CO2 storage facilities
Successful capture technologies result in significant amounts of highly concentrated CO2 – often of the order of megatonnes per annum. For this reason, the permanent, secure geological storage of CO2 fulfils an important function as other technologies will not be available on a large-scale for the foreseeable future.
Following on from promising pilot tests on geological storage in saline aquifiers (e.g. in the CO2SINK project in Ketzin), these technologies must now be transferred to larger demonstration systems as the next step. The focus here is on natural gas fields that have been almost fully exhausted and also on larger saline aquifiers as geological storage facilities.
The various separation technologies available result in CO2-rich gases containing various impurities. A detailed understanding of the interactions of the various gases with the ground will play a significant role in the safe storage of CO2 in the long term.
Also of major importance when taking strategic decisions is detailed knowledge of the "offshore and onshore" storage potential available under the seabed and underground on land. Suitable monitoring technologies have to be developed and refined for these storage facilities to ensure that monitoring can be conducted during and after injection, alongside the application of these technologies in exploration for suitable storage areas. The development of seals that are safe and reliable in the long-term for geological storage facilities is of major importance.
Influence of CO2 exhaust gas quality on transport, injection and storage
- Thermodynamic and general engineering behaviour of CO2 and CO2-gas mixtures
- Quality requirements that apply to exhaust gas CO2 for transport and injection
- Experimental investigation of corrosion rates of borehole steels as a function of the concentration of various components of the CO2 mixture
- Increasing the long-term corrosion resistance of the borehole casing
- Experimental and analytical investigations of the petrophysical and geochemical properties of rock types that are subject to contact with CO2 and CO2-gas mixtures
- Influence of impurities in CO2 on the storage facility and the cap rock
Information system for CO2 storage rock and cap rock
- CO2 storage atlas: Systematic survey, classification and evaluation of storage sites in Germany
- Specific exploration and development technologies for geological storage facilities
- Characterisation of selected storage and cap layers: Geology, lithology, hydrology, capacity, injectivity, reactivity, stability
- Permeability of storage and cap rock for supercritical CO2
- Leakage and reaction behaviour of naturally occurring CO2 deposits
- Creation of a database of parameters and models for the evaluation of storage suitability
Development of methods to increase the efficiency, safety and reliability of storage
- Numerical simulations of the geoprocesses in the storage facility and the geological platform in the case of CO2 injection
- Optimisation of thermodynamic behaviour for CO2 and CO2 mixtures in the case of injection
- Improvement of geoscientific monitoring technologies for CO2 storage as regards spatial and temporal distribution, penetration depth, sensitivity, reliability and costs
- Development of technology for safely sealing CO2 borehole storage facilities after the end of a project and demonstration of the long-term seal integrity of the storage facility
- Monitoring of geologically stored CO2 and verification of planned spreading in the ground during the operation and post-operation phases
- Development of methods of qualitative and quantitative risk assessment
The focuses required for current and future research and development for CO2 storage are the following three areas:
1. Influence of CO2 exhaust gas quality on transport, injection and storage
This includes: investigations of the thermodynamic and general engineering behaviour of CO2 and CO2-gas mixtures; quality requirements that apply to exhaust gas CO2 for transport and injection; experimental investigation of corrosion rates of borehole materials; investigations of the long-term corrosion resistance of the borehole casing; experimental and analytical investigations of the geochemical properties of rock types that are subject to contact with CO2 and CO2-gas mixtures; and influence of impurities in CO2 on the storage facility and the cap rock. These areas require targeted R&D efforts, as the purity requirement directly affects the upstream capture and CO2 treatment technology (compression, distillation/flash). The higher the requirements, the greater the technical complexity and costs of the upstream technology. High purity requirements can even determine the choice of overall CCS approach.
2. Information system for CO2 storage facilities and cap rock
This includes: systematic surveying, classification and evaluation of storage sites in Germany (one storage area is currently at the development stage); specific exploration and development technologies for geological storage facilities; characterisation of selected storage and cap layers; investigation of leakage and reaction behaviour of naturally occurring CO2 deposits; and creation of a database of parameters and models for the evaluation of storage suitability.
3. Development of methods to increase the efficiency, safety and reliability of storage
This includes: numerical simulations of geoprocesses; optimisation of thermodynamic behaviour for CO2 and CO2 mixtures in the case of injection; improvement of geoscientific monitoring technologies for CO2 storage as regards spatial and temporal distribution, penetration depth, sensitivity, reliability and costs. In addition, development work is required in the following areas: technology for safely sealing CO2 borehole storage facilities after the end of a project; methods for the verification of planned spreading in the ground (operation and post-operation phases); and methods of qualitative and quantitative risk assessment.
The operation of power plants with CO2 capture technology creates a need for transport and storage of carbon dioxide. Since start of the 1970s, a CO2 pipeline grid with a transport capacity of around 45 million t p.a. has been built in the USA. This grid now has a total length of around 3,100 km. The purpose of this grid is to transport CO2 for use in oil production in order to increase extraction rates. CO2 pipelines are thus state-of-the-art technology. CO2 pipeline grids with a total length of around 4,000 km are currently installed worldwide.
The main candidates for CO2 storage in Germany are deep saline aquifiers. Natural gas fields that have been exhausted have a significantly lower storage capacity. Offshore storage of CO2 represents a further alternative. There are major uncertainties associated with current data on potential storage capacity. Based on the amount of CO2 emissions from current power plants in Germany, the static range of onshore storage facilities would cover a maximum of two generations of power plants (around 80 years).
The largest current storage projects in the world are in Norway (Sleipner, 1 million t CO2 p.a., saline aquifier), Algeria (In Salah, 1.2 million t CO2 p.a., saline aquifier) and Canada (Weyburn, 1 million t CO2 p.a., petroleum storage facility). Alongside these, there are a range of smaller projects worldwide that are being used to investigate various challenges associated with CO2 storage. As part of the EU's CO2SINK research programme, a storage project was executed from 2004 to 2010 in Germany (Ketzin, 0.06 million t CO2). Further research projects are delayed (e.g. Altmark, Birkholz/Beeskow). Initial indications as regards the future legal framework will be provided by an act to regulate the capture, transport and long-term storage of carbon dioxide that is in negotiations between the Upper and the Lower House of German Parliament in 2012.
5 current research projects
CO2SINK joint project – CORTIS subproject
Organisation carrying out research: Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences
Project number: 0327735A
Purity requirements for CO2 mixtures after capture from power plants on the basis of thermodynamic and engineering investigations
Organisation carrying out research: DBI Gas- und Umwelttechnik GmbH, Leipzig
Project number: 0327790B
Combined experimental geomechanical and geochemical investigations
Organisation carrying out research: Martin-Luther-Universität Halle-Wittenberg - Faculty of Natural Sciences III - Institute of Geosciences
Project number: 0327790D
Process gas definition, transport grid and corrosion
Organisation carrying out research: Technische Universität Hamburg-Harburg - Institute of Energy Systems
Project number: 0327790E
System and phase behaviour of CO2-rich streams from power plants in the presence of moisture
Organisation carrying out research: Technische Universität Hamburg-Harburg - Institut für Thermische Verfahrenstechnik
Project number: 0327790F