Despite the rise of renewable energy and advancements in decarbonisation, global CO2 emissions reached a peak in 2023 and are expected to continue rising in the coming decades. Even nations with strong climate commitments, such as the UK with its goal of zero-carbon electricity by 2035, are still investing in new natural gas-fired power plants to ensure reliable energy. Meanwhile, coal use remains at record levels. While industrial CO2 emissions are declining, the pace is not rapid enough to meet global climate targets. In this challenging context, Carbon Capture and Storage (CCS) technologies are emerging as a critical tool to help achieve climate goals and buy time for other clean technologies to mature.
The Role of Carbon Capture Technologies
Carbon capture technologies are designed to reduce atmospheric CO2 by capturing emissions from industrial processes and power generation. These technologies are divided into two main categories: pre-combustion and post-combustion.
Pre-Combustion Capture
Pre-combustion capture involves removing CO2 from fuels before combustion. This process typically converts fossil fuels into a hydrogen and CO2 mixture, captures the CO2, and uses the hydrogen for energy. This method achieves high capture rates but is mainly applicable in facilities where fuel processing is integrated and often requires higher initial capital costs.
Post-Combustion Capture
Post-combustion capture takes place after fossil fuels are burned. This method uses chemical solvents or other processes to extract CO2 from emissions produced by point sources, such as industrial flue gases. The primary advantage is that these technologies can be retrofitted to existing facilities, making it possible to continue operations while reducing emissions. Post-combustion capture is particularly effective in sectors like power generation and heavy industry, which are responsible for over 60% of global CO2 emissions.
Solvent-Based Methods
Solvent-based methods are among the most established post-combustion technologies. They use solvents, usually amines, to absorb CO2 from flue gases. The CO2 is then released from the solvent through heating, compressed, and transported for further use or storage.
Emerging Technologies: Direct Air Capture and Ocean Capture
Direct Air Capture (DAC)
Direct Air Capture (DAC) is a groundbreaking technology that extracts CO2 directly from the atmosphere. Although it is still relatively new and expensive, DAC holds promise for large-scale CO2 removal. The technology received a significant boost from the Inflation Reduction Act (IRA) in the U.S., which offers tax credits of up to $180 per tonne of CO2 captured and stored. Companies like Climeworks have secured substantial funding to develop DAC technologies further, making them more cost-effective over time.
Ocean Capture
Ocean capture involves removing CO2 from seawater, enhancing the ocean’s natural ability to absorb atmospheric CO2. This method not only aids in CO2 removal but also addresses ocean acidification, which negatively impacts marine biodiversity.
The Economics of Carbon Capture
Currently, the cost of carbon capture remains high. For example, capturing CO2 from iron and steel production ranges between $40 and $100 per tonne, while DAC can reach up to $342 per tonne. With carbon prices around €70 per tonne in Europe and U.S. tax credits offering up to $85 per tonne for industrial capture and $180 for DAC, many carbon capture technologies still face economic challenges.
However, the outlook for reducing costs is promising. Technological advancements have led to significant cost reductions. For instance, DAC costs have dropped from the American Physical Society’s 2011 prediction of $600 per tonne to as low as $100 per tonne in some cases. Additionally, industrial point-source capture costs are expected to fall below $30 per tonne.
Beyond Capture: The CCUS Value Chain
Carbon capture is just the beginning of a broader carbon capture, utilisation, and storage (CCUS) value chain. The subsequent processes—sequestration and CO2 utilisation—introduce additional economic and commercial factors. While capturing CO2 is a crucial first step, the overall value chain must balance the costs of processing with the rewards available in carbon markets and utilisation sectors.
In summary, CCS technologies are vital for meeting global climate goals and providing a bridge to more mature clean technologies. Despite current economic challenges, ongoing advancements and supportive policies offer hope for CCS becoming a cornerstone of climate mitigation strategies.