Carbon capture, use and storage (CCUS)

What is carbon capture, use and storage?

CCUS is a group of technologies that prevent carbon dioxide from reaching the atmosphere.  Carbon dioxide is emitted by the burning of fuels and from some industrial processes like curing cement or making steel. With CCUS, the carbon dioxide is separated from other emissions (carbon capture) and can be locked into products (use) or transported and stored safely underground (storage).

Why is CCUS important for achieving net zero?

CCUS is an enabler for the energy transition. It can:

  • help to decarbonize industries like steel, cement and petrochemicals that currently have no alternatives at scale and account for around 70% of direct carbon dioxide emissions.
  • provide low carbon gas power as a back up to renewables.
  • enable the scale up of low carbon products (such as hydrogen, cement and steel) that will help to accelerate decarbonization in industry, buildings and transport.
  • create the infrastructure for carbon removals by putting carbon dioxide that is taken out of the air back into the subsurface.

CCUS is particularly important in industrial regions, where its deployment can help industrial companies make the transition to a net-zero economy, maintaining stable and well-paid jobs. The availability of open carbon transport and storage infrastructure in hubs also attracts new clean industries – a phenomenon that is starting to take place, for example, around the emerging Net Zero Teesside and Zero Carbon Humber hubs in the UK and the Northern Lights hub in Norway.

The deployment of CCUS itself creates jobs in the construction, operation and maintenance of facilities and this will rise significantly as the industry scales up.  For example, to reach the levels of deployment outlined in the IEA Sustainable Development Scenario, over 2,000 facilities would need to be in operation by 2050, a build rate of 70-100 facilities per year. This would require around 70,000 to 100,000 construction workers and 30,000 to 40,000 capture facility operators. In addition, the transport and storage network would require additional workers. In Europe’s North Sea region, for example, an additional 10,000 people could be employed in a centralized transport and storage industry.

How much CO2 storage is needed?

The International Energy Agency estimates that around 2.5 Gt of carbon dioxide will need to be captured and stored every year by 2040, rising to between 4 Gt and 5.5 Gt per year by 2050.

Currently just 40 Mt of carbon dioxide is stored each year. Momentum is picking up quickly, with well over 30 industrial scale projects and hubs now in planning and investment doubling since 2017. But around 20 times that amount is needed over the next decade to get back on track.

Where can carbon dioxide be stored?

Potential storage sites include saline aquifers or depleted oil and gas reservoirs, typically 1 km or more underground. Saline aquifers are permeable rocks saturated with salt water and capped with layers of impermeable rock formation.

The Quest CCS project in Alberta, Canada, for example, injects its captured CO2 in a sandstone saline aquifer 2 km underground, with well over 5 million tonnes already stored. The proposed site for the Net Zero Teesside hub is a saline aquifer, known as Endurance, located 1.6 km below the seabed in the North Sea. The Rotterdam CCUS hub in the Netherlands plans to store CO2 in an empty gas field 3 km below the North Sea.

OGCI is working to improve the availability of storage resources. It publishes a CO2 Storage Resource Catalogue, in collaboration with the Global CCS Institute and Pale Blue Dot Energy. Updated annually, the Catalogue uses a standardized methodology to provide investor-level confidence in the maturity of geologic CO2 storage resources available to CCUS project globally.

How does carbon storage work?

Before injection can take place, the subsurface is studied and tested with seismic analysis to verify that the site is appropriate for storage. A well is then drilled and tested to ensure the right geological conditions. The key is to identify the right place to inject and contain the carbon dioxide, which is trapped in microscopic rock pores by the same process that trapped oil and gas and natural CO2 for millions of years.

Close monitoring, using seismic data, helps to refine theoretical models and check that the carbon dioxide is moving within the rock space as expected (this is known as plume migration). Equinor, for example, has two decades of experience with storing and monitoring CO2 in two offshore locations in Norway, to avoid venting into the atmosphere. Plume monitoring with time-lapse seismic analysis (see image) shows that some of the CO2 is trapped in rock spaces due to capillary forces, some dissolved in brine and some mineralized into rock.

CO2 storage simulation at Snøhvit, Norway (Osdal et al, 2014)

How do carbon capture technologies work?

A range of different technologies can be used to separate out and collect carbon dioxide, and new technologies and refinements are under development, aiming to reduce the cost of capture.

In most cases carbon dioxide is captured from the exhaust gases post-combustion. For gas producers, it is possible to separate out the carbon dioxide pre-combustion. In this process, natural gas is processed to produce hydrogen that can be burnt as a fuel without producing any emissions and a pure stream of CO2 that can be stored or used. This hydrogen is known as ‘blue’ hydrogen. Another far less mature approach is to embed CCUS as part of gas power production, using oxygen rather than air to burn the fuel, producing a pure stream of CO2 that can be stored or used.

Capture is generally the biggest contributor to the overall cost of CCUS, but it is significantly cheaper to capture CO2 where it is highly concentrated and under high pressure, such as in ethanol production or liquefied natural gas processing, than it is for power generation, for example, where the carbon dioxide is dilute. As technologies mature and new ones are developed, the cost of capture is expected to fall.

How does CCUS relate to negative emissions technologies?

CCUS focuses on stopping carbon dioxide emissions from power or industry from entering the atmosphere. As with other clean technologies, it helps to avoid making the climate situation worse. Negative emissions technologies, such as direct air capture and storage (DACS) and biomass with storage (BECCS), focus on removing carbon dioxide from the atmosphere to reduce the concentration of carbon dioxide. CCUS helps to facilitate technology-based carbon removal by developing storage infrastructure that it can use. CCUS hubs, such as Net Zero Teesside and Northern Lights, are increasingly working with BECCS and DACS operators to add negative emissions to their climate offering.