It is in virtually everything that is constructed but cement has a climate impact that needs addressing.
CEMENT is a key material in construction. According to the UN, the cement industry is the fourth largest carbon dioxide (CO2) emitter by fuel type after coal, oil and gas.
And Asia dominates as the emitter of industrial greenhouse gasses emissions from cement, iron and steel, reports the Intergovernmental Panel on Climate Change (IPCC, 2014).
But compared to fossil fuels, cement is not as widely known for its contribution to the climate crisis.
(Photo: From buildings to pavements, cement is everywhere around us. | Photo by SL Wong)
Still, cement made a showing at the recent COP26 climate summit in Glasgow. Reducing the climate footprint of cement and steel in public projects was actually one of numerous pledges made.
Five countries who are major consumers of cement and steel pledged to attain net zero in the “major public construction” use of concrete and steel by 2050. This includes India, the world’s second largest producer of cement.
Globally, the IPCC estimates that cement production accounts for roughly 8% of global CO2 emissions. In Malaysia, cement appears to follow global trends in terms of CO2 emissions, producing around 12 million tons each year since 2018 (4% of emission among fuels) (see graph).
Emissions in cement production come from 3 segments: process emissions, fuel emissions and transport. At the same time, industry and researchers have been working on solutions to reduce these emissions.
Half of the overall CO2 emissions from the cement industry come from CO2 being released from the chemical reactions when cement is produced and mixed. According to the IPCC, process emissions “are unavoidable so can be reduced only through reduced demand, including through improved material efficiency”.
One way to use less cement is to increase the lifespan of current buildings. The core elements of buildings can last over 200 years if well maintained, according to the IPCC.
However, a 2010 study that the report references, indicates that the lifetime of infrastructure and buildings is 40% of that. In Asia, it is even less, only 20% of that, about 40 years.
Another way to reduce process emissions is through more efficient use of materials. Through innovative design, fabric moulds, for example, use 40% less concrete, while “ultra-high-strength concrete” has lowered emissions by 40%.
Meanwhile, CO2 emissions have been reduced by substituting or reducing a key component in making cement, clinker.
Substitutes including fly ash (a by-product of burning coal) have decreased CO2 emissions per tonne of cement produced by 20% relative to the 1980s according to the Trends in Global CO2 Emissions report (2015).
The next highest source of the cement industry’s emissions comes from fuel that is burnt to make cement. According to the IPCC, 40% of this is from burning coal to power the cement kilns.
To reduce these CO2 emissions, industries and countries have been transitioning to alternative fuels.
In 2014, IPCC reported that the Netherlands had switched to as much as 83% biomass waste to power their cement kilns. And as countries switch to renewable sources to generate electricity, there are CO2 savings to be made there too.
Other mitigation measures in the industry include improving the efficiency of the kilns through plant design and upgrading motors and mills which in general optimises the amount of energy used.
Meanwhile, the cement industry players themselves are pledging to reduce their carbon footprint. The Global Cement and Concrete Association presented at COP26 its plans to cut CO2 emissions by 25% by 2030. This is part of their 2050 decarbonisation roadmap.
The group numbers 40 major cement and concrete producers who represent 80% of total production outside China. Among them is Malaysia’s YTL Corp, who produces over half of the country’s cement.
Chief among the global group’s strategies post-2030 is carbon capture and utilisation or storage, which it is projecting to offset 36% of its carbon emissions to reach net zero.
[Edited by SL Wong]
Natasha Zulaikha (@natashazlkh) is a Macaranga Sprouts journalist. We thank the supporters of the Sprouts initiative who made this story possible. Natasha reported for this article during her time in the Rimbun Dahan’s Conservation Research Writing Residency.
Look out for her next story: What is the Real Worth of Limestone?