India needs solutions to maximise utilisation of fly ash and reduce consumption of clay and air pollution from fired clay brick kilns
Recently, the Ministry of Environment, Forest & Climate Change (MoEF&CC) came out with a draft notification that mandates that, “No new red clay brick kiln shall be installed and operated within 300 km from a coal or lignite based thermal power plant and the existing red clay brick kilns located within 300 km shall be converted into fly ash based bricks or blocks or tiles manufacturing within one year from the date of publication of this notification.” Let us understand its implications.
At present, 80 per cent of all bricks produced in the country are fired clay bricks (also called red clay bricks). These bricks are produced from clay by burning them in a kiln. There are other types of bricks, called non-fired bricks (such as fly ash bricks, concrete blocks), which are produced from fly ash, sand, lime, gypsum and cement.
Fired clay brick industry has a large environmental footprint. It is the fifth largest consumer of coal in the country. It is a huge source of particulate matter emissions and one of the largest emitters of greenhouse gases like carbon dioxide and black carbon. Most brick kilns also use polluting technologies and hence do not meet emission norms. But their most significant environmental impact is the destruction of topsoil. It is estimated that every year 600 million tonnes (MT) of clay, obtained mostly by excavating agriculture fields, is used for the production of bricks. This results in long-term land degradation and endangering food production.
To restrict the excavation of topsoil, MoEF&CC has been promoting the use of fly ash from coal- and lignite-based thermal power plants (TPPs) for the manufacture of bricks. In 1999, MoEF&CC came out with a notification which mandated that within a radius of 50 km from a TPP, fired clay bricks should only be produced by mixing at least 25 per cent of fly ash. Since then, the notification has been amended thrice — in 2003, 2009 and 2016. In each amendment, the radius around TPPs has successively been increased and so has the percentage of fly ash in the fired clay brick. The latest draft notification now extends the radius to 300 km.
India has about 250 coal- and lignite-based TPPs. If one draws a radius of 300 km from each TPP on the map of India, it covers almost the entire country except some parts of the Northeast and the Himalayan states. The notification, therefore, practically bans the manufacture of red clay bricks and substitutes it with fly ash bricks. But is this implementable? The answer is no.
The construction industry currently requires 250 billion bricks annually. The weight of each brick is about 3 kg. If we assume that all bricks are produced using only 50 per cent fly ash, we will need 375 MT of fly ash annually. But our power plants produce only 200 MT and of this, 50 MT goes for cement manufacturing and 40 MT are poor quality ash that should not be used for brick making. So, we are left with 110 MT fly ash for bricks. This will only produce one-third of the bricks required by the industry. Thus, we do not have enough fly ash to meet the brick demand of the country. This draft notification, therefore, is classic case of a top-down law that cannot be implemented simply because it would shut down the construction industry.
It is clear that both fired clay bricks and non-fired bricks will be required to meet the demands of the construction industry. The question is how can we maximise the utilisation of fly ash and significantly reduce the consumption of clay and the air pollution from fired clay brick kilns? This will require much more innovative solutions than just banning fired clay bricks.
(This article was first published in Down To Earth's print edition dated May 16-31, 2019)
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