Carbon capture, use and storage (CCUS)
Carbon capture, use and storage: technology, innovation and implementation
Decarbonisation Climate change
Organisations such as the International Energy Agency (IEA) consider carbon capture, use and storage (CCUS) technology essential to achieving net zero emissions targets and tackling climate change. This technology not only helps reduce emissions but also enables the reuse of CO₂ in sectors such as construction and synthetic fuel production.
Carbon capture, use and storage (CCUS) technology captures carbon dioxide before it is released into the atmosphere and either reuses it in various applications or stores it in deep underground reservoirs. Its aim is to reduce the climate impact of certain fossil fuel-intensive sectors, such as heat generation and processes in heavy industry.
The process comprises four stages: capture, transport, and use or storage. Current technologies are not yet fully mature and include direct air capture and membrane systems, which can be installed in existing industrial facilities to reduce their carbon footprint. According to the International Energy Agency (IEA), as of 2024 there were around 700 carbon capture projects at various stages of development, although many of them do not yet have a final investment decision.
What is carbon capture and storage?
Carbon capture, use and storage (CCUS) is a process that uses technologies to separate CO₂ from other gases emitted by industrial facilities, preventing it from reaching the atmosphere. The CO₂ is compressed or liquefied and, if not reused on-site, is transported to another facility where it is either used in specific applications or permanently stored in underground reservoirs, such as depleted oil fields. The International Energy Agency (IEA) considers CCUS a necessary technology for achieving greenhouse gas (GHG) reduction and sustainability targets and for contributing to climate action.
Carbon capture and storage (CCS) differs from carbon removal in that the latter focuses on eliminating CO₂ already present in the atmosphere. Carbon removal can be achieved through natural carbon sinks, such as tree planting for reforestation – trees absorb carbon dioxide during photosynthesis – or through technological processes like direct air capture using systems that extract greenhouse gases directly from the environment. Iberdrola reached its goal of planting five million trees by the end of 2024, increasing to 20 million by 2030.
The process is also known as carbon capture, utilisation and storage (CCUS), which, in addition to the option of storing extracted CO₂, involves using carbon dioxide in the manufacture of products such as concrete or chemicals.
How can carbon capture and storage (CCUS) help prevent global warming?
Global warming is caused by the accumulation of greenhouse gases in the Earth’s atmosphere, such as carbon dioxide, which trap heat from solar radiation. Although some of these emissions come from natural sources and maintain a natural balance, they also come from human activities, particularly the burning of fossil fuels for energy. These are the emissions responsible for the global rise in temperatures. CCUS enables the interception of CO₂ emissions before they are released into the atmosphere, thereby reducing the amount of greenhouse gases in the air and helping to mitigate global warming.
How does CCUS technology work?
CCUS technology consists of three main stages
1 Capture
In the first stage of the process, carbon dioxide is separated from other gases emitted by industrial facilities, such as cement plants or industrial boilers that use coal and gas.
2 Transport
Once separated, CO₂ can be cooled to -80°C to convert it to liquid form and allow for transport by truck or ship. However, the most common method is to transport it at ambient temperature under high pressure through pipelines, especially when dealing with large volumes.
3 Use
The next step in recovering captured carbon dioxide involves its use in various industries, such as the food and beverage sector for carbonation and preservation; in medicine for anaesthetic procedures; in agriculture to support greenhouse plant growth; and in supercritical extraction to obtain compounds from plants and chemicals. It is also used in steel welding, fire extinguisher production and as dry ice for shipping frozen goods and cleaning industrial surfaces.
In addition, new and innovative applications of CO₂ are being explored, such as its conversion into plastics, concrete, synthetic fuels and algae-based biofuels, as well as fertilisers to promote plant growth.
4 Storage
Carbon dioxide can also be injected into deep underground geological formations, such as depleted oil fields or saline caverns, where it is stored safely. According to the Global CCS Institute, around 300 million tonnes of CO₂ have been injected underground worldwide as part of carbon capture projects (as a reference, Spain emits around 250 million tonnes of CO₂ each year).
Most of the projects currently in operation belong to the oil industry, where CO₂ is injected into active reservoirs to increase underground pressure and help extract more oil. From a climate perspective, this process is not considered sustainable, as although CO₂ is removed from the atmosphere, it is used to produce more oil and ultimately results in more CO₂ being emitted when the oil is burned.
SEE INFOGRAPHIC: How does CCUS technology work? [PDF]
Carbon capture technology: innovative approaches for a cleaner future
Innovation is a key driver in the development and improvement of carbon capture technology. Below are some of the current approaches being developed to advance these techniques.
Direct air capture (DAC)
Unlike traditional CCUS methods, which capture CO₂ directly from emitting sources such as industrial facilities, direct air capture (DAC) removes carbon dioxide from the atmosphere. In recent years, efforts have been made to move this technology from laboratory research to commercial-scale facilities, and to reduce its high energy and material consumption. In fact, one US company already operates a large pilot facility that is expected to reach the market in the coming years. DAC plants use sorbents (insoluble materials that capture liquids or gases) and large amounts of electricity to extract carbon dioxide directly from the air. This technology is effective at removing between 95% and 99% of atmospheric CO₂.
Solvent-based carbon capture
Solvent absorption has long been used to capture carbon dioxide, as it offers a cost-effective way of absorbing the gas, especially from flue gas streams. Amine solvents have proven effective in capturing large volumes of CO₂ by separating it from combustion gases. When the reaction is reversed, pure CO₂ is released for capture, while the solvent is recycled for reuse. Research continues to focus on developing new solvents that improve absorption rates, capture capacity and the energy efficiency of the process.
Membranes
In addition to solvents, research and development efforts also focus on the use of membranes – permeable or semi-permeable materials that allow for the selective separation of CO₂ from a gas stream.
Carbon storage technology: effective strategies for carbon management
According to the International Energy Agency (IEA), significant progress was made in carbon storage and management in 2023. In Europe, for example, over 160 million tonnes of CO₂ are expected to be stored, particularly in the North Sea region. The IEA also reported the launch of the pilot phase of a storage project in Denmark, which will involve injecting liquid CO₂ into a depleted oil field in the Danish North Sea.
The United States, for its part, plans to increase CO₂ storage capacity by 250% between 2022 and 2030, and applications for new CO₂ injection sites have risen significantly in recent years. According to the IEA, in 2024 there were around 43 projects with permits under review.
China, Malaysia, Singapore and Thailand have also announced plans to develop their first CO₂ storage infrastructure. Meanwhile, Japan, South Korea and Indonesia have plans to expand their existing industries.
There are also several projects around the world aimed at creating infrastructure to facilitate CO₂ transport. These include the construction of a CO₂ receiving terminal in Norway, as well as the development of new low-pressure liquid CO₂ carriers, which are expected to become operational in 2025 and 2026.
The high costs of carbon capture and storage
Although carbon capture and storage (CCUS) technologies are effective at removing between 95% and 99% of carbon dioxide from the atmosphere and mitigating climate change, they face several challenges. The main one is the high cost, particularly of the equipment, and the large amount of energy required for both capturing and compressing and/or liquefying the gas. In addition, CO₂ transport presents difficulties, as it requires significant amounts of energy to compress and cool the gas so that it can be moved via pipelines, ships or trucks. On the other hand, although there is broad consensus that there are sufficient underground storage sites for sequestered CO₂, there are ongoing concerns about the long-term risk of leaks, which could pose a threat to humans, wildlife and the environment. Furthermore, the geographical distribution of these storage sites is not uniform across the globe. For this reason, some areas have seen public opposition to the development of such projects.
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