Harnessing potential of biological CO2 capture for Circular Economy

CCUS encompasses a comprehensive array of technologies designed to address the reduction of carbon dioxide (CO₂) emissions originating from large point sources like power plants, refineries and other industrial facilities, or the removal of existing CO₂ from the atmosphere. Additionally, it involves the extraction of existing CO₂ from the atmosphere. This multifaceted approach is considered pivotal in achieving and maintaining global climate objectives. At its core, CCUS involves the interception of carbon dioxide emissions at the source of industrial operations, preventing their release into the atmosphere. This preemptive action significantly mitigates emissions. The captured carbon dioxide emissions undergo distinct strategies. One approach involves transforming CO₂ into various useful materials, such as building components (utilization). Alternatively, the captured emissions can be securely stored, typically thousands of feet below the Earth’s surface (storage). If the captured CO₂ is not being used on-site, it is compressed and delivered via pipeline, ship, rail, or truck to be utilized in various applications or injected into deep geological formations. Geologic formations selected for carbon dioxide storage are varied and include oil and gas reservoirs, unmineable coal seams, and deep saline reservoirs. These structures have served as natural repositories for substances like crude oil, natural gas, brine, and carbon dioxide over millions of years. While the concept of CCUS itself is straightforward, its effective implementation requires robust infrastructure and comprehensive policy frameworks. Esteemed organizations such as the International Energy Agency (IEA), International Renewable Energy Agency (IRENA), Intergovernmental Panel on Climate Change (IPCC), and Bloomberg New Energy Finance (BNEF) have projected long-term energy strategies reliant on the accelerated expansion of CCUS. This expansion is essential in order to cap global temperature rise at the critical threshold of 1.5°C.

CCUS operates through a comprehensive three-stage process involving Capture, Transport and Storage (or Utilization) of CO2.

1. Capture

This initial stage focuses on the separation of CO₂ from other gases produced in various industrial processes. Multiple proven and effective capture methods are employed, tailored to different emission sources. Three primary methods stand out:

Post-combustion: Employing chemical solvents, post-combustion technology isolates CO₂ from flue gas after fuel combustion.

Pre-combustion:  This method involves converting fuel into a mixture of hydrogen and CO₂ before combustion. The separated CO₂ allows the remaining hydrogen-rich mixture to be utilized as fuel.

Oxy-fuel combustion: Burning fuel with nearly pure oxygen generates CO₂ and steam, enabling the capture of released CO₂.

Both post-combustion and oxy-fuel equipment can be added to new or existing facilities, with pre-combustion methods necessitating more significant modifications, making them better suited for new plants.

Current operational facilities equipped with CCUS demonstrate the capability to capture around 90% of CO₂ present in flue gas. Further research aims to enhance capture rates and reduce associated costs. Additionally, direct CO₂ capture from the atmosphere involves drawing in air via fans and passing it through solid sorbents or liquid solvents. However, this method is more energy-intensive and costlier due to the lower concentration of CO₂ in the atmosphere compared to flue gas.

2. Transport

Once the CO₂ has been captured, undergoes compression into a liquid state, preparing it for transportation via pipeline, ship, rail, or road tanker. This compression elevates pressure, enabling CO₂ to behave as a liquid. Dehydration follows compression before CO₂ enters the transport system.

3. Storage

Following transportation, CO₂ is injected into deep geological formations, typically at depths exceeding 1 km, for permanent storage. The favored technique involves geological carbon storage, where CO₂ is inserted into deeply entrenched rock formations. This insertion occurs under intense pressure, rendering the CO₂ in a supercritical state—densely liquid yet possessing gas-like viscosity. These geologic formations have housed fossil fuels like oil and gas for millions of years, trapped in microscopic rock pores and under impermeable cap rocks. Potential risks of leakage exist, especially in abandoned or improperly sealed wells, necessitating a thorough review to ensure their capability to contain high-pressure CO₂. Furthermore, CO₂ injection into vast saline aquifers—where porous rocks harbor brine—presents an alternative. While some CO₂ gets trapped in small pores, the majority flows upwards to be trapped under the impermeable caprock. Over hundreds to thousands of years the CO₂ dissolves into the brine, eventually chemically bonding with the rock. Globally, evidence suggests an abundance of underground storage capacity surpassing climate targets, notably in nations emitting substantial CO₂. In-depth evaluations conducted by the Oil and Gas Climate Initiative have identified 850 potential geological sites across 30 countries in their CO₂ Storage Resource Catalogue. These assessments total approximately 14,000 gigatonnes, an ample reservoir capable of meeting projected CCUS demands for the foreseeable century.

An alternative to permanent storage involves using captured CO₂ as an input for commercial products and services. However, the climate implications of this approach require careful examination due to its complexities and potential environmental impacts.

CCUS stands as an indispensable asset within the arsenal of tools facilitating the energy transition. It serves as a practical and feasible method to alleviate emissions stemming from current infrastructure and industrial operations. By doing so, it actively contributes to steering the world towards a future that prioritizes sustainability and a significant reduction in carbon emissions.

• Emissions Reduction: CCUS technology enables the mitigation of carbon dioxide emissions from large-scale industrial processes, power plants, and other facilities. By capturing CO₂ before it enters the atmosphere, CCUS significantly reduces greenhouse gas emissions, crucial in combating climate change.
• Power supporter. In the transition towards renewable energy sources like wind and solar, CCUS acts as a bridge technology. Given that solar and wind power output hinges on weather conditions rather than immediate demand, there will be occasions when these sources cannot generate energy. During such times, natural gas steps in as a backup, offering the potential for supplying low-carbon electricity when paired with CCUS technology.
• Addressing Existing Infrastructure: CCUS allows for the continued use of existing infrastructure, such as power plants and industrial facilities, by retrofitting them with carbon capture technology. This prolongs their operational lifespan and prevents premature decommissioning, aiding in the transition process.
• Hydrogen launcher: As we navigate towards a sustainable future, hydrogen’s significance continues to grow within decarbonization blueprints. While the ultimate aim is to produce most hydrogen using surplus renewable energy, countries abundant in natural gas can presently spearhead the clean hydrogen market by harnessing their gas resources. However, this production method generates CO₂, necessitating the integration of CCUS to effectively mitigate its environmental impact.

Air purifier. Beyond simply reducing emissions, it’s imperative to extract some carbon dioxide from the atmosphere. This process, termed carbon removal, is essential to counterbalance any residual greenhouse gas emissions and offset historical emissions. The storage facet within CCUS plays a pivotal role in safeguarding the extracted carbon, preventing its re-release into the atmosphere.

Several key concerns surround the implementation and widespread adoption of CCUS:

• Cost and Economics: The primary concern revolves around the substantial costs associated with CCUS technology deployment. The expenses encompass capturing CO₂, transportation, storage, and infrastructure development. These expenses often pose financial challenges, raising questions about the economic viability of widespread CCUS adoption.
• Energy Requirements: CCUS processes often demand significant amounts of energy. The energy needed for capturing, compressing, transporting, and storing CO₂ can be substantial, potentially offsetting the emissions reductions achieved. This energy demand might pose challenges in regions where renewable energy sources are not readily available.
• Storage Integrity and Leakage: The long-term integrity of storage sites is a concern. Ensuring that injected CO₂ remains securely stored without leakage or unintended releases is crucial for effective carbon sequestration. Leakage from storage sites or poorly sealed wells can negate the intended climate benefits of CCUS.
• Scale and Infrastructure: Scaling up CCUS to a level where it significantly impacts global emissions requires extensive infrastructure development. This involves establishing pipelines, storage facilities, and retrofitting existing industrial operations, which presents logistical and regulatory challenges.
• Public Perception and Acceptance: CCUS faces public scepticism and opposition in some quarters due to concerns about safety, environmental impacts, and the potential for CO₂ Addressing public concerns and garnering societal acceptance is crucial for widespread adoption.