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Glossary · Energy industry & energy transition

CCUS, Carbon Capture, Utilization and Storage

CCUS CCS CCU CO2 capture CO2 storage Industry Climate protection carbon management

CCUS stands for Carbon Capture, Utilization and Storage. It refers to the capture of carbon dioxide from flue gases, process gases or ambient air. The CO₂ is then either used or permanently stored in geological formations. The term thus combines two different pathways: CCS (Carbon Capture and Storage) and CCU (Carbon Capture and Utilization). Both begin with the capture of CO₂. They differ in what subsequently happens to the captured carbon and how long it stays out of the atmosphere.

The most important reference unit is usually the tonne of CO₂. The assessment looks at capture volumes, capture rates, remaining residual emissions, energy demand, transport volumes and the duration of storage or use. A plant that captures about 90 percent of the CO₂ from a flue gas stream must be judged differently in terms of climate policy than a plant with a lower capture rate or high additional emissions from energy consumption, auxiliary materials and transport. The label "with CCUS" therefore says little about the climate impact. A balance across the entire process is needed.

Capture, utilization and storage

In CCS, CO₂ is captured, processed, compressed, transported by pipeline or ship and injected into suitable geological formations. Deep saline aquifers and depleted oil or gas fields are the main candidates. A cap rock must retain the CO₂. German law describes permanent storage as injection and containerless emplacement in deep rock layers. The aim is to prevent leakage for an unlimited period of time. This requires geological suitability, modelling, ongoing monitoring, liability rules and clear responsibility for operation, decommissioning and post-closure care.

CCU refers to the use of captured CO₂ as a raw material, for example for synthetic fuels, chemicals, plastics, building materials or in the food industry. The climate impact depends strongly on the use pathway. One example: CO₂ is bound in a synthetic fuel and released again when that fuel is burned. In that case, no CO₂ is permanently removed from the atmosphere. A benefit can nevertheless arise if the fuel replaces fossil carbon and the energy used comes from low-emission sources. CCU is more durable when CO₂ is mineralized or bound in very long-lived products. However, many CCU applications merely shift emissions in time or to another sector.

CO₂ removal from the atmosphere must be distinguished from this. Direct Air Capture removes CO₂ directly from ambient air. If this CO₂ is then permanently stored, negative emissions can result. CCUS at a fossil source, by contrast, only prevents part of the ongoing emissions from reaching the atmosphere. In principle, it does not generate negative emissions, because the carbon comes from fossil deposits. This distinction is central because political debates often mix up capture, avoidance and removal.

Relevance for industry and the power system

CCUS is relevant above all where CO₂ cannot be avoided by electrification, efficiency or a switch to renewable energy sources alone. The Federal Government names the cement and lime industry, parts of the basic chemicals industry and waste incineration as examples. In cement and lime, a large share of emissions arises not from fuels but from the chemical decomposition of limestone. These process emissions remain even when the kiln is run on climate-neutral energy. CCUS targets precisely such residual emissions. In the steel industry, by contrast, CCUS competes with hydrogen-based processes. Its role there depends more on the process route chosen.

In the power system, CCUS plays a different role. Fossil power plants with CO₂ capture could provide firm capacity while emitting less than conventional plants. In practice, there are several constraints. Capture reduces efficiency because additional energy is needed for solvent regeneration, compression and auxiliary systems. A power plant with capture therefore needs more fuel per kilowatt hour generated than the same plant without capture. In addition, residual emissions at the stack, methane emissions in the natural gas upstream chain and emissions from the construction and operation of the infrastructure remain relevant. In Germany, a legal limit is added: CO₂ from coal combustion for energy generation receives no access to CO₂ pipeline networks and storage sites (see below).

In a power system with a high share of renewable energy, the question also arises of how often such plants run. If a power plant with CCUS runs only a few hours, for example for peak load or when there is little wind and solar power, the high investment costs are spread over few operating hours. Economic viability then depends strongly on capacity mechanisms, CO₂ prices, support rules or state-backed revenue models. The technical term CCUS thus leads directly to questions of market design, security of supply and the financing of reserve and firm capacity.

CCUS can also create additional energy demand. Capture, compression, pumping, transport and, where applicable, chemical conversion consume energy. In CCU applications such as synthetic fuels, a high demand for renewable electricity for hydrogen production is added. CCUS thereby touches on system costs, grid expansion and competition for renewable energy. A tonne of captured CO₂ says little in terms of climate policy as long as it remains unclear what energy was used for it and which other use that energy displaced.

Legal framework in the EU and Germany

In the EU, the CCS Directive 2009/31/EC governs the geological storage of CO₂ in the territory of the Member States, in their exclusive economic zones and on their continental shelves. It requires storage permits, monitoring, measures in the event of leakage, obligations for closure and post-closure care, and financial security. Responsibility for a closed storage site can pass to the state only after a minimum period of, in principle, 20 years. Before then, it must be demonstrated that the CO₂ is completely and permanently contained. The Directive does not apply to research projects with a total planned storage volume below 100 kilotonnes.

The Net-Zero Industry Act (EU) 2024/1735 sets an EU target of at least 50 million tonnes of annual CO₂ injection capacity in geological storage sites by 2030. Oil and gas producers holding extraction licences in the EU must contribute to this target proportionately. The European Commission estimates that from around 2040, roughly 250 million tonnes of CO₂ per year would need to be captured and permanently stored in order to achieve climate neutrality by 2050. The 50-million-tonne target is an expansion target for storage capacity. It does not describe a storage volume that has already been achieved.

In Germany, the Carbon Dioxide Storage Act of 2012 permitted storage until 2025 practically only for research and demonstration. The amendment entered into force on 28 November 2025. Since then, the act has been called the Carbon Dioxide Storage and Transport Act (KSpTG). It permits CO₂ storage on an industrial scale and, for the first time, comprehensively regulates pipeline transport. As of November 2026, the key points include the following:

  • Offshore focus: Storage sites are approved that lie largely in the exclusive economic zone and on the continental shelf. Injection in the territorial sea is excluded. The federal states can opt in to specify that onshore storage is also permitted on their territory, if applicable only in certain areas.

  • Marine protection: In marine protected areas (as of 31 December 2023) and at a distance of less than 8 kilometres from them, injection facilities and injection points are not permitted. Storage formations beneath such areas are likewise excluded. An extension of the storage areas is possible only by statutory ordinance with the consent of the Bundestag and Bundesrat.

  • Transport: The construction, operation and modification of CO₂ pipelines and CO₂ storage sites are in the overriding public interest, except in protected marine areas. Pipelines are subject to plan approval. Under certain conditions, expropriations are also permissible.

  • Third-party access: Operators of CO₂ pipeline networks and storage sites must grant other companies non-discriminatory connection and access. The Federal Network Agency monitors this.

  • Coal exclusion: For CO₂ from the combustion of coal in energy generation plants covered by emissions trading, operators must refuse connection and access. For gas-fired power plants, the act contains no corresponding exclusion.

  • Liability and post-closure care: Storage operators are liable for damage and must provide financial coverage. Responsibility can pass to the competent federal state at the earliest 40 years after completion of decommissioning, earlier only where long-term safety has been demonstrated. In addition, a post-closure care contribution is due, intended to cover at least the monitoring costs for 30 years after the transfer.

  • Research storage: Projects with a total of less than 100,000 tonnes of injected CO₂ count as research storage.

The legal framework does not mean the infrastructure has been built. According to the Federal Government, building up transport and storage infrastructure can take seven to ten years. For the export of CO₂ for storage in other countries, international law rules on marine disposal are also relevant.

Common misconceptions

A widespread misconception is that CCUS is a simple continuation of fossil use with downstream cleaning. However, capture rarely covers all emissions of a plant. In addition there are emissions from fuel extraction, transport, construction of the infrastructure and the additional energy demand. Anyone assessing CCUS must therefore distinguish between the capture rate at the stack and the net climate impact across the entire value chain.

A second misconception concerns CCU. The use of CO₂ sounds like recycling a waste, but says nothing about how long it is bound. CO₂ in beverages, fuels or short-lived chemicals usually returns to the atmosphere quickly. Such applications can make sense in individual markets. But they do not replace permanent storage if greenhouse gases are to be reliably reduced. CCU becomes a robust climate protection instrument only when the origin of the CO₂, energy input, product lifetime and the fossil alternative replaced are properly accounted for.

A third misconception is equating CCUS with negative emissions. Negative emissions arise only when CO₂ is removed from the atmosphere and permanently stored. This applies, for example, to Direct Air Capture with storage or to biogenic CO₂ from sustainable biomass with geological storage (BECCS). CCUS at a fossil source reduces emissions compared with a plant without capture. But it does not remove CO₂ that is already in the atmosphere.

Infrastructure, liability and political order

CCUS is not a single plant but a chain of capture, processing, transport, and storage or use. Each stage needs technical standards and institutional rules. CO₂ pipelines, ships, intermediate storage, compressors and measurement systems must be planned, approved and financed. Storage sites need geological exploration, long-term monitoring and liability rules for possible leakage. The quality of the CO₂ stream is also regulated: it must consist overwhelmingly of CO₂ and must not contain waste for disposal. Who is responsible for stored CO₂ over decades is answered by the deadlines for the transfer of responsibility. Nevertheless, the question remains a political one as well.

The economic incentives are not neutral either. A high and reliable CO₂ price can make CCUS more attractive for hard-to-abate industrial processes. If the price is not sufficient or risks are hard to calculate, support schemes, contracts for difference, state guarantees or regulated infrastructures emerge. CCUS thus becomes a governance question. Which emissions count as hard to abate? Which plants receive access to storage infrastructure? Who bears the transport and storage costs? And how is it prevented that scarce storage capacity is occupied by avoidable emissions? The German act expressly provides for future evaluations to examine whether remote emitters without proximity to the coast or to clusters can be connected to pipelines at all or must bear high network charges.

For distinguishing CCUS from other climate protection options, the order of priority matters. Avoidance through efficiency, renewable energy, electrification or material substitution reduces the need for CO₂ infrastructure. CCUS addresses the remaining emissions whose avoidance is technically difficult, very expensive or process-related. This classification prevents two misjudgements: dismissing CCUS across the board as a false solution, or overestimating it as a universal climate protection technology.

CCUS thus denotes not a single technical trick but a process chain with clear physical, economic and institutional conditions. The term becomes precise only with concrete information: where the CO₂ arises, how much of it is captured, what energy is used for this, whether it is used or stored, how durable the binding is, and who bears responsibility for transport, storage and verification.

Sources

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Edited by eCMS on 11.11.2026 17:08

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