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Glossary · Energy industry & energy transition

Carbon Capture and Utilization, CCU

CCU Carbon capture and utilization CO2 utilization E-Fuels Industry Carbon footprint power-to-X

Definition

Carbon Capture and Utilization, or CCU for short, refers to the capture of carbon dioxide and its subsequent use as a raw material or auxiliary material. The captured CO₂ does not enter the atmosphere immediately but is fed into a technical or industrial process. Examples include basic chemicals, plastics, synthetic fuels, mineral construction materials, beverages, greenhouses, and cooling and fire-extinguishing applications. EU law describes utilization as a technical process in which captured CO₂ serves as a feedstock for the manufacture of products.

The term covers two steps that must be assessed separately. The first step is CO₂ capture. It can take place at point sources, such as cement and lime plants, waste incineration plants, chemical plants or power plants. CO₂ can also be captured directly from ambient air; this is known as Direct Air Capture. The second step is utilization, and its effect varies greatly in how far it reaches. In a synthetic fuel, the carbon is released again after a short time during combustion. In mineral carbonates, by contrast, it can remain bound for centuries. CCU is therefore not a uniform climate mitigation mechanism but a collective term for very different pathways that the carbon can take.

Current use: orders of magnitude

According to the International Energy Agency (IEA), around 230 million tonnes of CO₂ are used worldwide each year. The largest share goes to urea production for fertilizers, at about 130 million tonnes. This is followed by oil production with CO₂ injection, known as Enhanced Oil Recovery, at about 70 to 80 million tonnes. Both examples show that utilization does not automatically mean climate protection. The carbon in urea is released again after it is applied to the field. In oil production, the CO₂ is used to extract additional fossil oil. Newer utilization pathways such as synthetic fuels, chemicals and construction material aggregates are still small by comparison.

Distinction from CCS and CCUS

CCU is most often confused with CCS. With CCS (Carbon Capture and Storage), CO₂ is captured and permanently stored geologically. The climate benefit there arises from long-term containment, provided that capture, transport and storage work reliably. With CCU, by contrast, the CO₂ is used. Whether emissions fall permanently as a result depends on the product and on the entire process chain. The umbrella term CCUS combines utilization and storage and can obscure this difference. If the carbon is released again after days, months or a few years, utilization is not storage. A tonne of CO₂ that is only temporarily used therefore does not do the same for climate targets, funding programmes and emissions accounting as a tonne that is permanently stored.

Legal framework in the EU: emissions trading

In the EU emissions trading system, Article 12(3b) of the Emissions Trading Directive 2003/87/EC, as amended in 2023, governs how utilized CO₂ is treated. Accordingly, no allowances need to be surrendered for captured CO₂ if it is permanently chemically bound in a product. Under normal use, the CO₂ must not enter the atmosphere, including through common processes after the end of the product's lifetime. Delegated Regulation (EU) 2024/2620 of 30 July 2024 sets out the criteria. It was published on 4 October 2024 and has been in force since 24 October 2024. The CO₂ must be measurably bound through an active and controlled utilization process and must remain bound for at least several centuries. The positive list in the annex currently includes mainly mineral carbonates in construction products, such as in cement, lime, hydraulic binders or bricks. If a product can release CO₂ again at the end of its life, for example through waste incineration, it does not count as permanent binding.

This exception therefore does not apply to short-lived products such as fuels or many plastics. The release is not simply booked as avoided at the emitter just because the CO₂ was initially passed on. How renewable and low-carbon fuels that are used are credited for users in the emissions trading system is governed by separate provisions of the Monitoring Regulation. This coordination is intended to prevent the same tonne from being counted twice: once as an avoided emission at the capturer and again as a climate-friendly raw material at the user.

Legal framework in the EU: synthetic fuels

For renewable fuels of non-biological origin (RFNBO), which include many e-fuels, Delegated Regulation (EU) 2023/1185 sets out the greenhouse gas accounting methodology. Incorporated CO₂ may be deducted as an avoided emission only under certain conditions. CO₂ from the air, sustainable biogenic CO₂ and CO₂ from naturally occurring geological sources are permitted without a time limit. Fossil CO₂ from industrial plants is permitted only if the plant is subject to effective carbon pricing, and even then only on a transitional basis. For CO₂ from electricity generation, crediting applies until 2035, and for other industrial sources until 2040. In addition, there are requirements for the electricity used, such as additionality and temporal and geographical correlation. These rules apply to crediting within the EU framework. They are not a general judgement on the climate impact of individual plants.

Origin of the CO₂ and climate balance

The origin of the CO₂ is a central point. CO₂ from fossil point sources remains fossil carbon. If it is captured, used and later released, CCU merely shifts the emission in time and often in space. The advantage then lies at most in the fact that fossil raw materials are replaced in the product. The source's emission is not eliminated as a result. CO₂ from sustainably produced biomass comes from the short-term carbon cycle. CO₂ from the air was previously removed from the atmosphere. A fuel that releases CO₂ during combustion can therefore only be approximately climate-neutral if the carbon comes from the air or from sustainable biogenic sources and all process energy is provided with low emissions. Net removals from the atmosphere arise only through permanent storage, for example with BECCS or through permanent mineral binding, and not through short-lived utilization.

The tonne of CO₂ is the usual metric but is not sufficient for an assessment. A captured tonne is not automatically an avoided tonne. Factors to be taken into account include the energy required for capture, purification, compression, transport and conversion, the origin of the CO₂ and the electricity, the lifetime of the product and the product that is replaced. A further question is whether the utilization economically supports a fossil source that would otherwise be avoided.

Energy demand and relationship to the power system

CO₂ is a very stable, low-energy molecule. Because a great deal of energy is released when carbon is burned, converting it back into energy-rich products such as fuels correspondingly requires a lot of energy. The IEA emphasizes that low-carbon energy is crucial precisely for fuels and chemical intermediates because these processes are very energy-intensive. For synthetic hydrocarbons, CO₂ is combined with hydrogen, which is usually produced by electrolysis. CCU is therefore closely linked to Power-to-X and to the expansion of renewable electricity generation. The value of CO₂ as a raw material arises only through hydrogen, electricity, heat, catalysts and plant technology. Costs are therefore determined mainly by electricity price, plant utilization, full-load hours of electrolysis, transport and regulation, and hardly by the CO₂ itself. For mineral applications, material flows, standards and building approvals come into play as well.

For the power system, CCU means additional demand. Electrolysers, synthesis plants and CO₂ capture can be flexible consumers if they respond to prices, grid bottlenecks and the supply of wind and solar power. However, they can also form a permanent baseload that burdens grids and requires additional firm capacity. Whether CCU supports the integration of renewable energy depends on location, mode of operation, grid connection, storability of the intermediate products and market design.

Efficiency and sensible fields of application

Direct electrification is more energy-efficient than the detour via hydrogen and synthetic hydrocarbons in many applications. An electric car uses electricity much more efficiently than a vehicle running on synthetic fuel. A heat pump obtains several kilowatt-hours of heat from one kilowatt-hour of electricity, whereas synthetic fuels involve high conversion losses. CCU-based fuels are therefore discussed above all where direct electrification is difficult: in international aviation, in parts of shipping and in the chemical industry, which continues to need carbon-containing molecules.

A distinction is also necessary for unavoidable industrial emissions. In cement production, process-related CO₂ arises when limestone is chemically transformed. If this CO₂ ends up in short-lived products, it is not permanently neutralized. With permanent mineral binding, by contrast, it is also treated differently in legal terms. CCU can be part of a carbon strategy but solves the problem of permanence only in certain applications.

Conclusion

CCU is not an automatic CO₂ sink but the industrial use of captured carbon dioxide. The term becomes meaningful only when five points are disclosed: the source of the CO₂, the energy input and its origin, the duration of binding, the product replaced and the rules against double counting. If this information is missing, neither the climate impact nor the benefit to the energy system can be reliably derived.

Sources

Related glossary entries

Edited by eCMS on 11.11.2026 17:05

© 2026 Erik Schmidt. All rights reserved. Quotations with a link to the source are welcome.