Carbon storage

Carbon storage is the process of capturing carbon dioxide (CO₂) and keeping it out of the atmosphere for an extended period of time. It can take place in natural ecosystems, such as forests or soils, or through technological solutions designed to store it in a stable way, for example in geological formations.

For many companies, the starting point is measuring their carbon footprint: understanding how much they emit and where. But measuring is not enough. Even after reducing emissions, there is always a portion that cannot be fully eliminated. This is where carbon storage comes in: as a tool to manage those residual emissions within a broader decarbonization strategy.

How it works

Carbon storage involves three main stages: capture, CO₂ management, and final storage. The difference between solutions lies in how each of these stages is implemented.

1. CO₂ capture

Carbon can be captured:

• At source: directly from industrial or energy processes before it reaches the atmosphere
• From the air: using specific technologies that filter CO₂ already present in the atmosphere

2. Conditioning and transport

Once captured, CO₂ is compressed to reduce its volume and facilitate handling. If the storage site is located elsewhere, it is transported—typically via pipelines, but also by ship or truck.

3. Storage

This is where the effectiveness of the process is ultimately determined. CO₂ is injected into a system that keeps it isolated from the atmosphere.
Over time, in some cases, it transitions from being “stored” to being permanently fixed.

What makes the difference

Not all solutions perform equally. Three key factors determine their effectiveness:

• Permanence: how long the CO₂ remains out of the atmosphere
• Leakage risk: the likelihood of CO₂ being released again
• Measurability: the level of certainty around how much carbon has been stored

Where carbon is stored (types)

Natural storage

CO₂ is captured and stored in ecosystems such as forests, soils, or wetlands. It is scalable and accessible, but less stable: carbon can be released if the ecosystem degrades, burns, or changes its use.

Geological storage

CO₂ is injected deep underground, typically into rock formations that have held fluids or gases for millions of years (such as depleted oil fields or saline aquifers).

Mineralization

In this case, CO₂ is not just stored but chemically transformed. It reacts with certain minerals (e.g., basalt) and becomes solid carbonates, similar to rock.

DACCS (Direct Air Capture with Carbon Storage)

This combines two elements:

• Capturing CO₂ directly from the air
• Storing it afterwards (typically through geological storage or mineralization)

It is one of the few solutions capable of removing already emitted carbon at scale. Today, its main limitations are cost and energy consumption.

What it is used for

Carbon storage is used when emissions reduction reaches its limits. In other words, even after optimizing processes and reducing the carbon footprint, some residual emissions remain unavoidable.

In practice, it serves three main purposes:

• Managing residual emissions: sectors such as transport, industry, or agriculture cannot always eliminate all emissions. Storage helps address what remains.
• Meeting climate targets: many net-zero strategies rely on storage to balance unavoidable emissions.
• Generating carbon credits: some projects allow stored carbon to be certified and converted into credits for voluntary markets.

Regulation

European Union

• EU ETS (Emissions Trading System): includes certain carbon capture and storage technologies within regulated sectors
• CRCF (Carbon Removal Certification Framework): establishes common criteria for certifying carbon removal, focused on permanence, additionality, and verification
• EU Taxonomy: defines which activities can be considered sustainable, including some related to carbon capture and storage under specific technical criteria

International standards

• GHG Protocol: the main framework for emissions accounting
• ISO 14064 and 14067: standards for quantification and reporting
• Science Based Targets initiative (SBTi): prioritizes emissions reduction and limits the use of storage to residual emissions

Carbon storage makes it possible to remove CO₂ and keep it out of the atmosphere, but its impact depends on how it is implemented. Not all solutions offer the same level of permanence or reliability. Rather than a standalone solution, it is a tool that needs to be integrated into a well-defined decarbonization strategy.