Carbon capture, utilisation and storage

The Industrial Revolution ushered in an era of great economic, social and technological change, bringing humanity greater prosperity and incredible advances in science and technology. But it was also the beginning of one of the biggest current and especially future problems, climate change. The biggest culprit is the increase in greenhouse gas emissions, the most well known of which is CO₂.

For generations it was ignored, for the sake of economic growth that covered up the problems that future generations could have. Large companies were already aware of the fatal repercussions of increased emissions. Scientists, increasingly vocal on the global stage, providing data and studies, and above all increasingly frequent and extreme meteorological phenomena, have set alarm bells ringing in society and institutions. These apocalyptic visions are coming closer and closer, and one question is becoming more and more common: What do we do now?

Graph 1: Global historical CO₂ emissions 1757-2021. Source: Statista Research Department.

Technology, one of the great beneficiaries of the Industrial Revolution, must respond to this major problem. And so was born one of the measures to mitigate the impact of polluting gas emissions, the capture and storage of CO₂ (CCUS, Capture Carbon, Utilisation and Storage).

Although the aim is to reduce CO₂ emissions, there are industries such as cement, steel, aluminium, paper and refineries, which have inherent emissions in their production processes. In this way, through carbon capture, use and storage, emissions in these sectors are significantly reduced, as well as helping to remove carbon from the atmosphere.

CCS, Carbon Capture and Storage

CO₂ captured from the industries described above, from power generation plants using fossil fuel sources, or directly from the atmosphere, is separated from most associated substances and transported by pipeline or in tanks, after compression, by sea, rail or road, to facilities where it is injected under deep geological formations, such as depleted gas or oil fields, or saline aquifers, which can trap and store CO₂ permanently.

Image 1: Graphical scheme of the carbon capture and storage process. Source: European Commission.

Some technologies that are used in conjunction with CCS are:

• DACCS (direct air capture and carbon storage) is the combination of capturing CO₂ directly from the air (DAC), and its subsequent storage (CCS). The difficulty of this process lies in the low concentration of CO₂ in ambient air (around 400 ppm). The advantage of direct air capture is that it allows CO₂ to be captured when and where there are no point sources. DAC uses engineered processes based on chemical capture to extract carbon dioxide directly from the atmosphere into a separating agent that is regenerated with heat, water or both. The CO₂ is then desorbed from the agent and released as a high-purity stream.
• BECCS (bioenergy carbon capture and storage) is the combination of power generation from biomass and carbon capture and storage. Apart from the feedstock being specifically of biological origin, the technologies used to capture, transport and store CO₂ are the same as for CCS. CO₂ for BECCS can come from biological processes such as fermentation (e.g. for biofuel production), but also from biomass combustion for heat and power generation.

CCU, Carbon Capture and Utilisation

The captured CO₂ can be used in production processes that use carbon dioxide as a raw material, thus avoiding releasing it into the atmosphere. Examples include:

• Direct use of CO₂ in soft drinks or greenhouses.
• Using it as a working fluid or solvent, e.g. for enhanced oil recovery (EOR).
• Using CO₂ as a feedstock and converting it into value-added products such as polymers, building materials, chemicals and synthetic fuels.

This latest family of novel technologies using CO₂ as a feedstock can contribute to the circular economy and climate change mitigation goals.

Some 230 Mt of CO₂ per year are currently used, mainly in the fertiliser industry for the manufacture of urea (~130 Mt) and for enhanced oil recovery (~80 Mt). The use of captured carbon in the production of synthetic fuels, chemicals and CO₂-based construction aggregates is also growing. By 2030, ongoing projects indicate that around 5 Mt of CO2 could be captured for the production of synthetic fuels. While this level of deployment is not far from the 7.5 Mt CO₂ used in the production of synthetic fuels in 2030 in the Net Zero scenario, half of the announced projects are at an early stage of development and require further support to become operational.

Present and future

Due to the limited market uptake for utilisation applications of captured CO₂, storage should remain the main focus of carbon capture, utilisation and storage (CCUS) deployment. In the Net Zero Scenario, more than 95% of the CO₂ captured in 2030 is geologically stored, and less than 5% is utilised. With a sequestration time in the order of millions of years, construction aggregates are the only CO₂ use application that could qualify as permanent sequestration. This would not be the case for fuels and chemicals, which typically retain CO₂ for one year and up to ten years respectively.

Graph 2: Capacity of current and planned CO₂ capture projects by sector. Source: IEA.

There are currently some 35 commercial installations applying CCUS to industrial processes, fuel transformation and power generation. Still, CCUS deployment has not lived up to past expectations, but momentum has grown substantially in recent years, with some 300 projects in various stages of development across the CCUS value chain. Project developers have announced their ambition to have more than 200 new capture facilities operational by 2030, capturing more than 220 Mt CO₂ per year. However, even at that level, CCUS deployment would still be substantially lower than required in the Net Zero Scenario.

Graph 3: Capacity of existing and planned large-scale CO₂ capture projects against the Net Zero Scenario, 2020-2030. Source: IEA.

But recent problems in the Norwegian CO₂ storage projects at Sleipner and SnØvhit, which are regarded as successful examples of CO₂ storage by-products of gas production, cast doubt on the technology and its future. Both subsoils were thoroughly studied beforehand, and since 1996 in the case of Sleipner and 2008 in the case of SnØvhit, some 22 Mt of CO₂ have been stored under the ocean floor. But in the case of the first field, the CO₂ unexpectedly moved to an area not previously identified by engineers. In the case of SnØvhit, storage conditions deviated drastically from design plans some 18 months after the start of injection, necessitating major interventions and investments. This highlights that every corner of the planet has specific geology and conditions, and despite extensive studies, the earth’s strata are in continuous movement.

It is clear that the future of the CCUS lies in increased investment in research and technology improvement, in order to reach the Net Zero Scenario targets, to mitigate the problems that have arisen and may arise in the future, to make it more attractive to investors and to make the current rate of announced investments grow.

Aleix Pujols | Energy Consultant