Impact of cement on the environment, monitoring air quality to reduce the effects

February 21, 2022

Table of contents

HIGHLIGHTS

  • The cement industry and the environment go hand in hand. The environmental impact of this industry is particularly evident in the release of particulate matter (PM10, PM2.5 and PM1), as well as other substances such as nitrogen oxides and sulphur dioxide.
  • The carbon footprint of cement is also an aspect to consider, as it is an industry with very high energy requirements that can only be met by fossil fuels.
  • A clear example of the benefits of air quality monitoring in the surroundings of cement plants is the project developed by Kunak at the CEMEX plant in Monterrey (Mexico).
  • Cement production represents approximately 7% of global CO2 emissions, which highlights the need to find ways to reduce its environmental impact to promote more sustainable development.
  • Emissions from the cement industry negatively affect the environment and human health and therefore need to be controlled.

 

Cement production is one of the most important activities in the world economy. After all, it and concrete, one of its main derivatives, are responsible for the major constructions and infrastructures that make urban development possible.

However, this productive activity can generate various problems for the environment. Thus, it is common for the environmental impact of the cement industry to be felt both in the extraction of raw materials and in the manufacturing processes. And one of the main receptors of these impacts is the atmosphere, which is why our solutions take on special relevance.

 

Environmental impact of cement analysis

Cement is an essential building material, but it is also one of the most polluting. Its production generates a large amount of greenhouse gas emissions, such as carbon dioxide (CO2), other pollutants such as nitrogen oxides (NOx), sulphur dioxide (SO2), chlorides and fluorides, VOC emissions and heavy metals, as well as suspended particles (PM10, PM4, PM2.5 and PM1) that affect air quality and people’s health. In this article, we will look at the environmental impact of cement, its causes and consequences, and some possible solutions to reduce it.

 

How much does cement production pollute?

Cement production is responsible for approximately 8% of global CO2 emissions, according to a study (4) published in the journal Nature. This is mainly due to two factors: the use of fossil fuels to generate the heat needed to make clinker, the main component of cement, and the chemical reactions that release CO2 when limestone, the main ingredient in clinker, is calcined.

According to a study in Ecuador, the production of one tonne of cement requires 3,191.95 MJ of energy and generates emissions of 510.57 kg of CO2. The dominant energy contributions are due to the consumption of limestone, fuel oil and electricity. The unit process that generates the greatest impact is the production of clinker, both because of the chemical reactions that take place in the kiln and because of its fuel consumption.

In addition to CO2 emissions, cement production also generates particulate emissions into the atmosphere from the combustion of fuels, the handling of raw materials and the cement grinding and storage processes. According to the World Health Organisation (WHO), exposure to particulate matter can cause respiratory and cardiovascular diseases, lung cancer and premature death (5).

Environmental impact of cement - Kunak

Environmental impact of cement

 

How can we minimise the impact of construction on the environment?

One of the ways to reduce the environmental impact of cement is to reduce the use of this material by opting for more sustainable alternatives, such as wood, bamboo, straw or recycled materials. These materials have a lower carbon footprint, lower energy and water consumption, and a higher capacity for thermal and acoustic insulation.

Another way to reduce the environmental impact of cement is to improve the energy efficiency of cement production by using renewable energy sources, such as solar, wind or hydroelectric, and by optimising the use of resources and processes. For example, waste heat from kilns can be used to generate electricity or to heat water, or the water used to cool clinker can be recycled.

A third way to reduce the environmental impact of cement is to reduce the clinker content of cement by replacing it with other materials that have similar or better properties, such as fly ash, metakaolin, blast furnace slag or geopolymers. These materials are called hybrid cement and have the advantage of reducing the clinker factor, i.e. the proportion of clinker in cement, which means lower CO2 emissions and greater mechanical strength.

But all these environmental impact reduction measures must be quantifiable in some way. This requires emission monitoring and control systems, such as those offered by Kunak.

 

Which damages can cement cause?

Cement not only has a negative environmental impact in its production but also in its use and disposal. Cement can cause damage to both the natural and urban environment, affecting biodiversity, landscape, cultural heritage and people’s quality of life.

One of the damages that cement can cause is the waterproofing of the soil, i.e. the loss of its capacity to infiltrate and retain water. This can lead to problems of run-off, erosion, flooding, drought, desertification and contamination of surface and groundwater. Cement consumes almost one-tenth of industrial water use, and 75% of this consumption occurs in regions suffering from drought.

Another damage that cement can cause is the alteration of the local and global climate, due to the emission of greenhouse gases and the urban heat island effect. This effect consists of an increase in temperature in urban areas compared to rural areas, due to the absorption and emission of heat by artificial surfaces such as asphalt, concrete or metal. This effect can have negative consequences on human health, energy consumption, air quality and biodiversity.

A third damage that cement can cause is the degradation of cultural and natural heritage, due to the construction of infrastructures and buildings that do not respect the environment, history and identity of places. Cement can cause the loss of aesthetic, historical, archaeological, landscape and ecological values, as well as the homogenisation and trivialisation of architecture and urban planning.

Environmental impact of cement - Kunak

Workers exposed to suspended dust

 

How much CO2 does cement produce?

Cement is one of the main contributors to the emission of CO2, the most abundant greenhouse gas and the most implicated in climate change. According to a report by the International Energy Agency (IEA), the cement sector emitted 2.2 gigatonnes (Gt) of CO2 in 2018, representing 7% of global CO2 emissions.

Most of these emissions are caused by the production of clinker, the main component of cement, which requires a temperature of around 1,450°C for its manufacture. This temperature is achieved through the combustion of fossil fuels, such as coal, oil or natural gas, which release CO2 when burned. In addition, the calcination of limestone, the main ingredient of clinker, also releases CO2 as calcium carbonate (CaCO3) decomposes into calcium oxide (CaO) and CO2.

According to the IEA, the production of one tonne of clinker generates about 0.9 tonnes of CO2, of which 60% comes from the calcination of limestone and 40% from the combustion of fuels. Therefore, the production of one tonne of cement, which contains 65% clinker on average, generates about 0.6 tonnes of CO2.

 

 

The cement industry and the environment: why is air quality monitoring useful?

Cement is a pulverulent material formed from a mixture of limestone, slate, marble, etc. Its manufacture requires the extraction of raw materials in a quarry, which are transformed through a process that includes crushing operations, calcination in powerful kilns or grinding.

Cement manufacture Source: World Business Council for Sustainable Development & International Energy Agency (2009) 104

Infographic – Cement production process

But this manufacturing process, as described below, releases pollutant gases and particulate matter that can cause a public nuisance.

 

The suitability of measuring air quality through a practical case study

It was the public outcry that prompted CEMEX, one of the world’s leading cement manufacturers, to contact Kunak.

The objective was to install a perimeter monitoring ring at its production plant in Monterey (Mexico).

This Mexican multinational has been investing heavily in sustainability for several years, demonstrating its commitment to the well-being of the local population, its employees and its compliance with environmental regulations.

So calling on our expertise was an almost obligatory step in their emissions reduction strategy. After all, the innovative technologies and excellent data quality provided by solutions like our Kunak AIR Pro make all the difference and contribute to more informed decision-making.

And the results have certainly not been slow in coming. In 2019, CEMEX achieved a significant reduction in its emissions compared to 2005 levels, year zero when it began investing in improving air quality.

 

Major air emissions from cement

This case study shows how our solutions help to improve air quality. However, we believe it is worth delving a little deeper into the type of pollutants and the environmental impact of the cement industry on the atmosphere.

For example, the most common emissions include (1):

  • Particulate matter (PM10, PM2.5 and PM1): two of the main sources of dust are the transport of material in lorries and the chimneys of the kiln system. The installation of exhaust filters has, however, reduced the incidence of this problem.
  • Nitrogen oxides (NOx): these are generated during combustion processes at high temperatures.
  • Sulphur dioxide (SO2): its release is largely determined by the sulphur content of the raw materials.
  • Chlorides and fluorides: their origin can be either in the raw materials or in the fuels used during the manufacturing process.
  • VOC, CO and NH3 emissions: these are insignificant emissions due to the high combustion temperatures.
  • Heavy metals: may be retained in small quantities in the clinker.

 

Environmental impact of cement - Kunak

Cement production plant

The carbon footprint of cement, the contribution to global warming

Cement manufacturing not only releases polluting gases that can be harmful to human health. It is also a voracious consumer of energy, needed to raise the temperature of the kilns to the required 1400-1500°C. About 11% of the industry’s total energy consumption is attributed to this sector (2).

A consequence of this process is the CO2 emissions that contribute to global warming. Globally, cement production accounts for about 7% of global carbon dioxide emissions (3).

 

 

Conclusion

The environmental impact of cement is undoubtedly high. Exposure to the particulate matter or gaseous pollutants it emits can cause problems for human health. These emissions are one of the most relevant issues that this type of industry has to face.

But its contribution is, today, essential to the progress of the economy as we know it. If cement did not exist, the world would be very different from the way we know it.

The secret, in our view, lies in learning to combine economic growth with environmental protection. In making use, for example, of best practices and technologies to reduce particulate matter emissions.

The key, in our view, lies in learning how to combine economic growth with environmental protection. Making use, for example, of best practices and technologies to reduce emissions of particulate matter. And monitoring air quality to track progress (or setbacks) is going to be a must.

 

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