Carbon capture and use technologies are solutions to reduce CO2 emissions and move away from fossil resources –


This article was written by Dr Célia Sapart, Communications and Climate Science Director att CO2 Promote Europe.

Today, the extraction and use of fossil carbon is the primary controller of the Earth’s thermostat. To mitigate climate change, the urgency is to substitute fossil products and implement circular carbon solutions to generate essential goods and services.

While discussions on eliminating carbon occupy a high place on political agendas, we often observe some confusion between solutions to reduce CO.2 emissions, avoid new emissions or eliminate CO2 of the atmosphere. This does not make it easier to understand the potential and limits of either concept and can affect public and political acceptance1. However, most of these technologies, if combined judiciously, will be of great help in achieving climate goals. In this article, we discuss the role and climate impact of Carbon Capture Utilization Technologies (CCU)2.

CCU is a general term that covers processes aimed at capturing CO2 from flue gases or directly from air and converting them into a variety of products such as renewable fuels, chemicals and materials. CO2 is already used for decades with mature technologies in various industrial processes to produce, for example, beverages, fertilizers, etc. But today, many new CCU technologies in various stages of development and commercialization aim to mitigate climate change3.4. These technologies have the potential to 1) reduce net CO2 emissions, 2) eliminate CO2 from air, 3) provide substitutes for carbon-intensive and fossil-based products, 4) store and transport renewable energy, and 5) generate marketable products.

Temporary CO2 storage does not mean delaying the emission because the emissions were avoided in the first place

CCU is often mixed up with Carbon Capture and Storage (CCS) when the two concepts differ markedly. CCS consists of capturing CO2, transporting and storing it underground, while CCU is a circular approach that converts and stores CO2 in essential products5. The duration of the CO2 storage in a product varies greatly from days to centuries depending on the application. However, unlike CCS, CCU should not be assessed solely based on the duration and / or storage capacity in a product, but rather with a full life cycle analysis of CO.2based product generated6. If CO2 based products can be produced with a lower climate impact than conventional products or if the CO2 is captured again at the end of the life of CCU products, in both cases, a climatic benefit can be claimed regardless of the duration of the CO2 storage in the product.

CCU can allow permanent CO lockout2 in materials

CO2 mineralization7, an emerging CCU pathway, allows a permanent CO2 storage room. This approach makes CO2 react with mineral-rich wastes to form carbonates, which are stable chemical compounds. Because it uses the chemical energy available in the waste, this method is a low-energy, low-cost way to reduce emissions and permanently lock in CO.2 in valuable building materials such as concrete, aggregate, asphalt, building fill, etc. life cycle analysis8.9, all CCU technologies considered for mineralization could reduce climate impacts over the entire life cycle of products based on the current state of the art and the current energy mix.

These CO2-based materials do not only remove CO2 from fumes or air, but they can also replace products with high carbon intensity (cement for example). Current data8.10 suggests that up to 1/4 of the cement market could be replaced by mineralization products that would significantly reduce the carbon footprint of building materials globally.

Moreover, when CO2 is captured directly from the air11 to become permanently stored in such material, mineralization can create negative emissions and thus be considered carbon dioxide removal technology (CDR)12.

Several carbon mineralization technologies13.14 are already marketed globally and the first sidewalk made of CO2brick-based15 was installed in Ghent, Belgium in 2020.

The proposal to revise the emissions trading system16 now recognizes that the CO2 which is chemically and permanently bound in a product and, therefore, is not released to the atmosphere during normal use of the product – as in CO2 mineralization – is excluded from the obligation to surrender emission allowances.

CCU is a solution to stimulate the transition to renewable energies

CCU technologies, via the Power-to-X principle17, play a crucial role in supporting the clean energy transition by facilitating the adoption, storage and transport of electricity. How it works? Power-to-X means converting electricity into products or in other words storing electricity into products such as fuels and chemicals. Through this approach, synthetic hydrocarbon fuels (also called e-fuels) can be produced, using renewable electricity to generate hydrogen via the electrolysis of water, and reacting it with CO2. For example, CO2 emissions from cement or steel plants can be captured and used with renewable hydrogen to produce sustainable aviation fuel18. This allows a net reduction of CO2 emissions from industrial plants and a reduction in the use of fossil fuels for aviation fuels; if CO2 is captured directly in the air, this concept can also lead to a net zero emission as envisaged, for example in the Norsk Electric Fuel Project19 in Norway.

These CO2Renewable fuel-based fuels are alternatives for hard-to-reduce industries such as aviation, shipping, and energy-intensive industries. They have volumetric energy densities several orders of magnitude greater than those of hydrogen, so they may be easier to transport and store; they also have the advantage of bringing renewable energies to sectors, where direct electrification is not obvious, without modifying the storage, distribution and use infrastructures. Surplus renewable energy, generated when energy demand is low, could then provide a cheap energy supply to produce renewable fuels.

These CO2Product-based products are recognized as “Renewable Fuels of Non-Biological Origin (RFNBO)” in the EU Green Agreement legislative packages20, and their production and use in energy and non-energy applications are promoted as solutions to mitigate climate change.

And after?

While efforts at all levels should initially focus on sober solutions and the prevention of greenhouse gas emissions, CCU technologies remain impactful solutions for many sectors, especially for those where no other alternative does not exist. The large-scale deployment of these technologies will largely depend on the development of a strong enabling policy framework. Therefore, we welcome recent steps taken in this direction (e.g. the Fit-for-55 package), and we call for consistent and fair recognition of CCU, when it leads to a net reduction in carbon emissions. CO2 (based on a full life cycle analysis), and when it helps move away from fossil fuels.

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