Net-zero Carbon Concrete by 2050

Concrete, a cornerstone of global infrastructure, is second only to water as the most consumed substance on Earth. However, its production is a significant contributor to global greenhouse gas (GHG) emissions due to its reliance on cement, particularly its key ingredient - clinker. Cement production alone accounts for approximately 7% of global GHG emissions, largely due to the energy-intensive process of converting limestone into clinker through calcination. Addressing these emissions is imperative for combating climate change. This article is adapted from “Roadmap to Net-Zero Carbon Concrete by 2050" by Innovation, Science, and Economic Development Canada which outlines a comprehensive roadmap for achieving net-zero carbon concrete by 2050 in Canada.

 Figure 1: Clinker Production and Cement Production 

Concrete Industry in Canada

The concrete industry in Canada includes over 1,100 plants for ready-mixed concrete, precast concrete, concrete pipe, and masonry. This sector supports around 158,000 jobs and contributes $76 billion annually to the Canadian economy. The Canadian cement production mainly serves the domestic market, but exports to the U.S. have grown from $840 million in 2016 to $1.1 billion in 2019. Due to factors like population growth and urbanization, concrete use is expected to increase both globally and in Canada. Over the years of 2023-2028, Canada will produce approximately 55 million tonnes of cement and 400 million tonnes of concrete.

Cement production accounts for a significant share of Canada’s current GHG emissions. Facility-level reporting through Canada’s Greenhouse Gas Reporting Program listed 11.2 megatonnes (Mt) of carbon dioxide (CO2) in 2019 for the cement manufacturing industry. This represents about 1.5% of Canada’s emissions. Therefore’ decarbonizing Canada’s cement and concrete sector is a priority. While that is a complex multi-faceted challenge, it also presents the Canadian industry with significant opportunities.

Near-term and Long-term Concrete Decarbonization Strategies in Canada

In the present to near-term, the cement and concrete sector is focused on optimizing clinker substitutes, reducing reliance on fossil fuels by switching to lower-carbon alternatives, increasing use of recycled materials contributing to the circular economy, promoting market uptake of low-carbon cements and concretes, and maximizing efficiency in concrete design and construction. In the longer term, priority actions include continuing to deploy clinker substitutes and alternative clinker technologies, as well as harnessing new energy sources such as alternative fuels, clean electricity, and utilizing innovations to maximize concrete’s ability to sequester carbon via a variety of carbon mineralization approaches.

Clinker and Cement Decarbonization

Reducing Clinker Volumes: The production of clinker is the most energy-intensive process in the overall production of concrete. Clinker is an intermediate precursor to cement, and its production is a major source of CO2 in relation to cement. This process is responsible for more than 60% of the CO2 emissions from cement manufacturing. The key to reducing emissions in cement production lies in reducing the volume of clinker used in cement which can be achieved by replacing some of the limestone in the kiln therefore reducing the total emissions from the production of clinker. This can be achieved by incorporating alternative cementitious materials such as certain types of clay, natural pozzolans, industrial by-products (e.g., fly ash, blast furnace slag), and fine gradations from recycled concrete. These materials have already undergone calcination or do not emit CO2 when heated, making them ideal substitutes.

Alternative Fuels: Cement kilns require extremely high temperatures (approximately 1,450°C) which traditionally have been generated using fossil fuels. Transitioning to low-emission alternatives such as biomass and waste-derived fuels can significantly reduce carbon emissions.

Efficiency Measures and Clean Electricity Sources: Improving energy efficiency at cement plants is essential. Key measures include upgrading grinding technologies, such as switching from ball mills to vertical roller mills, optimizing process control, and automating production lines. Additionally, transitioning to clean electricity sources such as wind, solar, and hydropower can dramatically lower emissions.

Carbon Capture, Utilization, and Storage (CCUS): CCUS is considered the most promising technology for reducing process emissions in cement production. Emerging technologies such as direct CO2 injection into concrete and carbon mineralization into synthetic aggregates are also gaining traction. 

Concrete and Construction

Solutions required to decarbonize concrete production and its use in construction include concrete mix optimization, concrete manufacturing and transportation, and the optimization of design and construction.

Concrete Mix Optimization: Replacing traditional cement with supplementary cementitious materials (SCMs) such as fly ash, slag, and calcined clays can reduce CO2 emissions while maintaining or enhancing concrete strength. Additionally, advanced chemical admixtures can further improve the performance of low-carbon concrete. 

Manufacturing and Transportation: Electrifying production plants and transportation fleets is essential. Cement manufacturers are encouraged to switch to electric trucks and improve logistical efficiency by sourcing materials locally. This minimizes transportation related emissions. 

Design and Construction Optimization: Optimizing structural design can minimize concrete usage without compromising safety or performance. Techniques such as 3D printing, modular construction, and smart sensor integration can reduce material waste and enhance project efficiency. Furthermore, designing for adaptive reuse and recycling can prolong a structure’s lifespan and reduce its environmental impact.

Action Plans to 2030 and 2050

Action Plan to 2030

According to the “Roadmap to Net-Zero Carbon Concrete by 2050" by Innovation, Science, and Economic Development Canada, as a first step, the near-term Action Plan to 2030 intends to address immediate efforts and includes a plan for R&D to get to the 2050 targets. The action plan is centered on 3 overarching priority areas that must be advanced as the industry transitions to net-zero. The goals of these priority areas are to:

a. Drive Canadian Market Development

To support the transition of the Canadian market toward net-zero carbon concrete by 2050, efforts should focus on promoting innovation, advancing technology and R&D, developing green procurement policies, improving data on low-carbon cement and concrete, adopting performance-based codes and standards, updating specifications to encourage lower-carbon solutions, and providing professional development programs to educate stakeholders on implementing low-carbon provisions in codes, standards, and specifications.

b. Drive Innovation and Transition within Industry

To drive innovation and transition within the cement and concrete industry, efforts should include collaborating with stakeholders to enhance R&D and deployment, fostering academic partnerships to sustain leadership in low-carbon solutions, addressing future needs in circular and net-zero sectors as traditional by-products become limited, developing technologies like innovative SCMs, admixtures, and low-carbon production methods, promoting the adoption of new technologies through demonstration projects in low-risk infrastructure, and leveraging voluntary standards to encourage innovation in construction.

c. Position Canada as a Global Leader in Production, Adoption and Export of Low-carbon Cement and Concrete Products and Technologies

To position Canada as a global leader in low-carbon building materials, strategic actions should focus on identifying key international markets for Canadian low-carbon cement and concrete, assessing technologies like CCUS and low-carbon fuels, ensuring transparent carbon accounting and verification practices, promoting 'buy clean' initiatives to support low-carbon products, and exploring international collaboration on Carbon Border Adjustment Mechanism (CBAM) measures.

Figure 2: Estimated Canadian Concrete-related GHG emissions by 2030

Action Plan to 2050 

Building on measures identified in the Action Plan to 2030, achieving net-zero by 2050 will depend on the adoption of a number of key technologies in the sector—most notably, CCUS. Only about one-third of emissions from cement manufacturing results from the combustion of fossil fuels. The remaining two-thirds (more than 60%) is almost entirely process emissions that result when limestone, the primary mineral input in cement manufacturing, is converted to lime by the high temperatures in the cement kiln. While combustion emissions can be managed through fuel switching and efficiency gains, without CCUS, the process emissions in cement manufacturing are effectively irreducible. There are other smaller and less expensive technology options for cement - including new heat exchangers and digital solutions for energy efficiency - that incrementally reduce emissions; however, there are no known largescale or breakthrough technologies that fully address CO2 emissions at their production point, other than CCUS. Canada is already a global leader in CCUS expertise, technologies and infrastructure, but to achieve our net -zero carbon concrete by 2050 ambitions, the deployment of carbon capture technology at full scale is essential.

The roadmap to achieve net-zero carbon concrete by 2050 focuses on three key themes: driving market development, fostering industry innovation and transition, and positioning Canada as a global leader. With strong regulatory support, clean electricity, and innovative technologies, Canada is well-positioned to be a global leader in low-carbon cement and concrete production.