What is carbon capture, and how does a capture facility work?

Carbon capture is an industrial method for removing all or part of the CO2 emissions from an industrial process. It is often used in industries that cannot eliminate their emissions through measures such as electrification, but need or want to take action to reduce their climate impact.

Carbon capture plays a key role in the transition to a society based more on renewable resources.

Carbon capture has taken on a prominent role in climate strategies in recent years. A carbon capture facility makes it possible to reduce major emissions from waste incineration and industrial processes that cannot be eliminated by other means. Here, we explain what a carbon capture facility is, how the process works, and the role Hafslund Celsio’s facility at Klemetsrud will play in Norway’s ongoing climate efforts.

In brief

• A carbon capture facility captures CO2 directly from the flue gas.
• The CO2 is separated, liquefied, and prepared for transport and permanent storage.
• The captured CO2 is stored 2,600 metres beneath the seabed in the North Sea.
• The technology reduces emissions from sectors that cannot be electrified.
• Hafslund's carbon capture facility at Klemetsrud will be one of Norway's largest individual emissions-reduction measures.

What is a carbon capture facility?

A carbon capture facility is an industrial installation that separates carbon dioxide (CO2) from flue gas before it reaches the atmosphere. This is particularly important in sectors where emissions cannot be eliminated by other means, such as waste incineration.

The technology makes it possible to tackle emissions that cannot be eliminated by other means and contribute to significant emissions reductions in both Norway and Europe.

“The waste incineration plant at Klemetsrud is currently Oslo’s largest single source of emissions. Once the carbon capture facility is operational, it will become one of Norway’s largest carbon sinks. In other words, we will remove CO2 from the atmosphere. This technology works, and it represents one of the most important emissions reductions we can make right now,” says Truls Jemtland, Head of Communications at Hafslund Celsio.

How does a carbon capture facility work?

A carbon capture plant captures CO2 from flue gas using a capture agent, separates the CO2 from the rest of the gas, and liquefies it for further transport and storage. The process mainly consists of three steps:

1. CO2 capture – CO2 is bound in an amine solution.

2. Release – the solution is heated, and CO2 is separated out.

3. Handling – CO2 is liquefied and prepared for transport.

Hafslund is building a carbon capture facility at a waste-to-energy plant that will remain operational throughout the construction period. The capture facility will use steam from the existing incineration process and recover surplus energy from the capture process to maintain the city’s district heating supply. The combination of retrofitting and safeguarding the energy supply makes the project an important national reference project.

Why are carbon capture facilities being built? Climate impact and opportunities

Carbon capture plays an important role in achieving Norway's climate targets and is essential in sectors where emissions cannot be eliminated by other means. This technology will support efforts to achieve Oslo's target of reducing greenhouse gas emissions by 2030.

Why this matters for the climate:

• Reduces CO2 quickly and effectively.
• The reductions are measurable and permanent.
• Important for achieving both Oslo’s and Norway’s emissions targets.

Industrial and socioeconomic opportunities

• Strengthens Norway's position in green technology.
• Creates new jobs and centers of expertise.
• Develops a growing market for CO2 transport and storage.
• The capture and storage of biogenic CO2 enables the issuance of carbon removal certificates. This represents a new revenue opportunity for the company.

Hafslund's carbon capture project at Klemetsrud

Hafslund's project will reduce Oslo's emissions by around 20 percent, making it one of Norway's largest and most important climate initiatives. The project is also an integral part of the national initiative Carbon capture and storage, and will be directly connected to Northern Lights' storage infrastructure.

Read more about carbon capture at Klemetsrud here.

The process of capturing and storing CO2 from waste incineration

It is not always easy to understand how carbon capture and storage actually works. That is why we have illustrated the process below.

How we will capture CO2

1. The waste collection trucks deliver sorted residual and commercial waste to the waste incineration plant.

2. The waste is incinerated in three large furnaces. The temperature in the boilers is between 850 and 900 degrees Celsius.

3. The heat generated by waste incineration heats water in pipes, turning it into steam. The steam is used to produce district heating and electricity.

4. The flue gas generated during waste incineration passes through an advanced treatment system and is thoroughly cleaned before being routed to the carbon capture plant.

5. The flue gas, which now consists of water vapor and CO2, enters the carbon capture plant. In the first chamber, the CO2 binds to an added organic substance consisting of "amines". This is the capture agent.

6. In the second chamber, the amine solution is heated, causing the amines to release the CO2 molecules. The amines are continuously circulated and reused, while the CO2 is transferred to tanks.

7. Here, the CO2 gas is compressed and cooled into a liquid.

8. Liquid CO2 is transported in zero-emission trucks to an intermediate storage facility at the Port of Oslo. The CO2 is stored here pending transfer to Northern Lights, which ensures its safe transport and permanent storage.

How we will store CO2

1. CO2 is captured from flue gas and liquefied at Hafslund’s carbon capture facility at Klemetsrud.

2. Liquid CO2 is transported by zero-emission trucks to the Port of Oslo.

3. Liquid CO2 is stored in an intermediate storage facility at the port.

4. The liquefied CO2 is transferred to Northern Lights and loaded onto ships. It is then transported to Northern Lights' receiving terminal in the Naturgassparken industrial area in Øygarden municipality, Vestland.

5. The CO2 is unloaded at the receiving terminal and transferred to an onshore CO2 storage facility. From there, the CO2 is transported 100 kilometres out into the North Sea through pipelines.

6. Liquid CO2 is pumped beneath the seabed and permanently stored in a reservoir called Aurora, 2,600 metres below the seabed.

7. The reservoir is a porous sandstone formation with a layer of shale above it. Over time and under pressure, the CO2 will slowly be converted into minerals.

Challenges and future prospects

Implementing carbon capture at industrial sources, such as waste incineration plants, presents challenges on several levels. It requires considerable space, and established industrial facilities often have limited space available. New technologies such as carbon capture plants are often physically large and require significant investment. The supplier market is evolving, and lessons learned from previous projects are being used to develop the plants of the future.

Efforts to establish carbon capture at the Klemetsrud waste-to-energy plant have been under way since 2015, spanning three different ownership structures. The high capital expenditure (Capex) has been one of several concerns. Through the Longship partnership, the project has become a strong example of public-private collaboration aimed at launching one of the world’s first carbon capture facilities at a waste-to-energy plant. The project receives substantial public funding, the City of Oslo has invested directly in it, and the company and its owners have also committed significant investment.

Read more about the investment decision here.

The investment decision was made in January 2025. In April of the same year, Hafslund Celsio announced the world’s first sale of carbon removals from waste incineration. The company entered into an agreement with the buyer group Frontier for the advance purchase of carbon removals. This agreement was an important part of the basis for Hafslund Celsio’s investment decision earlier this year on the carbon capture project in Oslo. In June of the same year, the company announced a 10-year carbon removal agreement with Microsoft. The two agreements have reduced the financial risk. By 2029, Hafslund Celsio, in collaboration with Aker Solutions AS and SLB Capturi Norway AS, which have formed a partnership and will jointly deliver the project, will build a capture facility at Klemetsrud and a CO2 terminal at the Port of Oslo.

A carbon capture facility requires energy, investment and a sound regulatory framework. At the same time, the direction of travel is clear: more Norwegian industrial companies are considering carbon capture, and Europe has a significant need for storage capacity.

Hafslund’s project at Klemetsrud will therefore not only reduce emissions but also mark a technological milestone that could pave the way for more facilities.