How carbon storage in building materials can save the planet

Reducing carbon dioxide emissions is no longer enough to combat climate change – active removal of CO₂ from the atmosphere is now essential.

To restore atmospheric CO₂ levels to the safer target of 350 ppm, equivalent to the concentration in 1988, approximately 400 billion tons of carbon need to be removed. This immense quantity translates to roughly 1,500 billion tons of CO₂.

To combat this urgent climate issue, scientists at Empa are pioneering a groundbreaking carbon storage solution that converts excess carbon into building materials like concrete and asphalt.

This innovative approach not only helps store carbon safely but also transforms it into valuable resources, paving the way for a sustainable and economically viable strategy to restore atmospheric CO₂ levels to safer limits.

The role of building materials in carbon storage

Empa researchers propose using surplus renewable energy to convert CO₂ into carbon-based materials such as polymers, hydrogen, and solid carbon.

These materials can then be incorporated into commonly used construction components for carbon storage. Among these, concrete emerges as the ideal candidate due to its capacity to absorb substantial amounts of carbon without compromising its structural integrity.

Globally, the demand for construction materials like concrete, asphalt, and plastics far exceeds the amount of excess atmospheric carbon.

This makes the strategy not only feasible but also scalable. However, optimising how carbon can be efficiently and sustainably introduced into these materials remains a critical challenge.

Advantages over traditional storage methods

Compared to underground carbon storage, integrating carbon into building materials offers distinct advantages.

These materials provide long-term stability, reduce the risk of hazards like fires, and can be reused in multiple recycling cycles before safe disposal.

Additionally, carbon-enriched materials replace conventional CO₂-emitting options, creating a dual benefit of storage and emission reduction.

This approach also aligns with decentralised implementation, allowing different regions to adopt and adapt the methodology based on local resources and needs.

Furthermore, using carbon to produce advanced materials like polymers and graphene adds significant economic value to the process, making it both environmentally and financially viable.

Silicon carbide: The key to faster carbon absorption

Silicon carbide, a ceramic material with exceptional mechanical properties, could accelerate the timeline for carbon removal. It binds carbon indefinitely, making it a highly efficient storage medium.

However, its production requires substantial energy input, presenting both a technical and financial challenge.

By combining silicon carbide with porous carbon aggregates, researchers aim to enhance the durability and capacity of concrete to store carbon.

This hybrid approach has the potential to bind up to 10 gigatons of carbon annually, enabling significant progress toward the target of 350 ppm CO₂ within 50 to 150 years.

However, the realisation of this optimistic scenario hinges on the availability of abundant renewable energy post-2050.

Economic and environmental benefits of carbon storage

Empa’s ‘Mining the Atmosphere’ initiative envisions a carbon-binding economy where atmospheric CO₂ becomes a valuable raw material.

Carbon captured from the air could be used to manufacture high-value products like carbon fibres and nanotubes, alongside construction materials.

At the end of their lifecycle, these materials can be stored permanently, ensuring that the captured carbon remains out of the atmosphere.

Additionally, synthetic methane derived from captured CO₂ offers another advantage: the ability to transport renewable energy from Sun-rich regions to areas with seasonal energy deficits. This solution could revolutionise energy distribution while further reducing greenhouse gas emissions.

Turning carbon into opportunity

For the widespread adoption of carbon storage in building materials, significant advancements in materials research and renewable energy utilisation are required. Processes must be developed to handle fluctuating and decentralised energy supplies efficiently.

Furthermore, policy support, economic incentives, and new business models will be crucial to make this innovative approach a cornerstone of a carbon-neutral society.

The transformation of excess atmospheric CO₂ into building materials offers a promising pathway to combat climate change.

While challenges remain, the potential to restore the atmosphere to safer CO₂ levels and reshape industries makes this an initiative worth pursuing.