Laying the Foundation of Cement and Concrete Decarbonization

Decarbonizing the industrial sector has long been challenging due to the number of different subsectors and the variety of emissions sources. This is the first post in a series that will break down the complexities of industrial emissions by walking through the top four industrial subsectors and how we can decarbonize them. First up, decarbonizing our concrete landscape.

From skyscrapers to scraped knees, concrete is foundational in our world. And it is the most used human-made resource in the world. However, the emissions packed into this built environment are less noticeable in our everyday lives. Cement, the key ingredient in concrete, makes up about 7 to 8 percent of carbon dioxide (CO2) emissions globally, and 1.3 percent of total US emissions.

Key takeaways:

  • Cement is the key ingredient in concrete, and cement production is responsible for most of the emissions associated with concrete.
  • The cement sector is the world’s third-largest CO2 emitter. Globally, cement production releases around 2.7 billion metric tons of CO2 a year as of 2021, and it is expected to increase. That is the equivalent to over half a billion gas-powered cars driven for one year.
  • Decarbonization solutions, including carbon capture, fuel switching, energy efficiency, and material substitutions, can be applied throughout the cement and concrete production process.
  • Many solutions depend on the specific circumstances of a facility, and a supportive policy landscape will be essential to the widespread deployment of decarbonization technologies.

Concrete is a mix of cement, different sizes of crushed rock and sand, air, and water. While cement only constitutes around 10 to 15 percent of concrete by mass, it accounts for nearly 80 percent of its CO2 emissions. These numbers help explain why, if the cement industry were a country, it would be the third-largest emitter of CO2 behind China and the United States.

Demand for cement and concrete is increasing. This is largely due to a growing global population and urbanization. This sector is also critical to the global economy and workforce. The cement sector contributes over 5 percent of global gross domestic product, or GDP, and nearly 8 percent of employment worldwide.

How Concrete is Made: Cement Production, Emissions, and Emissions Solutions 

So, how does a single industry end up producing such a large share of global CO2 emissions?

Before diving into the where and how of CO2 emissions from cement, it’s important to take a step back to understand why industrial emissions present a particular challenge when it comes to meeting midcentury net-zero targets in the US and abroad.

In industrial production, CO2 is emitted into the atmosphere in two ways: at the facility or at the power plant supplying the facility with electricity. Emissions released at the facility are called “direct emissions” and can come from combustion or non-combustion sources. Most industrial sector emissions originate from fossil fuels that are combusted for heat. The second type of direct emissions come from chemical reactions that release CO2 as a byproduct called “process emissions.” Because these emissions result from the chemical transformation of the materials, they are inherent to the production process. Common examples of industrial products that emit more process emissions than combustion emissions include steel, chemicals, and cement. Industrial processes also require energy from off-site electricity generation. These emissions from the power plant are called “indirect emissions.”

The difference between direct and indirect emissions is important when considering the full scope of solutions required for industrial decarbonization. However, direct emissions will play the biggest role in understanding why the process of making cement is so carbon-intensive.

Figure 1. Breakdown of Emission Sources from Concrete Production

Cement production accounts for 80 percent of emissions in concrete. This is predominantly a mix of process (about half) and combustion (about a third) emissions from the kiln as explained in Step 2 of the production process outlined in the paragraphs below.
Graph based on data from the 2018 Energy Transitions Commission’s Mission Possible Cement Report.

Production Process

The concrete production process can be simplified to four major steps: quarrying, grinding, and pretreating, the production of clinker, the production of cement, and finally, the creation of the end product, concrete. This process outlined below includes possible decarbonization solutions intervening at each step.

STEP 1: The first step in the cement process is the quarrying and grinding of raw materials, primarily limestone. The materials are ground into a fine powder. Depending on the facility, these materials undergo various pretreatments before entering the kiln for calcination.

STEP 2: In a rotary kiln, the limestone mixture is heated to over 2,500 degrees Fahrenheit to produce clinker, the main, and most critical, ingredient in cement. This process is called calcination.

As the mixture is heated, it breaks down into calcium oxide (clinker) and CO2. The equation below shows how this transformation occurs. This step in the production process accounts for roughly 90 percent of the emissions associated with cement production, which is a mix of process and combustion emissions.

Calcination: CaCO3 (calcium carbonate from limestone) + heat (over 2,500 degrees) = CaO (calcium oxide – clinker) + CO2 (emissions)

STEP 3: The clinker is then cooled before being blended with a small amount of gypsum, limestone, or other additives. The mixture is then ground to a powder to form cement. Cement produced in this manner is called Portland cement and is the most commonly used cement worldwide.

STEP 4: Last, the cement is mixed with water, aggregates, and sand to form the end product, concrete. Roughly 80 percent of the CO2 emissions from concrete come from the cement production process. The other 20 percent comes from the energy needed for activities across the value chain, including quarrying, transport, grinding, etc.

Concrete = Cement + water + aggregates + sand

Policy Landscape & Market Solutions 

The applicability of each of these decarbonization solutions is often dependent on the local context of an industrial facility, such as the facility’s age, the availability of alternative fuels and materials, and the proximity of infrastructure for transport, use, or storage of captured CO2. Additionally, many of the solutions described have various levels of technological readiness and cost considerations, making a supportive policy landscape crucial for spurring deployment.

Procurement policies are one type of policy instrument that can create favorable market conditions for deployment. Procurement of low-embodied carbon materials requires disclosure, incentives, and standards to leverage the purchasing power of public agencies at the federal, state, or local level and, less frequently, by private building owners.

Several best practices can be considered when designing an effective procurement policy:

  • Implementing effective procurement practices requires comparable, easily reported data on emissions intensity across products (i.e., disclosure). This is commonly achieved through environmental product declarations, or EPDs, which are sometimes compared to a nutrition label for construction materials.
  • Complementary incentives can encourage early participation and broader implementation from industry through financial support for technological upgrades, technical assistance or bid incentives.
  • Setting emissions limits and benchmarks for eligible products encourages domestic manufacturing and innovation while discouraging emissions outsourcing. To discourage emissions leakage, some countries are also considering a carbon border adjustment mechanism to tax imported cement and concrete based on their carbon intensity.

Effective procurement policies can leverage government purchasing power to play a significant role in supporting domestic manufacturers by creating a demand for green products. With last year’s Bipartisan Infrastructure Law only increasing demand for cement in domestic infrastructure projects, both state and federal agencies are poised to play an essential part in defining sustainable procurement policy informed by industry.

In December 2021, the Biden administration announced its Federal Sustainability Plan and Executive Order 14057, launching a Buy Clean Task Force to promote the use of low-carbon, made-in-America construction materials. In response, the General Services Administration issued its first “Buy Clean” standard for concrete, and the Department of Transportation released its first agency-wide “Buy Clean” policy to bolster more sustainable procurement practices across its programs. Additionally, in September 2022, the federal government announced that it will prioritize the purchase of concrete with lower levels of embodied greenhouse gas emissions.

Meanwhile, many states have passed or introduced legislation to promote the use of low-carbon concrete in public projects, including California, Colorado, New Jersey, and Oregon.

Procurement policies are only one side of the equation. To use novel and blended lower carbon, cement and concrete mixes in construction projects, less prescriptive, performance-based material standards must also be adopted and promoted for use of these mixes   

As government officials design domestic decarbonization policies, it will also be key to consider trade policy and the global marketplace to avoid offshoring cement and concrete manufacturing and the leakage of associated emissions to less regulated countries. International cooperation can play an important role as well. Coalitions like the Industrial Deep Decarbonization Initiative, with the US as its newest member, can encourage the use of green public procurement and the adoption of harmonized and ambitious standards for low-emission cement.

Several emerging technologies will be required to achieve cement sector decarbonization on a 2050 timeline—but these vary widely in terms of cost, timeline for deployment, and maturity. For instance, while carbon capture technologies will be essential for the industry to reduce emissions in the long term, carbon capture has not yet reached a commercial scale of deployment. Likewise, novel cements and alternative materials will require further research and development to enable near-term use. For the cement sector to decarbonize, research, development, and demonstration for both near- and long-term solutions will be critical to achieving cost-effective and timely deployment.

By creating a favorable market and policy environment, these policies can retain and generate workforce opportunities and bolster the US manufacturing sector, ensuring decarbonization along each step of the value chain.

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Carbon Management Program Associate, GPI

Alana joined GPI in 2024 as a program associate on the Carbon Management team, specifically supporting the Industrial Innovation Initiative, where she helps to advance industrial decarbonization through GPI’s consensus-building approach. Alana previously worked as an account executive at Jamf, where she helped current K-12 education customers improve and scale the management and security of their Apple device deployments. Alana has spent most of her professional years working with Minnesota nonprofits, including two years as an AmeriCorps member with Twin Cities Habitat for Humanity.  She holds a bachelor’s degree in community environmental studies from the University of Wisconsin-Eau Claire.

Ankita Gangotra, Associate, WRI

Dr. Ankita Gangotra is an Associate in WRI’s US Climate Program, researching avenues to decarbonize the industrial sector, focusing on cement and steel decarbonization, environmental trade policies and international cooperation. Prior to joining WRI, Ankita was a postdoctoral research fellow in the School of Foreign Service and the Department of Physics at Georgetown University. Her research looked at the readily available technology and policy options for upgrading low-carbon cement production in the United States. Ankita has an integrated Master's in Electronics Engineering with Nanotechnology from the University of York, UK (2015) and a Ph.D. in Physics from the University of Auckland, New Zealand (2020). During her time in New Zealand, Ankita interned at the Office of the Prime Minister's Chief Science Advisor looking into equity, diversity and inclusion policy options for New Zealand’s science, research and innovation workforce.

Carrie Dellesky, Program and Outreach Manager, Carbon Removal and Industrial Innovation, WRI

Carrie Dellesky is the Program and Outreach Manager for Carbon Removal and Industrial Innovation. She develops strategies to advance policies and practices for scaling up a suite of carbon removal approaches and decarbonizing the industrial sector. She engages allies and builds and expands partnerships to mobilize champions and enhance visibility, action and impact. She also leads communications to amplify research and thought leadership, including messaging, media relations, event planning, social media and digital strategy.

Zachary Byrum, Research Analyst, WRI

Zachary Byrum is a Research Analyst in WRI's U.S. Climate Program, where he provides technology and policy analysis for carbon removal and deep decarbonization. His work focuses on pathways to reduce industrial emissions as well as bolstering technological carbon removal. Prior to WRI, Zach was a research assistant in the Carbon Management Research Initiative at the Center on Global Energy Policy. In the preceding years, he served as White House Intern in the National Economic Council under the Obama Administration and then an assistant analyst at the Congressional Budget Office. Zach holds a Master of Public Administration in Environmental Science and Policy from the School of International and Public Affairs at Columbia University and a B.A. in Economics and Political Science from Goucher College.

Katie Lebling, Associate, WRI

Katie Lebling is an Associate in WRI's Climate Program where she works on research and analysis of technological carbon removal approaches and industrial decarbonization. Before joining WRI, she worked at The Asia Group, and interned at the Woodrow Wilson Center’s China Environment Forum and the Treasury Department’s Office of Environment and Energy. She holds a Master's degree from Johns Hopkins School of Advanced International Studies in Energy, Resources, and the Environment, where she spent one year of the program studying in Nanjing, China, and has a B.A. from Colby College in Biology and Chinese language.

Debbie Weyl, Deputy Director, WRI United States

Debbie Karpay Weyl is the Deputy Director for WRI U.S. She previously served as Manager for the Buildings Initiative at WRI Ross Center for Sustainable Cities. She led an expanding global partnership to accelerate building energy efficiency in cities around the world. She also contributed to program management and development, research, and knowledge exchange for urban energy efficiency and sustainability. Debbie joined WRI from CLASP, a global non-profit organization that improves the environmental and energy performance of appliances, lighting and equipment. From 2011-2016 Debbie managed and developed global programs, led research projects, and facilitated collaboration among international experts and other representatives in the public, private, and non-profit sectors. Prior to joining CLASP, Debbie worked at the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, where she was a contractor supporting building efficiency and other energy efficiency programs in the United States. Debbie holds a Master of Science in Environment and Development from the London School of Economics and Political Science, and a B.A. in Politics (Political Economy and International Relations) from Princeton University.

Angela Anderson, Director of Industrial Innovation and Carbon Removal, WRI United States

Angela Anderson is the Director of Industrial Innovation and Carbon Removal in the Climate Program. She leads WRI's growing portfolio of work in industrial decarbonization and carbon removal and aims to change narratives around “hard-to-abate” sectors and promote the natural and technological interventions required to achieve net-zero targets. Prior to joining WRI, Angela worked as a program director, coalition builder, international advocate, and campaign strategist. She led the Climate and Energy Program at the Union of Concerned Scientists for ten years; facilitated US-NGO engagement in the international climate negotiations while at US Climate Action Network and at the Pew Environmental Trust; and founded Clear the Air, a national coalition to reduce pollution from power plants. Angela holds a B.A. in political science from Colorado State University.

Patrice Lahlum, Vice President of Carbon Management, GPI

Patrice Lahlum is the vice president of the Carbon Management program at the Great Plains Institute. The Institute, headquartered in Minneapolis, MN, works with diverse stakeholders and communities across the country to transform the energy system to benefit people, the economy, and the environment. We strive to combine our unique consensus-building approach, expert knowledge and analysis, and local action to promote solutions that strengthen communities, shore up the nation’s industrial base, and enhance domestic energy independence, all while eliminating carbon emissions. Patrice oversees several initiatives including the Carbon Capture Coalition, Industrial Innovation Initiative, Carbon Action Alliance, and the Regional Carbon Capture Deployment Initiative.

Kate Sullivan, Senior Program Coordinator, Carbon Management, GPI

Kate Sullivan joined the Great Plains Institute in 2019. As Senior rogram Coordinator, Kate uses her analytical and design skills to provide research, writing, and logistical support across the Carbon Management team. Prior to joining GPI, Kate worked as an Energy Counselor in the Center for Energy and Environment’s residential department, assisting homeowners with their energy needs and providing resources for efficiency upgrades. Kate earned her BA in Biology from St. Olaf College with an emphasis in Environmental Studies.

David Soll, Industrial Decarbonization Manager, GPI

David Soll joined the Great Plains Institute in 2023 and serves as Industrial Decarbonization Manager. He oversees the Industrial Innovation Initiative, a coalition advancing decarbonization solutions for the Midcontinent region’s most important industrial sectors. Prior to joining GPI, he taught history and environmental studies at the University of Wisconsin-Eau Claire, where he focused on urban infrastructure and energy conservation. David earned a Master’s in government from the University of Texas at Austin and a PhD in history from Brandeis University.

Jill Syvrud, Senior Program Manager, Carbon Management, GPI

Jill Syvrud joined the Great Plains Institute in 2017 and serves as the program manager for the Carbon Management Program. In addition to overseeing the overall program, Jill directly supports the Industrial Innovation Initiative, a coalition advancing decarbonization solutions for the Midcontinent region’s most important industrial sectors. Jill earned a bachelor of science in biology from the University of Wisconsin–Eau Claire and a master of science degree in science technology and environmental policy from the University of Minnesota’s Humphrey School of Public Affairs. Jill’s past experience includes multiple graduate research assistantships concentrating on technology innovation and sustainable megacities along and a previous position as an administrative and outreach coordination intern with the Midwest Renewable Energy Association.