Cement Industry and Carbon dioxide emission

Who doesn't want to enjoy good infrastructure in their every service ranging from hospitals, schools, dams, roads, own houses, and public places like restaurants, and parks? All such infrastructure come into existence from products that were once raw material, natural product in their pure form which undergoes different kind of processes to meet our specific requirements. Out of many products, one is the cement which is a binder substance used for construction that sets and adheres materials to bind them together. 

CEMENT: ANCIENT TIME Vs PRESENT TIME

Cement chemically speaking is a product that includes lime as a primary binding ingredient, but is far from the first material used in cementation. The Babylonians and Assyrians used bitumen to bind together burn brick or alabaster slabs. In ancient Egypt stone blocks were cemented together with mortar made of sand and roughly burnt gypsum which often contained calcium carbonate. The important raw material of cement production is limestone, and clay which are extracted from quarries by blasting or by ripping using heavy machinery. 

Cement manufacturing is a complex process that begins with mining and then grinding raw materials (limestone and clay) to fine powder material which is then heated to a temperature of as high as 1450°C in a cement kiln leading to form new compounds which we called clinker. Clinker is ground to a fine powder and mixed with gypsum to create cement. CO2 is emitted as a by-product of clinker production an intermediary product in cement manufacture in which calcium carbonate is calcinated and converted to lime (CaO) the primary compound of cement.

China is the highest producer and produced 2.5 billion metric tons in 2021 which equates to over half of the world's cement. India was the second largest producer, with a production of 300 metric tons in 2021. 

CEMENT AND POLLUTION

There are more than 20 types of cement; but its popularity come at an environmental cost. The production of concrete which is made with cement mix contributes about 8% of all carbon dioxide emissions worldwide. For every 1 kg of cement produced 0.9 kg of carbon dioxide is evolved and this affects the evolution of about 3.24 billion times of carbon dioxide per year; this figure doesn't take into account the emission from quarrying and transportation of raw material.

The production of cement contributes to greenhouse gases in two ways :

• first through the production of carbon dioxide when calcium carbonate is thermally decomposed producing lime and carbon dioxide

• second through the use of energy particulate particularly from the combustion of fossil fuels. Fuels need to mine and transport raw material as well as fuel used for electricity production for operating other processes in cement manufacturing. 

As a material that creates the majority of the world's bridges, roads, dams, and construction; concrete releases an extreme amount of carbon dioxide each year. It is the highest consumed product on earth besides water. Being a major contributor to an approximate number of 4,90,000 annual deaths attributed to the cement industry.

MEASURES TO PREVENT CEMENT POLLUTION

Any product or process is worth it if, it shows sustainable existence which is not evident here. To deal with this, revised 1996 IPCC guidelines for National greenhouse gas inventories (IPCC guideline), provide a general approach to estimating carbon dioxide emission from clinker production in which the amount of clinker produced is multiplied by clinker emission. 

IPCC guidelines recommend two possible methods for calculating factors:

• first method: use IPCC default value for the fraction of lime in clinker 

• second method: calculate average lime concentration in clinker by collecting data on clinker production and lime production 

Guideline state that the difference between the default value and value based on collected data is expected to be small. If clinker production data are not available it is recommended that countries back-calculate the clinker production from the cement data while applying a correction factor for clinker imports or exports. Once the estimate has been derived, emission can be estimated through the clinker emission factor. The IPCC recommends using clinker data rather than cement data, to estimate CO2 emission because CO2 is emitted during clinker production and not during cement production. If clinker is traded internationally using cement production data, results in biased emission estimates because cement could potentially be produced from clinker that was made in another country.

Other measures we should follow to reduce the environmental impact of cement production are 

1. Use of alternative binding materials to reduce cement production emission, improve energy efficiency and switch to lower carbon fuels, and optimize the use of cement would help reduce demand along the entire construction value chain. 

2. Deployment of innovative technology including Carbon Capsule Utilization and Storage (CCUS) can reduce CO2 emission, particularly the process emission released during limestone calcination. 

3. Increased use of fly ash can help to reduce CO2 emission through reduce fuel combustion and reducing limestone calcination.

For a better and brighter tomorrow, we need to come together with the big picture of our expectations and the processes we are following to fulfill them. The end goal should be sustainable living and for this, it is high time to understand the value of leading a minimal lifestyle.

-BHAVNA GEED.