Carbon capture

Circular economy

6 minute read

CCS and CCU. Mind explaining what these are again?

Carbon capture with permanent storage (CCS) or utilization of the captured CO2 (CCU) are tools for reducing emissions, and both are needed to combat climate change. While CCU is an integral part of the long-term vision, CCS is necessary on the way to reach large-scale reduction of CO2 emissions as quickly as possible.

Eva Amsen

Dr. Eva Amsen


Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are concepts making their way to the energy domain. The two techniques can be harnessed to create carbon-neutral processes or even to reach a net negative greenhouse gas intensity of products. Today CCS is used to prevent almost 40 million tons of carbon dioxide (CO2) per year from escaping into the atmosphere and hundreds of additional carbon capture projects are currently being developed or ongoing. 

According to a United Nations report, to reach the climate goals set out in the Paris climate agreement a concerted effort to capture (CO2) emissions is required. CCS and CCU play a major role in meeting this objective.

To make sense of the potential - and need - for CCS and CCU, we compiled an information-packed article to help learn about the developments around them. 

What are CCS and CCU and how can CO2 be captured?

CCS and CCU refer to the process of capturing CO2 and either storing it permanently (CCS) or utilizing it by converting it into valuable products, such as fuels and chemicals (CCU). Both CCS and CCU are based on carbon capture and the difference between the two lies in what happens after the capture step. 

New technologies for capturing CO2 are evolving rapidly, and a number of methods are already successfully applied to capture CO2 from different sources. The capture technologies fall into three main categories:

  • Post-combustion – Waste gas released from industrial combustion or power stations is captured and the CO2 is separated. 

  • Pre-combustion – This involves pre-treatment of fuels so that carbon is separated from the finally burnt components. For example by first converting coal into a mixture of CO2 and hydrogen by gasification, then capturing the CO2 and burning only the hydrogen.  

  • Oxy-fuel combustion – By burning fuel with pure oxygen instead of regular air, CO2 makes up a larger fraction of the waste gas, which makes it easier to separate out and store or repurpose.

Are these technologies already being used and what can be done with CO2 after it is captured?

Post-combustion carbon capture has been implemented in large scale and several CO2 storage projects are being developed around the world (e.g. Europe and the U.S.). Storage of captured CO2 can take place, for example, in off-shore geological storage sites such as old oil and gas fields.

Some industries can directly reuse captured CO2. The food industry uses CO2 to produce beverages or use it as dry ice to transport foods and ingredients that need to stay cold. Such applications do not lead to emission reductions but are ways to utilize the captured CO2. 

But CCS can also pave the way towards CCU in other ways, if in the future captured CO2 is used as a raw material for new products. Captured CO2 can, for example, be turned into fuels or chemicals by combining it with renewable hydrogen. This is the “Power-to-X” solution, which enables conversion of renewable electricity (power) into fuels, chemicals or materials (X), and is considered as one of the key technologies in accelerating the emergence of carbon-neutral transport and materials. The key objective in these CCU activities is to use the captured CO2 to replace fossil carbon raw materials in the production of the fuels, chemicals and materials. 

“One of the most interesting applications of Power-to-X solutions utilizing CO2 are found in fields that will continue requiring liquid fuels in the long term. Power-to-X utilizing CO2 provides also an interesting opportunity to sequestrate carbon into durable and recyclable materials,” says Suvi Kurkijärvi, Business Development Manager Renewable Hydrogen and Power-to-X at Neste.

The aviation sector is a good example of an industry within which renewable electricity is difficult to use directly; hence, liquid fuels will be required in the aviation sector in the long-term. Power-to-X enables production of jet fuels utilizing renewable electricity and CO2, providing an interesting solution for this sector in approximately 10 to 15 years. Other interesting applications of CCU solutions are in the plastics industry, in which the captured carbon can be turned into materials.

Why are businesses and investors interested in carbon capture?

Separating and collecting the CO2 output of a single facility is currently the most common type of carbon capture. These systems are already in use around the world. Considering that energy use in industry contributed to a quarter of all global greenhouse gas emissions, carbon capture is in a key position regarding reaching climate targets such as those set by the EU.

Carbon capture and storage is considered to provide scalable means to reach the necessary large-scale carbon emission reductions in sectors, which otherwise would have difficulties to do so quickly enough. For instance, liquid fuels, fertilizers and plastics are continuously needed, and developing their production processes to cause less emissions could take decades. In the meantime, capturing and storing the carbon emissions from these processes is seen as a viable, scalable alternative for such emission reductions.

At Neste, plans are already underway to be part of this new CCU economy. 

“We are actively working with partners to develop CCU as a new business for future growth,” says Kurkijärvi.

What’s holding back large-scale adaptation of carbon capture solutions?

The good news is we already have the technology to capture CO2 and permanently store it or convert it to new materials. The challenge is to make the technology economically viable.

“One of the things hindering large-scale implementation is the cost,” says Kurkijärvi.

To be able to scale up, regulatory support would be needed to allow for funding and incentives in this area or increase the regulated cost of carbon-emitting solutions.

“Demonstrations and pilot projects are key for the industry and policy makers to get a sense of what can be done with carbon capture, which can then move regulations forward,” Kurkijärvi adds.

What does the future hold for CCS and CCU?

Neste has made a commitment to reach carbon neutral production by 2035. Reaching the target requires the company to significantly reduce emissions from its production, which also means sizable efforts in CO2 capture. According to Neste’s experts, CCS is timewise first in line to handle the captured CO2. Neste is also assessing the applications in which CO2 has value, in order to enable the captured CO2 to circulate. This is one of the tasks that Neste Innovation together with partners is currently studying. 

“We warmly welcome more partners to join us in this work”, Suvi Kurkijärvi from Neste concludes. 

Credits: Dr. Eva Amsen, a science writer and communicator whose work has appeared on Forbes, Nautilus and The Scientist. Twitter