Detailed explanation
Carbon Capture and Utilisation (CCU) is an innovative technology for reducing carbon dioxide (CO2) emissions. The greenhouse gas is not only captured, but also utilised in a meaningful way.
Carbon Capture and Storage (CCS) technology is different. Here, the CO2 is merely stored. CCS technology emphasises the economic use of the captured carbon dioxide.
Significance and benefits of CCU technology
The existing CO2 mitigation measures alone are not sufficient to effectively limit the increase in carbon dioxide in the atmosphere. The use of CO2 as a raw material is therefore prioritised in order to create both economic and ecological benefits.
Methanisation: a promising approach
One promising approach within CCU technology is methanisation. This process converts CO2 and hydrogen into methane and water, which can be used as a chemical energy carrier.
This method also offers a way to store surplus electricity from renewable energy sources. However, this process requires large quantities of green hydrogen. This brings with it the challenge of CO2-neutral production of this element.
A key advantage of methanisation is that the methane produced can be used in a variety of ways. It can be used to generate electricity and heat or be further processed as a raw material in the chemical industry. Nevertheless, the production of green hydrogen remains a critical factor influencing the economic feasibility of this technology.
Production of synthesis gas
Another utilisation pathway is the production of synthesis gas, a mixture of carbon monoxide (CO) and hydrogen (H2). This gas can be further processed in the chemical industry. But here too, CO2 is ultimately released again.
This means stabilisation rather than an actual reduction in emissions. Synthesis gas can be used in the production of plastics or fuels, for example. This can reduce dependence on fossil raw materials.
The process for producing synthesis gas often involves the so-called water-gas shift reaction. This involves converting CO and water (H2O) into CO2 and H2. Alternatively, synthesis gas can be produced by dry reforming with methane in a catalytic high-temperature process.
However, these processes also require large quantities of green hydrogen. Their application is therefore limited to the availability and economic viability of green hydrogen.
Carbonation of mineral raw materials
A third approach is the carbonatisation of mineral raw materials. In this process, CO2 reacts exothermically with certain rocks or industrial residues to form stable carbonates.
This method occurs naturally in nature over long periods of time. It excludes a renewed release of CO2. Despite the stability and safety of this approach, the economic viability is limited due to the high costs involved.
Carbonation uses mineral raw materials such as calcium or magnesium silicates, which react with CO2 to form stable carbonates. This reaction can be utilised in industrial processes. For example, to treat waste such as steelworks slag or fly ash and bind CO2 at the same time.
This method offers a permanent solution for binding CO2. However, it is expensive due to the infrastructure and energy required.
Other possible uses for CO2
In addition to these three main approaches, there are other ideas for the economic utilisation of CO2. For example, photocatalysis, dream reactions or biological utilisation methods. However, these technologies are often still in the early stages of research and are currently not widely applicable.
Photocatalysis
Photocatalysis uses light energy to accelerate chemical reactions that convert CO2 into valuable products. This technology has the potential to convert CO2 into hydrocarbons or alcohols. These can then be used as fuels or chemicals. However, the main disadvantage is the currently still low efficiency and the high cost of the required catalysts.
Dream reactions
Dream reactions are innovative chemical reactions. In theory, they are highly efficient at converting CO2 into useful products. However, the reactions are often not yet practically realisable. They require further research and development to test their feasibility.
Biological utilisation pathways
Biological utilisation pathways use microorganisms or plants to convert CO2 into biomass or bio-based products. These approaches have the potential to be sustainable. However, they require extensive agricultural land or special biotechnological processes, which can also be resource-intensive.
CCU as part of the circular economy
An important aspect of CCU technology is its potential role in creating a circular economy.
By using CO2 as a raw material, waste products can be minimised and valuable materials can be produced at the same time. This can reduce dependence on fossil fuels and minimise the environmental footprint of industrial processes.
Challenges and prospects
Despite the promising approaches and technologies, CCU projects face various challenges. One of the biggest hurdles is the economic viability of the processes. Many of the technologies currently available are costly and require significant investment in infrastructure and research. In addition, the availability of green hydrogen is a critical factor influencing the feasibility of several CCU methods.
Another important issue is the scalability of CCU technologies. Some methods are already successful in the laboratory and in pilot projects. However, they still need to be implemented on an industrial scale. This requires further research and development as well as support from political framework conditions and funding programmes.
Furthermore, environmental and social aspects must also be taken into account when implementing CCU technologies. This includes assessing the environmental impact of the various processes and ensuring that they are sustainable and socially acceptable.
Carbon capture and utilisation (CCU) is therefore a promising approach to reducing CO2 emissions. As is the utilisation of CO2 as a valuable raw material. While some technologies are already advanced, others still require substantial research and development.
CCU alone is not enough to achieve the global climate targets. However, it can play an important role in a comprehensive approach to tackling climate change.
CCU and CCS: differences and synergies
Carbon Capture and Utilisation (CCU) and Carbon Capture and Storage (CCS) are complementary technologies that aim to reduce CO₂ emissions. While CCS aims to permanently store CO₂ in geological formations, CCU focuses on using CO₂ as a raw material and converting it into valuable products such as fuels, chemicals or building materials.
CCU offers an economic advantage as it can replace fossil raw materials and contribute to the circular economy. CCS, on the other hand, is particularly suitable for binding unavoidable emissions from heavy industries in the long term. Both approaches can be used in combination to increase the efficiency of emissions reduction and achieve global climate targets more quickly.
