A Concrete Path to Decarbonizing Cement

A Concrete Path to Decarbonizing Cement

A Concrete Path to Decarbonizing Cement

by: Kayla Carey and Andrew Primo | October 27, 2022


Cement PowderCement is a powdery substance that can be mixed with sand, water, and gravel to form concrete.

Most people are familiar with cement, the key ingredient in concrete, but few are likely aware of how foundational this material is to contemporary life. Buildings, roads, bridges, canals, sidewalks, railways, ports, power lines, wind, and solar farms… nearly all infrastructure requires cement and lots of it. The International Energy Agency estimates that nearly 4.3 billion tons of cement were produced in 2021 alone, making enough concrete to build the equivalent of over 2,800 Hoover Dams.

And this number will only grow. By mid-century, the global population is expected to approach 10 billion people, over two-thirds of whom will live in cities, according to the UN Department of Economic and Social Affairs. Add to that the massive buildout of electricity, renewable energy, efficient transportation, and carbon capture infrastructure required to support a decarbonized society, and the need for a significant increase in today’s already record-high cement production levels becomes abundantly clear.

Why are cement emissions so difficult to reduce?

There is, however, a fatal catch to this skyrocketing demand: cement, as it is produced today, has a tremendous greenhouse gas footprint. And decarbonizing isn’t as simple as substituting coal with renewable energy or electrifying vehicles. At least half of all emissions generated from the production of Portland cement (the global standard) are released during production through the creation of “clinker,” one of the primary steps in cement production.

Clinker is produced in giant kilns, where limestone and other minerals are superheated to temperatures up to 2,700 degrees Fahrenheit.  The chemical byproduct of this process is tremendous amounts of carbon dioxide (CO2): in the United States,  one metric ton of CO2 is emitted for every metric ton of Portland cement produced. Because of the difficulty in avoiding the process emissions from this critical step in production, cement is considered a “hard-to-abate” industry.

How Cement & Concrete are madeClinker production requires high heat and releases carbon dioxide as waste. Image Source: Cement Association of Canada

With such huge volumes of cement produced each year at such high emission rates, the cement industry has become one of the most carbon-intensive on the planet, contributing approximately 2.4 billion metric tons of CO2. That’s more than all aviation and maritime shipping emissions combined, and these will only continue to increase unless rapid steps are taken to reduce cement’s carbon intensity.

How can we reduce cement’s hard-to-abate emissions?

With the increasing demand for infrastructure paired with the urgency for decarbonization, how can the cement industry balance this paradox? Unsurprisingly, there is not a single or simple solution.

The Global Cement and Concrete Association’s (GCCA) 2050 Net-Zero Roadmap identifies several actions that the cement industry can adopt to slash greenhouse gas emissions and limit the most severe consequences of climate change. These strategies include:

  • Improving operational efficiency;
  • Switching to less carbon-intensive fuel sources;
  • Replacing traditional limestone-derived clinker with alternative materials; and
  • Deploying carbon capture utilization and storage (CCUS) technologies.

Each pathway can have a significant impact on lowering the carbon intensity of cement; however, only a couple of technologies can reduce the troublesome emissions released during clinker production – clinker replacement and CCUS.

Clinker Replacement: In certain applications, clinker can be at least partially replaced with alternative products called supplementary cementitious materials (SCMs). Typical SCMs are byproducts of industrial processes, such as coal and steel production; however, transitions in these industries, such as the closing of coal-fired power plants and the shift to more efficient steel-production furnaces, have limited the availability of these commonly used SCMs, creating a gap between supply and demand. Some companies have launched demonstration projects to produce additional clinker replacements, such as fly ash harvested from landfills and naturally occurring substances—known as “natural pozzolans”—like volcanic ash. But producing and treating these materials so that they can be used in cement is complicated and expensive, and they have not yet reached the scale needed to meet the worsening SCM supply void.

Carbon Capture Utilization and Storage: CCUS—in which the CO2 released in clinker production is captured and stored or used in other applications—is another key approach to reducing cement’s process emissions. Very few CCUS projects currently exist, especially at cement plants. Nearly all CCUS projects worldwide are still in the pilot phase as the technology faces substantial implementation challenges and is extremely cost-prohibitive. 

Building with CementNearly 4.3 billion tons of cement were produced in 2021, which is enough concrete to build the equivalent of over 2,800 Hoover Dams. 

Leveraging the Voluntary Carbon Market

For hard-to-abate sectors to meet net-zero targets on time, they must work together to employ a mix of proven and emerging technologies, such as clinker replacement and CCUS. But how can the industry overcome existing economic and technical challenges to scaling these technologies? The voluntary carbon market could be an important lever in bringing new SCMs to market and making CCUS more economically viable.

Today, there are a growing number of opportunities for the cement industry to generate voluntary carbon credits. One of the most trusted carbon offset registries, the Climate Action Reserve, recently announced the development of a Low-Carbon Cement Protocol that will incentivize the production of innovative SCMs to address the current supply gap. In addition to tax incentives, new opportunities are also emerging to generate carbon credits from CCUS projects. The cement industry can leverage the voluntary carbon market to direct much-needed financing to the sector and accelerate the road to decarbonization. 


About the Authors

Kayla Carey is a Manager for Program Development, specializing in decarbonization for hard-to-abate sectors. With experience in sustainability management and energy policy, she helps energy and industrial clients navigate environmental markets and develop new quantitative methodologies. She holds a master’s degree in Environmental and Natural Resources Policy and a Bachelor of Arts in Ecology and Evolutionary Biology, both from the University of Colorado Boulder.

Andrew Primo is a Manager on ClimeCo’s Program Development team, based out of Denver, Colorado. He assesses the feasibility of new emission reduction projects in hard-to-abate sectors, including heavy industry, waste management, and shipping. He works with corporate partners and carbon registries to develop new technical methodologies for carbon crediting programs.

The Climate Change Quagmire

The Climate Change Quagmire

The Climate Change Quagmire

Consider this: Wildfires in Greece, Sweden, and California that have appeared earlier in the year than expected.  A 10-acre wildfire in California growing to1000 acres in just one night.

National Oceanic and Atmospheric Administration (NOAA) predictions that 2018 will be a record year for floods due to record-breaking amounts of rainfall.  On June 22nd, Richmond, VA set an all-time record for hourly rainfall with 4.09” recorded between 3:54 and 4:54 AM, shattering the previous record of 2.82” in July 1969. August 2018 floods in Pennsylvania, New Jersey, and Rhode Island.

July high temperatures of over 105°F in Korea, 120°F in Algeria, and over 90°F seen in a Swedish village north of the Arctic Circle. Japan’s 2018 record heat has been blamed for 86 deaths in July alone with temperatures sustaining 105°F in early August.

Colorado experienced hail so large that it killed zoo birds, injured 14 patrons, and left 3,400 people stranded at the Cheyenne Mountain Zoo afterward due to their damaged vehicles.

These are just a few of the extreme weather events we have experienced so far in 2018.  Climate change experts have been warning us for the past 30 years of such extreme weather conditions due to global warming, and this reality should be setting in for many of us as we watch weather patterns become more and more intense.

Taking Voluntary Action

As individuals, we try to do our part to reduce our environmental impact.  We recycle, we buy electric cars, we support conservation efforts, we buy clean electricity … but have you ever stopped to wonder what corporations are doing to help prevent global warming?

Many companies have risen to the challenge of addressing this task by voluntarily reducing their environmental footprints.  You have probably heard of greenhouse gas reductions and carbon offset projects as one way to reach environmental goals.  These types of projects offer real, tangible emission decreases that make a huge difference and benefit our climate.  Companies are striving to be good citizens and neighbors to mother earth. To that end, more and more are making voluntary changes and addressing their carbon footprint.  Their goal includes the additional desire to try to limit high, long-range costs and harms.  Nevertheless, emissions also result from activities caused offsite, for example, from power generation needed to supply requisite electricity, such activities result in what is referred to as “indirect” emissions.  Ultimately, their focus is the realization that not only is the corporation affected, but also their employees and communities. 

Clean Energy to the Rescue

Bloomberg New Energy Finance (Bloomberg) has recently announced that corporations have thus far purchased 7.2 GW of clean energy during 2018 (which is already 2 GW more than what was purchased all of last year!), with a total of 10 GW predicted to be purchased by the end of this year.  In their August 2018 report, Bloomberg predicts that companies will need to purchase another 197 TWh of clean energy to meet their sustainability targets by 2030.

There is no doubt that corporations (in addition to individuals) have begun to play a part in striving to minimize the impact of climate change.  We have witnessed this through actual carbon dioxide equivalent (CO2e) emission decreases that have been financed and encouraged using carbon credits.  Where there was once a glut of voluntary carbon credits, companies have proceeded to gobble up this supply, and new projects are coming online to meet growing demand.  Carbon offsetting for direct emissions of CO2e from manufacturing and on-site operations just makes good, tangible sense.  So too does a focus on electricity consumption considered as indirect emissions of CO2e.  As a result, corporations have added renewable energy credits (RECs) to their voluntary portfolio to help attain their environmental goals.

The Creation of RECs

RECs came about as the result of states and provinces implementing renewable portfolio standards (RPS), whereby a percentage of electricity sold must come from renewable resources that are described and defined by regulation, or from voluntary programs such as the very well-established Green E program ( ), which verifies clean energy production.  One REC is equivalent to 1 MWh of electricity produced by a renewable power generation facility, such as (but certainly not limited to) a wind turbine, solar panel, hydropower facility, or biogas generation facility.  While states and provinces have continued to cause fundamental changes in electricity production beyond fossil fuels using their RPS, corporations are increasingly using RECs to offset their electricity consumption from conventional fossil fuel generation. 

The Use of RECs

In a simplified explanation, corporations calculate how much power they annually consume and then buy RECs commensurate with their annual power consumption.  Of course, this process can be done quarterly, annually, or under any timeframe that a corporation deems is appropriate and accurate.  Google was an early adopter of such an approach, which they explained on their web blog in mid-2010. By 2017, Google announced that they had become powered by 100% renewables with 2.6 Gigawatts of wind and solar power commitments. (Google 100% renewable)

The Cost of RECs

With renewable generation facilities becoming more prevalent, production and installation costs for renewable technologies have become more reasonable and more competitive with the cost of fossil-generated electricity.  State and provincial RPS programs have fostered the installation of clean power production facilities, some of which produce excess clean power.  Corporate executives and their colleagues’ corporate desire to do something in response to climate change has provided an ever-increasing interest in the voluntary use of RECs commensurate with annual electricity consumption. 

A Simple Tool to Make a Difference

Ultimately, voluntary RECs and carbon credits are simple tools for corporations to use in meeting their corporate desire (and their shareholder’s desires too!) to do something about climate change.  The image of clean power has become clearer, and the availability greater.

About the Author

Andy Kruger, Esq. serves as Senior Director, Environmental Markets at ClimeCo.  Andy has more than 30 years of experience in environmental markets and policy.  He earned his Bachelor of Engineering from George Washington University and his Juris Doctorate from Quinnipiac University School of Law.