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Energy Business
Ujjal Ghosh, Ph D
Ujjal Ghosh, Ph D
 · Posted in Energy Business

Building a Greener Future: Achieving Net-Zero Emissions in the Cement Industry with CCUS

Why Cement?

Cement is an essential component for economic and social development. It is a vital constituent in concrete, which ranks second only to water in terms of global usage. Modern life, with its infrastructure and buildings, is inextricably linked to the use of cement. It is utilized in constructing homes, hospitals, schools, roads, dams, bridges, and tunnels. In fact, it is practically impossible to envision any significant construction project without cement. The global annual production of cement is around 3.5 billion tonnes of Ordinary Portland Cement, contributing approximately 7-8% of global anthropogenic CO2 emissions. This equates to about 622 kg of CO2 per tonne of cement produced, highlighting the environmental impact of the cement industry.

Cement Production Process

Cement serves as the binder in concrete, holding together fine and coarse materials. Although cement comprises roughly 12% of concrete by volume, it accounts for nearly all the CO2 emissions associated with concrete production. The production process involves several steps. Raw materials such as limestone (CaCO3) and clay are ground into a fine powder and then heated at high temperatures (around 1450°C) in a cement kiln to form clinker—rounded lumps of 1-25 mm. The clinker is then crushed into a fine powder, and gypsum is added to produce cement.

CO2 Emission Reduction Strategies

Given its widespread use and performance, cement is expected to remain the primary construction material globally. Reducing CO2 emissions while meeting the increasing demand for cement is a significant challenge. Key strategies include:

  1. Improving Energy Efficiency: Enhancing the efficiency of the cement production process can significantly reduce emissions. This can involve upgrading equipment, optimizing processes, and employing advanced technologies.
  2. Switching to Lower-Carbon Fuels: Utilizing alternative fuels such as cross-laminated timber (CLT) can help reduce the carbon footprint of cement production.
  3. Promoting Material Efficiency: Better design and construction practices can minimize the amount of cement needed without compromising the structural integrity of buildings.
  4. Increased Use of Building Information Modeling (BIM) and Modular Construction: These practices can improve precision and reduce waste in construction projects, further decreasing the demand for cement.

Implementing CCUS in Cement Production

Carbon Capture, Utilization, and Storage (CCUS) is a critical technology for decarbonizing cement manufacture. CO2 emissions in cement production arise from both the production process and fuel combustion. Approximately two-thirds of these emissions are due to the calcination of limestone (CaCO3) to form calcium oxide (CaO) and CO2.

Calcium Looping Process: This process involves using calcium-based sorbents to capture CO2 at high temperatures. The CO2 is absorbed by CaO, forming CaCO3. The CaCO3 is then calcined in an oxyfuel calcination process, regenerating CaO and releasing almost pure CO2, which can then be captured and stored.

Oxyfuel Technology: This involves burning fuel in pure oxygen instead of air, resulting in a flue gas that is primarily CO2 and water vapor, making CO2 capture easier and more efficient.

Examples of CCUS in Cement Industries

Although commercial deployment of CCUS in cement industries is limited, there are several notable examples:

  1. Texas, USA: A facility has been operational since 2014, capturing 15% of CO2 emissions using post-combustion capture with solvent absorption.
  2. Anhui Conch, China: Operational since 2018, this plant captures 50,000 tonnes of CO2 per year.
  3. Norcem, Norway: A full-scale plant is set to be operational by 2024, aiming for a high CO2 capture rate.
  4. Lehigh Cement, Canada: Feasibility studies are underway for a large-scale CCUS implementation.
  5. Dalmia Cement (Bharat) Limited, India: This company is collaborating with a CCUS technology provider to build a plant capable of capturing 500,000 tonnes of CO2 per year in Tamil Nadu, India.

Additional Insights and Future Directions

The cement industry is also exploring other innovative methods to reduce emissions:

  • Alternative Clinker Materials: Using alternative materials such as fly ash, slag, and natural pozzolans can reduce the amount of clinker required, thus cutting CO2 emissions.
  • Novel Cement Formulations: Developing new types of cement, such as belite-rich clinker or carbonate cement, which emit less CO2 during production.
  • Electrification of Kilns: Electrifying the heating process in kilns using renewable energy sources can significantly lower emissions from fuel combustion.
  • Carbon Mineralization: This involves permanently storing CO2 by reacting it with minerals to form stable carbonates, which can be used in construction materials.

Challenges and Conclusion

Despite the potential of CCUS and other technologies, several challenges remain. The processes are often energy-intensive and costly, requiring substantial investment and technological advancements to become economically viable. Additionally, the infrastructure for capturing, transporting, and storing CO2 needs to be developed and scaled up.

In conclusion, while the current utilization of CCUS in the cement industry is limited, significant opportunities exist for its expansion. Implementing these technologies, along with other emission reduction strategies, can help the cement industry move towards net-zero emissions. Continuous innovation, supportive policies, and investments in research and infrastructure will be crucial in realizing the full potential of these technologies and achieving a sustainable future.