Cement – Carbon Polluter

bfarrey — Thu, 05 Jun 2008 18:22:10 +0000

I have recently read about the production of Cement and how it contributes to carbon emmissions. At 5%, it is a top four contributor to world carbon dioxide levels. You have got to be kidding. I think most people, like me, are completely oblivious to this fact. If I start thinking about it, I see global construction at an all time high, China, Persian Gulf, India, Russia all with huge development projects, maybe we should be worried and get on top of this issue. But what to do.

First a little background;

The three steps to cement manufacturing are:
1. Virgin raw materials such as limestone and small quantities of sand and clay come from a quarry usually located near the cement manufacturing plant. The materials are blended and ground together.
2. The materials are heated in a kiln, which reaches temperatures of 1,870 degrees Centigrade or 3,400 degrees Fahrenheit. During this process, an intermediate product called clinker is formed.
3. Once cooled, the clinker is ground with a small amount of gypsum, forming a fine gray-colored powder called portland cement.

The carbon dioxide releases are in step 2, and step 3. Step 2, requires substantial energy, usually from coal plants to heat the materials. Step 3, contributes greenhouse gases directly when calcium carbonate is heated, producing lime and carbon dioxide.

The biggest producers continued to be China, India and the US.

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Cement – Carbon Polluter