Sustainable Cement and Carbon Credits: A Path to a Greener Future?
Cement is a fundamental component of construction, playing a crucial role in the development of infrastructure worldwide. However, traditional cement production is a significant source of carbon dioxide (CO2) emissions. At Guardyan Conservation, we are dedicated to discussing sustainable practices and reducing the environmental impact in all different industries. In this post, we explore the differences between cement and sustainable cement, their respective CO2 emissions, and how sustainable cement can contribute to carbon credits.
What Exactly is Cement?
Cement, also known as Ordinary Portland Cement (OPC), is the most commonly used type of cement. It is produced by heating limestone and other materials to high temperatures in a kiln, resulting in the formation of clinker. The clinker is then ground into a fine powder, which, when mixed with water, forms a hard, durable material. The cement is then used to make concrete, which is the most consumed manufactured substance in the world, used to build and create many different structures.
CO2 Emissions from Normal Cement
The production of cement, specifically the heating process, produces a significantly large amount of CO2, which contributes to overall global emissions (IEA, 2018). The process involves two key sources of emissions:
Calcination: The chemical transformation of limestone (calcium carbonate) into lime (calcium oxide) releases a significant amount of CO2.
Combustion: The fuel burned to heat the kiln also emits CO2.
Together, these processes account for approximately 8% of global human emissions, making cement production one of the largest industrial sources of greenhouse gases (Scientific American, 2023).
What is Sustainable Cement?
Sustainable cement refers to innovative alternatives to traditional OPC that aim to reduce the environmental impact of cement production through many different ways like reducing energy consumption and CO2 emissions for example. These alternatives can include:
Blended Cements: Incorporating industrial by-products such as fly ash, slag, and others to replace a portion of the clinker (Glavind, 2009).
Geopolymer Cements: Using aluminosilicate materials instead of limestone, which can be activated with alkaline solutions.
Carbon Sequestration: Injecting captured CO2 into the cement mix, where it chemically reacts to form stable calcium carbonate, permanently sequestering the CO2.
The primary differences between sustainable cement and traditional cement lie in the raw materials used and the production processes. Sustainable cement often uses industrial by-products or alternative materials that require less energy to process and generate fewer emissions. Additionally, some sustainable cements actively sequester CO2, further reducing their carbon footprint.
CO2 Emissions from Sustainable Cement
The CO2 emissions from sustainable cement are significantly lower than those from traditional cement. The exact reduction depends on the specific type of sustainable cement and the technologies employed. For example, blended cements can reduce CO2 emissions by 20% to 25% (World Resource Institute, 2024). Carbon sequestration in cement can further reduce emissions by sequestering CO2 during the production process (IEA, 2018).
How Do Carbon Credits Fit Into the Picture?
Carbon credits are a market-based mechanism that provides economic incentives for reducing greenhouse gas emissions. Sustainable cement can generate carbon credits through several pathways:
Emission Reductions: By producing cement with lower CO2 emissions, companies can earn carbon credits for the avoided emissions compared to traditional cement production.
Carbon Sequestration: that sequester CO2 in the cement can earn additional carbon credits for the amount of CO2 permanently captured and stored.
Lifecycle Assessments: Life cycle assessments play a vital role in identifying carbon offset opportunities by determining emission hotspots, optimizing processes and promoting the use of low-carbon materials and technologies.
Applicable Methodologies
Some examples of Clean Development Mechanism (CDM) methodologies involved in mitigating emissions within the cement industry are AM0121 Emission reduction from partial switching of raw materials and increasing the share of additives in the production of blended cement, ACM0015 emission reductions from raw material switch in clinker production, and ACM0005 Increasing the blend in cement production: (https://cdm.unfccc.int/methodologies/documentation/2303/230426_BLS23047_CDM_booklet_v04.pdf).
An example of a methodology in the voluntary market is Climate Action Reserve’s U.S. Low-Carbon Cement Protocol:(https://www.climateactionreserve.org/how/protocols/industrial/low-carbon-cement/dev/).
Sustainable cement represents a promising solution to the environmental challenges posed by traditional cement production. By reducing CO2 emissions and leveraging carbon credit mechanisms, sustainable cement can play a vital role in mitigating climate change. By shifting to sustainable cement production, companies can not only contribute to environmental sustainability but also create an additional revenue stream through the sale of carbon credits. At Guardyan Conservation, we are committed to supporting companies with their environmental initiatives, helping drive the adoption of sustainable practices into everyday life.
Sources:
https://www.cement.org/sustainability
https://www.climateactionreserve.org/how/protocols/industrial/low-carbon-cement/dev/
https://cdm.unfccc.int/methodologies/documentation/2303/230426_BLS23047_CDM_booklet_v04.pdf