In its Net Zero Emissions by 2050 (NZE) Scenario, the International Energy Agency (IEA) anticipates that around 1 Gt CO₂/y will have to be captured and stored. More ambitiously, the Intergovernmental Panel on Climate Change’s (IPCC) Special Report on Emission Scenarios projects that up to 10 Gt CO₂/y could be captured (see also a recent IEA report on CCUS).

In Europe, funding for underground storage of carbon began in 1990. The world’s first commercial CCS project began operating in 1996, capturing CO₂ for enhanced oil recovery (EOR) in the Sleipner field in the Norwegian North Sea, operated by Equinor. Meanwhile, the US began funding CCS research in 1997, with more than $5bn invested since 2010, according to the Geoengineering Monitor.

However, the amount of CO₂ being captured and stored by large-scale CCUS facilities today falls well short of the targets needed to keep the world within the 1.5°C limit. There are just 51 large-scale CCUS projects in operation worldwide, according to the IEA, collectively capturing 69.65mn tCO₂/y. This is far behind the IEA’s 2009 target to capture 300mn t/y by 2020.

Despite billions in funding and decades of research, CCUS remains in its infancy. Of 149 CCUS projects planned to be capturing and storing carbon by 2020, over 100 were cancelled or placed on indefinite hold. Likewise, more than 80% of proposed CCUS projects in the US have failed to become operational. Of the projects that are operating globally, about three-quarters of the carbon captured is used for EOR, which enables companies to make money from capturing carbon but raises questions about its net climate impacts.

So, can CCUS fulfil its crucial role in the energy transition puzzle?

What is the history of carbon capture?   
CCUS projects date back to the early 1970s when the concept was first proposed to mitigate climate change. A series of natural gas processing plants in Val Verde, Texas, US, began employing CCS in the early 1970s with the captured CO₂ transported via pipeline to EOR projects. Capture capacity is currently 1.3mn t/y, although this is expected to fall as some of the feeder plants are closing.

However, it wasn’t until the 1990s that the first large-scale CCS projects began to emerge.

Early projects and milestones:

• Sleipner project (1996): Located in the Norwegian North Sea, the world’s first commercial-scale CCUS project has been capturing and storing about 1mn t/y of CO₂ from natural gas processing in a saline reservoir.
• Weyburn-Midale project (2000): This project in Saskatchewan, Canada, began injecting CO₂ for EOR and has stored over 40mn tonnes of CO₂ to date.
• In Salah project (2004–2011): Located in Algeria, this project stored about 3.8mn tonnes of CO₂ in a depleted gas reservoir before operations ceased due to reservoir pressure concerns.

The technologies involved  
CCS involves three main steps: capture, transport, and storage. Each step employs various technologies.

Capture technologies include:

• Pre-combustion capture. Fuel is converted into a mixture of hydrogen and CO₂ before combustion. This is typically used in industrial processes.
• Post-combustion capture. CO₂ is separated from flue gases after fuel combustion. This is used in power plants.
• Oxyfuel combustion. Pure oxygen instead of air is used for combustion, resulting in a more concentrated CO₂ stream.
• Direct air capture (DAC). CO₂ is captured directly from the atmosphere. While promising, this technology is still in its early stages and is currently very expensive.

Transport is a crucial link in the CCS chain. The choice of transport method depends on distance, volume of CO₂, geography and economics.

Pipelines are the most common and cost-effective method for transporting large volumes of CO₂ over long distances, especially onshore. As of 2020, there were approximately 5,000 miles (8,047 km) of CO₂ pipelines in the US, primarily used for EOR.

CO₂ is typically transported in a supercritical state (high pressure, moderate temperature) to maximise efficiency.

The key challenges for CO₂ transport include the significant investment and long-term planning required to build extensive pipeline networks or shipping facilities; the need to establish clear regulations for CO₂ transport across regions and international borders; and the challenge of addressing safety concerns and gaining public support for new transport infrastructure. In addition, improving transport efficiency, reducing energy requirements and minimising losses during transport are ongoing areas of research.

How do you store CO₂ for the long term?  
Storage is the final and crucial step in the CCS process to prevent its release into the atmosphere. Geological storage is the most well-developed method and involves injecting CO₂ into deep underground formations. However, it requires careful site selection and characterisation. Monitoring systems are vital to ensure that the CO₂ remains trapped. And large storage capacity is required – with estimated global capacity of 8,000–55,000 Gt CO₂.

While primarily used for increasing oil production, EOR can result in significant CO₂ storage. It provides an economic incentive through increased oil production. The net climate benefit depends on the source of CO₂ and the fate of produced oil; it can end up creating more emissions overall. And storage security can be compromised if wells are not properly managed.

Mineral carbonation involves reacting CO₂ with metal oxides to form stable carbonate minerals. This process provides very secure, permanent storage. However, it is currently limited by high energy requirements and costs.

Environmental concerns, such as acidification, and international marine conventions are limiting the practice of ocean storage, although research continues on potential methods. Theoretically, the oceans offer large storage capacity.

Bioenergy with CCS (BECCS) combines biomass energy production with CCS, potentially achieving negative emissions. However, there are concerns about land use and competition with food production. And the process is still in early stages of development at scale.

As of 2023, the global CCUS industry remains far behind the scale needed to meet climate targets. Although the IEA lists 51 large-scale CCUS facilities in operation globally, the Global CCS Institute’s latest report tracks just 41 in operation with a further 351 in development.

What are the main CCUS challenges?   
While global storage capacity is potentially large, detailed site-specific assessments are needed to identify suitable locations. Long-term monitoring technologies and protocols are crucial for ensuring storage security and public acceptance. Clear regulations for long-term liability and storage site management are still evolving in many jurisdictions. Addressing public concerns about safety and long-term storage integrity remains a challenge. There is still work to do on improving injection technologies and site characterisation methods to reduce overall storage costs. Broadly speaking, developing optimised, full-chain CCS systems that match capture rates with storage capacity and transport capabilities can be challenging.

The majority of operational projects are in North America. The US and Canada lead in this area largely due to early investments in EOR and government incentives. Europe and Asia have seen significant growth in recent years, especially in countries like Norway, the UK and China. Most current projects are in natural gas processing, fertiliser production and hydrogen production, with fewer in power generation, mainly due to the higher costs and technical challenges associated with capturing CO₂ from power plants.

While costs remain high, there is evidence of declining costs in some areas. For example, the cost of carbon capture in power generation has decreased by 35% since 2005. Along the CCUS value chain, the IEA suggests that there is significant potential to reduce costs. As the market grows, the technology develops, finance costs fall, economies of scale are reached, and experience of building and operating CCUS facilities accumulates, CCUS should decline in cost.

How is CCUS funded?  
Funding for CCUS comes from various sources:

• Government funding. Most funding for CCS comes from the public purse. Many countries provide direct funding, tax credits and other incentives. For example, the US 45Q tax credit offers up to $50/t of CO₂ stored.
• Private investment. Companies, particularly in the oil and gas sector, are investing in CCS. For instance, Occidental Petroleum plans to invest $1bn in DAC, according to ICIS.
• Multilateral organisations. The World Bank and other international organisations provide funding and technical assistance for CCS projects in developing countries.
• Carbon markets. In some regions, carbon pricing mechanisms provide financial incentives for CCS projects.

Path to meeting 2050 targets  
To reach the IEA’s target of capturing 1 Gt CO₂/y by 2050, several key actions are necessary. First, the number of large-scale CCS projects needs to increase dramatically. The Global CCS Institute estimates that 70–100 new facilities need to be built each year from 2030 to 2050 to meet the IEA’s target of capturing 1 Gt of CO₂/y.

Secondly, continued research and development, along with economies of scale, are needed to bring down costs. The US Department of Energy aims to reduce the cost of carbon capture to $30/t by 2030.

Significant investment in CO₂ transport and storage infrastructure is required. The IEA estimates that the CO₂ transport and storage network needs to expand 100-fold by 2050.

To ensure that these actions are taken, stronger and more consistent policy support is needed, including carbon pricing, regulatory frameworks and public funding for research and development. Likewise, the public needs to be won over. Improving public understanding and acceptance of CCUS technology is crucial for project development, especially in densely populated areas.

Moreover, to meet the 2050 targets, there needs to be a greater focus on employing CCUS in hard-to-abate sectors such as cement, steel and chemicals, where alternatives for deep decarbonisation are limited.

Finally, DAC needs to develop as an industry. While currently expensive, scaling up DAC technology could be crucial for achieving negative emissions in the long term.

In summary, significant challenges remain in terms of costs, infrastructure development and policy support. However, with concerted effort from governments, industry and the research community to provide policy support and investment, and improve public awareness, CCUS could still play its crucial role in the global energy transition and the fight against climate change.

• Further reading: ‘CCUS – a $196bn investment opportunity’. Global carbon capture, utilisation and storage will require $196bn in investments by 2034, with North America and Europe leading the charge, according to a new report from Wood Mackenzie. Government funding will play a crucial role, contributing $80bn across five key countries, predominantly the US, UK and Canada.
• Find more about Norway’s Northern Lights carbon capture, use and storage project, which is heading towards start-up in 2025 with a first-phase capacity of 1.5mn t/y, rising to 5mn t/y in the second phase. That schedule puts the scheme in the running to be among Europe’s first large-scale CCUS projects to start up.