Why is traditional cement unsustainable?
The production of traditional Portland cement releases CO₂ from multiple sources. Its main raw material, limestone, emits roughly 50% of the total CO₂ when turned into clinker. Around 40% comes from burning fuels to heat the kilns, 5% comes from electricity used in the plant, and another 5% comes from transport. Together, these factors make traditional cement a major contributor to greenhouse gas emissions and an unsustainable option for long-term use in construction.
What is green cement?
Green cement is a sustainable type of cement engineered to reduce the environmental impact of traditional Portland cement. Instead of relying heavily on clinker, the most carbon-intensive ingredient, green cement replaces a significant portion of it with supplementary cementitious materials such as fly ash, ground granulated blast-furnace slag (GGBFS), silica fume, or metakaolin. These materials are often industrial by-products, which reduces CO₂ emissions and helps recycle waste.
Existing and emerging regulations supporting green cement:
Public policy is gradually becoming crucial to decarbonizing the cement industry. As a globally traded commodity with tight profit margins, cement faces economic hurdles to adopting low-carbon solutions. Strong regulations and targeted incentives are crucial to addressing these barriers and accelerating the sector’s progress toward net zero.
Stimulating demand for green cement
Problem: The market for low-carbon cement remains underdeveloped because many construction firms and public agencies still default to traditional cement. This preference is driven by the lower price, wide availability, and familiarity of conventional products compared to newer green alternatives.
Policy approach: Governments are intervening through procurement rules designed to create predictable demand for low-carbon cement. These policies set strict embodied-carbon limits for materials used in publicly funded projects, ensuring contractors source greener options. They also require Environmental Product Declarations (EPDs) to verify actual performance, increasing transparency and holding suppliers accountable.
Examples: US “Buy Clean” laws in California, Colorado, and Washington prioritize low-carbon materials in public projects. Toronto mandates a maximum 350 kg CO₂e/m² for city-owned buildings. The U.S. Federal–State Buy Clean Partnership goes further by offering preferential bidding and contract-for-difference mechanisms to incentivize suppliers of low-carbon cement.
Revising technical standards
Problem: Many current building codes and procurement specifications are outdated, recognizing only conventional cement blends. This creates a structural barrier for introducing and scaling low-carbon alternatives in construction projects. Without formal recognition in official standards, greener cement products struggle to gain acceptance, even when they meet performance needs.
Policy approach: Governments and regulatory bodies are revising technical standards to explicitly permit low-carbon cement options. These include Portland-limestone cement (Type IL) and mixes with supplementary cementitious materials, which can reduce CO₂ emissions without compromising structural integrity. Updating these standards removes a major obstacle to adoption by ensuring greener alternatives are treated as valid and compliant options.
Examples: Marin County, California, became the first jurisdiction to mandate low-carbon concrete mixes in its building code. In the US, 44 state Departments of Transportation have approved Type IL cement, which produces about 10% less CO₂ than standard cement. These changes signal a shift toward embedding sustainability into the very specifications that govern construction materials.
Harmonizing global benchmarks
Problem: Cement producers face a fragmented system of sustainability criteria that varies by country and region. This lack of alignment makes it difficult for low-carbon products to compete in international markets. Inconsistent benchmarks also create additional costs for manufacturers who must adapt products to meet multiple, sometimes conflicting, requirements.
Policy approach: Establishing harmonized building codes and embodied-carbon thresholds can provide consistent expectations across markets. Unified standards would enable producers to meet the criteria without repeated modifications.
Examples: The International Green Construction Code (IgCC) incorporates lifecycle performance and material efficiency provisions applicable across different regions. France has introduced binding embodied-carbon limits that will progressively tighten from 2030 onward, offering a clear long-term framework for producers to plan investments.
Improving price parity
Problem: Low-carbon cement often costs more than conventional alternatives, making it less attractive for price-sensitive buyers. Higher production costs, driven by newer technologies and renewable energy inputs, create a disadvantage in competitive bidding. This price gap hinders adoption, especially in markets where upfront costs are prioritized over long-term environmental benefits.
Policy approach: Governments can help close this cost gap through targeted subsidies, green procurement quotas, and product labeling. Subsidies reduce production costs and improve price parity with conventional cement. Quotas in public projects guarantee demand, while labeling schemes make sustainable products more visible and easier for buyers to identify.
Examples: Germany’s green-industry market program provides direct subsidies, sets quotas for low-emission materials in public procurement, and introduces a labeling system to promote recognition. China has expanded its Renewable Portfolio Standards to cover cement production, requiring a higher share of renewable energy in manufacturing to lower emissions and operational costs.
Expanding climate finance access
Problem: Securing capital for upgrading cement plants or scaling innovative production processes remains challenging. Investors often perceive these projects as high-risk due to long payback periods and uncertain market demand. This lack of financing slows the transition toward lower-emission production methods and slows the pace of industry transformation.
Policy approach: Climate finance mechanisms can create new revenue streams to support investment in sustainable production. Tools such as carbon credits, emissions trading systems, and demand-side procurement signals reward emission reductions, thereby improving project profitability.
Examples: In the US and EU, carbon finance and emissions trading programs are increasingly tied to public procurement policies. This integration directs funds toward projects that meet sustainability criteria, helping channel investment into industrial-scale transitions.
How is green cement made?
Green cement is manufactured by adapting conventional cement production methods to reduce carbon emissions and energy consumption. The following stages outline how the process is optimized to create a more sustainable alternative.
Raw material preparation
The process begins similarly to traditional cement production, utilizing materials such as limestone, clay, and other minerals. However, green cement often includes recycled or industrial by-products, namely fly ash or slag, from the outset, to reduce the need for raw material extraction.
Clinker reduction during grinding
In the grinding stage, a large portion of traditional clinker is replaced with low-carbon substitutes like fly ash, ground granulated blast furnace slag, or calcined clay. This substitution is crucial for reducing emissions, as clinker is the most carbon-intensive component of cement.
The table below summarizes key low-carbon alternatives to clinker in cement production, detailing their sources, typical replacement ratios, and potential for CO₂ reduction.