Carbon Capture, Utilization, & Storage (CCUS) Technologies
The Paris Agreement aims to limit global warming to 1.5-2°C by reducing greenhouse gas emissions. The IEA’s Net Zero Emissions scenario outlines capturing 7.6 Gt of CO₂ annually by 2050 to achieve net zero. Carbon capture, utilization, and storage (CCUS) technologies are crucial, capturing CO₂ at the source, transporting, and storing or reusing it. Despite challenges like high costs, there is growing public and private investment in CCUS innovations like Climeworks’ direct air capture technology.
The main aim of the Paris Agreement is to reduce global greenhouse gas emissions to limit global warming to 2°C this century while continuing efforts to restrict it to 1.5°C. Emissions must rapidly peak and decline, aiming for balance with carbon sinks by 2050.
In particular, the International Energy Agency has studied the Net Zero Emissions scenario, which defines the path to be followed by the global energy sector to achieve net zero CO₂ emissions by 2050. This scenario incorporates all the conditions of the Paris Agreement, intending to attain uncompromising climate, energy access, and air pollution targets. In this scenario, published in 2021, nearly 5 Gt of CO₂ should be removed from the atmosphere annually in the second half of this century. These research topics are not new. As early as 2006, the IEA studied scenarios for limiting CO₂ emissions, using ETP Accelerated Technology (ACT) scenarios to limit emissions to 2005 levels by 2050.
Today, the study of emission limits is crucial to achieving climate objectives. Given that natural carbon sinks are insufficient to balance anthropogenic emissions, engineered solutions are becoming an attractive option for both industry and policy-makers in the hope of meeting climate targets. The role of CCUS is thus at the heart of the matter.
WHAT DOES CCUS MEAN?
Carbon Capture, Use, and Storage technologies aim to capture CO₂ at the source of its production, store it underground and recover it. This involves an industrial and commercial chain from CO₂ capture to transport and storage. Many heavy industries, such as cement, require technologies to significantly reduce their CO₂ emissions in the absence of alternative lower-emission technologies.
CCUS TECHNOLOGY MILESTONES
Capture: The first step is to capture the CO₂, whether it comes from industrial emissions or directly from the atmosphere. Here are the different capture technologies:
Pre-combustion capture: decarbonizing the fuel before it is burned;
Post-combustion capture: recovery of CO₂ through scrubbing of combustion flue gases;
Oxycombustion capture: combustion of carbonaceous fuels in the presence of pure oxygen instead of air;
DAC (Direct Air Capture) technologies: capture CO₂ directly from the air, rather than from plant fumes. There are two sub-types:
Liquid DAC: the air is passed through a chemical solution to remove the CO₂;
Solid DAC: using absorbent filters that create a chemical bond with the CO₂. CO₂ can be captured, stored, and reused.
Transportation: The second step in the process, after the capture stage, is transporting the CO₂. To be transported to a storage site, CO₂ can be conveyed in several ways:
Ship
Pipeline
Tanker truck
Train
Storage: Once transported to the storage site, the CO₂ must be injected underground. There are two possible CO₂ storage sites:
Deep saline aquifers: reservoirs of non-potable salt water located at great depth, representing the greatest storage potential;
Depleted hydrocarbon deposits (oil and gas).
Utilization: Numerous studies have been conducted to analyze the potential for CO₂ re-utilization, but many avenues are still being explored and require further research. Here are a few examples:
Chemical recovery: to produce urea or energy-rich products such as e-fuel;
Biological recovery: by cultivating CO₂-consuming microalgae;
Direct CO₂ recovery: useful for enhanced oil recovery.
MAJOR CHALLENGES
The swift advancement of renewable energies is impacting the development of CCUS technologies in certain sectors, particularly in the electricity industry. Several challenges must be overcome if these technologies are to gain a greater market share, including:
High capture costs;
Security of CO₂ storage and containment over long periods (up to thousands of years);
Regulatory issues;
Realization of low-cost CO₂ recovery solutions.
GROWING INTEREST
There is real public support for the development of these technologies, as demonstrated by the European Union’s ReFuelEU Aviation proposal. From a financial point of view, private and public funds allocated to companies in this sector are increasing. By 2022, global venture capital investment in CO₂ capture companies had reached over 500 million USD. Governments are also taking responsibility for financing these technologies. In the European Union, for example, five large-scale CCUS projects have been selected for funding under the EU’s Innovation Fund 2022 funding call for proposals.
Sources:
https://www.iea.org/energy-system/carbon-capture-utilisation-and-storage/co2-capture-and-utilisation
https://unfccc.int/fr/a-propos-des-ndcs/l-accord-de-paris
https://www.iea.org/reports/global-energy-and-climate-model/understanding-gec-model-scenarios
