the umbrella of the CO2MAN research project, successor of the CO2SINK project, which was successfully concluded in March 2010.
The carbon dioxide for Ketzin originates at the Leuna industrial park, 175 kilometres away, where it is produced from refinery offgas. Linde purifies it in a multi-step preparation process and liquefies it at between – 35°C and – 25°C.
The liquefied CO2 bound for Ketzin is delivered by road tanker and initially stored in Linde silos. To prepare it for injection, it is then returned to a gaseous state by increasing the temperature to 30°C and the pressure to between 70 and 100 bar.
The technology used here is similar to that of a water carbonator, where carbon dioxide is injected from a metal cylinder into a water bottle. In Ketzin, this process occurs 700 metres below ground.
At the pilot site in Ketzin, researchers began pumping 1.5 tonnes of carbon dioxide per hour into the plutonic rock through arm-width pipes in June 2008. The CO2 is injected into saline aquifers, i.e. porous sandstone reservoirs filled with highly concentrated salt water. If the gas is injected at high enough pressure, a certain amount dissolves into the water. The rest of the CO2 forces the water out through the pores in the rock.
What happens next is the actual focus of the research project - the gathering of measurements that will give the first detailed picture of the way CO2 dissipates underground.
The most important question of all is whether the final storage sites are leak-proof. The prevailing view among geologists is that the layer of plaster and clay that caps the several square-kilometre sandstone formation should be completely impenetrable, even if it had to cope with ten times the planned 60,000 tonnes of CO2.
The amount injected at Ketzin is also at a level naturally emitted by bacteria or from rock, for instance through soil erosion.
At a glance | |
| Name: | CO2 separation |
| Country: | Germany |
| Raw material: | CO2 |
| Process technology: | CO2 storage |
| Cooperation partner: | GeoForschungs- Zentrum GFZ |
| More information: | www.co2ketzin.de |
