Understanding carbon dioxide removal (CDR) technologies

As the world grapples with the escalating impacts of climate change, reducing emissions alone isn’t enough to meet global climate goals. Enter carbon dioxide removal (CDR) - an essential approach to achieving net zero emissions by actively removing CO₂ from the atmosphere. While promising, not all CDR technologies are created equal. Each comes with its own benefits, challenges, and applications. Here’s an overview of the most prominent types.

1. Nature-based solutions

Nature has been capturing CO₂ for millennia. Leveraging these processes can provide scalable, cost-effective, and co-beneficial solutions:

• Afforestation and reforestation: Planting trees or restoring degraded forests absorbs CO₂ as trees grow. These projects can improve biodiversity, soil health, and water cycles but require careful management to ensure permanence.

• Soil carbon sequestration: Improving agricultural practices, such as no-till farming and crop rotation, can enhance soil’s ability to store carbon. While beneficial for food security, results depend on soil type and management.

• Wetland restoration: Rehabilitating wetlands, mangroves, or peatlands locks CO₂ in organic matter while protecting ecosystems from erosion and flooding.

2. Direct air capture (DAC)

Direct air capture technologies use chemical processes to pull CO₂ directly from ambient air:

• Solid sorbents and liquid solvents: These systems capture CO₂ and release it during regeneration cycles, making it available for storage or utilisation.

• Applications and storage: Once captured, CO₂ can be permanently stored in geological formations or used in products like synthetic fuels. However, high energy demands and costs are challenges.

3. Bioenergy with carbon capture and storage (BECCS)

BECCS combines biomass energy production with CO₂ capture:

• Process: Biomass (like crops, waste, or algae) is burned for energy, and the resulting CO₂ is captured and stored.

• Potential: BECCS can produce negative emissions while generating energy, but concerns include land use, water consumption, and competition with food production.

4. Ocean-based CDR

The ocean already absorbs around 25% of annual CO₂ emissions. Ocean-based approaches aim to enhance this process:

• Alkalinity enhancement: Adding crushed minerals like olivine increases the ocean’s ability to store CO₂.

• Seaweed farming: Large-scale cultivation of seaweed absorbs CO₂ as it grows. Once harvested, it can be processed or sunk to the deep ocean for long-term sequestration.

• Concerns: These methods require rigorous testing to avoid unintended ecological consequences.

5. Geochemical approaches

These methods leverage chemical reactions to store CO₂:

• Mineral carbonation: CO₂ reacts with minerals like basalt to form stable carbonates, effectively locking carbon away for millennia.

• Applications: Suitable for areas with abundant reactive rocks, but deployment is geographically constrained.

6. Hybrid technologies

Some emerging solutions combine elements of these approaches:

• Enhanced weathering: Spreading finely crushed silicate minerals over land or in oceans accelerates natural weathering processes that draw down CO₂.

• Biochar: Heating organic material in a low-oxygen environment creates a stable form of carbon that can be used as a soil amendment, enhancing agricultural productivity while sequestering carbon.

Choosing the right CDR approach

Each CDR technology comes with trade-offs, making context-critical decisions essential. Factors to consider include scalability, cost, energy requirements, and impacts on communities and ecosystems. No single solution will solve the climate crisis, but a portfolio of approaches can help us bridge the gap to a sustainable future.

As we advance, robust governance, innovation, and investment in monitoring technologies will ensure these solutions live up to their promise.

At Atmoz, we’re here to help businesses and policymakers navigate the evolving CDR landscape, ensuring actions align with climate goals and regulations. Ready to take action? Get in touch with us today.