Measuring the Impact: How Much CO₂ Can We Sequester?

With growing concerns about climate change, carbon sequestration has emerged as a vital process for mitigating atmospheric CO₂ levels. Carbon sequestration refers to the process of capturing and storing atmospheric carbon dioxide. The primary goal is to reduce the concentration of CO₂ in the atmosphere and slow global warming. Understanding the amount of CO₂ that can be sequestered requires an examination of different methods, their capacities, and the conditions under which they are effective. This article provides an overview of the main types of carbon sequestration, their effectiveness, and how they can be scaled to have a meaningful impact.

Types of Carbon Sequestration

There are three main types of carbon sequestration:

1. Terrestrial Sequestration Terrestrial carbon sequestration uses plants, soils, and forests to naturally capture and store CO₂. Plants absorb CO₂ from the atmosphere through photosynthesis and store it in biomass (stems, roots, leaves) and soil. Forests, grasslands, and agricultural soils all contribute to terrestrial sequestration. Terrestrial sequestration provides both carbon storage and ecosystem benefits, such as improved biodiversity and soil health. However, it is vulnerable to disturbances such as forest fires, droughts, and deforestation, which can release stored CO₂ back into the atmosphere and therefore requires sustainable management.

Examples:

• Afforestation and Reforestation: Planting trees in new and deforested areas has proven effective in sequestering CO₂. For example, the Amazon rainforest, often called the “lungs of the earth,” is one of the world’s largest carbon sinks. A mature tree can absorb about 22 kg of CO₂ per year.
• Agroforestry: By integrating trees into agricultural systems, farmers can create additional carbon sinks. For example, coffee and cocoa farmers often plant trees that provide shade, improve soil quality, and sequester carbon.
• Soil Carbon Sequestration: The use of no-till farming techniques and cover crops can increase the carbon storage potential of soils. Healthy soils can store up to 5-15% of atmospheric CO₂, depending on the area.

2. Geological Sequestration Geological sequestration involves storing CO₂ in underground rock formations, particularly saline aquifers and depleted oil and gas reservoirs. This method requires capturing CO₂ emissions from industrial sources, compressing them, and injecting them deep into the earth. Geological sequestration has immense potential because it allows for the long-term storage of CO₂ in stable environments. The Intergovernmental Panel on Climate Change (IPCC) estimates that geological storage can sequester up to 10 billion tons of CO₂ per year. However, the technology is still in its early stages and will require significant investment and rigorous monitoring to prevent leakage.

Examples:

• Carbon Capture and Storage (CCS): Large industrial facilities, such as power plants and steel factories, capture CO₂ emissions and inject them underground. For example, the Boundary Dam Power Station in Canada captures about 1 million tons of CO₂ annually and injects it into nearby geological formations.
• Enhanced Oil Recovery (EOR): In this process, captured CO₂ is injected into oil fields to increase oil recovery rates. The addition of CO₂ increases the overall pressure of an oil reservoir, forcing the oil toward production wells. The CO₂ remains trapped underground, reducing atmospheric CO₂ levels.
• Saline Aquifers: Saline aquifers are deep, porous, and permeable rock formations filled with saltwater, found below potable water sources. Due to their geological properties and wide availability, they offer significant potential for long-term CO₂ storage

3. Ocean Sequestration The world’s oceans naturally absorb about 25% of all CO₂ emissions. Ocean sequestration aims to enhance this process by storing CO₂ in the deep ocean or boosting the ocean’s natural carbon-capturing capacity. However, this method requires a cautious approach due to potential impacts on marine ecosystems. Oceans have a vast capacity for CO₂ sequestration; however, the potential for ocean acidification poses a significant environmental risk. Altering oceanic carbon levels could disrupt marine life, impacting biodiversity and food security source.

Examples:

• Ocean Fertilization: This process involves adding nutrients like iron to specific ocean regions to stimulate phytoplankton growth. As these microorganisms photosynthesize, they absorb CO₂. When they die, they sink to the ocean floor, theoretically trapping carbon for centuries. While promising, the environmental impact of ocean fertilization on marine ecosystems remains uncertain.
• Artificial Upwelling: By bringing nutrient-rich waters from the ocean depths to the surface, artificial upwelling encourages CO₂ absorption. Phytoplankton growth accelerates, capturing CO₂ that eventually sinks to the depths. This method is in the research phase but holds potential for future application.
• Direct Injection: In this experimental approach, CO₂ is captured from industrial sources, liquefied, and injected into deep ocean waters. The CO₂ is stored at depths where it is less likely to reach the atmosphere again. Japan and Norway have conducted pilot projects to test the viability of this method.

Quantifying Carbon Sequestration Potential

Estimating sequestration potential varies with each method. For example:

• Terrestrial sequestration can offset up to 1.5 billion tons of CO₂ per year globally through reforestation and improved land management.
• Geological sequestration has a potential range of 10 billion tons per year, depending on available reservoirs and technological advancements.
• Ocean sequestration theoretically offers even higher capacity but requires extensive study to mitigate ecological risks.

Why It Matters for Ecobal

At Ecobal, we are committed to staying at the forefront of technological advancements in CO₂ sequestration. By integrating cutting-edge technologies such as ultra-fast CO₂ hydrate formation, we enhance our efforts to transform former agricultural or barren lands into thriving ecosystems. Ecobal has achieved significant milestones, including establishing Nature Spots in five different EU countries: France, Italy, Poland, Spain, and Romania. Ecobal’s storage capacity encompasses 155 hectares across the EU, storing approximately 1,581 tons of CO₂ and releasing about 1,150 tons of oxygen per year. This ensures that our projects not only effectively sequester CO₂ but also contribute to sustainable biodiversity conservation.

Ecobal’s Mission

• Raise awareness and establish authority to certify the ecological health and capacity of rural and natural landscapes.
• Monetize ecosystem services to demonstrate the economic value of nature.
• Use natural ecosystems as efficient carbon sinks for CH₄ and CO₂ sequestration and biodiversity conservation.
• Turn CO₂ and CH₄ from challenges into valuable, tradable commodities.
• Manage soil microbiota and fauna to improve soil health and ecosystem functionality.
• Restore biodiversity through the reintroduction and conservation of native species.

About the Author

This article is written by Dr. Amisalu Milkias, Ecobal’s CO₂ Project Specialist. Dr. Milkias is a leading expert in restoration ecology, actively contributing to the advancement of nature-based solutions for climate resilience, carbon sequestration, and biodiversity conservation across Europe.