Detailed explanation
Climate change is one of the greatest challenges of our time. A central cause of this change is the high level of greenhouse gases in the atmosphere. In particular, carbon dioxide (CO2), which is released by human activities such as the burning of fossil fuels. Carbon capture and storage technology has been developed to reduce these emissions. And thus mitigate the effects of climate change.
Climate change is one of the greatest challenges of our time. A central cause of this change is the high level of greenhouse gases in the atmosphere. In particular, carbon dioxide (CO2), which is released by human activities such as the burning of fossil fuels. Carbon capture and storage technology has been developed to reduce these emissions. And thus mitigate the effects of climate change.
How carbon capture technology works
CCS is based on a three-stage process: capture, transport and storage. Each of these steps is crucial. This is the only way to ensure that CO2 is safely and effectively removed from the atmosphere. It is then trapped in geological formations.
1. Capture
Capture is the first step in the CCS process and involves capturing CO2 from industrial waste gases. This can be done in different ways:
- Post-combustion capture: in this method, CO2 is extracted from the exhaust gases after the combustion of fossil fuels. This is the most widely used method and can be retrofitted in existing power stations and industrial plants.
- Pre-combustion capture: Here, the fuel is converted into a mixture of hydrogen and CO2 before combustion. The CO2 is then separated before combustion and the hydrogen is burnt.
- Oxyfuel combustion: Here, the fuel is burned in a pure oxygen environment. As a result, the exhaust gases consist mainly of CO2 and water vapour. The water vapour can be easily condensed, leaving almost pure CO2.
2. Transport
Once the CO2 has been captured, it must be transported to a suitable storage site. Transport can take place in various ways:
- Pipeline: The most common and efficient way to transport CO2 is through pipelines. These can move large quantities of CO2 over long distances. They are particularly cost-effective in regions with existing pipeline infrastructure.
- Tankers: In situations where pipelines are not practical, CO2 can also be transported by ship or lorry. However, this is often more expensive and less efficient than transport by pipeline.
3. Storage
The final step in the process is the permanent storage of CO2. There are various methods of storage:
- Geological storage: this is the most commonly used method. It involves injecting CO2 into deep underground rock formations. Suitable formations include depleted oil and gas fields, deep saline aquifers and undeveloped coal deposits.
- Mineralisation: In this method, CO2 is allowed to react with minerals. This creates stable carbonates that can then be stored permanently.
- Ocean storage: This method is the subject of much debate. There are considerable concerns about the potential environmental impact. It is therefore rarely used.
Advantages and challenges of carbon capture and storage
Advantages
CCS offers several advantages that make it an attractive technology in the fight against climate change:
- Reduction of CO2 emissions: By capturing and storing CO2, CO2 emissions can be significantly reduced. It is assumed that CCS can capture up to 90% of CO2 emissions from fossil fuel power plants.
- Industry support: CCS allows existing fossil fuel plants to continue operating while reducing emissions. This can be of particular interest to countries that are heavily dependent on fossil fuels.
- Transition technology: As the transition to renewable energy progresses, CCS can be an important interim solution. CO2 emissions are permanently reduced.
The challenges
Despite the promising advantages, the implementation of CCS faces considerable challenges:
- High costs: building the infrastructure to capture, transport and store CO2 is extremely costly. This includes the cost of modifying existing plants and building new pipelines and storage facilities.
- Technological challenges: CO2 capture technologies are not yet fully mature. They require further research and development to become cost-effective and efficient.
- Storage capacity: The availability of suitable geological formations for storing CO2 is limited. There are also concerns about the long-term stability and safety of these storage facilities.
- Public acceptance: There is significant public opposition to CO2 storage projects, particularly due to safety concerns and potential environmental impacts. This can make the realisation of such projects more difficult.
Utilisation of CCS in the steel industry
CCS is of particular interest to the steel industry as large quantities of CO2 are released during the steel production process. The blast furnace route in particular, in which coke and coal are used to reduce iron ore, produces considerable CO2 emissions. The use of renewable energy sources cannot fully compensate for this.
CCS as an interim solution
CCS can represent an important interim solution here. By implementing CCS technologies in steelworks, CO2 emissions can be significantly reduced. Until carbon-neutral processes, such as direct reduction with hydrogen, are widely available. Blast furnaces can then be converted so that the captured CO2 is efficiently captured and stored.
Challenges in the steel industry
However, the application of CCS in the steel industry faces similar challenges as in other sectors:
- High implementation costs: retrofitting existing blast furnaces with CCS technologies is cost-intensive. Building the necessary infrastructure to transport and store the captured CO2 also poses considerable financial hurdles.
- Technical complexity: The integration of capture technology into the ongoing production process is technically demanding. It requires specialised knowledge and technologies.
- Long-term perspective: CCS is seen as a transitional technology. It is only needed until carbon-neutral production processes such as direct reduction can be implemented across the board.
Future prospects for CCS
The future of CCS depends on various factors, including technological developments, economic conditions and political support. Some of the possible developments in this area are
Technological innovations
Ongoing efforts are being made to improve the efficiency and cost-effectiveness of CCS. Research and development is focussed on new methods of carbon capture and storage and on improving existing technologies. Innovations could lead to CCS becoming more cost-effective and practical in the future.
Political support
Governments around the world play a crucial role in promoting CCS technologies. Policy measures and financial incentives could include
- Subsidies
- Tax breaks
- Stricter emissions regulations that encourage companies to invest in CCS and implement these technologies
Economic factors
The economic viability of CCS depends heavily on the cost of CO2 emissions. With increasing CO2 prices and stricter emission regulations, CCS may become more economically attractive. Companies may then be more willing to invest in this technology. In order to fulfil their emissions obligations and avoid potential financial penalties.
Integration with other technologies
CCS can also be used in combination with other CO2 reduction technologies.
Here is an example:
CO2 capture and storage can generate negative emissions through biomass combustion. This removes CO2 from the atmosphere. This technology is also called Bioenergy with Carbon Capture and Storage (BECCS).
Such integrated approaches could further increase the effectiveness of CCS.
CCS in the context of methane leakage and renewable energies
An important aspect to consider when assessing CCS is methane leakage along the fossil fuel supply chain. Methane is a greenhouse gas with a much stronger climate impact than CO₂. Leakages during the extraction, processing and transport of natural gas can have a significant impact on the carbon footprint of CCS. To make CCS more effective, stricter monitoring and reduction measures for methane emissions are therefore required.
In addition, CCS can be used as a complement to renewable energy. While renewable energy sources such as wind and solar power enable carbon-free energy production, CCS technologies can help reduce unavoidable CO₂ emissions from industries or fossil-fuelled power plants. This hybrid approach can accelerate the transition to a carbon-free economy by combining both approaches.
