Green Cement: thanks to NOVACEM.

A British start-up company, NOVACEM, has developed a cement which has low carbon footprint [ Reuters.com , dated06.08.09 ] . This cement has negative carbon footprint of 0.6 tonnes per tonne of standard cement. The conventional Portland cement is responsible for an estimated 5 percent of global carbon di-oxide emissions; this is more than the aviation industry.
In conventional method, the essential costituents of cement are the limestone, silica and alumina. During manufacturing process when reactions take place in rotary kiln, in average temperature zone [ 800-1000 degree Celsius ], the limestone, decomposes into lime and carbon di-oxide. Thus, this stage is the main emitter of carbon di-oxide. Novacem used a new technique; this is, to make cement from magnesium silicates rather than limestone coz this material does not emit carbon di-oxide in manufacture and absorbs the carbon di-oxide as it ages. Novacem estimates that for every ton of Portland cement replaced by its product, around three-quarters of a ton of carbon di-oxide is saved. This technology breakthrough by Novacem will definately turn the cement industry to a big absorber of carbon from a big emitter. Thank you NOVACEM. [ Prabhat Misra ]