Cement is also responsible for climate change, can we replace it?

All our activities are surrounded by concrete. The buildings, streets and structures that we see are made, in some percentage, of this material.

According to the World Cement and Concrete Association (GCCA), concrete is the most consumed material in the world: 14,000 million cubic meters are used per year.

Its success is such that the construction sector represents 13% of the world GDP, but it hides a problem: the production of cement, one of the key elements in the concrete mix, is responsible for about 8% of global emissions of carbon dioxide (CO₂).

8% of all world's CO2 emissions

Scientists say the cement industry will need to reduce its annual emissions by at least 16 per cent by 2030 to be in line with the Paris Agreement. But between 2002 and 2021, global emissions from the industry doubled from 1.4 billion tons of carbon dioxide to nearly 2.9 billion tons, according to data from the CICERO Center for International Climate Research and the Global Carbon Project that was shared with Associated Press.

Cement manufacturing now accounts for at least 8 per cent of all the world's CO2 emissions. By comparison, aviation accounts for about 2.8 per cent of total global emissions, according to a 2020 report from the International Energy Agency.

Every year more than 4,000 million tons of cement are produced in the world, according to the Making Concrete Change report, issued in June 2018 by the British Chatham House, also known as the Royal Institute of International Affairs. 

We are talking about the third largest industrial energy consumer sector in the world, responsible for 7% of industrial energy use, and the second global industrial emitter of CO₂. And there are sources that raise their contribution to global GHG emissions to 8%, as the Chatham House report itself points out.

Which countries have high cement emissions?

China is by far the largest producer of cement, followed by far behind India and the EU countries combined, as the chart below from a recent Chatham House report shows.

Three-quarters of cement production since 1990 has been in China, which used more cement between 2011 and 2013 than the US in the entire 20th century.

Emissions cement production

The environmental impact of cement is so great that two reports recently published by the International Energy Agency (IEA) and the World Meteorological Organization (WMO) highlight the importance of reducing the emissions it causes. In fact, the IEA said that one of the most important milestones to be achieved by 2030 is to capture and store the emissions that come from cement production.

This document provides the scientific basis for sector-specific 1.5ºC decarbonisation pathways. It includes detailed guidance on how to set goals and approach processes that are specific to the cement and concrete industry, greenhouse gas accounting criteria and recommendations, as well as examples of how different types of companies can use the tools and guidance to present a goal for validation. This sector is the second largest industrial emitter of CO2, representing around 7% of CO2 emissions worldwide.

What is cement?

Cement is used in construction to bind other materials. It is mixed with sand, gravel and water to produce concrete, the most widely used building material in the world. More than 10 billion tons of concrete are used each year.

The industry standard is a type called Portland cement. This was invented in the early 1800s and named after a building stone widely used in England at the time. It is currently used in 98% of concrete worldwide, with 4 billion tons produced each year.

So how do you solve the problem?

There is no single solution, but several proposals or alternatives, for now: The United Nations Environment Program (UNEP) has funded research into alternatives to calcium carbonate. It appears that the only alternative to calcium carbonate, in terms of chemical properties and availability, is Al2O3, also known as bauxite or aluminium ore, which contains large amounts of aluminium oxide, the global supply of which is currently required to produce aluminium.

Other alternatives exist, but none are available in the volume required to meet the global demand for cement.

In the same way, certain admixtures can also reduce the carbon footprint of concrete. Clay can add strength and reduce emissions in cement. But ironically, some useful fortification additives are themselves by-products of carbon-polluting industries.

Canadian startup CarbonCure Technologies, for its part, has a very interesting initiative: it embeds CO2 into fresh concrete, strengthening it while trapping carbon through a mineralization process.

In addition, three of the five largest cement companies in the world (HeidelbergCement, the Swiss group LafargeHolcim and CEMEX) have set adequate emissions targets for 2030; and all three have their sights set on becoming carbon neutral by 2050.

Another option is to recycle the concrete

Recycling hardened concrete from demolished buildings offers the additional potential to reduce carbon emissions. Crushed concrete is not only a viable option to replace construction sand, which is now in short supply, but could also reduce emissions associated with concrete. It could be a very promising approach.

Achieving this goal of carbon neutrality by 2050 represents a challenging transition for companies with large-scale operations around the world, but it also offers the opportunity to make substantive changes that will result in significant CO₂ reductions globally; which, in turn, will help advance this important energy transition.

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