Environment impact of Brick Kilns

India’s traditional brick kilns are noxious sources of pollution. The exhaust from the kilns mixes with diesel emissions and other fumes to form vast brown smog, known as an atmospheric brown cloud, which is up to 3km thick and thousands of kilometres long. Two of its main ingredients, the small carbon particles which the soot is composed of, and ozone, a triatomic form of oxygen, are important contributors to the greenhouse effect, and thus to climate change.

Among other negative effects, the cloud is thought to be accelerating the retreat of Himalayan glaciers, which are found at a similar altitude.

In theory, burning the coal that fires the kilns in a more efficient and less polluting way should save money for the kiln’s owners — an alignment of interests that might encourage the change to happen. Unfortunately, the main recommended change of design (at least, the change recommended by the United Nations Environment Programme) is a rather expensive one: to switch from the traditional style of kiln, known as a Bull’s trench kiln, to a more modern design called a vertical-shaft kiln.

Vertical Shaft Kilns

Vertical-shaft kilns cut soot emissions by three-quarters, but they cost around 10m rupees ($200,000) each and require good-quality clay, able to withstand rapid heating. That makes them too expensive for most kiln owners. But recent research conducted as a collaboration between two Indian green-technology and consulting firms, Greentech Knowledge Solutions and Enzen Global Solutions, has suggested some more easily affordable changes that can be applied to existing kilns. Greentech’s main suggestions are to increase the number of air ducts in the kilns’ smokestacks and set the bricks to be fired in a zigzag pattern, rather than in the current block arrangement. These two simple measures improve the circulation of air within a kiln, and thus the process of combustion. That, the company says, reduces a kiln’s emissions of soot by 60%. It also reduces its fuel consumption by 15%. The cost, around 1m rupees a kiln, can then be recouped in three or four months. (©The Economist Newspaper Limited 2012)