Carbon Capture: A Limited Tool in the Climate Fight

As the urgency to address climate change grows, carbon capture and storage (CCS) technology is often promoted as a solution for our ever increasing carbon dioxide (CO₂) emissions. Although CCS holds potential for specific industrial sectors, its overall impact is limited due to challenges with cost, energy efficiency, and scalability. Rather than serving as a primary climate strategy, CCS should be considered a complementary tool, while scalable and cost-effective solutions like renewable energy take center stage.

Limited Impact on Global Emissions

CCS has so far played a small role in reducing global emissions. As of now, CCS captures around 49 million metric tons of CO₂ annually, which is less than 0.1% of global emissions, which reached 36.3 billion tons in 2021 (Global CCS Institute, 2022). The vast majority of emissions remain unaddressed, and scaling CCS to meet global needs would require a massive infrastructure overhaul with a negative end result.   

Energy Intensity and Efficiency Concerns

A significant challenge with CCS is the amount of energy required to capture and store CO₂. According to the International Energy Agency (IEA), installing CCS at a power plant can reduce its efficiency by 20-30%, meaning more fuel is needed to produce the same amount of electricity. This energy penalty undermines some of the environmental benefits of CCS, as the increased energy consumption leads to additional emissions. This would in turn cause the energy costs associated with CCS power plants to be prohibitively expensive - far more than renewable energy sources.  

For example, the Mammoth project, the world’s largest direct air capture (DAC) facility, aims to capture 36,000 tons of CO₂ annually. However, DAC technologies are particularly energy-intensive; the Mammoth project requires around 1,200 kWh of energy per ton of CO₂ removed.  For perspective, one ton of captured CO2 is equivalent to the daily energy use of 85 Irish homes. This clearly shows that in many cases, the energy used to power CCS could be more efficiently invested in clean energy technologies like wind, solar, and battery storage systems.  

High Costs and Economic Viability

The economic viability of CCS remains another substantial hurdle. According to a study by the Global Energy Prize, adding CCS to a combined-cycle power plant can more than double the plant's cost, increasing capital expenses from $1,350/kW to $3,019/kW. Furthermore, capturing and storing one ton of CO₂ costs around $100. At this rate, offsetting global carbon emissions would cost over $1.8 trillion annually, highlighting the sheer economic scale of the challenge.

For large-scale DAC projects like Mammoth, the high costs are even more daunting. To achieve its target of 36,000 tons per year, the project would require upwards of $3,600,000 annually in operating costs, assuming a capture price of $100 per ton.

In contrast, renewable energy technologies such as wind and solar have become increasingly affordable and scalable. Investment in these areas often provides more immediate and impactful results in reducing emissions.

Storage Risks and Geographic Limitations

Once CO₂ is captured, it must be stored, typically in underground geological formations. However, not all regions have suitable storage sites, and there are concerns about potential leaks over time. Even small leakages could erode the long-term climate benefits of carbon storage, particularly if they occur over decades or centuries.

The uneven distribution of storage capacity further complicates the role of CCS as a global climate solution. Only certain regions have the geological features required for effective long-term storage, limiting where CCS can be effectively deployed.

The Case for Direct Emissions Reductions

Given the high costs and energy demands of CCS, investing in renewable energy and efficiency improvements is often a more effective approach in reducing emissions. Renewable energy sources like wind and solar directly generate electricity without emitting CO₂, and their costs continue to decline as technologies advance and scale.

For instance, energy that would otherwise be used to power CCS systems could instead support renewable infrastructure, leading to greater overall emissions reductions. A study by the UK’s Energy Systems Catapult found that powering CCS plants with renewable energy reduces their net emissions benefits by 15-20%, reinforcing the case for prioritizing direct emissions reductions through clean energy.

Complementary Role for CCS

Despite its challenges, CCS could play a role in sectors where emissions are difficult to eliminate, such as cement, steel, and chemical manufacturing. However, it should not be viewed as a silver bullet for climate mitigation. Instead, CCS should complement more proven strategies like expanding renewable energy and improving energy efficiency. By focusing on direct emissions reductions and integrating CCS where it makes sense, policymakers can maximize the effectiveness of climate efforts.

Policymakers must carefully balance their investments to ensure that limited resources are directed toward the most impactful and scalable technologies in the fight against climate change.