On August 29, 2013, the GFZ German Research Centre for Geosciences terminated the injection of carbon dioxide (CO2) near the town Ketzin/Havel after about five years of operation. Injection work at the Ketzin site has been safe and reliable from June 2008 till August 2013. In total 67,271 tons CO2 were injected at the pilot site. The GFZ reported about the stop of injection via a press release.
Storage operations took place consistently all year long. The GFZ had appointed VNG Gasspeicher GmbH (VGS) to manage the operations. The plant was staffed around the clock in order to monitor and manage the injection. The experienced VGS personnel monitored the delivery of CO2, its intermediate storage in the tank systems and the entire injection process.
The plant engineers and scientists from GFZ held weekly meetings to evaluate the progress of the injection. The plant operated under the requirement that the scientific work programs run safe and in agreement with the operating plans approved by the LBGR (Brandenburg State Agency for Mining, Geology and Raw Materials / Landesamt für Bergbau, Geologie und Rohstoffe Brandenburg).
The CO2 that was delivered to Ketzin was kept in two 50-ton storage tanks. Therein, it was liquid and had a temperature of about -20°C, and the tanks were pressurized to about 18 bar. In order to inject the CO2 into the well or the storage layer, respectively, it was heated to about 35 °C and compressed to 60 bar.
The primary CO2 source for the Ketzin pilot site was food grade CO2 (purity > 99.9 %) from Linde AG. Since June 2008, more than 65,000 tonnes food-grade CO2 have been injected. Only within an experiment from May 04, 2011 to June 13, 2011 a total amount of 1,515 tonnes CO2 (purity > 99.7 %) from the oxyfuel pilot plant Schwarze Pumpe (Vattenfall) was used. This experiment with CO2 from Schwarze Pumpe was the first one worldwide where technical CO2 captured at a power plant was stored.
In the autumn of 2014, a two-week CO2 back-production test at the Ketzin pilot site was successfully completed. In total, 240 tons of CO2 were back-produced from the reservoir. On the one hand, this experiment fulfilled a requirement by the competent authority (Landesamt für Bergbau, Geologie und Rohstoffe Brandenburg - LBGR). For the Ketzin pilot site, it should be demonstrated that a back production of CO2 is possible in principle. On the other hand, during the back production the pressure and temperature conditions were continuously monitored in the CO2 reservoir and in the production well. Afterwards, the values obtained were scientifically evaluated. Also the back produced CO2 was sampled and afterwards chemically analysed. In addition, scientists of the Helmholtz Centre for Environmental Research - UFZ and of the Federal Institute for Geosciences and Natural Resources (BGR). The experiment clearly showed that a safe and controlled back production of CO2 from the reservoir is possible. In respect of a potential CO2 storage on an industrial scale this experiment can be regarded as an important step.
