SiteChar - Frequently Asked Questions

Do you have questions on the project or on site characterisation procedures?
Please, send your questions to info@sitechar-co2.eu

Science &Technology

1. What is CCS?

Carbon capture and storage

2. What is the difference between an onshore and an offshore storage site?

For the storage of CO2, there is no difference between onshore and offshore. An onshore site is on land (on the continent) while an offshore site is at sea bottom. CO2 can be stored in underground layers deep below the surface, at depths greater than 800 m. Layers that are suitable for CO2 storage are can be found below the surface, both onshore and offshore. The only difference is that the installations at the surface (the injection location) are located onshore or offshore.

3. What does CO2 geological storage really mean?

You can find an answer to this question in the CO2GeoNet brochure on CO2 geological storage, now available in 26 languages at this link http://www.co2geonet.com/NewsData.aspx?IdNews=44&ViewType=Old&IdType=18

4. How do you select a suitable site for CO2 storage?

The selection of a storage site suitable for CO₂ storage is a long process, quite similar to the search for oil or gas fields. A detailed image of the layers deep below the surface is made, using seismic waves (sound wave reflections of the different layers). This shows the geologist the suitable locations. A test well is then drilled to take samples of the layers. This shows whether there are suitable layers for storage and whether there are suitable layers that prevent the CO₂ from moving slowly back to the surface. Examples of such layers (‘cap rocks’) are clay, which does not allow CO₂ to pass, and salt, which is an even better seal. Then, when a good layer is found, the test well, or a different, new well, is used to do an injection test. This is necessary to see whether the layer can really be used and whether all the CO₂ that must be stored can be stored in the layer.

5. Which are the important issues to be considered when selecting a CO2 storage site?

The main issue to be addressed is about the storage safety of the site. In addition a full set of economic considerations have to be taken into account. This includes the vicinity of the source of CO2, e.g. a production or power plant, CO2 injection rates and capacity of the storage formation, necessary technical and personnel expenses for injection of CO2 into the formation, and monitoring of the site.

6. How do you know how much CO2 you can store in a site?

The amount of CO2 potentially injected into a given storage site depends on a number of factors. The most important ones are: the available pore space in the storage site, the pressure increase related to the CO2 injection, the number of suitable injection sites, and the injectivity (how easy or difficult injecting is) into the storage formation. To estimate the total effective storage capacity is therefore a process which needs to take into account multiple parameters related both to the reservoir’s characteristics and to injection technology.

7. What does a CO2 storage site look like?

A CO2 storage site is comparable with a petroleum exploration site, i.e. it is composed of a reservoir and a cap rock in the subsurface and of adequate technical installations at the surface. However, instead of extracting petroleum from the site CO2 is injected into the reservoir formation.

8. Where is CO2 going to be stored?

A storage site uses underground layers deep below the surface (800 metres or more), in which CO2 is injected. In most cases, the layer in which CO2 is stored (the reservoir) is a layer of sandstone. The sandstone consists of very small sand particles that have been glued together under the high pressure and temperature that exist at depth. Between the particles there is some space (“pores”) filled with salt water, but sometimes there is natural gas (gas field) or oil (oil field). Some of this space can be available for storing CO2. The area of the sandstone reservoir is of the order of several kilometers by several kilometers.

9. What does multicompartment storage complex mean?

A storage location uses layers deep below the surface, in which CO₂ is injected. In most cases, the layer in which CO₂ is stored (the reservoir) is a layer of sandstone. The sandstone layer can be broken up into a number of compartments that are not connected. In that case, several wells are needed to inject CO₂ in each compartment. This is what is called a multicompartment storage complex: a reservoir that consists of several parts that are not connected.

10. What are the costs of CCS?

The European Technology Platform for Zero Emission Fossil Fuel Power Plants (ZEP) has released a key report for estimating the costs of CCS, download the summary report

Related Document: Overall-CO2-Costs-Report.pdf

11. What are the costs of Capture?

The European Technology Platform for Zero Emission Fossil Fuel Power Plants (ZEP) has released a key report on Carbon Capture costs estimation, download report

Related Document: CO2-Capture-Report.pdf

12. What are the costs of Transport?

The European Technology Platform for Zero Emission Fossil Fuel Power Plants (ZEP) has released a key report on Carbon Transport costs estimation, download report

Related Document: CO2-Transport-Report.pdf

13. What are the costs of Storage?

The European Technology Platform for Zero Emission Fossil Fuel Power Plants (ZEP) has released a key report on Carbon Storage costs estimation, download report

Related Document: CO2-Storage-Report.pdf

14. Where can I find information on European CCS Demonstration Projects?

https://www.ccsnetwork.eu/ - The European CCS Demonstration Project Network

Login

FAQ

Science &Technology

1. What is CCS?

2. What is the difference between an onshore and an offshore storage site?

3. What does CO2 geological storage really mean?

4. How do you select a suitable site for CO2 storage?

5. Which are the important issues to be considered when selecting a CO2 storage site?

6. How do you know how much CO2 you can store in a site?

7. What does a CO2 storage site look like?

8. Where is CO2 going to be stored?

9. What does multicompartment storage complex mean?

10. What are the costs of CCS?

11. What are the costs of Capture?

12. What are the costs of Transport?

13. What are the costs of Storage?

14. Where can I find information on European CCS Demonstration Projects?

Policy & Regulation

1. EU Regulation - Directive

2. European Directive Guidance Document 1

3. European Directive Guidance Document 2

4. European Directive Guidance Document 3

5. European Directive Guidance Document 4

6. Is my national regulatory system ready for CCS?