CCS

Challenges for CO2 Measurement Technology

At each stage of the Carbon, Capture and Storage (CCS) chain the captured CO2 must be accurately measured. This is necessary for detecting CO2 leakages, but also essential for verification of the CO2 quantity accounted under offsetting within emissions trading scheme (ETS). Only for the amount of CO2 which is safely stored in geological formations emission certificates will be refunded. According to the European Directive on the geological storage of carbon dioxide also the purity of the CO2 must be monitored. For ETS and the requirements of the Monitoring Guidelines uncertainties of less than 1.5 % must be achieved. Therefore the Federal Environmental Agency initiated a research project on the uncertainties and capability of existing continuous emission monitoring systems (CEMS) for CCS. The study was executed by TUEV SUED Industrie Service GmbH*.

Relevant manufacturers of analysing technology were asked to answer a questionnaire regarding measurement of CO2 to contents up to 100 %. The experiences from operators of pilot plants, literature research and own experiences were compiled and evaluated. It yielded that common CO2 analysing technology like non-dispersive infrared spectrometer (NDIR) is theoretically suitable for determine CO2 contents up to 100 %. But all this analysis devices are mechanically not able to cope with the pressures in CO2 pipelines or at the injection sites. Therefore CO2-flow has to be expanded to atmospheric conditions to be analysed. For determine the mass of CO2 the volume respectively the mass flow must be known. Thus, at the next step the existing flow metering technology regarding CO2 in the dense or supercritical stage was evaluated. Orifice plate meters, ultrasonic meters or coriolis meters could measure a CO2 flow but all of them have restrictions and the demanded uncertainties could not be guaranteed under conditions like pressure drops, two-phase conditions or at the supercritical stage. Within the research project existing analysis and flow metering technology were evaluated and the challenges and restrictions were summarized. It identifies main areas of future research and development work on existing technology in order to cope with the identified restrictions. Thus will giving a guideline for the next future regarding this very important aspect of CCS.

The main results were presented to the European Compliance Group at the Federal Environmental Agency in Berlin on the 15th March.

Contact: Kathrin Petrat