THIS is with reference to the article ‘Decarbonising cement industry’ (Dec 31), according to which, usage of agricultural residues, such as rice husk, wheat straw, etc., holds the potential to replace 20-35 per cent of coal being used in cement kilns. However, experts are of the view that coal usage is simply not replaceable in cement manufacturing.

Prof Vaclav Smil in his 2022 book, How the World Really Works, discusses the fact that the coal usage in both cement and steel manufacturing is inevitable and cannot be replaced. “Limestone needs to be heated at 1,450 degree centigrade to produce clinker” (p93), and such temperatures cannot be achieved by any other form of energy available to the mankind on a mass scale.

Many cement manufacturers in the country have already signed memo-randums of understanding (MoUs) with the Sindh Engro Coal Mining Company, which will not only save import bills worth billions of dollars, but will shield the local manufacturers of cement from international price fluctuations.

Furthermore, agricultural residues have much smaller energy density compared to coal, and cannot generate temperatures of 1,450 degree centigrade that is needed for cement manufacturing. Wheat straw prices have skyrocketed recently because of it being important fodder for cows and buffaloes. It is already more expensive than coal if we compare it with coal by per kilogram price, or by the number of energy units extracted.

Besides, burning agricultural residues will emit carbon dioxide which adds to the climate change burden. Many experts have suggested natural gas as a transition fuel, as it emits less carbon dioxide compared to coal. The problem is that Pakistan has natural gas reserves that will last only 12 years at the current rate of consumption.

The country badly needs a gas pipeline from Iran and/or energy-rich Central Asia. However, more than 50pc of the country’s electricity generation should be done from Thar coal in order to save expen- sive import bill related to fossil fuels.

Imtiaz Ali Pitafee
Karachi

Published in Dawn, January 30th, 2024