Decarbonizing Cement Production: Carbon Core as a Solution for Carbon Capture and Utilization for Renewable Natural Gas

Cement production, accounting for about 8% of global CO2 emissions, is a significant challenge in the quest for net-zero emissions. The process involves extracting and heating limestone, producing clinker, and mixing it with additives to create cement. This process emits CO2 both from the chemical reactions involved and the energy required to achieve high temperatures. Even with a transition to clean energy, further innovation is essential to reduce these emissions to zero.

Challenges in Decarbonizing Cement

Cement is a low-cost, essential material in construction, making it difficult to replace. Its unique properties are hard to replicate cost-effectively, and traditional building codes favor its use. Most emissions stem from the chemical reactions needed to produce cement from conventional feedstocks. With global demand for cement expected to rise, finding effective decarbonization pathways is crucial.

Potential Solutions

Several pathways can reduce GHG emissions in cement production. These include using alternative materials, reducing clinker content in cement, switching to decarbonized energy sources, and employing carbon capture and sequestration (CCS). Each solution has its challenges and potential, often requiring regional adaptation based on local resources and regulations.

Carbon Core: Carbon Capture and Utilization for Renewable Natural Gas

Livolt 's Carbon Core stands out as a critical solution for carbon capture and utilization (CCU) in the cement decarbonization challenge, focusing on the production of renewable natural gas. Here’s how:

1. Carbon Capture Integration: Carbon Core’s technology captures CO2 emissions directly from the cement production process. By capturing CO2 emissions at the source, it mitigates a substantial portion of emissions from both calcination and energy consumption.

2. Renewable Natural Gas Production: The captured CO2 is then utilized to produce renewable natural gas (RNG). This process involves converting CO2 into methane through a series of chemical reactions, effectively turning a waste product into a valuable energy source.

Understanding Cement Emissions

Cement production is responsible for 95% of concrete CO2 emissions. The cement production process involves several stages:

- Extraction and Grinding: Raw materials, predominantly limestone, are extracted and ground.

- Calcination: The ground materials are heated to temperatures above 1,400°C in a kiln to produce clinker.

- Mixing: Clinker is mixed with additives and supplementary cementitious materials (SCMs) to make cement.

About two-thirds of cement’s emissions are process emissions from the calcination of limestone, which releases CO2 as a byproduct. The remaining one-third comes from energy consumption required to reach the high temperatures needed to make cement. Therefore, even with a full transition to clean energy and the phasing out of fossil fuels, cement production will continue to be a significant source of CO2 without further innovation.

The Hard-to-Abate Nature of Cement

Cement is foundational to modern society, and demand is expected to rise with continued global industrialization. It is one of the most challenging industries to decarbonize because:

- Cost-Effectiveness: Cement is cheap (less than $125/ton) and, on a per-dollar basis, generates more emissions than any other product manufactured at scale.

- Unique Properties: The unique properties of cement are hard to cost-effectively replicate with alternatives.

- Chemical Reactions: Most emissions are created because of the chemical reactions needed to make cement from conventional feedstocks.

- Construction Experience: Centuries of construction experience with Ordinary Portland Cement (OPC) favor its use. Strict building codes often mandate OPC and specify concrete composition or performance standards, heavily favoring traditional practices.

Pathways to Address GHG Emissions in Cement

Despite these challenges, several potential solutions exist to address GHG emissions in the cement industry. Many of these solutions complement each other. The lowest-cost decarbonization path will be region-specific, depending on the local mix of energy, feedstock, policy, and existing infrastructure assets. Pathways include:

1. Alternative Materials

Concrete made with Ordinary Portland Cement is not the only building material available. Other options include timber, clay, brick, and alternative, non-OPC cement chemistries (e.g., geopolymers). The main barriers to adopting alternative materials are regulation and market acceptance. New materials also have a high bar of performance and reliability to overcome. Not all alternative materials can match the performance of, or be used in the full breadth of applications as, OPC. Alternative materials need to have an incredibly low emissions intensity because, on a per-mass basis, concrete is actually one of the lowest-emissions building materials in use today—we just use so much of it.

2. Cement Use Extension

Because the cement production process is responsible for the majority of concrete emissions, reducing the amount of clinker in cement and the amount of cement in concrete can reduce the emissions intensity of the final product.

Three Breakthrough Energy Ventures portfolio companies are working on cement use extension. CarbonCure’s technologies inject and permanently store captured CO2 in concrete, maintaining the concrete’s strength while reducing the amount of clinker required to achieve the same performance. TerraCO2’s technology enables a reliable supply of engineered SCMs that can partially displace clinker in conventional mix designs—or even fully displace it in unconventional designs.

Ecocem recently received a European Technical Assessment for their groundbreaking ACT technology—low-carbon cement technology that combines SCMs with limestone filler and novel admixtures. The technology is undergoing rigorous trials, already demonstrating a 70% reduction in CO2 compared with the average European cement blend. Ecocem plans to supply the first ACT cement to customers in its European markets in 2024, with full commercialization by 2026.

3. Decarbonized Energy for Cement Production

Approximately one-third of cement emissions come from the energy used in production. Energy decarbonization can occur by reducing cement production’s energy intensity, fuel switching to lower emissions-intensity fuels, or electrification with clean electricity. Breakthroughs in the cost of clean energy, technology innovation, and regulatory support are likely necessary for significant reductions in the energy emissions of cement production.

4. Carbon Capture and Sequestration (CCS)

Carbon capture and sequestration (CCS) is the default decarbonization solution presumed by the industry, absent innovation. Cement production presents a relatively concentrated stream of CO2 that can be targeted for point-source capture. This requires significant additional capital expenditure, operational expenditure, and energy. The estimate of the green premium for cement with CCS is 75-140%. Innovation in cement plant design, carbon capture technology, and the further cost-down of clean electricity can help reduce the green premium.

5. New Feedstocks for OPC

The majority of cement emissions (two-thirds) are associated with process emissions from using limestone (CaCO3) as the feedstock for the principal ingredient of cement—CaO. Limestone is not the only source of calcium from which OPC can be produced.

Brimstone has developed a process to make the same ASTM C-150 OPC using silicates instead of limestone. The calcium in silicates (the most abundant source of calcium in the crust) does not contain CO2; thus, Brimstone can make the same OPC without process emissions. Because a portion of the calcium in cement carbonates over the lifetime of the poured concrete, sequestering CO2 in the process, using non-carbonate feedstocks, when combined with decarbonized energy, could result in carbon-negative cement production.

Carbon Core: Carbon Capture and Utilization for Renewable Natural Gas

Carbon Core offers a critical approach to CO2 emissions abatement in the cement industry through carbon capture and utilization for renewable natural gas. Here’s how it stands as a critical player in reducing emissions:

- Carbon Capture Integration: Carbon Core's technology captures CO2 emissions directly from the cement production process, mitigating emissions at the source.

- Renewable Natural Gas Production: The captured CO2 is then converted into renewable natural gas (RNG). This process involves transforming CO2 into methane through chemical reactions, turning a waste product into a valuable energy source.

Conclusion

The path to decarbonizing cement is complex and multifaceted. With innovations and comprehensive strategies like those offered by Carbon Core, it is possible to achieve significant reductions in emissions. Carbon Core’s focus on carbon capture and utilization for renewable natural gas positions it as a pivotal player in the transition to net-zero and potentially net-negative cement production. With continued regulatory, industry, and financial support, Carbon Core can accelerate the pace of this critical transition, leading the way to a sustainable future in cement manufacturing.